Journal of Conference Abstracts

Session J09:3B

J09 : 3B/25 : G6

Trace Metal Sensitive Areas and Background Level in Relation to Environmental Factors in France: Different Scale Approaches

Clotilde Fevrier (cfevrier@illite.u-strasbg.fr),

Anne Probst (aprobst@illite.u-strasbg.fr),

Jean-Paul Party (jpparty@illite.u-strasbg.fr) &

Pascale Prudent (pprudent@illite.u-strasbg.fr)

CGS, 1 rue Blessig, 67084, Strasbourg Cedex

During the last decades much attention has focused on heavily contaminated areas by trace metals. However, particularly in France, only few investigations were carried out on "natural" ecosystems. To evaluate their sensitivity to long-range atmospheric pollution, the background level of trace metals must be established according to bedrock, soil, and vegetation diversity. Three different scales are considered. Investigations are conducted at the whole territory scale, at a regional scale in sensitive areas and at a local scale (small catchment) where both pedogeogenic and hydrochemical processes can be studied precisely.

At the country scale, sedimentary rocks are trace metal enriched compared to mafic rocks. Lead and cadmium content is in the range 10-30 and 0.05-0.20 ppm, respectively in limestones, whereas it is generally less than 10 and 0.10 ppm, respectively in mafic rocks. Hence, the triassic sandstones and the jurassic limestones appear to be the most sensitive bedrocks to trace metals regarding atmospheric inputs. However, the data are scarce and a calibration based on local and regional investigations is needed. Concerning soils, a statistical investigations of heavy metal content based on 102 humus from national networks for forest health protection has been performed. Brownic saturated soils contain in average 0.5, 11 and 70 ppm of Cd, Cu, Zn, respectively, whereas it is only 0.3, 8, 45 ppm, respectively in podzolic soils. Moreover, metal content decreases with soil degradation. However, this trend was not obvious for lead because of its high organic matter affinity supposed to hide this relationship. Similar investigations will be performed in the deeper soil layers, particularly in relation to weathering processes.

Data on trace metal content in surface waters from two sensitive areas where acidification processes may influence the trace metal mobility are presented. Pb and Cd concentrations are in average respectively, 0.30 and 0.07 ppb in the Vosges mountains (29 streams) and 0.25 and 0.03 ppb for the Massif-Central (54 streams).

Finally, at the small Strengbach catchment scale (Vosges mountains), trace metal concentration and distribution can be related to chemical characteristics in aquatic phases, soils and bedrocks. The dissolved trace element concentrations (0.8<Zn<7 µ g/L; 0.25<Pb<1.5 µ g/L; 0.3<Cu<2 µ g/L, 0.3<Ni<2 µ g/L) are in the range of values typical of non-polluted sites. In the down part of the catchment, trace element concentrations can be locally higher, particularly for Zn (25 µ g/L), indicating local anthropogenic activities. The most important factors controlling Hg, Pb, Cd, Cu, Ni and Zn distribution are pH and organic matter content. The distribution of metal content in relation to pedogenic processes and atmospheric inputs are in progress in the granitic sensitive upper part of this catchment. These results are of crucial importance to determine processes by which trace metals are distributed in non-heavily polluted areas and to determine background levels in the objective of atmospheric pollutant reductions.

J09 : 3B/26 : G6

Trace Metals and M/Sc Ratios in Pre-Anthropogenic Atmospheric Aerosols, and Comparison with Crustal Values, Using a Peat Core from an Ombrotrophic Bog, Jura Mountains, Switzerland

William Shotyk (shotyk@geo.unibe.ch)

Geological Institute, University of Berne, Baltzerstrasse 1, Switzerland

A peat profile from an ombrotrophic bog in the Jura Mountains, Switzerland, contains a record of atmospheric Pb which extends back 12,370 ¹⁴C yr BP (Shotyk et al., 1998). Here the profiles for As, Cd, Cu, Pb, Sb, and Zn are presented, and both natural and anthropogenic sources of the metals identified. Arsenic, Sb, Sc, and Zn were measured using INAA, Cu and Pb using EMMA XRF, and Cd by ICP-MS. Enrichment factors were calculated as EF = (M/Sc) sample / (M/Sc) crust and this approach is commonly used for calculating trace metal enrichments in modern aerosols. Using the crustal values reported by Taylor and McLennan (1995), the pre-anthropogenic peat samples from 405 to 235 cm below the bog surface (dating from 8030 to 5320 ¹⁴C yr BP) yielded the following average EFs: 2.2 Pb, Zn; 10.4 Cu, 28.1 Sb, 30.1 As, and 181 Cd. These enrichments in ancient peats, relative to crustal abundance, imply a natural, geochemical enrichment of these elements in the fine fraction of soils during rock weathering. Given the widespread interest in the anthropogenic dispersion of these elements, the natural enrichment of these elements during chemical weathering, and the chemical composition of pre-anthropogenic aerosols, requires further study.

Shotyk, W, et al, Science, 281, 1635-1640, (1998).

Taylor SR & McLennan SM, Rev. Geophys, 33, 241-265, (1995).

J09 : 3B/27 : G6

Preanthropogenic Mercury Background Values Estimated Using an Ombrotrophic Peat Bog, Xistral Mountains, NW Spain

Antonio Martinez Cortizas (edantxon@usc.es)¹,

Eduardo Garcia-Rodeja,

Xabier Pontevedra-Pombal &

William Shotyk (shotyk@geo.unibe.ch)²

¹ Dpt. Edafologia y Quimica Agricola, Facultad de Biologia, Campus Sur s/n, Spain

² Geologisches Institut, Universitat Bern, Baltzerstrasse, CH-3015 Bern

Mercury concentrations were determined in a peat core from an ombrotrophic bog located in NW Spain, that dates back to 4,000 ¹⁴C yr BP (Martinez-Cortizas et al., 1997). Mercury was measured in wet (HgT) and dry samples (samples dried at 30°C and 105°C for two weeks, Hg30° and Hg105°) using a LECO-ALTEC AMA-254 mercury analyzer. Total mercury concentrations (HgT) ranged from 22 to 436 ng g^-1, Hg30° from 18 to 315 ng g^-1 and Hg105° from 11 to 285 ng g^-1. The HgT represents enrichments of 14 to 290 times the rock content (which is 1.52 ng g^-1). Three thermal lability classes were defined as proportions of Hg released-retained by the peats after drying: low stability Hg, Hg-L, proportion of HgT lost at 30°C; high stability Hg, Hg-H, proportion of HgT retained by the peat after drying at 105°C; and moderate stability Hg, Hg-M, proportion of HgT released by the peat between 30°C and 105°C. The HgT profile and the thermal lability classes revealed a profound control by air temperatures at the time of deposition, to the extent that a simple linear model using the thermal lability classes as predicting variables explained 95% of the variance of HgT for preanthropogenic samples (24 samples, correlation coeficient 0.97). As the Hg accumulated in preanthropogenic peat layers was provided to the bog exclusively via atmospheric deposition, these concentrations can be considered as background values and the model that predicts them as a good estimation of the variations in Hg accumulation related to climate conditions. The mean preanthropogenic background concentrations were 43.0 ±4.0 ng g^-1 (n= 10) for cold, 32.8 ±4.9 ng g^-1 (n= 7) for warm-humid and 26.2 ±2.7 ng g^-1 (n= 7) for warm-dry climates.

Martinez-Cortizas A, Pontevedra-Pombal X, Novoa-Munoz JC & Garcia-Rodeja E, Water Air and Soil Pollut, 100, 387-402, (1997).

J09 : 3B/28 : G6

Chemical Characteristics of the Fresh Water Lakes of the Larsemann Hills, East Antarctica: Natural Backgrounds and Human Impacts

Massimo Gasparon (massimo@earthsciences.uq.edu.au)¹,

James Burgess (j-burgess@adfa.gov.au)²,

Ruth Lanyon (Ruth.Lanyon@dhs.sa.gov.au)¹ &

Ingvar Sigurdsson (iasig@raunvis.hi.is)³

¹ Department of Earth Sciences, The University of Queensland, St Lucia Qld 4072, Australia

² Department of Geography and Oceanography, University of New South Wales (ADFA), Canberra ACT 2600, Australia

³ Science Institute, University of Iceland, Reykjavik IS-101, Iceland

The Larsemann Hills comprise an approximately 50 km² ice-free coastal "oasis" area located on the southern shore of Prydz Bay, East Antarctica, and characterized by the presence of more than 150 freshwater lakes. The presence of both occupied and abandoned research stations within the Larsemann Hills, as well as a small year-round human population, are believed to have contributed to some anthropogenic input into the lake systems.

Vertical profiles (temperature, pH, conductivity, salinity, dissolved oxygen, and turbidity) for seven lakes were obtained during early February 1996, and some chemical parameters (Al, Cl₂, SO₄^2-, SiO₂, major cations, and trace element concentrations) were measured during the autumn turn-over early in 1997. During the summer, these lakes have low salinity and conductivity (< 1‰ and ¾0.4 mS/cm, respectively), and the values remain constant for increasing depths. Temperatures range from approximately 6°C to 0°C, pH values are near neutral (approximately 7±1), turbidity values are extremely low (¾5 NTU), and all the lakes are close to DO saturation (± 10%). These values are typical of well-mixed, oligotrophic meltwater lakes. Lakes situated in the vicinity of presently occupied or abandoned research stations have higher pH (7.5 to 8.6) and higher conductivity (up to 5.5 mS/cm).

Temperature, pH, and DO values in the water column of each lake are controlled by weather conditions, biological activity (also a function of weather conditions), and by the dimensions of the lakes. Stratification of the water column in terms of T, pH, and DO values was observed at day-time in some of the lakes. Conductivity and salinity values, however, are constant throughout the water column in each lake. Consequently, water stratification, if existing at all, is short-lived, and the water column gets homogenized again overnight by the action of the persistent, strong katabatic winds.

Overall, Larsemann Hills fresh waters contain very low concentrations of trace elements of environmental significance such as Pb, U, and Cd. Concentrations of toxic elements in the lake waters are consistently lower (by several orders of magnitude, for some elements) than International Drinking Water Guidelines. The chemistry of the lakes is dominated by natural processes, such as sea-spray and groundwater input. With a few exceptions, and despite field evidence for human impacts at some of the lakes (those in the vicinity of research stations and vehicular tracks), trace metal anthropogenic contamination of the water column is below detection. This suggests that either trace metal contaminants were never introduced into the lake systems (but this is contrary to field evidence), or that they have been extracted from the water column and accumulated in organic material or fine-grained sediments.

J09 : 3B/29 : G6

Role of the Clay Fraction in the Immobilisation of Pb and Zn in Polluted Soils of Northern France

Sophie Sobanska

(Sophie.Sobanska@univ-lille1.fr) &

Béatrice Ledésert

(Béatrice.Ledesert@univ-lille1.fr)

¹ UFR Sciences de la Terre, Båt SN5, UMR 8577, Villeneuve d'Ascq, Cedex, 59655, France

Soils of the Pas-de-Calais coal-field (Northern France) are contaminated by fallouts of dust from Pb and Zn smelters. Previous studies (Gommy, 1997) performed by selective chemical extractions (SCE) have shown that the contaminants (mostly Pb and Zn) are mainly found in the fine fraction (<2 microns) and thus in clays. As a consequence, this fraction needs to be well known in order to understand the mechanisms of metal retention and their possible impacts on environment. X-ray diffraction (XRD) performed on the clay fraction treated with hydroxylamine during sequential extraction shows that the structure of the clay minerals is strongly affected by this treatment. This indicates that chemical extractions are not sufficient to understand the speciation of metals in soils. Thus physical technics need to be used to better constrain it. To this end, a study has been performed on the surface horizon of two sites (M1 and M8). The M8 site is the most heavily polluted: Pb=3550 ppm and Zn=2035 ppm. The metal enrichment factors for the <2 microns fraction of the M1 site are as follows. Pb: x1.7, Zn: x2.1. They are calculated as a function of the total metal amount in the global soil (Pb: 1330 ppm, Zn: 1137 ppm). They indicate that the metal amounts are twice as high in the clay fraction as in the global soil. In M1, it appears that metals are mostly linked with oxides in the <2 microns fraction. A clay particle observed by electron microscopy (SEM and TEM) presents alternations of groups of clay layers with oxide layers. Microchemical analyses of this "sandwich" indicate that the clay layers are metal-free while oxide layers contain Pb and Zn. In M8, glauconite grains found in the vicinity of pores in a thin section contain non negligble amounts of Pb and Zn (up to 1500 ppm of Zn and of Pb). The mechanisms of metal immobilisation by glauconite are not well understood yet.

Gommy C, Thèse de l'Université de Compiègne (Optimisation d'un schéma de spéciation des métaux Pb, Zn, Cd et Cu: application à des sols pollués du Nord de la France), 355, (1997).

