| Heavy metal pollution is particularly significant in Lake Erie. Sediments act as both sink and source for metal contaminants. Sediment core samples were collected in May and June, 2004, from the eastern basin of Lake Erie in order to assess the mobility of heavy metals in benthic ecosystems. Five extractions were applied to solid phase analysis including acetic acid, ascorbic acid, sodium dithionite, nitric acid/oxalic acid and total digestion.; Pore water and solid data revealed that mobility of heavy metals was influenced by redox reactions. Manganese, Fe and S were the crucial elements for Eh profiles. Distributions of trace metals were affected by the oxidization and reduction of Mn and Fe. Three zones were identified by the profiles of dissolved Mn and Fe: Mn oxidation, Mn reduction and Fe reduction. Cadmium had high mobility in the Mn oxide zone while Ni and Co were released with reducible Mn. Solid extractions indicated that anthropogenic pollution has improved in Lake Erie; reactive Mn and Fe oxides remobilize trace metals; the distribution of trace metal oxides are associated with the oxides of Fe, Al and Si. (Abstract shortened by UMI.)... |
