Les vermiculites hydroxy-alumineuses du Massif Armoricain (France) approches mineralogique,microanalytique et thermodynamique

Hydroxy-aluminous vermiculites have been identified in samples of soils and weathering products from the Armorican Massif of France by a combination of mineralogic, microanalytic and thermodynamic techniques.The hydroxy-aluminous vermiculites behave originally as intergrades between vermiculites sensu stricto and chlorites. The interlayered aluminum responsible for the intergrade behaviour cannot be removed by means of ammonia oxalate but can be by sodium citrate. After such a treatment the mineral loses its intergrade behaviour and acquires the behaviour of sensu stricto vermiculite. The extracting solution contains 12 mg of aluminum per gramme of clay in the studied sample.Further evidence on the nature of the aluminous vermiculites follows from microanalysis in situ. Such in situ quantitative microanalysis makes it possible to establish the structural formulae of minerals. This technique has been applied to weathering products of micas. The data obtained indicate that these weathering products are vermiculites and that one part of the aluminum must be in interlayer positions.The thermodynamic study of equilibrium between waters and aluminous vermiculites needs to be set in a multidimensional space Rⁿ. In such space the chemical composition of a water is represented by one point. Waters in equilibrium with a given mineral are situated in a (n ? 1) dimension hyperplan. For a given population of waters and minerals a program can calculate water-hyperplan distances. The use of this program shows that one part of the examined waters is compatible with the equilibrium with aluminous vermiculites.     

Deposition of Copper in the Eutrophic,Submontane Dobczyce Dam Reservoir (Southern Poland) – Role of Speciation

In order to better understand Cu behaviour in the submontane, eutrophic Dobczyce dam Reservoir (southern Poland), speciationmeasurements of Cu in the water and the sediment were conducted. To investigate the partitioning of Cu in the main components ofthe sediment, a scheme of VI-step sequential extraction was used.In addition, other physical and chemical parameters of the water,such as temperature, pH, dissolved O₂, nutrients, and suspended particulate matter were determined. Copper content in the water and the sediment was low (1.1–7.4 μg L^-1 and 5.5–45.4 μg g^-1, respectively). In the water Cu was usually present in the dissolved state (with the exception ofthe near-bottom water). This was probably the main reason of itssmall accumulation (cumulation coefficient K = 10687.5) in the sediment of the Dobczyce Reservoir. The seasonal variations inCu contents in the dissolved and particulate phases as well as observed correlations with the physico-chemical parameters of thewater are discussed. In the sediment Cu occurred mainly in astrongly bound form. Most Cu found there was in the moderatelyreducible phase and residual. Therefore, copper (re-)mobilization from the sediment to the water was probably not of importance.     

The Bioaccumulation Performance of Reeds and Cattails in a Constructed Treatment Wetland for Removal of Heavy Metals in Landfill Leachate Treatment (Etueffont,France)

The aim of this study was to evaluate and compare the capacities of cattail (Typha latifolia L.) and reed (Phragmites australis L.) for heavy metal storage in the phytomass. Samples were studied in the fourth of the four interconnected natural lagooning basins of a constructed treatment wetland, developed as an integrated pilot system for the treatment of leachates in a domestic landfill site at Etueffont (Territoire de Belfort, France). The efficiency of the lagooning system was evaluated through physical and chemical parameter measurements over a period of three seasons. Anion/cation and heavy metal concentrations were sampled and analyzed in water flowing into and out of the lagooning basin. Simultaneously, reed and cattail biomass samples (roots/rhizomes, shoots) were collected at both inflow and outflow, and the biomass characteristics were determined. The average above-ground biomass of T. latifolia and P. australis varied, respectively, from 0.41 to 1.81 kg DW m⁻² in the fall, 0.31 to 1.34 kg DW m⁻² in winter, and 0.38 to 1.68 kg DW m⁻² in spring, with significant seasonal variations. The greatest mean concentrations of heavy metals were found in the below-ground plant parts of the two species during the spring season. The average standing stock of heavy metals was higher in the below-ground than in the above-ground phytomass, whatever the season. With the exception of nickel, heavy metal concentrations in the inflow were correlated to the plant content of both species.     