J09 : 3B/30 : G6

Deposition of Heavy Metals in the Oder River Discharge Area ­ Pollution and Pathways

Thomas Neumann

(thomas.neumann@bio-geo.uni-karlsruhe.de)

Institute of Petrography and Geochemistry, University of Karlsruhe, Kaiserstrasse 12, 76128 Karlsruhe, Germany

The Oder river drains a highly polluted industrial area and enters the Baltic Sea through a system of shallow lagoons. Surficial sediments in the discharge area of the Oder are highly enriched in heavy metals compared to their preindustrial levels. Accumulation rates of heavy metals in surficial sediments indicate that pollutants at present bypass the Oderhaff lagoon, whereas off-shore basins (Arkona and Bornholm Basin) act as sinks for the heavy metals. The data point to a 2 to 3-times higher heavy metal accumulation in the Arkona Basin compared to the Bornholm Basin. This reflects the prefered NW-direction outflow of the Oder river during spring time, when the river load is at its highest, and the weak exchange of water masses between the two basins. Since the beginning of industrialization, the anthropogenic Cu is about 30% of the total Cu-accumulation, for Zn about 40% and for Pb about 50%.Pore water studies in short sediment cores reveal anoxic environments over the entire sediment column, except for a suboxic layer in the uppermost 5 to 20 mm of the sediment where Mn- and Fe-oxyhydroxides are reduced by organic matter degradation. Cu, Zn and Pb are mobilized within the suboxic zones in the fresh water environment of the inner lagoon and in the brackish water environment of the open Baltic. In contrast, surficial sediments of the fresh water environment in the outer lagoon, which is directly affected by sea level fluctuation in the Baltic, represent a sink for heavy metals. This may be associated with the high rate of iron sulphide formation occuring there, at least seasonally during salt-water inflow.

J09 : 3B/33 : G6

Anthropogenic and Natural Heavy Metal Enrichments in Lake Bottom Sediments from the Russian Arctic, Taymyr Peninsula

Marina Golubeva (marinag@zedat.fu-berlin.de)¹,

Hans-Wolfgang Hubberten

(hubbert@awi-potsdam.de)² &

Hans Friedrichsen (hfriedri@zedat.fu-berlin.de)

¹ FU-Berlin, Geochemie, Malteserstrasse 74-100, Berlin, Germany

² AWI-Potsdam, Telegrafenberg A43, Potsdam, Germany

It was the purpose of this study to get a better understanding of heavy metal enrichments in lake sediments produced by anthropogenic pollution in comparison to natural effects. Therefore, sediments from two lakes, one with a significant anthropogenic load and another from a remote area have been analysed. Since 1930 heavy metal Cu-Ni mining and exploration has been developed in the Noril'sk district. The Pyasino lake is located close to the Talnach ore deposits and the Noril'sk metal smelters. Pollutants are transported into the lake through the atmosphere and waste water. The Kokora lake, on the other hand, is not polluted by heavy metals, since it is located more than 400 km away from any industrial settlement. A possible contamination only can occur by long-term air mass transportation. Major elements as well as Co, Cu, Zn, Ni, Sr, V, Pb, Cd, As, the grain size distribution and organic carbon contents were determined in sediments from both lakes.

In the upper sediment column of the Pyasino lake Cd, Cu, Ag, Ni and Pb are enriched by a factor of 44.5, 6.7, 5.3, 4.0 and 2.3 respectively in comparison to the deeper unpolluted layers. But isotope signals ^207/206Pb, ^86/87Sr and ^143/144Nd do not reflect any significant difference between anthropogenic and natural influx.

In the Kokora lake sediments we observe an enrichment of Mn, Fe and organic carbon in the oxic-anoxic boundary at a depth of about 9 cm. Zn, Cu, Cd, Pb and As are also concentrated at the same depth. Such heavy metal enrichments in the Kokora lake sediment are comparable with the amplitude of industrial pollution, but are rather natural and attributed to changing redox conditions and/or organic degradation.

J09 : 3B/34 : G6

Pb Isotopes as Reliable Marker of Early Mining and Smelting in the Northern Harz Province (Germany)

Kay F. F. Hamer (khamer@uni-bremen.de)¹,

Fabrice Monna (monna@terre.unige.ch)² &

Michael Sauer³

¹ Section Geochemistry and Hydrogeology, Dep. Earth Sciences of the University of Bremen, 28334 Bremen, Germany

² Institut FA Forel, 10 route de Suisse, 1290 Versoix, Switzerland

³ Justus-Liebig-Str. 21, 28257 Bremen, Germany

Overbank sediment cores were sampled close to the mouth of the river Weser draining a surface of 40.000 km², including a part of the Harz mineralisation complex. Dating, determined from pollen analysis, revealed that our sampling represents an integration of the deposition over the last 500-5000 years.

The Pb isotopic composition- and Pb concentration-profiles show wide variations. The lowest Pb contents (~ 30 mg.g^-1) were recorded in the sediments buried 3500-5000 years BP, whereas they present the highest ²⁰⁶Pb/²⁰⁷Pb ratios (~ 1.215). Towards younger sediments the Pb concentrations significantly increase more or less regularly to reach a peak in the 500-900 years BP horizons (135 mg.g^-1). At that time, the ²⁰⁶Pb/²⁰⁷Pb ratios range about 1.180.

At least two distinct Pb sources have to be invoked to explain these results. From a simple binary mixing model, one can calculate that the «natural» and regional background defined from the oldest horizons was variably mixed with another component, more concentrated, characterised by ²⁰⁶Pb/²⁰⁷Pb ratios of about 1.175. Among all the geological formations present on the river Weser catchment, only the Pb ore deposits of Harz mountains fit well (²⁰⁶Pb/²⁰⁷Pb: 1.165 - 1.178). Actually, it is not surprising to find such a source considering the previous historical knowledge. Mining presumably started in the Bronze Age. Several phases of exploitation were recognised between the 3rd and the 10th century. From 1445, mining became more intensive than before. After a last phase during the industrialisation period, the mining was shut down in 1988 after more than 1000 years of activity.

This study shows that the pollutant influence of early mining and smelting activities in Harz mountains is strongly recorded in the overbank sediments sampled more than 200 km downstream the sources. Pb isotopic geochemistry could be successfully and easily used in the future to apportion the Pb deriving from these mining activities over the past two thousand years or more. That enables interesting new opportunities in archaeology, history or geochemical mapping.

J09 : 3B/35 : G6

Platinum-Group-Metals Emitted from Automobile Converters and the Distribution in the Environment

Joerg-Detlef Eckhardt

(detlef.eckhardt@bio-geo.uni-karlsruhe.de) &

Jeorg Schaefer

Institute of Petrography and Geochemistry, University of Karlsruhe, D76128 Karlsruhe, Germany

During the last decade the amount of automobiles equipped with exhaust-converters has increased in most European countries. The converters are coated with up to 3 grams of Platinum Group Metals (PGM), resulting in a new-type of emission from automobiles. The steady output of PGM causes contamination of soils and vegetation adjacent to roads and the environment. Three of the noble metals - Pt, Rh and Pd - are presently used as catalytic elements in exhaust converters: Pt has still the highest amount. Rh has been used in a quantity one-fifth of the Pt content over a long period. Pd has become more important as cheaper replacement for Pt. This results in differing Pd-content in the environment.The highest concentrations of PGM are found in urban road dust, variations depend on the amount of vehicles. In road dust, the element ratios reflect the present average composition of the catalysts. Road dust is distributed in the adjacent environment of roads, resulting in typical pattern in the soil with distance to the road. The element ratios in the soil reflect the long-time average use of Pt, Rh and Pd. The Pt/Rh ratio is about 6 in most soil samples. Our investigations with greenhouse plants show, that there is a surprisingly high uptake of PGM by plants, grown on heavily contaminated soil. The transfer coefficients range between that of Pb (immobile) and those of Cu or Zn (moderate mobile), which are essential trace elements for plants.In contrast to contamination of soil and plants, traffic-related PGM is not high in sewage sludge, as can be shown by a Pt/Rh ratios of about 20. Altogether, the concentration of traffic-related PGM has strongly increased during the nineties. In road dust, which is not accumulating heavy metals but show the present trend, values have doubled from 1990 to 1997. During the last 3 years the PGM concentrations in soils have increased by a factor of 5 to 10, depending on the local conditions.

J09 : 3B/36 : G6

Distribution of Copper in Vineyards Soils, as Influenced by Organic Amendments

Elisabeth Besnard (besnard@versailles.inra.fr),

Claire Chenu (chenu@versailles.inra.fr) &

Michel Robert (robert@versailles.inra.fr)

INRA Versailles, Station de Science du Sol, Route de St Cyr, 78026 Versailles cedex.

In French vineyards, copper sulfate (Bordeaux mixture) has been used as a fungicide against mildew for more than a hundred years. This treatment has resulted in a significant Cu accumulation in soils (from 100 to 1500 mg kg^-1). Today, 8 million hectares in the world, 4 in the EC and about 1 in France are concerned by this pollution. To study Cu bioavailability and mobility, numerous chemical speciation methods are described in literature but artefacts were currently. Recently, physical methods as soil fractionations were described, showing that Cu is dominantly concentrated in the coarse organic fraction, associated with plant residues, and in the clay fraction. The latter results need to be confirmed and even generalized.

In Reuil sur Marne, near Reims (51), vineyards are on steep slopes. Important problems of erosion, especially during thunderstorms, occur. Cu is carried away by run-off, inducing an important risk of environmental pollution, in particular for the Marne river. Organic amendments are brought to soils in avoid to limit erosion.

The aim of this study is to analyse the impact of these organic amendments on Cu retention in soils and to identify soil components responsible for Cu retention and of its possible environmental dispersion.

Surface layers (0-10 cm) of 4 soils under vineyard were sampled. Soils presented similar agricultural historics, slopes, CaCO₃ contents and textures but received different organic. Samples were analysed for total C,N and Cu. They contained 248 to 378 mg Cu kg^-1 soil. The higher their Organic Matter (OM) content, the higher their Cu content. Samples were then physically fractionated, without OM destruction, depending on size and nature of separated fractions. The fractionation method combinated a sieving method with densimetric separations in water. Analysis of each organic, mineral and organo-mineral fractions separated allowed to determine Cu distribution in relation to soil components and to components inherited from organic amendments.

Results showed that soils had very different Particulate Organic Matter (POM) (i.e vegetal debris > 50 µm) contents according to their organic management. POM's, in particular fine POM 50-200µm were very rich in Cu, until 2500 mg Cu kg^-1 fraction. When expressing results on a gravimetric basis, the clay fraction displayed the highest Cu contribution. In these calcareous soils, we showed the preferential but double role of the OM: it limits erosion and accumulates, as does the clay fraction, Cu in soils.

We actually investigate aggregate stability and identify Cu location in aggregate size-fractions. In situ, we also analyse soil fractions responsible for Cu mobilisation during run-off. In addition, the soil with no amendment and the soil receiving vine shoots were equiped with run-off collector systems.

J09 : 3B/37 : G6

Zinc Speciation in Smelter-Impacted Soils by a Combination of Synchrotron-Based Techniques and Selective Chemical Extractions

Farid Juillot (juillot@lmcp.jussieu.fr)¹,

Guillaume Morin (morin@lmcp.jussieu.fr)¹,

Philippe Ildefonse (ildefons@@lmcp.jussieu.fr)¹,

Georges Calas (calas@lmcp.jussieu.fr)¹,

Marc Benedetti (benedett@cicrp.jussieu.fr)²,

Camille Dumat (dumat@ccr.jussieu.fr)²,

Pierre Chevallier (pcheval@lure-upsud.fr)³,

Gordon E. Brown Jr.

(gordon@pangea.stanford.edu)⁴ &

Thomas Thomas (trainor@pangea.stanford.edu)⁴

¹ Universités Paris 6 et 7, UMR7590 et IPGP, Laboratoire de Minéralogie Cristallographie, 4 place Jussieu case 115 75252 Paris cedex 05, France

² Université Paris 6, Laboratoire de Géochimie-Métallogénie, 4 place Jussieu 75252 Paris cedex 05, France

³ LURE, Bat 209D, 91405 Orsay cedex, France

⁴ Dept of Geological & Environmental sciences, Stanford University, Stanford CA94305-21115, USA

Soils are known to be an effective sink for sequestering heavy metals released in the environment. Among toxic metals, zinc is one of the most widespread element in soils. Its accumulation may occur from atmospheric deposition originating from smelting activities (in association with lead) or to the use of sewage sludges in agriculture. Zinc speciation was studied in two smelter-impacted soils differing by their pH and organic matter content. A combination of separation procedures was used to isolate different metal-bearing fractions from both topsoils. Chemical and mineralogical characterization of these different fractions were conducted by XRD, EMPA and SEM-EDS. Synchrotron-based techniques (µ -SXRF and EXAFS) were used for in situ localization of the different pools containing zinc and to directly determine the speciation of this element. In the dense fraction extracted from the 50-200 µ m fraction of both topsoils, EXAFS data show that Zn²⁺ is partially substituted for Fe²⁺ in the tetrahedral sites of magnetite (Fe₃O₄) identified by XRD as a major component. In the < 2 µ m fraction of both topsoils studied (2700-4400 ppm of Zn), the combination of selective chemical extractions and EXAFS revealed the occurence of a significant fraction (57%) of "organically-bound" Zn in the < 2 µ m fraction of the soil with the higher organic matter content and the lowest pH. This "organically-bound" Zn was mainly found to be "exchangeable" (38%) indicating that zinc sorbs onto organic soil components as outer-sphere Zn complexes or as weakly bound inner sphere complexes. Mixed-Zn/Al hydroxides (hydrotalcite-like structures) were identified as the major zinc species in the < 2 µ m fraction of both topsoils. Mixed-cations hydroxides (hydrotalcite-like structures) represent an important way to immoblize metals released in contaminated soils since their formation occurs in solutions sub-saturated with respect to the homogeneous hydroxide phases.

