Changes in catchment conditions lead to enhanced remobilization of arsenic in a water reservoir

• Published in: The Science of the total environment 2013-04, Vol.449, p.63-70
• Main Authors: Weiske, Arndt, Schaller, Jörg, Hegewald, Tilo, Kranz, Ulrike, Feger, Karl-Heinz, Werner, Ingo, Dudel, E. Gert
• Format: Article
• Language: English
• Subjects: Applied sciences; Arsenic; Arsenic - analysis; Arsenic fluxes; Carbon - analysis; Catchments; Combustion; Continental surface waters; Environmental Monitoring - methods; Exact sciences and technology; Fluxes; Freshwater; Geologic Sediments - chemistry; Germany; Iron; Metalloid; Natural water pollution; Nitrate; Nitrates; Pollution; Pollution sources. Measurement results; Reservoirs; Runoff; Sediments; Soil and sediments pollution; Water Pollutants, Chemical - analysis; Water Supply - analysis; Water treatment and pollution
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2013.01.041

Increasing arsenic concentrations in freshwater ecosystems is of global concern. Processes affecting arsenic fluxes in catchments are known. These processes are in turn controlled by the underlying geology and air pollution history. In contrast to the knowledge on catchment processes less is known about the hydrochemical processes controlling the fixation/remobilization of arsenic within lakes and artificial reservoirs. Consequently, we examined a reservoir system in the Ore Mts. (Germany) regarding its sink and source potentials affecting arsenic fluxes. This area was faced with heavy deposition inputs from coal burning based acid rain until the beginning of the 1990s. Hereafter concentrations of sulfate and nitrate in runoff waters decreased, whereas dissolved organic carbon (DOC) concentrations are still increasing. Along with this, arsenic concentrations in the water discharge from the catchments increase. Our results reveal that the sediments of the investigated reservoir system contain high inventories of arsenic in association with ferric and organic phases. A nitrate deficit dependent arsenic release is suggested. It is indicated that arsenic release from the reservoir sediments may be controlled by water nitrate concentration, which in turn is dependent on the nitrate concentration in the runoff water from the catchment. ► We examine increasing dissolved arsenic in water reservoirs. ► Arsenic release from sediments was controlled by decreasing water nitrate concentration. ► Basin sediment arsenic was found in ferric and humic matter. ► A long term trend of arsenic in water is negatively related to nitrate.