Sources,distribution and transport of atrazine in the St. Lawrence River (Canada)

A Lagragangian sampling strategy was chosen in order to evaluate the main sources of atrazine to the St. Lawrence River, Canada. Lagrangian sampling was carried out during six sampling trips, one at every hydrological season except winter from the period of the summer low flow of 1990 to the spring freshet of 1992. Loadings of atrazine are subject to annual variations induced by different climatic and hydrological conditions. Loadings of atrazine are also dependent on season. Results emphasize the persistence of atrazine as it was found in significant amounts at the end of the growing season and in the following spring. Variations in loadings of atrazine along the river as well as the lateral distribution of atrazine concentrations in a downstream direction suggest inputs within the province of Quebec. The Great Lakes and the international corridor of the St. Lawrence River contribute 68% of the loading exported to the estuary, while Quebec tributaries account for 8% of the inputs. The inportance of the unmeasured sources within the river itself (24%) stresses the need for further research on internal processes and contaminant transfer in the aquatic environment.     

Heavy Metal Concentration Survey in Soils and Plants of the Les Malines Mining District (Southern France): Implications for Soil Restoration

Mining activities generate spoils and effluents with extremely high metal concentrations of heavy metals that might have adverse effects on ecosystems and human health. Therefore, information on soil and plant metal concentrations is needed to assess the severity of the pollution and develop a strategy for soil reclamation such as phytoremediation. Here, we studied soils and vegetation in three heavily contaminated sites with potential toxic metals and metalloids (Zn, Pb, Cd, As, TI) in the mining district of Les Malines in the Languedoc region (southern France). Extremely high concentrations were found at different places such as the Les Aviniéres tailing basins (up to 160,000 mg kg^?C1 Zn, 90,000 mg kg^?C1 Pb, 9,700 mg kg^?C1 of As and 245 mg kg^?C1 of Tl) near a former furnace. Metal contamination extended several kilometres away from the mine sites probably because of the transport of toxic mining residues by wind and water. Spontaneous vegetation growing on the three mine sites was highly diversified and included 116 plant species. The vegetation cover consisted of species also found in non-contaminated soils, some of which have been shown to be metal-tolerant ecotypes (Festuca arvernensis, Koeleria vallesiana and Armeria arenaria) and several Zn, Cd and Tl hyperaccumulators such as Anthyllis vulneraria, Thlaspi caerulescens, Iberis intermedia and Silene latifolia. This latter species was highlighted as a new thallium hyperaccumulator, accumulating nearly 1,500 mg kg^?C1. These species represent a patrimonial interest for their potential use for the phytoremediation of toxic metal-polluted areas.     

Polycyclic aromatic hydrocarbons in soils of Vasilievsky Island (St. Petersburg)

The composition and accumulation patterns of priority polycyclic aromatic hydrocarbons (PAHs) in soils of Vasilievsky Island in Saint Petersburg were studied. Concentrations of benzo[a]pyrene were found to exceed maximum permissible concentrations in all the samples, and the maximum recorded concentration exceeded the MPC by 50 times. Concentrations of other PAHs also exceeded the background values. The main soil pollutants were found to be fluoranthene, pyrene, benzo[b]fluoranthene, benzo[a]pyrene, and benzo[g, h, i] perylene, the part of which in the total content of PAHs was 65–80%.     

Surface cracking and aggregate formation observed in a Rendzina soil,La Touche (Vienne) France

A one-cycle field wetting and drying experiment was conducted in order to observe pore space developed in a cultivated Rendzina soil due to surface cracking and to soil aggregate formation at 3-cm depth. Image analysis of 2D representations of pore size distribution and fractal analysis of the spatial distribution of the pores indicates that pore space due to surface cracking does not develop in the same manner as does that formed in the aggregation processes. Both pore-size distribution and fractal dimension vary in different ways at the soil–air interface and at 3-cm depth as drying progresses. Surface cracking occurs as a two-step process where total crack length increases until a maximum and then the cracks widen. Fractal dimensions appear to change as pore space develops. Pores developed when aggregates form show a more continuous process of development of pore sizes with a constant fractal dimension as porosity increases.     