J09 : 3B/38 : G6

Benthic Foraminiferids as Indicators of Heavy Metal Pollution

Ashraf Samir (ashrafsamir@alex.eun.eg) &

Ahmed Badr El-Din

Geology Dept., Faculty of Science, Alexandria University,P.O. Box 21526, Alexandria, Egypt.

A detailed comparative study of a Recent benthic foraminiferal population was carried out at two bays (El-Mex and Miami) located along the Mediterranean coast of Alexandria, Egypt. A total of 78 species of benthic foraminiferal taxa belonging to 19 families were identified. Porcellaneous forms dominate the population, comprising 65% and 68% of the total population in El-Mex and Miami bays respectively.

El-Mex bay is much more polluted than Miami bay. It is currently being contaminated by a variety of heavy metals and this results in lower species diversity and population density, associated with an increase in tolerant or opportunistic species. In this contaminated environment, foraminiferal tests were smaller, and aberrant tests of members of the suborder Miliolina as well as representatives of the family Cibicididae were frequently found. The degree of deformation ranges from mild to extreme.

X-ray microanalysis revealed that deformed specimens contain higher levels of heavy metals (Al, Cu, Zn, and Fe) than non-deformed ones. This indicates that heavy metals may be responsible for the abnormalities in foraminiferal tests.

This study illustrates that benthic foraminifera reflect human-induced environmental perturbation and they can be used as a sensitive marker for monitoring coastal pollution.

Session J09:4A

J09 : 4A/01 : G6

Particulate and Dissolved Phosphorus Released from Sewage Sludge Applied on Agricultural Soils. Anthropogenic Versus Natural Background

Hugues Vanden Bossche

(etupetro@univ-rennes1.fr)¹,

Chantal Gascuel-Odoux (cgascuel@roazhon.inra.fr)² &

Guilhem Bourrié

(Guilhem.Bourrie@univ-rennes1.fr)²

¹ Géosciences Rennes, Campus de beaulieu, 35042 Rennes, Cedex, France

² INRA - Sols et agronomie, 65, rue de St Brieuc, 35042 Rennes, Cedex, France

The application of sewage sludge on agricultural soils is an alternative to solve the problem of their disposal. But such substances are potentially harmful to the environment, on account of their nutrients concentrations, notably their phosphorus content that might lead to continental water eutrophication.

Little information is available on losses phosphorus from agricultural surfaces fertilised with sludge (Tunney and others, 1997). Furthermore, the relative contribution of dissolved species is often neglected because of the predominance of particulate bound transport. The aim of our study was to quantify the impact of sludge disposal: (1) on the total load of phosphorus transferred to overland flow water (OFW); (2) on the solutes contents of the OFW.

To allow assessment of the pollution risk in a critical situation, high intensity rainfall were simulated on the field. In order to avoid any other source of pollution, the OFW characteristics were monitored directly on the field. The device used to recover the sheet flow has been designed by Gascuel-Odoux, Cros-Cayot, and Durand (1996). Runoff water was collected in the spacing between two maize rows cultivated along the slope. A test parcel supplied with a liquid sludge (produced by a biological treatment plant, fitted out with biological P removal) was compared to a reference parcel (without sludge). Total P was determined after an acid oxidation. The particulate and dissolved fractions were separated through 0.2 mm filtration. Dissolved P was analyzed by colorimetry. Concentrations of major ions in the solution were measured by capillary electrophoresis.

Total fluxes showed no noticeable effect due to sludge application, because of the predominance of soil particulate matter in the transport of phosphorus. The solid load and the pollutant total concentrations were clearly linked to hydrological processes governing sheet flow intensity. On the contrary, the sludge led to drastic increase of dissolved phosphorus concentrations. They were 3.5 times higher on the test parcel. Their variations could also be related to hydrological processes. Therefore, solute transport appears to be an unobtrusive but efficient path of surface waters contamination. Furthermore, dissolved phosphorus is more likely to enhance eutrophication. But this relevant kind of pollution is usually screened by the particulate background losses that might be far less harmful to the environment.

Gascuel-Odoux C, Cros-Cayot S & Durand P, Earth Surface Processes and Landforms, 21, 843-851, (1996).

Tunney H, Carton OT, Brookes PC & Johnston AE, Phosphorus loss from soil to water. Cab International, 461, (1997).

J09 : 4A/02 : G6

Formation of Mixed Crystals in NH₄MgPO₄.6H₂O - KMgPO₄.6H₂O System: Phosphate Removal and Recovering from Waste Waters

Alexandra Andrade (andrade@geo.uu.nl)

Faculty of Earth Sciences, P.O. Box 80.021, 3508 TA Utrecht, Netherlands

Input of nutrients into natural environments deteriorates the quality of surface and ground waters. Excess of phosphates and ammonia produces eutrophication in surface waters and increases the concentration of nitrates in ground waters.

Precipitation of struvite (NH₄MgPO₄.6H₂O) is selected as a very promising route for the removal of nutrients from waste streams. Laboratory experiments show that struvite forms mixed crystals with KMgPO₄.6H₂O. End members and mixed crystals thereof were grown at 25 ºC from aqueous solutions with equimolar concentrations of phosphate and magnesium, in the range of 5 -50 mmol/l. The influence of pH (7-11) and concentrations of potassium and ammonium (10-80 mmol/l) on the formation of mixed crystals have been investigated. The crystals precipitate according to the reaction: x NH₄⁺+(1-x)K⁺ +Mg²⁺+PO₄^3-+ 6 H₂O = (x NH₄.(1-x)K)MgPO₄.6H₂O.

At certain pH and concentration conditions, other magnesium phosphates are present in the system, e.g., newberyite (MgHPO₄.3H₂O) and Mg₃PO₄)₂.22H₂O. In contact with the solution for longer than 100h, the latter transforms into the stable form of bobierrite (Mg₃(PO₄)₂.8H₂O). The main aim of the present study is to establish the right conditions for the growth of struvite, its K-analog and their mixed crystals, without co-precipitation of other magnesium phosphate compounds. The present study shows that for the precipitation of mixed crystals the concentration of [K+NH₄] must be much higher than that of [Mg] or [PO₄].

The solutions and the precipitates have been monitored by UV-Vis analysis, ICP, XRD, SEM. Infrared reflection spectroscopy can be very useful for the quantification of the ammonia content in the mixed crystals. At the experimental conditions ammonia has a much higher affinity for the incorporation into the crystalline struvite structure than potassium.

The chemical conditions control the crystal habits. At higher pH's, elongated forms are predominant for all compositions. At high supersaturations, twinned crystals, as well as dendrites, are present.

J09 : 4A/03 : G6

Fate of Anthracene in Contaminated Soil ­ Transport and Biodegradation Under Unsaturated Conditions

Harald Weigand

(harald.weigand@uni-bayreuth.de)¹,

Kai U. Totsche (totsche@uni-bayreuth.de)¹,

Ingrid Koegel-Knabner (koegel@pollux.edv.agrar.tu-muenchen.de)¹,

Eva Annweiler

(annweiler@geowiss.uni-hamburg.de)²,

Hans Richnow

(richnow@geowiss.uni-hamburg.de)² &

Walter Michaelis

(michaelis@geowiss.uni-hamburg.de)²

¹ LS Bodenkunde, TU Muenchen, 85350 Freising-Weihenstephan, Germany

² Institut für Biogechemie und Meereschemie /UNI Hamburg, Bundesstrasse 55, 20146 Hamburg, Germany

Desorption, sorption and biodegradation control the fate of polycyclic aromatic hydrocarbons (PAH) in contaminated soils. The interaction of these processes was studied in a two-layer column experiment with uncontaminated and spiked (¹³C anthracene) A-horizon material of a spodic Udipsamment under unsaturated conditions. The experiment involved two parts: (I) Constant irrigation at 0.2 ml min^-1 and (II) 5 consecutive stopped-flow events (48 to 232 hrs). Anthracene and its metabolites, dissolved organic carbon (DOC), total inorganic carbon (TIC), electrolytic conductivity (EC), and pH were monitored in the effluent. Part (I) was characterised by the development of a stationary effluent composition. Effluent pH equilibrated during the elution of the first 200 pore volumes (pvs). Effluent DOC showed a sharp drop after high initial concentrations (90 mg l^-1) reflecting the exhaustion of readily mobilised organic matter. The onset of anthracene breakthrough was observed after 350 pvs. Due to high affinity sorption towards soil organic matter, constant anthracene concentrations (12.5 µ g l^-1) were reached after 800 pvs. In part II, a pronounced response of solution phase parameters to flow interruptions was observed. Effluent DOC increased linearly with the time of flow interruption, indicating a zero order release kinetic. Effluent anthracene showed an oscillation after the 232 hrs stopped flow event pointing to rate-limitations of both the sorption and the desorption processes. Microbial activity in the soil column was indicated by increased respiration rates. The evolved CO² showed no enrichment in ¹³C, suggesting that respiration stemmed from the degradation of natural organic matter rather than from the mineralisation of anthracene. Biodegradation of the PAH was evident from ¹³C-labelled metabolites and the continuous decline of effluent concentrations after 1400 pvs. Due to the kinetics of mass-transfer between the solid and solution phases, anthracene transport in the unsaturated zone is strongly affected by the flow regime. Although microbial activity may effectively counteract PAH seepage, it leads to the generation of highly mobile metabolites thereby enhancing the mobility of the xenobiotic carbon.

J09 : 4A/04 : G6

Release and Mobility of PAH and Cyanide in Soil from a Former Manufactured Gas Production Site

Harald Weigand

(harald.weigand@uni-bayreuth.de)¹,

Tim Mansfeld

(mansfeld@geographie.ruhr-uni-bochum.de)²,

Kai U. Totsche (totsche@uni-bayreuth.de)³ &

Ingrid Koegel-Knabner (koegel@pollux.edv.agrar.tu-muenchen.de)¹

¹ LS Bodenkunde, TU Muenchen, 85350 Freising-Weihenstephan, Germany

² Geographisches Institut, Ruhr-Universitaet Bochum, 44801 Bochum, Germany

³ Abt. Bodenphysik/LS Bodenkunde, Universitaet Bayreuth, 95440 Bayreuth, Germany

Seepage of organic and inorganic pollutants from the unsaturated zone of manufactured gas production sites (MGP) poses a hazard to ground water quality. The mobility of polycyclic aromatic hydrocarbons (PAH) and cyanide (CN) as typical gas manufacturing by-products was studied in a column experiment using soil material from an MGP site. The experiment involved tree parts. (I) Constant irrigation at 0.2 ml min^-1 and pH 7, (II) a stopped-flow event of 180 hrs and (III) a step-increase to pH 9 performed under constant irrigation. Additionally, sequential batch-equilibrium experiments were conducted at both pH levels. Part (I) was characterised by the development of a stationary outflow composition. For both the PAH and the CN initial concentrations (115 ng l^-1 and 50 mg l^-1) were higher compared to the stationary level (60 ng l^-1 and 5 mg l^-1), indicating a fraction of the contaminants was readily mobilised during the initial stages of the experiment. CN reached a stationary effluent concentration after the first four porevolumes (pvs), whereas equilibration of effluent PAH in terms of concentration and solution phase pattern extended to 40 pvs. Both contaminants showed a pronounced concentration increase after the stopped flow event (part II), indicating a rate-limited release from the solid phase. Again, the decrease to stationary effluent concentrations was reached faster by the CN than by the PAH. Thus, rate-limitations to the mass-transfer seem to act on different release processes. While PAH concentrations establish as a result of desorption and diffusional mass-transfer from tar grains to pore water, CN concentrations are goverened by the dissolution kinetics solid phase CN (i.e. "Prussian Blue"). The step increase in pH (part III) showed no effect on either PAH and CN effluent concentration, probably due to the high native pH of the soil (7.5). This was confirmed by the sequential batch experiments. The mobility of PAH and CN at MGP sites is therefore governed by the flow regime of pore water rather than by the solution phase composition. Due to the rate-constraints to their release from the solid phase, experiments performed under continuous irrigation may severely underestimate the seepage of PAH and CN under field conditions.

J09 : 4A/05 : G6

Radon, Sediments and Seasonal Variability

Vidar Valen (viv@interconsult.no)¹,

Oddmund Soldal (ods@interconsult.no)¹ &

Aud Venke Sundal²

¹ Geofuturum as, Postbox 22, N-5049 Sandsli, Norway

² University in Bergen, Geological inst., Allegt. 41, N-5007 Bergen, Norway

Radon (²²²Rn) is a radioactive noble gas which generate from bedrock and soil. Radon is transported from the ground to housings either by airflow or diffusion. To live in radon contaminated housings over a period of several years can involve lung cancer.

