Seasonal variations and annual fluxes of arsenic in the Garonne, Dordogne and Isle Rivers, France

Daily measurements of water discharges and suspended particulate matter (SPM) concentrations and monthly analyses for arsenic were conducted from 1999 to 2005 on the Garonne, Dordogne and Isle Rivers, the three main tributaries of the Gironde Estuary, France. Despite the known historical polymetalli...

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Bibliographic Details
Published in:The Science of the total environment 2007-02, Vol.373 (1), p.196-207
Main Authors: Masson, Matthieu, Schäfer, Jörg, Blanc, Gérard, Pierre, Anschutz
Format: Article
Language:English
Subjects:
Applied sciences
Arsenic
Arsenic - analysis
Brackish
Continental surface waters
Earth sciences
Earth, ocean, space
Empirical model
Engineering and environment geology. Geothermics
Environmental Monitoring
Exact sciences and technology
France
Freshwater
Mass balance
Natural water pollution
Pollution
Pollution, environment geology
River
Rivers - chemistry
Seasonal variations
Seasons
Water Pollutants, Chemical - analysis
Water treatment and pollution
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Summary:Daily measurements of water discharges and suspended particulate matter (SPM) concentrations and monthly analyses for arsenic were conducted from 1999 to 2005 on the Garonne, Dordogne and Isle Rivers, the three main tributaries of the Gironde Estuary, France. Despite the known historical polymetallic pollution affecting the Lot–Garonne River system, the highest As concentration level was observed in the Isle River. This was explained by the geological context and various Au/As deposits in this watershed. In the three studied rivers, dissolved As concentrations showed important seasonal variations with maximum values in summer. The dissolved As concentrations were closely related to water temperature and their increase in spring/summer appeared to be induced by water temperatures above ∼ 15 °C, independently from discharge. The reduction of As(V) to more soluble As(III) and/or destruction of solid As carrier phases by micro-organisms could explain this observation, suggesting that temperature-dependent biogeochemical processes play an important role in controlling As partition and speciation in fluvial systems. Water and SPM fluxes in the Garonne River mainly control arsenic inputs into the Gironde Estuary and the downstream coastal zones. Based on the present data, we propose an empirical model to roughly estimate the annual dissolved and particulate As fluxes in the Garonne, Dordogne and Isle Rivers from annual water and SPM fluxes. The comparison of observed As fluxes and those estimated from the empirical model suggests that resuspension of historical, polluted reservoir sediments during a major flood accounted for ∼ 50% of the annual As fluxes in 2003.
ISSN:0048-9697
1879-1026
DOI:10.1016/j.scitotenv.2006.10.039