Distribution et mobilité de l’arsenic dans les sols: Effets de cycles redox successifs

....................................................................................................................................... 1 Processes affecting redox conditions in near surface soils and sediments ................................. 1 Oxygen transport from to the subsurface ................................................................................ 1 Anaerobic metabolism of organic matter ................................................................................ 4 Contaminant leachate plumes ................................................................................................. 8 Oxidation-Reduction Capacity of Sediment Matrix .................................................................. 9 Environments commonly subject to temporal cycles of oxidation and reduction .................... 10 Riparian floodplains ................................................................................................................ 10 Soils subjected to water table fluctuations ............................................................................ 11 Rice fields ................................................................................................................................ 12 Benthic sediments subject to bio-turbation by macro-fauna ................................................ 14 Soil subject to intense rainfall ................................................................................................ 14 Soil influenced by oxygenation within the rhizosphere ......................................................... 15 Redox controls on contaminant mobility and toxicity ............................................................... 15 Direct controls on oxidation state .......................................................................................... 15 Controls by surface sorption/desorption ............................................................................... 16 Controls by solid precipitation/dissolution ............................................................................ 17 Mercury .................................................................................................................................. 19 Uranium .................................................................................................................................. 25 Chromium ............................................................................................................................... 36 Arsenic .................................................................................................................................... 39 Chapter 2: Arsenic inputs to the exogenic biogeochemical cycle and distribution in the pedosphere ......................................................................................................................... 49 Abstract ...................................................................................................................................... 49..................................................................................................................................... 49 Arsenic input to the exogenic cycle: ........................................................................................... 51 Geogenic Input ........................................................................................................................... 53 Volcanic emission (280 – 17,150 x 10 kg yr) ....................................................................... 53 Erosional and weathering processes (?) ................................................................................. 53 Anthropogenic input .................................................................................................................. 58 te l-0 06 37 48 4, v er si on 2 7 D ec 2 01 1