Estimated danger of radon gas in housings have traditionally been based on type of bedrock beneath housings. In Kinsarvik, Norway extraordinary high radon levels in dwelling units are revealed. The bedrock geology was expected to give the answer to why the levels are so high. However, the uranium and radium content is not especially high. The answer does not lie in the bedrock, but in the glacial sediments on which the housings are situated. The main part of the sediment deposit is a considerable endmoraine which was generated at the end of last glacial. The high sea-level during deglaciation produced a capping of finer sediments above the much coarser moraine material. The blocky moraine is highly permeable and with a zone of more than 5 m above the phreatic zone, this layer is capable of a considerable airflow.

To understand how radon was transported in the ground in this approximately 0.2 km² area, we used C-39 alpha track detectors buried in 23 different localities. The detectors were sealed inside thin plastic bags to prevent immediately overexposure and were exposed for up to 3 days. This was repeated five times in different seasons.The results show distinct seasonal variability, implying a profound soil air movement in the coarse moraine below the fine sediment cap. There is a movement of relatively warm soil air towards the higher areas during winter, giving rise to a high radon content of the ground in the topographical elevated areas. In the summertime, the process is reversed, giving rise to a high radon content in lower parts of the area. This transport of air in the ground entails a more extensive range from where radon can be transported to housings. A radon potential mapping must therefore include both type of sediments and topography.

The conclusions of our research are that sediment permeability and size of the phreatic zone have a major influence on the radon content of housings. And, dependent on type of sediments, there can be a significant seasonal fluctuation of radon content in the ground. Thus, calculations of yearly average exposure to radon should not solely be based on measurements during winters.

Session J09:4P

J09 : 4P/01 : PO

Results of Heavy Metal Speciation by Sequential Extraction in Relation to Regional Background Data. A Case Study on Holocene Sediments from the River Weisse Elster, Western Saxony, Germany

Wolfgang Czegka (czegka@gmx.de)¹,

Lutz Zerling

(mueller@leopoldina.uni-leipzig.de)²,

Christiane Hanisch²,

Maritta Lohse (lohse@limnion.gm.ufz.de)³ &

Ansgar Müller²

¹ Karlsbader Ring 7, D- 68782 Bruehl (Baden), Germany

² Saxon Acad.Sci, Karl-Tauchnitz-Str.1, D-04107 Leipzig, Germany

³ UFZ Umweltforschungszentrum Leipzig-Halle Sektion Gewässerforschung, Brückstr. 3a, D-39114 Magdeburg, Germany

The river Weisse Elster (Western Saxony, Eastern Thuringia) drains together with the river Mulde (Central Saxony) an area within Central Germany most loaded by organic and inorganic pollutants (Müller et al. 1998). On a length of approx. 250 km and including a drainage basin of about 5000 km² (incl. tributary rivers) the Weisse Elster traverses several (former) mining areas (Uranium in the Gera region; lignite in the Zeitz-Altenburg district and in the so called "Südraum Leipzig") and several in-dustrial centers. Moreover the river is influenced by geogene input from the Western Erzgebirge, the Thuringian Schiefergebirge, the Thuringian basin and the Weisse Elster basin. In favour of a more detailed estimation of remediation concepts of con-taminated river sediments (e.g. microbiological remediation) a sequential speciation of heavy metals was realized (Czegka et al. 1998). The method was adapted from Förstner & Calmano (1982) as well as from Salomons & Förstner (1984). For the validation of the method compare Czegka (1996). With the ICP-MS method a rational, reliable multi-element determination was per-formed. Spectral interferences appeared as a result of the extraction by sodium acetate and ammonium acetate caused by molecular ions on the masses ⁶³Cu (⁴⁰Ar²³Na) and ⁵²Cr (⁴⁰Ar¹²C). In these cases the undisturbed isotopes ⁶⁵Cu and ⁵³Cr were used for the evaluation. The elements Fe and Mn were analyzed by ICP-OES. At the lithogene residual fraction (fraction VI of the sequential process) a micro-wave digestion method (Dittrich et al.1995) developed by the University of Leipzig and the Saxon Academy of Sciences (SAW) was used. The results of the heavy metal speciation compared with regional background data are presenting the frame for further studies.

Czegka W, , unpublished report, Sächs. Akad. Wiss. Leipzig, 153, (1996).

Czegka W, Hanisch C, Müller A, Zerling L, Lohse M, Z. dt. geol. Ges, 148, 491-498, (1998).

Förstner U, Calmano W, Vom Wasser, 59, 83-92, (1982).

Müller A, Hanisch C, Zerling L, Lohse M, Walter A, Abh. Sächs. Akad. Wiss. Leipzig, Math. -nat. Kl, 58, 199, (1998).

Dittrich K, Lohse M, Hanisch C, Walther A, Fresenius J. Anal. Chemistry, 353, 16-20, (1995).

Salomons W, Förstner U, Metals in hydrocycle, 349, (1984).

J09 : 4P/02 : PO

Natural Backgrounds in the Po Plain (Northern Italy) Evaluated Through Subsurface Sediments

Enrico Dinelli (dinelli@geomin.unibo.it),

Alessandro Amorosi,

Maria Carla Centineo &

Federico Lucchini

Dipartimento di scienze della Terra e Geologico-Ambientali, Piazza di Porta S. Donato, 1, I-40126 Bologna, Italy

Natural backgrounds in the eastern Po Plain have been investigated studying the chemical composition of the fine-grained portions of ten cores drilled in the Bologna, Ferrara and Ravenna provinces, as part of the new database produced by the Geological Survey of the Regione Emilia-Romagna. Samples belong to the highstand systems tract (HST, post-6 ka B.P.) of the Late Quaternary depositional sequence of the Po Basin. In the Ferrara and Ravenna areas, close to the present Po delta, the HST includes prodelta, lagoonal and marsh clays and silty clays. This varied facies architecture reflects a complex palaeogeographic framework, where combined marine and fluvial processes controlled sediment dispersal patterns. In a more landward position (northern Apennines foothills - Bologna area), the HST consists uniquely of overbank (floodplain/levee) fines, related to the Lamone and Reno rivers. Background values are not homogeneous, but change according to geographic position. Close to the Apennines mountain chain, where fluvial deposits are dominant, background values are sensitive to rock types cropping out in the mountain watersheds. In proximity of the Po delta, different background values are observed according to the more complex provenance of the sediment.Comparison with stream sediments draining the area has allowed the identification of possible anthropogenic influence on the natural fluxes (2x background values) for Zn, Pb and Cu in the Po river. Other elements, such as Cr and Ni, despite showing relatively high contents in the Po river sediments, do not significantly differ from background data. The Lamone river composition is homogeneous with HST deposits in its area, but also other nearby rivers draining similar lithologies are comparable with these reference, and do not show significant anomalies.

J09 : 4P/03 : PO

Local Versus Regional Toxic Metal Pollution: Impact of a Recent Road Opening in a Protected Mountain Area as Recorded in Nearby Lacustrine Deposits

Sébastien Aries (aries@lucid.ups-tlse.fr),

Mireille Polvé (polve@lucid.ups-tlse.fr) &

Joseph Dagnac (dagnac@cict.fr)

Laboratoire de Géochimie, 38, rue des 36 ponts, Toulouse, France

Toxic element trends (particularly those of heavy metals) in lacustrine sediment profiles have been widely used as indicators of historical pollution events (Chandrajith et al., 1995; Kolak et al., 1998) as precisely described by Rae et al. (1996) for some heavy metals and by the review of Fitzgerald et al. (1998) for Hg. In this study, we aim to trace local impact, as recorded by mountain lake sediments, caused by a nearby road. This road, built in the seventies, follows the Aumar lake in the Pyrénées Mountains (Néouvielle massif), France.

Sediment cores were collected using PVC tube corers handled by divers to allow a good and precise coring site (flat surface, undisturbed water-sediment interface).Toxic element concentrations were determined by ICP-MS (Pb, Zn, Cu, Ni, Cd,....) and by FI-HG-ICP-MS (Hg, As, Se) after leaching with concentrated HNO₃ in a microwave oven at high pressure in closed vessels. In order to determine toxic element concentration profiles versus time, we calculate accumulation rate by <gamma> -spectrometry of ²¹⁰Pb and ¹³⁷Cs which are typical markers for dating sediments over the last hundred years. Then, concentration profiles have been corrected from the porosity for avoiding possible compacting effects. Dilution effects by terrigeneous sediments or organic materials were also corrected by normalisation to a lithogenic element such as Sc or Al. In addition to concentration profiles, lead isotopic composition (accurately measured by ICP-MS as shown by Monna et al. (1998)) provide powerful informations about the origin of anthropogenic pollution (Monna et al., 1997). Their ratios are characteristic of lead deposits, thus lead use, thus origin of pollution. The major source of anthropogenic lead in the last decades is the lead added as antiknock agent in the gasoline, so lead isotopic composition represents the best way for tracing the impact of a road use. The origin of the pollution (local / global) is discriminated by comparing data, both on toxic elements and on lead isotopic composition, between this lake and a nearby non-polluted mountain lake).

Chandrajith RLR, Okumara M, Hashitani H, Applied Geochemistry, 10, 229-235, (1995).

Fitzgerald WF, Engstrom DR, Mason RP, Nater EA, Environ. Sci. Technol, 32, 1-7, (1998).

Kolak D, Long DT, Beals TM, Applied Geochemistry, 13, 59-75, (1998).

Monna F, Lancelot J, Croudace IW, Cundy AB, Lewis JT, Environ. Sci. Technol, 31, 2277-2286, (1997).

Monna F, Loizeau J-L, Thomas BA, Guéguen C, Favarger P-Y, Spectrochim. Acta, 53B, 1317-1333, (1998).

Rae JE, Parker A, Applied Geochemistry, 11, 211-215, (1996).

J09 : 4P/04 : PO

Heavy Metals Distribution in Coastal Sediments of the Dnister Water Reservoir (Ukraine). Application of Principal Component Analysis to The Determination of Background Levels

T Boyko¹,

W Kosmus² &

W Gössler²

¹ Institute of Geology and Geochemistry of Combustible Minerals,National Academy of Sciences of Ukraine, Lviv, Ukraine

² Institute of Analytical Chemistry, Karl-Franz University, Graz, Austria

Concentrations of mobile forms of 19 chemical elements (V, Cr, Mn, Co, Ni, Cu, Zn, As, Sr, Mo, Cd, Sn, Sb, Ba, Pb, Tl, Hg, Bi and U) in the coastal sediments from the Dnister water reservoir (Ukraine) were determined for the samples collected at 75 points on the length of river in the summer of 1995. The median metal concentrations have been found to be in order of - Mn > Sr > Ba >Cr > Ni > Zn > Pb > V > Cu > Co > As > Mo > Cd > Sn > U > Bi. Amounts of Sb, Hg and Tl are close to the detection limit - 0.2 ppb. Higher metal accumulation was observed in the upper reaches of the river, and relatively lower - downstream. Metal concentrations differ in 2-10 times and depend on the composition of sedimentary rock. Degree of metal accumulation was brought out by comparison with local background level, conservative element (vanadium) and global standard. Ratios of metal concentration to background vary from 0.5 to 3 for the most elements, but Sr and U are enriched in samples in a higher degree - from 1 to 20. Using of V as an element with a conservative behaviour for quantifying the results through the value of the Sediment Enrichment Factor is possible within the samples of the same rock type. Calculated percentage of mobile form of metals in coastal sediments ranged from 1 to 82%. Application of principal component methods of statistical data analysis gave a possibility to determine the background values for elements, according to the rock type of the region. Metal content in coastal sediments is controlled by lithological composition of sedimentary series as well as anthropogenic influence. It was proposed to separate the following element associations: "manganese" (Mn - Co - Zn - Ba - Cd - Cu - Pb - As - V - Bi), connected with the presence of manganese hydroxides in samples; strontium-uranium (Sr - U), typical for biogenetic limestone; sulphide (Pb - Zn - Cd), identified after using of vanadium as a conservative element, and anthropogenic (Cr - Ni - Sn - Mo), formed, probably, under the influence of urban sewage.

J09 : 4P/05 : PO

Heavy Metal Profiles in Sediment Cores from Santander Bay (Northern Spain)

María Jesús Irabien (nppirgum@lg.ehu.es) &

Iñaki Yusta (nppyuari@lg.ehu.es)

Dpt. of Mineralogy and Petrology., University of the Basque Country, P.O. Box 644. Bilbao 48080, Spain

The main aims of this work are to provide a preliminary view of the levels of pollution in the Santander Bay (Cantabria, Northern Spain) and to assess the sources of heavy metal enrichments (natural mechanisms and/or anthropogenic inputs).

Sediment samples were collected with a PVC handcorer (12.5 cm diameter x 50 cm length) from two sites in the Santander Bay on April 1997. Sampling sites were chosen according to their different environmental conditions: one represents a well preserved area (site 2), while the other is located near a industrialized zone (site 1). All analysis were carried out by X-ray fluorescence (XRF).

In order to correct the obtained data for grain-size effects, metal concentrations were normalized relative to Al contents. Although heavy metal profiles are essentially similar in both cores, levels are substantially higher in uppercore samples from the industrialized area (site 1). Concentrations of Fe, Mn, Zn, Pb, Cu and Ni decrease gradually towards the bottom of the cores and, below a certain depth (17 cm in site 1 and 20 cm in site 2), they fall to near constant values of 2.75% Fe, 0.025% Mn, 82 mg/kg Zn, 24 mg/kg Pb, 16 mg/kg Cu and 15 mg/kg Ni. These values reflect the "pre-industrial" levels of heavy metals in the Santander Bay. Enrichment factors relative to this baseline were calculated, using Al-normalized data, and maximum values were found in upper samples from site 1: 17.2 for Mn, 8.1 for Pb, 7.7 for Zn , 4.7 for Cu, 2.9 for Fe and 2.0 for Ni. In site 2 maximum enrichment factors are significantly lower: 4.5 for Zn, 4.0 for Mn, 2.5 for Pb, 2.5 for Fe, 2.0 for Ni and 1.8 for Cu.

