International audience

International audience

International audience

41 ref. doi:10.1016/j.envpol.2003.12.023 | International audience | Metal distribution patterns in superficial soil horizons of agricultural land affected by metallurgical point-source pollution were studied using optical and electron microscopy, synchrotron radiation and spectroscopy analyses. The site is located in northern France, at the center of a former entry lane to a bunker of World War II, temporarily paved with coarse industrial waste fragments and removed at the end of the war. Thin sections made from undisturbed soil samples from A and B horizons were studied. Optical microscopy revealed the occurrence of yellow micrometer-sized (Ap horizon) and red decamicrometer-sized spherulites (AB, B1g horizons) as well as distinct distribution patterns. The chemical composition of the spherulites was dominated by Fe, Mn, Zn, Pb, Ca, and P. Comparison of calculated Zn stocks, both in the groundmass and in spherulites, showed a quasi-exclusive Zn accumulation in these neoformed features. Their formation was related to several factors: (i) liberation of metal elements due to weathering of waste products, (ii) Ca and P supply from fertilizing practices, (iii) co-precipitation of metal elements and Ca and P in a porous soil environment, after slow exudation of a supersaturated soil solution in more confined mineral media.

International audience

Immunotoxicological effects of environmentally relevant concentrations (10, 23, 50, 100 μg/l) of atrazine were studied in Lymnaea stagnalis. Individual hemolymph sampling was performed at 0, 24, 48, 72, 96, 168, 336, 504 and 672 h during exposure. Every atrazine concentration induced a significant increase in the mean number of circulating hemocytes, without any concentration–response relation. A peak (1.6-fold increase) of hemocyte density was observed after 96 h of exposure. After 504 h, the number of hemocytes remained higher only in the snails exposed to the two highest concentrations. Granulocytes contributed most to the increase in hemocyte density in herbicide-exposed snails. Both short- (24 and 96 h) and long-term (504 h) exposures resulted in significant inhibition of hemocyte phagocytic activity upon E. coli. Over the long-term, phagocytosis recovered for the two lowest concentrations. After 504 h of exposure, every herbicide level resulted in a significant reduction of reactive oxygen species production in E. coli-stimulated hemocytes, which was not observed for short-term exposures.

International audience | The aim of this study is to assess the annual balance of the fluxes of Cd, Cu, Ni, Pb and Zn within different cropping systems, in an experimental site located near Versailles, France. Four fluxes through the cultivated horizon were considered to assess the annual heavy metal balance in these systems: 1) atmospheric depositions, 2) fertilisers as inputs, 3) crops and 4) leaching water as outputs. The water mass flow was estimated with a model (CERES) while the other parameters were actually measured through field sampling. Some large uncertainties are related to analytical detection limits, specially for Pb which presents very low concentrations in nitrogen fertilisers, in crops and in soil solution. Cd was also close to the detection limits in atmospheric deposition and in soil water, and Zn could not be analysed in soil solution. Nevertheless, the following trends clearly appeared: firstly, atmospheric deposition is the major input way of Cu, Ni, Pb and Zn in the soil, whatever the cropping system, whereas Cd is introduced mainly by fertilisers. Secondly, the uptake of heavy metal by wheat is generally larger than by a pea culture, except for Ni. Finally, the global pattern shows an accumulation of Cd, Ni and Pb in the cultivated horizon while Cu decreased. The annual balances, during the cropping year 2001–2002, represented about 0.33, −0.024, 0.014 and 0.014% of the actual stocks in the cultivated horizon, of Cd, Cu, Ni, and Pb, respectively.