Copper and arsenic (enargite) contamination of soils along a toposequence in Chinkuashih,northern Taiwan

This study investigates the species of Cu and As (enargite) residues present in soils of the Chinkuashih area, northern Taiwan. Two pedons, on the shoulder and footslope along a toposequence, were examined for their metal partitioning and geochemical origins. The bulk soils were analyzed by sequential extraction combined with mineralogical analyses, including X-ray diffraction (XRD) and scanning electron microscopy ∕ energy dispersive spectrometer (SEM ∕ EDS) analyses. Soil pH ranged from 4.23 to 4.91 with low base saturation, and the soils can be classified as fine, mixed, thermic, Typic Kandiudults. Mineralogical study indicated that enargite and pyrite particles mainly coexisted in silt and sand fractions, particularly in lower soil horizons of the footslope, showing high contents of Cu and As. Kaolinite and illite were dominant minerals in clay fractions. The footslope accumulated more total Cu and As than that of shoulder pedon. The sequential extraction experiments resulted in high proportions of Cu remaining in residual fractions, while the most of As was bound in amorphous Fe and Al oxyhydroxide fraction. The risk analyses of Cu and As (enargite) contamination in soils of the Chinkuashih area merits further study.     

Sediment Accumulation of Nutrients (N, P) in the Eastern Gulf of Finland (Baltic Sea)

Dry weight (DW), ignition loss (IL) and concentrations of total nitrogen (TN) and total phosphorus (TP) of the sediment surface layer (0 to 10 cm, 1 cm slices) were analyzed from 20 sites in the eastern Gulf of Finland. The distance of the sampling sites from the mouth of the River Neva explained the nutrient concentrations of the sediments well, while the effect of water depth was negligible. The increase of TN and the decrease of TP along the transect from the river mouth towards the open Gulf were caused by the diminishing share of allochthonous material supplied from the River Neva. The mean TN concentration of the different accumulation areas was about 40 % higher in the sediment surface than in the deeper layer (9 to 10 cm). The corresponding difference for TP varied from 53 to 56 %. The results suggest considerable netflux of nutrients from sediment to water. The net sediment accumulation of nutrients were estimated as 6.0 g m-2 a-1 of N and 1.7 g m-2 a-1 of P corresponding 22 000 t a-1 of N and 6 100 t a-1 of P for the whole eastern Gulf.     

Spatial distribution of earthworm species assemblages in a chalky slope of the Seine Valley (Normandy, France)

The aim of this study was to characterize the spatial distribution of earthworm species assemblages on a chalky slope of the Seine Valley (Upper Normandy, France), with contrasting vegetation cover representing the different stages of a typical post-pastoral secondary succession. Samples were hand sorted in a spatially explicit design consisting of a regular grid. A Principal Component Analysis was performed to identify species associations. Maps of the factorial coordinates of sample points together with geostatistical analysis were used to describe the spatial structure of the assemblages. The first axis of the PCA opposed points with high density to others with low. The resulting spatial structure was significant. The second axis opposed points where species assemblages were dominated either by an endogeic (Allolobophora chlorotica), an anecic (Aporrectodea longa) and an epigeic species (Lumbricus castaneus) to others dominated by two endogeics (Aporrectodea rosea and Octolasium cyaneum). A significant spatial structure was detected, with alternating patches characterised by one species assemblage or the other. The location of these structures did not seem to be clearly associated with a specific vegetation type. These results  revealed a complex determinism of species co-occurrence at small spatial scale.     

Regional and Seasonal Inputs of Mercury into Lake St. Pierre (St. Lawrence River), a Major Commercial and Sports Fisheries in Canada

Lake St. Pierre (LSP), constituted of a 120 km² stretching of the St. Lawrence River (Southern Québec), hosts the largest freshwater fishery industry in Canada. The lake drains, through its main tributaries, an important area of agrarian land and was subjected to intense industrial activities in the past century. In this paper, we present (1) an estimation of the seasonal aquatic mercury (Hg) inputs to LSP from the St-Lawrence River and two major tributaries; (2) a reconstruction, by the analysis of sediment cores, of the historic inputs of Hg into LSP and in a large riparian wetland, Bay St. François. Our results indicate that the aquatic Hg inputs to LSP (290 kg Hg between April 2003 and April 2004) are moderately elevated with most of the inputs occurring from the St. Lawrence River, either in spring or early winter, during high flow episodes. The sediment profiles suggest a recent decrease in Hg inputs, likely attributable to improvements of industrial practices. The observed perturbation of the surface sediments give evidence of an active hydrodynamic regime, suggesting that LSP could only act as a transitory system for suspended sediment and Hg, with seasonal accumulation and recurrent re-suspension resulting from changes in the hydrodynamic regime. Finally, we observed positive MeHg fluxes from the sediment to the water at different seasons in Bay St. François. However, Hg levels in fish like walleyes of LSP are reported to be low, which could be explained by faster fish growth rates following in part intense fishing pressure in LSP.     