Surface enrichment by heavy metals, particularly in site 2, seems to be related to increasing anthropogenic activities in the surrounding area during this century. Nevertheless, this vertical distribution may be partly due to early diagenetic reactions. Fe and Mn are frecuently enriched in sediments under oxic conditions, and it is well documented the capacities of these elements to scavenge heavy metals.

Acknowledgements: This work was supported by the Marcelino Botín Foundation as a part of the proyect "Geochemical and isotopic study of the heavy metal and organic compound pollution of the sediments from Santander Bay".

J09 : 4P/06 : PO

Environmental Transfer of Copper in Agricultural Calcareous Soils

Carolina Garcia-Rizo (ceeg311@fresno.csic.es),

Carmen Perez-Sirvent (ceeg311@fresno.csic.es) &

Josefa Martinez-Sanchez (ceeg311@fresno.csic.es)

C.S.I.C., Serrano 123, Madrid, Spain

Introduction: A study on the mobility of copper in calcareous agricultural soils near an old mining site in semi-aridic conditions (S.E. Spain) is presented. The process governing copper transfer from the element-rich zone to the neighbouring soils is strongly influenced by the semi-aridic climate and torrential rainfalls. The soils studied are calcaric fluvisols developed from Quaternary alluvial sediments from the sorrounding hills, some areas of which are dedicated to mining. Seasonal crops are cultivated, mostly tomatoes and melons, using traditional forms of irrigation and, more recently, drip irrigation systems.

Materials and Methods: Ten soil samples were obtained from a 5 km² sampling zone (1). The total metal content was determined by electrothermal atomization atomic absorption spectrometry (ETAAS) or flame atomic absorption spectrometry (FAAS). For this, the samples were slurried in a dilute hydrofluoric acid solution and the suspensions were directly introduced into the flame (2) or the electrothermal atomizer (3).

The selective extractants used were: water; 1 M ammonium acetate at pH 7.0 (4); 0.5 M ammonium acetate + 0.02 M EDTA + acetic acid at pH 4.65; 0.1 M sodium pyrophosphate, oxalic acid-oxalate (5); DTPA (6); sodium dithionite + sodium citrate (7). The metal content in each fraction was analyzed by ETAAS or FAAS.

The mineralogical composition of the samples was determined by XRD analysis using radiation Cu-K? Using the diffraction intensities obtained and the values for the same phases given in the bibliography, a semiquantitative analysis was made of the treated and untreated samples.

Results and Discussion: The extraction values in H₂O point to the natural inmobilization of copper when it is incorporated in carbonated soils, although these values diminish as we move further from the source.

Copper is mainly found associated with oxides and oxihidroxides as we can deduce from the values obtained in the Citrate-Ditionite extraction y oxalate, even though presence of carbonates must be also taken into account. The oxalic acid-oxalate (pH 3) extraction provides information about the metals which are associated to inorganic amorphous forms. This extractant also acts on active calcium carbonate since, due to its very small particle size, the compound is partially dissolved. Citrate-Ditionite release metals from amorphous forms or those of low crystallinity by reduction, this fraction being often the most abundant. Several carbonates are also solubilized in this extraction. Sodium pyrophosphate is a reagent which extracts forms bound to humic substances. In our case, because of the scarcity of humic matter content in the soils studied, it acts as a carbonate complexer and extractor.

The results obtained by using the selective extractants agreed with the data obtained from the XRD studies of both the original samples and the residues remaining after each extraction stage. A reliable assessment of metal availability in these highly calcareous soils must take into account the mineral phase in which the copper is present.

In accordance with the above, the behaviour of the metals with each reagent used reveals which phases in the soil they are associated with then. Thus, 40% (maximum value) of the Cu is associated to active calcium carbonate and inorganic amorphous materials and the rest is included in the network of silicates.

EDTA acts by complexing metals which seem to be associated to inorganic forms of Fe and Mn with low crystallinity and fine granulometry. Both the soluble metal and the metal associated to the exchange complex and to finely divided forms are affected by complexation with DTPA.

Perez-Sirvent C, Martinez-Sanchez J, Garci-Rizo C, IV Icbte Ext. Abstr., 729-731, (1997).

Bautista MA, Perez-Sirvent C, Lopez-Garcia I, Hernandez-Cordoba M, Fresenius J. Anal. Chem, 350, 359-364, (1994).

Lopez-Garcia I, Sanchez-Merlos M, Hernandez-Cordoba M, Anal. Chim. Acta, 328, 19-25, (1994).

Chapman HD, Methods of Soil Analysis C. A. Black ED, II, 891-900, (1965).

Grana MJ, Barral MT, Guitin FE, Guitin F, Suelo Y Planta, I, 303-321, (1991).

Mehra OP, Jackson ML, J. Clays and Clay Minerals, N-5, 317-327, (1960).

J09 : 4P/07 : PO

Grain Size Distribution of Copper and Organic Matter in Copper Contaminated Vineyard Soils

Corinne Parat (geoldeux@u-bourgogne.fr)¹,

Rémi Chaussod (Remi.Chaussod@dijon.inra.fr)² &

Francis Andreux (fandreux@u-bourgogne.fr)¹

¹ CST, 6, Bd Gabriel, 21000 Dijon, France

² CMSE, 17, rue de Sully, 21000 Dijon, France

The fungicide commonly used against mildew is predominantly copper sulfate, the "Bordeaux mixture", responsible for a large specific copper contamination of vineyard soils. A study of agricultural practices involving 36 sites widespread all over the Burgundy vineyard has shown a negative correlation between copper and microbial biomass (Quantin, 1997).

To specify the copper bioavailability in Burgundy vineyard soils in relation with the distribution of organic matter, iron and manganese, 10 plots among the 36 previously studied by Quantin (1997) were chosen and described. Grain size fractionation (Bartoli and al., 1991) was used to determine the distribution of copper, iron, manganese and carbon in soil fractions (0-2 µ m, 2-50 µ m, 50-200 µ m and 200-2000 µ m). The content of copper, iron and manganese were measured on whole soils and divided fractions using Atomic Absorption Spectrometry; carbon content was determined using elemental analysis (Carlo Erba Instrument). Chemical extractions using CaCl₂ and EDTA solutions and microbial biomass measures using the fumigation technique (Chaussod et al., 1986) were then carried out to estimate copper bioavailability on the 36 sites.

Three types of soils were identified: calcosol, calcisol and rendosol ; calcosol was the most represented. None of soil morphological characteristics was affect copper behaviour.

Grain size fractionation showed that 80% of copper and 90% of iron contents are localized in the fine (0-2 µ m and 2-50 µ m) fractions, whereas 65% of manganese content is found in the 2-50 µ m fraction. An accumulation of large amount of copper and iron in the 0-2 µ m fraction was occuring in soils exhibiting a high total manganese content. Carbon distribution differed from a plot to the others. The most copper contaminated soils showed a maximum carbon content in the coarse (50-200 µ m and 200-2000 µ m) fractions suggesting a slowing down of organic matter biodegradation.

The analysis of the 36 plots showed that copper toxicity seems to be related to the organic matter level of soil. In a general rule, copper is all the more toxic as soil organic matter content is small. As regard extractable copper, Cu-EDTA was negatively related to soil microbial biomass content suggering that Cu-EDTA featured copper toxic for microbial biomass. Contrary, Cu-CaCl₂ was positively related to labile fraction of soil organic matter and consequently seemed to be associated to small molecules produced by microbial biomass.

Bartoli F., Burtin G. & Herbillon A.J., Geoderma, 49, 301-307, (1991).

Chaussod R., Nicolardot B. & Catroux G., Science du Sol, 2, 201-211, (1986).

Quantin M., Rapport de DESS ERE, Université de Dijon, 0-53, (1997).

Arsenic Speciation in Buried Wastes at an Industrial Site and in a Soil Developed on a Mineralized Schist

Delphine Lecoq (lecoq@lmcp.jussieu.fr)¹,

Farid Juillot (juillot@lmcp.jussieu.fr),

Guillaume Morin (morin@lmcp.jussieu.fr),

Philippe Ildefonse (ildefons@lmcp.jussieu.fr),

Georges Calas (calas@lmcp.jussieu.fr) &

Christophe Gauthier (gauthier@esrf.fr)²

¹ Université Paris 6 et 7, UMR7590 and IPGP, Laboratoire de Minéralogie Cristallographie, 4 place Jussieu case 115 75252 Paris cedex 05, France

² ESRF, BP 220, 38043 Grenoble, France

Arsenic (As) is naturally released in the environment by alteration and volcanism but its most important source is industrial activity. Arsenic is a contaminant which represents a potential risk for man since it can enter the food chain through plants or water. Mobility and bioavailability of As depend on its speciation both in solutions and in solids. The present study focuses on the behavior of arsenic in two contrasting geochemical systems: an industrial area contaminated with by-products from the processing of arsenic-bearing ores and deposited on a limestone substratum, and a soil developed on As-mineralized schist. In both cases, arsenic has been mobilized by meteoric waters. In order to understand the arsenic dissemination on these sites, localization of arsenic and direct determination of its speciation in solids were used to determine the immobilization processes in the sites studied. Chemical and mineralogical characterization of sample studied were conducted by XRD, EMPA and SEM-EDS. Synchrotron-based techniques (µ -SXRF and EXAFS) were used for in situ localization and speciation of arsenic in soil. At the industrial sites, surficial waste piles (containing arsenolite, arsenopyrite and pyrite) were weathered by run-off waters (pH=7.9) which becomes acidic (pH=2.2). Dissolved arsenate species (A⁵⁺) interact with the limestone substratum, providing dissolved calcium which reacts with arsenic to precipitate 1:1 calcium arsenates (weilite CaHAsO₄, haidingerite CaHAsO_4.H₂O and pharmacolite CaHAsO_4.2H₂O) and, in minor amounts, calcium-magnesium arsenates (picropharmacolite (Ca,Mg)₃(AsO₄)₂ 6H₂O). The 1:1 calcium arsenates identified are known to precipitate at low pH (3-6) and seem to be stable in media with high dissolved CO₂, in comparison with other types of calcium arsenates.In the natural analogue studied, µ -SXRF and SEM observations evidence that As, released from arsenopyrite weathering, is sinked in secondary Fe-As mineral compounds. EXAFS spectroscopy gives complementary information on the As speciation in this soil. The stability of the different forms of As in the two sites studied will be compared to geochemical data, in order to predict if the identified phases are relevant candidates to immobilize arsenic in contaminated surficial environments.

J09 : 4P/09 : PO

Environmental Contamination from Autocatalyst-Derived Platinum

Kym Jarvis (k.jarvis@ic.ac.uk),

Rachel Brown (rachel.brown@ic.ac.uk) &

Jacqui Piper

NERC ICP-MS Facility, Imperial College, Silwood Park, Ascot, SL5 7TE, UK

The platinum group elements (ruthenium, rhodium, palladium, osmium, iridium and platinum) are the least abundant elements in the earths crust, but their unique blend of physical, electrical and chemical properties have resulted in widespread technical application. The emission of PGEs from autocatalysts represents a highly mobile source of environmental contamination. Pt, Pd and Rh in catalysts dust are deposited along roadways and adjacent soil, vegetation, and water bodies, either directly or in runoff. Therefore concern about the release of PGEs into the environment, and subsequent human exposure, by direct contact, inhalation, and potentially through the food chain, has increased following the compulsory fitting of catalysts to all new cars.

Although inert in metallic form, platinum salts pose a real health risk, particularly if they occur at less than 10 microns in diameter. At this size they are easily inhaled and are known to cause hyper-sensitisation and enhanced susceptibility to conditions such as asthma.

This research has shown that over a single year, the concentration of Pt, Pd and Rh in roadside dusts collected at two sites in SE England, fluctuates to some degree with season. The levels of palladium in particular can be correlated with rainfall and solubility experiments have demonstrated the relatively high solubility of this metal at pH 5-6. At both sites studied, there was an overall increase in the absolute concentration of all three metals by the end of the year, raising serious questions about long-term trends.

Current research seeks to identify the chemical form, and hence potential impact of PGE release from auto catalysts in airborne particulate matter using selected sites adjacent to the M25 and M4 motorways in SE England. The results of the year-long study of roadside deposits will be presented along with air particulate data obtained using laser ablation ICP-MS. Particulate characterisation is the key to assessing the environmental impact of auto-catalysts.

