Benthic exchanges of sedimentary metals (Cd, Cu, Fe, Mn, Ni, Pb and Zn) in Deûle River (Northern France)

International audienceExperiments were performed on the Deûle River (Northern France), which is strongly polluted by smelting plants, in the aim to investigate the influence of diagenetic processes and benthic macro-faunal activity on trace metal (Cd, Cu, Ni and Zn) and major metal (Fe, Mn) exchanges occurring at the water-sediment interface. Diffusive metal fluxes were determined from pore water metal concentration gradients measured in sediment cores. Benthic metal fluxes were evaluated using incubation chambers under dark conditions, and by further examining key variables (O2, CO2, redox potential and pH) affecting metal release and sequestration processes. As a whole, it was demonstrated that benthic fluxes were strongly dependent upon medium oxygenation and generation of colloidal iron oxides and hydroxides at the overlying water-sediment interface, raising the possibility of trace-metal adsorption and (co)precipitation

Impacts of metal contamination in calcareous waters of Deûle river (France) : water quality and thermodynamic studies on metallic mobility

International audienceTo evaluate adverse impacts of metal pollution originating from smelting activities on the aquatic ecosystem of DeA >> le river in northern France, water samples were collected from five selected stations along a contaminated region of this river (during two surveys: April-June 2005 and April-May 2007). All samples were analysed using inductively coupled plasma (ICP) atomic emission spectroscopy and/or ICP-mass spectrometry. Both the concentrations of dissolved and particulate elements were determined, and analytical data were compared with national and international water/particle quality guidelines as well as with some values reported in the literature for polluted rivers. For all the metals studied (i.e. Cd, Cr, Cu, Mn, Ni, Pb and Zn), our investigations showed that the effects of the dissolved phase on this aquatic medium were weak, according to water quality status established by US Environmental Protection Agency, USEPA (1994, 1999). Conversely, the levels of metals in suspended particulate matter were found to be much higher than local background contents and natural reference levels in French catchments. These levels were further quantified as "serious" contamination, i.e. above the "red" range that was previously elaborated by most existing metal-contamination scales in French basins of similar geology. The affinity of these metals for the particulate phase in DeA >> le waters follows the order: Cd > Cr > Pb > Zn = Mn > Cu > Ni. The trace metals released from anthropogenic activities were found to be partly bound to the reactive particulate phase, calcite, which is sensitive to physico-chemical variations occurring in the river ecosystem. To appraise the risk of ecotoxicity by metals, predictions on the ability to release metallic pollutants from calcite into waters were made successfully by testing three equilibrium geochemical speciation models (JCHESS, VISUAL MINTEQ and WINHUMIC) in which soluble organic matter was taken into account. Calculations showed that metal-water-calcite systems in DeA >> le River are close to thermodynamic equilibrium with generation of solid solutions, Me alpha Ca(1-)alpha CO(3), by (co)precipitation and/or adsorption reactions. On the basis of results mentioned here, more measurements of river chemistry and assessments of predictive capabilities of chosen water-quality guidelines with time would be developed in aquatic and calcareous areas for controlled dredging operations or other treatment engineering works

Water-Quality Diagnosis and Metal Distribution in a Strongly Polluted Zone of Deûle River (Northern France)

Water Air Soil Poll 405ZA Times Cited:8 Cited References Count:49International audienceUsing ICP-AES and ICP-MS, several metals were analyzed in water and suspended particulate matter (SPM) samples collected under normal turbidity conditions at various stations from DeA >> le river (in northern France) to assess the impact of a former smelting plant on the fate of particulate elements and on the water quality in this aquatic environment. Compared to their regional background, particulate Pb, Zn and Cd were found to be most enriched, suggesting anthropogenic inputs from bed sediments into the water column mainly due to physical disturbances induced by barges traffics. Conversely, no significant enrichments of particulate metals such as Cu, Cr and Ni were observed in DeA >> le SPM. Characterization of SPM with analyses of mineralogical and chemical compositions-using environmental scanning electron microscopy equipped with an energy dispersive X-ray spectrometer (ESEM/EDS)-indicated the presence of micro-specimens attributed to anthropogenic minerals, mostly PbS and ZnS. The calculated enrichment index (or the geoaccumulation index, I (geo)), enrichment factor (EF) and the partition coefficient (K (d)) confirmed that SPM was strongly polluted in cadmium, lead and zinc, moderately polluted in copper and unpolluted in chromium and nickel. Based on the analytical data obtained for SPM from the BCR (European Community Bureau of Reference) sequential extraction scheme, it was concluded that: (i) the reducible phases were largely more important for the binding of Pb and Cd than that of Zn and Ni and in a lesser extent Cu and Cr; (ii) copper was found to be mostly associated with the sulphides/organics fraction; (iii) chromium with a lithogenic origin was extracted in the largest percentage in the residual phase; and (iv) zinc was bound to the exchangeable-carbonate phase in the largest percentage in the particles analysed, followed by nickel and cadmium, suggesting that these metals might be easily remobilized if changes in environmental conditions would occur

Determination of the scavenging coefficients of gaseous and particulate chlorine 36 by rain

International audienc

Determination of the scavenging coefficients of gaseous and particulate chlorine 36 by rain

International audienc

Determination of the scavenging coefficients of gaseous and particulate chlorine 36 by rain

International audienc

Determination of the scavenging coefficients of gaseous and particulate chlorine 36 by rain

International audienc

Monthly variation of trace metals in North Sea sediments: from experimental data to modeling calculations

Seasonal variation in trace metal contamination in surface sediments was studied through high resolution profiles assessed monthly by DGT probes in muddy sediments of the North Sea. General parameters such as pH, temperature, dissolved oxygen and sulfides were also recorded to estimate their role in the speciation of trace metals. Experimental data were included in a thermodynamic equilibrium model to calculate major (geo)chemical processes at the water-sediment interface and to predict the fate of the trace metals in case of (physico-)chemical changes. Results showed lowest Fe, Co, Ni and Cd concentrations in summer, which are most probably due to the very high sulfide concentrations according to our theoretical calculations. Cu and Pb behavior were found to be less influenced by sulfides, since they are also strongly associated to organic matter. The whole set of results clearly indicated that metal speciation in these sediments is controlled by sulfides and OM contents