Relationships between Collembola,soil chemistry and humus types in forest stands (France)

Soil samples were taken under four tree species in various forest sites located in southern France. For each sampled A horizon of the soil profile, pH, organic matter content, C:N ratio and amounts of exchangeable cations (K, Ca, Mg) were measured, and collembolan fauna was extracted using Berlese-Tullgren funnels. A total of 78 species representing 11 families and 47 genera were identified. The relationships between Collembola and soil parameters were determined by co-inertia analysis which corresponds to the simultaneous Correspondence Analysis of the collembolan data table and the Multiple Correspondence Analysis of the environmental data table. The analysis revealed that the distribution of 10 species was related to pH, organic matter content via C and N and to base cations (K, Ca, Mg). Samples, linking these collembolan species and chemical parameters, were clustered according to humus forms. Collembola seem to be linked closer to the physical structure of humus than to its chemical parameters. Their specific contribution to pedogenetic processes as yet remains to be clarified.     

Relationship between soil erodibility and topsoil aggregate stability or carbon content in a cultivated mediterranean highland (Aveyron,France)

Abstract

In the Rougiers de Camarès area (in the south of France), hillslopes are very susceptible to water erosion. This is the result of physical features (steep slopes, soft bedrocks, thin soils), climatic aggressiveness (frost, storms), as well as farming systems (intensive tillage, short crop cycles, land consolidation). The objective of this work was to study the relationships between soil erodibility, macroaggregate stability, and carbon content of surface samples (0–10 cm), in a Rougiers Entisol (Lithic Udorthent) under various management practices (flat or raised moldboard ploughing, superficial tillage, direct drilling, with inputs in the form of mineral fertilizers or sheep manure). The soil erodibility was assessed by field rainfall simulation (60 mm h^‐1) on manually retilled bare dry soil; water‐stable macroaggregation (>0.2 mm) was assessed by wet‐sieving, after immersion in water. Runoff, turbidity and soil losses were linked to water‐stable macroaggregation and carbon content in the 0–10 cm layer. During the first 30 minutes of rainfall, runoff and soil losses were closely correlated with topsoil initial water‐stable macroaggregation, but not with topsoil carbon content (although there was a correlation between water‐stable macroaggregation and carbon content). At the end of the rain (runoff steady state), turbidity and soil losses were closely correlated with topsoil carbon content, and to a lesser extent, with water‐stable macroaggregation. Water‐stable macroaggregation (which prevents crusting) and carbon content (which has an effect upon liquidity limit, among others) were thus important determining factors of erodibility for the studied soil. The influence of management practices on soil erodibility was therefore dependent upon their effects on these factors.     

Acute Copper Toxicity and Acclimation to Copper Using the Behavioral Endpoint of Shoaling,in the Least Killifish (Heterandria formosa)

Water, Air, &; Soil Pollution - The release of heavy oil from laboratory-contaminated sediments was studied in a series of kinetic and equilibrium experiments. The kinetic curves could be...     

Flux of Benzo(a)pyrene to the Ground Surface and its Distribution in the Ecosystem

Benzo(a)pyrene (BP) has been investigated in bulk atmospheric deposition, moss, needles of pine and some species of vascular plants. At two remote Lithuanian sites, for 1990-1995 the flux of benzo(a)pyrene from the atmosphere to the ground surface varied between 0.3 to 4.8 μg-2 mo-1. Consequently the territory of Lithuania (65,000 km2) yearly was exposed to 624-2574 kg of carcinogen. The distribution of BP in soil and various vascular plant tissues (Trifolium tepens, Elitrygea repens, Thymus serpyllum) indicates that benzo(a)pyrene is assimilated by flora. The concentration of BP is different in various organs of vascular plants and mostly depends on the degree of soil pollution. More than 300 samples of moss, mostly Hylocomium splendens and Pleurozium schreberi were analyzed for BP. From 3.1 to 896.0 μg kg-1 of BP were measured in the moss samples. The flux of BP to the ground surface correlates well with its concentration in moss. A map of BP flux across Lithuania was created.