J09 : 4P/10 : PO

A Cadmium Budget for the Lot-Garonne Fluvial System (France)

Gerard Blanc (blanc@geocean.u-bordeaux.fr),

Yvon Lapaquellerie,

Noëlle Maillet,

Stephane Audry &

Pierre Anschutz

DGO UMR CNRS 5805, Universite Bordeaux 1, Talence 33405, France

Routine measurements of river discharge and total suspended sediment concentration (TSS) are combined with regular analyses for particulate and dissolved cadmium to produce a box model that allow us to propose a cadmium mass balance for the Lot-Garonne man-influenced river system. Nearly half the cadmium in the Garonne river is supplied by the tributary Lot river. Cadmium input onto the Lot river comprises wet deposition from the atmosphere, molecular diffusion at the sediment-water interface, surface-water runoff, and discharge from the leaching of waste at a zinc refining plant. Approximately 85% of the cadmium in the Lot river is derived from anthropogenic origin. Cadmium in the industrial discharge is 80% dissolved and 20% in the particulate phase (4.2 and 1.1 t/yr, respectively). Total inputs are estimated at 4.81 t/yr and 1.54 t/yr for the dissolved cadmium and for the particulate phase, respectively. Budgeting estimates an output onto the Garonne river of 0.54 t/yr for the dissolved cadmium (about 8%) and 6.13 t/yr for the particulate cadmium (about 92%) indicating that downstream sediment-associated cadmium fluxes are enhanced by the 4.27 t/yr removed from solution and the 0.32 t/yr remobilised by the erosion of sediment blanketing the Lot river bed. These figures are found to be comparable with those generated by a dilution model which suggests that 97% of dissolved cadmium is taken up by the particulate phase over 0.5 km downstream from the primary anthropogenic source.

J09 : 4P/11 : PO

Temporal Variations of Mercury Contents in a Heavy Polluted River, the Thur (Northeastern France): Effect of Chloride, Organic Matter, pH and Impact on Groundwaters

Sandrine Remy (remy@illite.u-strasbg.fr),

Jean-Luc Probst (jlprobst@illite.u-strasbg.fr),

Pascale Prudent (pprudent@illite.u-strasbg.fr) &

Gérard Krempp (gkrempp@illite.u-strasbg.fr)

Ecole et Observatoire des Sciences de la Terre, Centre de Géochimie de la Surface, CNRS/Université Louis Pasteur, 1 rue Blessig, 67084 Strasbourg Cedex, France

In the upper part of the Ill river basin (tributary of the Rhine), the Thur river is heavily polluted by mercury because of industrial waste waters from chlorine and soda industry (Probst et al. 1996 and 1999). The main objectives of this study were to follow the daily and hourly variations of mercury contents in the different hydrosystem reservoirs (river water, groundwater, suspended matter SM, bottom sediment BS, aquatic bryophyte and river bank sediment) during a low water period (23-27 march 1998) at the exutory of the river basin (Ensisheim station), just before the confluence with the Ill river.

As previously shown by Probst et al. (1996 and 1999), the solute mercury content in the Thur river water is lower (1-30 ng.l^-1) than in the SM and BS (5-36 mg.g^-1). During the sampling period, the river discharge shows very low variations (1.9 to 2.3 m³.s^-1). The daily as well as the hourly mercury content variations in the river are more important in the dissolved phases than in SM and BS. Solute mercury seems to be independent of the different physico-chemical parameters of river water. On the contrary, mercury contents in SM and BS are mainly controlled by dissolved chloride concentration and by organic carbon content in the sediments. When the organic carbon percentage increases, the mercury content in BS increases too. With increasing chloride concentration in the solution, the mercury concentration in the sediments decreases as previously shown by several authors. Besides, with increasing pH, mercury content in particulate phases decreases contrary to what is generally observed. However, at high pH correspond high chloride concentrations, therefore this pH increase does not affect the mercury sorption processes onto sediments in such conditions (high chloride concentration). Consequently in this river water, high dissolved chloride concentration seems to minimise the effect of the pH.

The main problem in this basin is that the river supplies water to the groundwater which is used for drinking water. The first measurements we did in this area show that fortunately solute mercury concentrations in groundwater are very low (3.1-11.2 ng.l^-1) but some sediments collected in the wells indicate very high mercury contents (54 mg.g^-1). In addition, these groundwaters are heavily polluted by saline waters coming from potash mine industries and chloride concentrations (which have a great influence on mercury sorption onto solid phases) are very high (0.1 to 10 g.l^-1). These first results have to be confirmed but if they are, the main question would be "What will happen to mercury adsorbed for the moment onto these sediments if the physico-chemical composition of groundwater changes, particularly if the groundwater salinity decreases?"

Probst JL et al, Proc. IV Int. Conf. Mercury as a Global Polluant,August 4-8, Hamburg, 302, (1996).

Probst JL et al, Environmental Science "Mercury contaminated sites" (R. Ebinghaus et al. Eds), Springer Verlag, Berlin Heidelberg, 501-520, (1999).

J09 : 4P/12 : PO

Transfer of Colloids and Trace Metal Elements in Unpolluted and Polluted Loamy Soils

M. Réda Semlali (rsemlali@versailles.inra.fr)¹,

Laurence Denaix (denaix@bordeaux.inra.fr)²,

Francis Douay (douay@isa.fupl.asso.fr)³ &

Folkert van Oort (vanoort@versailles.inra.fr)¹

¹ Unité de Science du Sol, INRA, 78026 Versailles cedex, France

² Unité d'agronomie, INRA, BP 81, 33883 Villenave d'Ornon cedex, France

³ Laboratoire Sols et Environnement, ISA, 41 rue du Port, 59046 Lille cedex, France

Transfer of colloids and trace metals was studied in two ecosystems: a Luvisol under natural forest representing a natural geochemical background and a Colluvisol polluted by a non-ferrous metallurgical activity (Zn, Pb, Cd).

Our aims are i) quantify colloid and trace metal transfers ii) identify the nature of colloids.

General characteristics of soils studied.

Horizons Texture Zn Pb Cd

Depth cm pH OM% mg kg^-1

Luvisol Site

A 3-15 L 4.9 6.6 75 32.5 0.22

E_g 41-73 L 6.3 0.8 50 19.3 0.08

BT_g 73-120 LA 6.4 0.2 64 19.1 0.05

Colluvisol Site

A_1g 9-36 LSA 5.6 2.8 1819 383 15.5

A_3g 36-50 LAS 6.3 0.8 767 21.7 4.3

BT_1g 50-70 LAS 6.5 - 612 18.2 2.65

Zero-tension lysimeters were used for sampling gravitational water under the soil horizons. Soil solutions were collected after each major rainy period and filtered at 5 µm. Ultracentrifugation was performed in order to separate the colloidal and soluble fractions (Mavrocordatos and Perret, 1995). The size of colloids was fixed between 10 nm and 5 µm.

Total carbon, pH and trace metal elements contents were analysed, both in filtered bulk samples and in ultracentrifugated supernatants.

Observations and elemental analysis were performed on the colloidal fractions by transmission electron microscopy coupled with energy dispersive spectrometry (TEM-EDS). Mineralogical analysis were performed by X ray diffraction (XRD).

The chemical analysis of the two fractions shows that only a part of the metals is soluble.

In all samples, a part of the metals is associated to the colloidal fraction.

In the Colluvisol, metal concentrations in the soil solution may rich more than 10 ppm (for Zn), whereas in the luvisol, this amount was approximately 0.1 ppm.

We showed that Zn was associated to clay colloids whilst Pb was associated to colloidal organic matter.

Mavrocordatos D. and Perret D., Non-artifacted specimen preparation for transmission electron microscopy of submicron soil particles, Commun. Soil Sci. Plant Anal., 26, 2593-2602, (1995).

J09 : 4P/13 : PO

Pollution Caused by Metallic Fragments Introduced to Soil by 1^st World War Activities

Petra Souvent (petra@hamradio.si)¹,

Simon Pirc (simon.pirc@ntfgeo.uni-lj.si)¹ &

Leopold Vehovar²

¹ University of Ljubljana, Department of Geology, Askeceva 12, 1000 Ljubljana, Slovenia

² Institute of metals and tehnology, Lepi pot 11, 1001 Ljubljana, Slovenia

The influence of parent rock material and soil on the corrosion rate of metallic fragments that remained in soil after the 1^st World War in the Soca front area (Slovenia) were studied. Three types of parent material have been selected:

* marl (₄K₂³) on which rendzina has been developed;

* micritic limestone (K₁²⁺³) on which brown soil on carbonate rocks has been developed;

* flysch sandstone (E_1,2) on which distric brown soil has been developed. With x-ray diffraction the following corrosion products have been determined and observed:

* after steel and cast iron: goethite <alpha> -FeOOH, lepidocrocite <gamma> -FeOOH, magnetite Fe₃O₄ and haematite Fe₂O₃;

* after Pb alloy: massicote PbO, plattnerite PbO₂, cerussite PbCO₃, hydrocerussite Pb₃(OH)₂(CO₃)₂, lead-antimony oxide Pb₅Sb₂O₃ and PbSb₂O₄ and cervantite Sb₂O₄;

* after brass: cuprite Cu₂O.

The results of corrosion tests did not indicate appreciable differences in corrosion rates between various corrosion media. Consequently, corrosion rates are mostly influenced by soil aeration and soil humidity and also by microstructures of alloys. The obtained estimates are the rates of corrosion of alloys which are in permanent contact with the corrosion media. In nature, however, this occurs only at the beginning of the corrosion process, before passivation films or other coatings on alloys start to build up. On the contrary, the soil seems to have more influence on corrosion products that appear as a consequence of corrosion process. Important controls of stability of corrosion products are the soil pH and Eh. In pH and Eh ranges that prevail in the studied soils, only goethite is the stable mineral. Lead minerals are not stable, and lead, in a Pb²⁺ cation form is probably adsorbed on some minerals, especially on goethite, or is bound with organic matter. In distric brown soil lead stays in the cation form as Pb²⁺ because of very acid environment, and is toxic in groundwater to plants. Cuprite is stable in rendzina and brown soil on limestone, while in distric brown soil copper stays in solution in Cu²⁺ form.

J09 : 4P/14 : PO

Electrokinetic Remediation of Heavy-Metal Contaminated Soils with pH-Control

Stefan Preiss (preiss@gfz-potsdam.de) &

Wolfgang Czegka

GeoForschungsZentrum Potsdam, Telegrafenberg, D-14473 Potsdam, Germany

Recently electrochemical methods of in-situ soil remediation have been attracting increasing interest. The success of electrokinetic remediation has been shown by Hamed et al. (1991) and others in laboratory scale. This method is applicable to heavy-metal contaminated, fine-grained soils that can hardly be remediated by the commonly applied processes. Various numeric models are available (Choi et al. 1995) to simulate the remediation process. The technical application has several disadvantages: high energy consumption, corrosion of the anodes and precipitation of heavy metal hydroxides in the vicinity of the cathode.The main processes of electrokinetic remediation are ion migration and electroosmosis. There is a maximum of electroosmotic flow in alkaline solutions. Unfortunately the most heavy- metals are not mobile in this pH-range. Therefore, the process has to be performed with an optimized pH. The pH influences the following parameters: zetapotential, electrical conductivity, surface conductivity and the ratio of ionic to solid species of the heavy-metals. If the pH is low the energy consumption is too high, caused by high mobility of hydrogen ions. At low pH range the cations build a complex which then moves to the anode instead of the cathode. Our solution is the determination of electrokinetic parameters, calculation of the optimum pH and processing using this pH controlled by a circulation system at the electrodes. The corrosion of the anode has to be prevented through the use of carbon materials.

Choi YS, Lui R, J. Haz. Mat, 44, 61-75, (1995).

Hamed J, Acar YB, Gale RJ, J. Geotech. Eng, 117, 241-271, (1991).

J09 : 4P/15 : PO

The Influence of Water Macrophytes on Penetration of Toxic Elements into the Environment

Elena Hohzina (ecol@uiggm.nsc.ru) &

Dmitry Bessonov

United Institute Geology, Geophysics and Mineralogy, pr. Koptuga 3, 630090 Novosibirsk, Russia

This investigation is focused on the estimation of water vegetation role in processes of the toxic element redistribution in biogeocoenosis of technogenic landscapes. Research was carried out in the tailing impoundment of the Komsomolsky Gold Extracting Plant. The main peculiarity of this impoundment is the following: concentrations of As, Sb, Fe and Mn in the water and sediments are 100 times higher than the background one. The following plants were studied: forest bulrush (Scirpus sylvaticus), platyphyllous cattail (Typha latifolia) and common reed-grass (Phragmites communis). The chemical concentrations in the macrophytes are 1-2 order higher than the background one. This means that water plants can execute the role of biological barrier for chemical element migration from the impoundment into the environment. But we do not know whether the secondary pollution of water occurs after plants dying off or not? In the place of macrophyte growth, the employers of our laboratory picked out the sediment column (with a length of 36 cm). The concentration of Sb was determined in pore water and solid matter of each layer of the column (with a length of 3-10 cm). In the highest layer, containing plant remains, the minimum concentration of Sb in pore water (i.e., in dissolved sustain) and its maximum concentration in solid matter of sediment (i.e., in undissolved sustain) were observed. Therefore, water biota can concentrate Sb in the solid matter of tailing impoundment sediment. So, natural purification of water occurs. Analysis of acid extracts from cattail (pH=3) shows that elements are bounded irreversibly in the underground part of the plant, since the ratio between element concentration in the dry plant matter and its concentration in an extract is significantly higher than 1. As and Sb in the aboveground part of the cattail are bounded reversibly and are very mobile (ratio is close to 1). Fe and Mn are not so mobile elements relative to the cattail. So, under these conditions, As and Sb are the most mobile elements. This property of As and Sb can provide further penetration of harmful chemicals into food webs, since home animals eat cattail very actively and acidity of their stomach juice is good enough for rapid penetration of As and Sb into the digestion system. So, water macrophytes play ambivalent role in the processes of harmful chemical migration in the biogeocoenosis of technogenic landscapes. On one hand, plants come forward as biological barrier with further concentration of such an element as Sb in solid matter of sediments, but, on the other hand, they provide penetration of As and Sb in the food webs.

