Zinc and lead sequestration in an impacted wetland system |
| |
Authors: | Edward F PeltierSamuel M Webb Jean-François Gaillard |
| |
Institution: | Department of Civil and Environmental Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3109, USA |
| |
Abstract: | The fate and bioavailability of pollutant metals is important to the long-term health of freshwater wetland systems, particularly in areas with elevated background levels of trace metals. Precipitation of some authigenic mineral phases in wetland sediments can potentially limit metal bioavailability through sequestration in low-solubility compounds, such as metal sulfides. Zinc and Pb concentrations were analyzed in water, plant and sediment samples taken from a metal-contaminated wetland in Chicago, IL, USA in order to assess metal fate and bioavailability, while X-ray absorption spectroscopy (XAS) studies were conducted to determine zinc speciation in the wetland sediments. The results showed sequestration of metal into the pond sediments, most likely in iron precipitate phases. In surface sediments, re-release of Zn and Pb into pore waters was correlated with microbial iron reduction, while the presence of sulfide in anoxic pore waters corresponded to decreased dissolved concentrations of both elements. Analysis of extended X-ray absorption fine structure (EXAFS) data confirmed that sulfide compounds dominated zinc speciation throughout the sediment. Uptake of trace metals in Phragmites plants was limited primarily to plant roots, while concentrations of both Pb and Zn in aquatic vegetation were significantly elevated, representing a potential bioaccumulation hazard. |
| |
Keywords: | Wetlands Wetland restoration Sediments Bioavailability Heavy metals Sulfides X-Ray absorption spectroscopy Great Lakes |
本文献已被 ScienceDirect 等数据库收录! |
|