HR: 17:45h
AN: B24B-08    [Abstracts]
TI: Biogeochemical Gradients in Wetland Sediments and their Effect on the Fate Trace Metals
AU: * Jaffe, P R
EM: jaffe@princeton.edu
AF: Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ 08544 United States
AU: Choi, J
EM: jchoi@ewha.ac.kr
AF: Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ 08544 United States
AU: Choi, J
EM: jchoi@ewha.ac.kr
AF: Department of Environmental Science and Engineerin, Ewha Womans University, Seoul, xxxxx Korea, Republic of
AU: Xu, S
EM: shangping.xu@yale.edu
AF: Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ 08544 United States
AB: The interactions between sediment biogeochemistry processes and higher plants play a major role on trace metal mobility in wetlands. Most wetland sediments are characterized by steep redox gradients, resulting from the sequential utilization of different electron acceptors during the degradation of organic matter provided by leaf litter and root turnover. Metals in wetland sediments may be immobilized due to precipitation or adsorption to different organic and inorganic sediment constituents. Adsorption onto iron, and manganese oxides, are important in the rhizosphere where iron oxyhydroxide plaques may form on the surface of roots. As the sediments becomes more reduced, bioavailable iron and manganese oxides are used as electron acceptor and are gradually depleted, resulting in the mobilization of some adsorbed species (i.e., As(V), phosphate, etc.), the reduction of some trace metals such as Cr(VI) (which is then immobilized as Cr(III)), and for more reduced conditions the immobilization of trace metals (i.e., Cd, Pb, Zn) as sulfides. Results from numerical simulations, laboratory experiments, and field measurements will be presented, showing how redox gradients and hence, trace-metal immobilization, in wetlands respond to external forcing functions such as changes in nutrient loading, plant distribution, seasonal and diurnal plant activity (specifically evapotranspiration and oxygen release), and temporal or spatial changes in the profile of iron and manganese oxides.
DE: 0412 Biogeochemical kinetics and reaction modeling (0414, 0793, 1615, 4805, 4912)
DE: 0461 Metals
DE: 0466 Modeling
DE: 0488 Sulfur cycling
SC: Biogeosciences [B]
MN: Fall Meeting 2005