J09 : 4P/16 : PO

Natural and Anthropogenic Influences on Geochemistry of Soils in Barren and Mineralized Carbonate Terrains

Polona Vreca (polona.vreca@ijs.si)¹

Simon Pirc (simon.pirc@ntfgeo.uni-lj.si)² &

Robert Sajn³

¹ Jozef Stefan Institute, Ljubljana, Slovenia

² Dept. of Geology, University of Ljubljana, Ljubljana, Slovenia

³ Institute for Geology, Geotechnics and Geophysics, Ljubljana, Slovenia

The geochemical investigation of soils from Ravne across the Pb-Zn mining and smelting area of Mezica in northern Slovenia to Eisenkappel in southern Austria was performed in the framework of a common Alps-Adria Austrian-Croatian-Slovenian research project. The major part of the territory consists of Triassic limestones and dolomites containing Pb and Zn orebodies in the Mezica area and smaller occurrences also elsewhere. The aim was to study the geogenic and anthropogenic contamination of soils. In total, 513 samples of organic (153) and mineral (360) soil horizons were collected in 148 soil profiles in a 1x1 km grid. Major (Al, Ca, Fe, K, Mg, Na, Si), minor (Ba, Cl, Mn, Pb, Rb, Sr, Ti, Zr) and trace elements (Co, Cr, F, Ga, Mo, Nb, Ni, Pb, V, Y, Zn) in bulk samples were determined by X-ray fluorescence spectrometry in the Arsenal Laboratory in Vienna, Austria. Elemental distributions were studied by univariate statistical analysis and by R-mode factor analysis. By four factors 69% of total variability in data is explained for organic and 78% for mineral soil horizons. The mineralization factor that is loaded with Pb and Zn explains in both sets more than 10% variance. Results of statistical analysis were used for computer drawing of elemental and factor score geochemical maps.

The results show that concentrations of most elements increase on the average with soil depth. Several elements (Cr, Cu, Mo, Ni, Pb and Zn) tend to accumulate in organic horizons. Pb and Zn are relatively high, and are on the average above the allowed limits (100 ppm for Pb and 300 ppm for Zn) for soils. In the vicinity of the smelter at Zerjav in the Meza valley in organic soils elevated Pb concentrations (above 1000 ppm) decreasing rapidly with depth were observed. They indicate heavy airborne technogenic pollution from the time of operation of the smelter. Geochemical maps show distinctions in elemental concentrations in soils on different bedrocks and in different soil types as well as sources of elemental enhancement in soils. Besides the significant technogenic anomaly of Pb and Zn in organic soils of the smelter area, geogenic influence of mineralized bedrock on mineral horizons in several places is indicated.

J09 : 4P/17 : PO

Exploratory Geochemical Analysis of Groundwater Databases

Fernando A. L. Pacheco (fpacheco@utad.pt)¹ &

Cornelis H. Van der Weijden (chvdw@geo.uu.nl)²

¹ Geology Section, University of Tras-os Montes e Alto Douro, PT 5000 Vila Real, Portugal

² Geochemistry, Utrecht University, P.O. Box 80.021, NL 3508 TA Utrecht, Nederland

This paper corroborates a statistical approach developed by Pacheco (1998) to assess groundwater chemistry with little background information. The method states that the variation in the major inorganic composition of groundwater samples from crystalline rocks (e.g., granites, schists, amphibolites) may be explained by three or four hydrochemical parameters, namely: (a) The %-Pollution, a weighted ratio between the sum of contaminants chloride, sulphate and nitrate and this sum plus dissolved silica and bicarbonate, the weights being the corresponding factor-1 loadings determined by Correspondence Analysis (CA); (b) The %-Agriculture, a similar weighted ratio, now between the sum of contaminants sulphate and nitrate (agriculture) and this sum plus chloride (atmospheric input, domestic effluents), the weights being the factor-2/3 CA-loadings; (c) The bicarbonate to silica ratio; (d) And the sulphate to nitrate ratio.

Practical environmental applications of this type of analysis are readily envisaged: (a) The %-Pollution parameter may be used to separate between areas where the groundwater composition is dominated by pollution and areas where the natural backgrounds prevail; (b) The %-Agriculture parameter may be used to identify areas of predominant domestic contamination and areas where agriculture is the main source of pollution; (c) The bicarbonate to silica ratio gives an insight about the local water-mineral interactions allowing for the separation between different rock types; (d) And the sulphate to nitrate ratio alerts for the type of fertilizers commonly used in the study area.

The method of Pacheco (1998) was here applied to a set of 48 spring water samples collected in the Morais massif, a geological region in the Northeastern part of Portugal characterized by great lithological diversity, namely amphibolites, gabbros and flaser-gabbros, granulites, peridotites and serpentinites, gneisses and micaschists. Human occupation is characterized by 27 small villages distributed by 400 km²; land use by large areas of dry farming, olive yards and evergreen oak forests and small spots of chestnut forests and vine yards. Three hydrochemical parameters (items a, c and d as defined above) account for more than 76% of the total data variation, and when plotting the parameters scores on the corresponding sampling sites one may conclude that:

(a) The areas occupied by evergreen oak forests have %-Pollution < 25%. The areas of influence of the villages have %-Pollution scores in the range 50-100%. The remaining zones have %-Pollution around 25-50%;

(b) The bicarbonate to silica ratios (B/Si) roughly discriminate between the areas of granulites/peridotites/gabros/flaser-gabros/serpentinites (B/Si>15), and the areas of amphibolites (5<B/Si<15) or gneisses/micaschists (2.5<B/Si<7.5);

(c) The sulphate to nitrate ratios ([SO₄^2-]/[NO₃^-]) clearly separate the olive yards (3<[SO₄^2-/[NO₃^-]<4) from the evergreen forests (4<[SO₄^2-]/[NO₃^-]<10) or the areas where dry farming is the most common agricultural practice (0<[SO₄^2-]/[NO₃^-]<2).

Pacheco FAL, Mathematical Geology, 30, 129-155, (1998).

J09 : 4P/18 : PO

Contribution of Marine and Anthropic Atmospheric Particulate Matter to the Marble Weathering in the Mediterranean

Anne Chabas (chabas@lisa.univ-paris12.fr)

LISA-Université Paris XII, 61 av. du Général de Gaulle, Creteil, France

In the Mediterranean, the marble weathering is often observed by loss (desquamation, disagregation, dissolution) or supply of matter (brown crusts).

The marble desquamation and disagregation result from recurrent crystallization-dissolution cycles of salts - halite (NaCl) in particular - in the stone subsurface. These salts are generally transported by water capillary rises from the ground. The petrophysical studies performed on Naxos marbles used for the monuments of Delos Island (Cyclades) have shown that they have a very weak porosity (< 0.5%) with two mercury thresholds (6 and 0.15 µ m). Their porous network is heterogenous and represented by rectilinear and sinous cracks, which do not allow a capillary transfer on a long distance (i. e. beyond 0.1 m) from a ground alimentation in water and salts. It is not possible to justify these weathering forms at heights higher than 0.1 m by a brine migration from the ground. Moreover, the presence of marine particles on the marbles and in the air around them, shows that these particles have an atmospheric origin. Experiments performed on marbles few enriched in halite have shown that the variations of relative humidity between 95 and 84% can formed some brine by halite solvation, in 2-3 hours. This brine, which soaks the weak and superficial porosity of the marble, is then submitted to evaporation. These crystallization-dissolution cycles of salts lead to the marble desquamation and disagregation. The correlation of these data with the measurements of relative humidity in the Mediterranean confirms the possibility of this weathering mechanism which can be accentuated by smogs and dew.

Some analyses carried out on particles collected by air filtrations in different mediterranean sites, have revealed some high concentrations in excess S (anthropic S). The anticorrelation between Cl/Na and excess S is explained by the Eriksson's reaction: the halite particles of marine aerosols react with H₂SO₄ coming from the SO₂ oxidation. This reaction gives rise to HCl which can react on the marble and produce some dissolutions.

Brown crusts can be observed in the parts of marbles protected from rains and run-off water. They are gypseous (CaSO₄.2H₂O) and contain pollution particles like fly-ash. Fly-ash transports Fe and V which catalyse the SO₂ to SO₃ reaction. After hydratation, SO₃ is transformed in H₂SO₄ which attacks the marble and leads to the gypsum formation. The direct impaction of gypsum particles can also occur on the marble surface. Not leached by rains, these particles are included in the gypseous crust. The brown crusts are similar to the black crusts described in urban polluted atmospheres.

The examination of stone in its atmospheric environment, marine and polluted in this case, has allowed to explain some weathering mechanisms that the study of materials only could not permit to consider.

J09 : 4P/19 : PO

Photooxidation of Crude Oil Components Under Simulated Environmental Conditions

Armelle Charrie-Duhaut

(aduhaut@chimie.u-strasbg.fr)¹,

Pierre Adam (padam@chimie.u-strasbg.fr)¹,

Sylvie Lemoine (Sylvie.Lemoine@ECC.EXXON.sprint.com)¹,

Jacques Connan (Jacques.Connan@elf-p.fr)² &

Pierre Albrecht (albrecht@chimie.u-strasbg.fr)¹

¹ Laboratoire de Géochimie Organique, 1 rue Blaise Pascal, Université Louis Pasteur, Strasbourg, France

² Elf Exploration Production, CSTJF, Avenue Larribau, Pau, France

Geological organic matter exposed to the earth' surface undergoes the effects of various alteration processes such as water-washing, evaporation, biodegradation, abiotic oxidation. The investigation of these processes, at a molecular level, is important to understand the transformations undergone by petroleum exposed to atmospheric conditions. The aim of this study is, by means of simulation experiments involving light, oxygen and typical petroleum lipids (triaromatic steroids, 9-heptadecylphenanthrene 1, 4-butyldibenzothiophene, various alkylbenzothiophenes 4) to investigate the specific impact of abiotic oxidation.

The photooxidation of all the aromatic compounds investigated leads principally to the formation of oxygenated compounds (alcohols and ketones) resulting from the oxidation at the benzylic position. Degradation of the carbon skeletons (C-C bond cleavage reactions) affecting either the alkyl chains or the aromatic polycyclic systems was also demonstrated. Thus, the simulation experiments performed on 1 led to the formation of the related benzylic ketone 2, but also to a mixture of linear acids (C₁₃-C₁₈) resulting from the cleavage of the alkyl side chain, as well as to 3 resulting from the oxidation of the aromatic system. Similarly, alkylbenzothiophenes 4 were rapidly transformed into alkylated carboxybenzothiophenes 5 formed by oxidative cleavage at the benzylic position. However the major degradation pathway leading, in particular, to alkylated 2-thiobenzoic acid 6 or 2-sulfobenzoic acid 7, as well as to the related phenol 8 or the triacid 9 involves the opening of the thiophenic ring.

Most of the oxygenated compounds formed in the simulation experiments were similar to those detected in naturally oxidized bitumens. Their formation contributes to an increase of the water solubility of the constituents from petroleum favoring their removal by water-washing and their biodegradability. Furthermore, abiotic oxidative processes can contribute to the degradation of macromolecular constituents from petroleum, generally considered as highly refractory to atmospheric alteration either by release of oxygenated components resulting from the cleavage of C-C bonds at the benzylic positions of alkylaromatic subunits or by degradation of the (poly)aromatic skeletons.

J09 : 4P/20 : PO

A Concept for an Experimental Proof of the Transport and Reaction of Nitrogen During the Soil-Groundwater-Surface Water-Pathway

Katrin Vosbeck (vosbeck@soil.lysi.ufz.de) &

Ralph Meissner (meissner@soil.lysi.ufz.de)

UFZ-Lysimeterstation Falkenberg, Dorfstr. 55, 39615 Falkenberg, Germany

The proportion of the diffuse nitrogen pollution of the total amount of surface water pollution rose steadily during the past years. There is a lack of knowledge on the quantification of these diffuse nitrogen inputs. The considerable difference (about 50%) between the estimated agricultural input and the measured output into the streams (N-load of the streams) reflects this difficulty. The research project-carried out by the UFZ-Centre for Environmental Research Leipzig-Halle - has the objective to trace the pathways and transformations of nitrogen from the soil surface via groundwater to surface water experimentally. With this knowledge it may be possible to make a better prediction of the staying of nitrogen during input-output studies. The transport and transformation of nitrogen will be measured on the basis of detailed input and output studies on different scales: lysimeter, section in a catchment (20 to 50 m long) and small catchment areas.

The chosen catchment area is situated about 25 km north of Stendal in the lowland of the river Elbe in the northern part of Saxony-Anhalt (Germany). The surface water and a small proportion of the groundwater flow into a ditch. Sandy to loamy soil sediments (unsaturated Zone) overlie pleistocene sediments of the Saale and Weichsel ice age (saturated zone).

