Biogeochemical control on the temporal variability of trace element concentrations in the Oubangui river (Central African Republic)

Dissolved Ba, Cd, Co, Mn, Mo, Ni, Rb, Sb, Sr, U and V were measured in the Oubangui river (Central African Republic) during a complete flood period. The dissolved concentrations vary by factors ranging from 1.4 to 8.2 as a function of river discharge : Sr, Ba, Rb and Mo concentrations decrease with rising stage ; Ni, U, Sb, Cd, V and Mn concentrations increase with rising stage. These distributions are explained by a mixing of quick flow, mostly surface runoff with delayed flow, mostly groundwater. The dual origin of stream waters is demonstrated by the major element ratios, which are close to a silicate end-member during the high-flow period and trend towards a carbonate end-member during the low-flow period. Moreover, geological heterogeneities in the Oubangui basin may play a role in the variation of concentrations observed at the basin outlet. The previously indicated presence of a subsurface carbonate sequence in the lower part of the basin is confirmed. Cd, V, Mn and Co show peak concentrations during decreasing stage. We suggest that biological processes such as release from phytoplanktonic material and dissolution of oxides or carbonate phases may explain this maximum. (Résumé d'auteur

Dilution versus pollution in watercourses affected by acid mine drainage: a graphic model for the Iberian Pyrite Belt (SW Spain)

The aim of this study was to chemically characterize the water quality impacts of the 88 acid mine drainage (AMD) generating mines in the Spanish sector of the Iberian Pyrite Belt (IPB). This was necessary because the Water Framework Directive of the European Union and the hydrological plans of the Tinto, Odiel, and Piedras river basins require that water quality be improved enough to allow at least some of the rivers in the IPB to sustain healthy fish populations by 2027. The results indicate a clear decrease in metals, arsenic, and sulfate concentrations and increased pH between the AMD-sources and the river channels.info:eu-repo/semantics/publishedVersio

Harmful Elements in Estuarine and Coastal Systems

Estuaries and coastal zones are dynamic transitional systems which provide many economic and ecological benefits to humans, but also are an ideal habitat for other organisms as well. These areas are becoming contaminated by various anthropogenic activities due to a quick economic growth and urbanization. This chapter explores the sources, chemical speciation, sediment accumulation and removal mechanisms of the harmful elements in estuarine and coastal seawaters. It also describes the effects of toxic elements on aquatic flora and fauna. Finally, the toxic element pollution of the Venice Lagoon, a transitional water body located in the northeastern part of Italy, is discussed as a case study, by presenting the procedures adopted to measure the extent of the pollution, the impacts on organisms and the restoration activities

La navigation de plaisance : une source de pollution importante des écosystèmes marins côtiers souvent méconnue des plaisanciers. L’exemple de Port-Camargue

International audienc

Lake Robert data Elbaz-Poulichet et al., 2019 QSR

The data set contains the data and the supplementary information for the manuscript: A 10,000-year record of trace metal and metalloid (Cu, Hg, Sb, Pb) deposition in a western Alpine lake (Lake Robert, France): deciphering local and regional mining contamination Françoise Elbaz-Poulichet, Stéphane Guédron, Develle Anne-Lise, Rémi Freydier, Vincent Perrot, Magali Rossi, Christine Piot, Sophie Delpoux, Pierre Sabatier Manuscript number JQSR_2019_56

A reassessment of trace metal budgets in the western Mediterranean Sea

Workshop on Transport, Fate and Impact of the Trace Chemical Pollution Load in the Marine Environment, BARCELONA, SPAIN, SEP 29-OCT 01, 1999This paper presents inputs and output fluxes of dissolved metals (As, Cd, Co, Cu, Fe, Mn, Ni, Ph and Zn) into and out the Western Mediterranean. These flux estimates are based on the most recently published concentrations and fluxes for the atmosphere, the rivers and the straits, Comparison of the different sources shows the predominance of the inputs through the straits over other sources. The river input is smaller than the atmospheric input except for As. For all elements except Fe, output flux and input flux are balanced; iron budget indicates transfer from the dissolved to the particulate phase. (C) 2001 Elsevier Science Ltd. All rights reserved