The geological and pedological parameters were determined at the beginning. During the research project the following quantities are measured periodically:- precipitation,- meteorological data,- land use,- inorganic nitrogen in soil,- groundwater level,- stream discharge of the ditch and the- surface, seepage and groundwater chemistry.

A section was chosen within the catchment area where seepage- and groundwater measuring systems were installed in different depths on the streamline directed to the ditch. The seepage water flow on the boundary between surface water and groundwater is measured through a seepage measuring system in the stream bed.

The chemical and isotopic composition and variation is determined of the solid, fluid and gaseous phase (¹⁵N, ¹⁸O, ²H, ³⁴S in the different compounds of the three phases). Furthermore trace experiments are carried out with conservative tracers like chloride as well as natural isotopes (¹⁵N, ²H) in the unsaturated and saturated zone.

Similar trace experiments are done at the UFZ-Lysimeter Research Station in Falkenberg, Saxony-Anhalt to gain information on the behaviour of nitrate and other N-compounds during transport and reaction in the unsaturated zone under generally standardised conditions.

J09 : 4P/21 : PO

Transport Modelling of Heavy Metals Based on Geochemical Study in Soil at Edges of the Naples-Salerno Motorway

Stefano Caliro (caliro@unina.it),

Massimiliano Imperato (imperato@unina.it),

Vincenzo Monetti (monetti@unina.it),

Debora Naimo (naimo@unina.it),

Rossella Radatti (radatti@unina.it) &

Damiano Stanzione (stanzion@unina.it)

Dipartimento di Scienze della Terra - Università degli Studi di Napoli "Federico II", I-80134, Italy

This work analyses the distribution of heavy metals in soil adjacent to the Naples-Salerno motorway. The study area contains volcanic rocks belonging to the eruptive products of Somma Vesuvio. The volcanic soils in the area derived from recent pyroclastic deposits. The various concentrations in the soil of Pb, Cd, Zn, Mn, Cu and Cr found in different portions of the motorway (embankment, road cut, field level) are reported. The data obtained indicate high levels of pollution in soil adjacent to the motorway fencing, with maximum concentrations of 1220 ppm Pb, 1,9 ppm Cd and 341 ppm Zn. Gradients of decreasing pollution with distance from the fencing and with altitude from the road surface are highest for Zn followed by Pb and Cd. The presence of these three metals in depth follows an averagely constant falling gradient, with minimum detected values at 50 cm depth. The spatial distribution of Cr does not reveal any significant differences. Relatively big levels are due to the presence in the soil of Chromium-rich minerals such as augite and olivine. Mn and Cu are found, due to local contributions, probably as a consequence of the use of copper compounds in agriculture. The way by which Pb, Zn & Cd bearing particles are transported, may be envisaged from soil concentration, patterns in the various environments. It appear that, once emitted from vehicle exhaust systems, these metals hardly ever propagated to an altitude of more than 2.5 m, but it does spread laterally to distances of several tens of meters.

J09 : 4P/22 : PO

Heavy Metal Distribution in Recent Lacustrine Sediments of Sebkha Ariana (Tunisia): Environmental Anthropic Impacts

Fadila Darragi¹,

Karem Dassi¹,

Luis Martinez (martinez@illite.u-srasbg.fr)²,

Joelle Duplay (jduplay@illite.u-strasbg.fr)² &

Besma Ben Henda¹

¹ University of Tunis, Tunisia

² CGS 1 rue blessig 67084 strasbourg Cedex, France

Natural sedimentary environments as costal lakes or lagoons are very sensitive to human activity. Sebkha Ariana in the northern area of Tunisia is representative of a lagoonal system submitted to urban development which affects its natural equilibrium. The aim of this study is to analyse the distribution of metal pollution in sebkha Ariana recent sediments, to study clay control on heavy metal mobility and to assess human pollution.

Sedimentological and mineralogical analysis: Thirty sediment cores were taken across the Ariana basin following NW-SE and N-S directions (Ben Henda, 1997). The core depth ranges between 2 and 5 meters. Sedimentation is mainly sandy and silty. The minerals pointed out by X-ray diffraction are essentially quartz, calcite, clays and traces of dolomite, gypsum and halite.Clay minerals from the less than 2 micron fraction are smectite, kaolinite, illite and minor amounts of chlorite. One can notice that high concentrations of smectite and elevated amounts of organic carbone are located in the same levels of cores and at the same area.

Geochemistry: The highest abundances of Zn, Cu, Pb and Cd are found in the sediments surrounding the waste water stations, a dumping ground and the opening of a river. The greatest concentrations of Cu and Zn were found at the bottom of most samples whereas high Pb concentrations are observed at the top of cores.Correlative analyses were done on heavy elements, clay minerals, carbonate minerals and organic matter abundances. They point out that Cu and Zn are often associated. For example, the corrrelation with smectite is clearly positive for Cu and Zn whereas it is negative for Pb. Correlations also indicate that clay and organic matter seem to be in competition for Cu and Zn adsorption. Carbonates may also adsorb heavy elements as it is the case for Zn and Cu, what is pointed out by a positive correlation. On the other hand no correlation could be established for in case of Cd and Pb.STEM investigations on samples containing high concentrations of Zn and Pb show that smectites are poor in these metals wheras carbonate and salt mineral clusters contain well detectable quantities of metal. The latter is in good agreement with correlation analysis.

Ben Henda B, Mémoire de DEA, Université de Tunis II, 128 p, (1997).

J09 : 4P/23 : PO

Pollution and Oganic Matter in Recent Lagoonal Environments (Sebkha Ariana, Tunisia)

Joelle Duplay (jduplay@illite.u-strasbg.fr)¹,

Luis Martinez (martinez@illite.u-strasbg.fr)¹,

Fadila Darragi²,

Monique Schuler (mschuler@illite.u-starsbg.fr)¹ &

Besma Ben Henda²

¹ CGS 1 rue Blessig 67084 Strasbourg Cedex, France

² University of Tunis, Tunisia

The Sebkha Ariana located at the northern part of Tunis is an example of recent lagoonal system submitted to urban development which compromises its natural equilibrium. It is important to know the geochemical evolution and the effect of the pollution from neighbouring urban environments in order to manage environmental protection. The aim of this study is to point out how organic matter traps the heavy elements in these recent sediments. Indeed, living or fossile organic matter may transport or trap a large number of elements including heavy metals.Thus natural lacustrine sediments record every chemical change from neighbouring areas and the chemical composition of polluated sediments is then very different from the background composition of continental, marine and lacustrine sediments (Van Krevlen diagram).

Results: Thirty sediment samples were taken across the Ariana basin following NW-SE and N-S transects. The core depth is between 2 and 5 meters. The laterally and vertically evolution of organic carbon (OC) in the sekha sediments was analysed:

- a progressive increase in total organic matter through the profile was observed until 2 meters depth. This suggests a better preservation with depth i.e. with time as sediments change from oxidizing to anoxic conditions. The upper part of profile is enriched in gypsum and contains minor amount of COT (0,30%).- in the vicinity of basin continental shore line, the COT contents decreases with depth. This is attributed to the preservation of organic matter by fresh detritic fractions and the low activities of aerobic and anaerobic bacterias at basin surface.

Organic matter elements: Samples near the waste disposal were choosen for their high concentration in organic matter. X-ray diffraction point out that these o.m. -rich sediments are also rich in clay minerals. O. m. was separated by dissolution of silicate and carbonate minerals and identified by optic microscopy. The different components are essentially amorphous o.m. (originating from the sedimentary basin) and minor amounts of figured biogenic compounds either continental (spores, pollens, cuticles, ligneous fragments) or lacustrine (algal spores) and marine (dinocysts).

Pyrite was detected by microprobe analyses what gives evidence of anoxic conditions in these o. m. rich sediments. The amorphous organic matter is often sulphur-rich but poor in heavy metals. Some isolated particles showing an amorphous o.m. morphology are enriched in Ti which suggests that this element was trapped by o.m.

Ben Henda B., Mémoire de DEA, Université de Tunis II, 128 p., (1997).

J09 : 4P/24 : PO

A Preliminary Model for the Occurrence of Radon-Prone Areas in Central Portugal

A. J. S. C. Pereira (apereira@cygnus.ci.uc.pt),

L. J. P. F. Neves (lneves@cygnus.ci.uc.pt) &

M. M. Godinho

Departamento de Ciencias da Terra, Universidade de Coimbra, Coimbra, Portugal

Previous studies carried out in Central Portugal have shown the importance of geological factors, namely lithology and fractures, on the distribution of soil-gas radon concentrations (Pereira et al., 1998). In Central Portugal two broad geological units have generally been considered: the Hesperian Massif, mostly made of hercynian granitoids and metamorphosed schists and graywackes, locally covered with thin Cretaceous to Tertiary detritic deposits, and the Meso-Cenozoic sedimentary Western Borderland, in most part of detritic and carbonate nature. U-rich ores are relatively common in the Hesperian Massif and are spatially related with the Hercynian younger granites. These U mineralizations are often composed of U secondary minerals concentrated in fractures, typically at a depth of no more than 50 meters. Thus, localized potentially high radon sources can occur. Soil-gas radon emanometric measurements in Central Portugal have shown that the background of radon concentrations in rocks is generally less than 150 kBq.m^-3. However, a large number of small areas (up to a few thousand square meters) with very high radon content (frequently above 1000 kBq.m^-3) were identified. Post-tectonic porphyritic biotite granite is the main lithology in these areas, but small metamorphic enclaves, up to a few thousand square meters, can be also found. High radon concentrations in soils are structurally controlled, showing a preferential relation with the N30ºE fault system. Small-scale studies, carried out in some of these radon-prone areas, show that: a) they are usually located in a band along N30ºE faults; b) their width is quite variable, ranging from 5 to 200 meters; c) radon content is ca. 1000 kBq.m^-3 in average, and; d) the highest values observed, up to 12 800 kBq.m^-3, can be linked with other fractures, namely the N60-80ºE faults, which are conjugate of the N30ºE system. This preliminary radon distribution model can provide useful constraints for radon risk mapping purposes, specially in small-scale studies of urban areas.

Pereira AJSC, Neves LJPF & Godinho, MM, IV International Workshop on the Geological Aspects of Radon Risk Mapping, Czech Geological Survey, (1998).

J09 : 4P/25 : PO

Geochemical Modelling of Cadmium Species in Soil Solution on the Natural Environmental Condition

Marta Svetina (marta.svetina@guest.arnes.si)¹,

Simon Pirc (simon.pirc@ntfgeo.uni-lj.si)² &

Margot Isenbeck-Schröter

(missch@geoch.uni-heidelberg.de)³

¹ ERICo Velenje, Velenje, Slovenia.

² Dep. Geol., University Ljubljana, Ljubljana, Slovenia.

³ Inst. Environ. Geoch., Ruprecht-Karls University, Heidelberg, Germany.

There is a choice of various computer programs available for modelling the geochemical reactions in soil. PHREEQE is useful to deal with problems that occur in surface and ground water hydrogeochemical studies (Parkhurst et al., 1990). Kent et al. suggest that modelling of the transport of redox-sensitive species by assuming thermodynamic equilibrium is likely to have limited success (Kent et al., 1994), whereas Postma et al. (1996) used modelling of partial equilibrium to interpret iron and sulphate reduction processes in groundwater systems. Results of batch studies in oxic systems could be explained using PHREEQE calculations in the case of Cd, Zn, and Cu (Fic et al., 1988).

This paper presents a test of PHREEQE applied, to on explanation of behaviour and fate of atmospheric Cd in the soil. Analysis of precipitations in the Salek valley (Slovenia) showed increased cadmium levels in the urban area, also significantly above typical levels for industrial precipitations (16.2 µg/l) (Svetina et al., 1996). With computer modelling assistance we tried to establish what happens to Cd after its percolation through soil layer and mixing with the existing soil solution. Owing to their igneous origin associated with moderately low pH, the soils represent disadvantageous environment for Cd bioaviability. As input for the geochemical model program the measured concentrations of Cd, several other heavy metals and major cations and anions in precipitation and soil water were taken. By using the step of mixing two solutions the speciation of Cd in equilibrium solutions were calculated. The soluble and insoluble Cd species in soil solution at different pH values were also estimated. In soil solution after mixing with rain water at real pH conditions (pH 5) predominates the Cd²⁺ ion (90%). The remaining 10% are insoluble species, above all CdSO₄, obviously due to large amount of SO₄^2- in precipitation. At simulated pH 9 in soil solution the Cd²⁺ ion diminishes to 60% on account of insoluble CdCO₃.

Fic M, Isenbeck-Schröter, 1988, J. Contam., Hydrology, 4, 69, (1988).

Kent DB, Davis JA, Anderson LC D, Rea BA 1994, Water Resour. Res. , 30, 1099, (1994).

Parkhurst DL, Thorstenson DC, Plummer LN, Water Resour. Invest. R, 80, 159, (1990).

Postma D, Jakobsen R, 1996, Geochem. Cosmochem. Acta, 60, 3169, (1996).

Svetina M, Pirc S, Proceed. Sym. Envir. Cont, 712, (1996).