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Communication at the NABS Annual meeting, Keystone, 2000
(490) ARSENIC AND MERCURY CONCENTRATIONS IN MAJOR LANDSCAPE COMPONENTS OF AN INTENSIVELY CULTIVATED WATERSHED.
C.M. Cooper. United States Department of Agriculture-Agricultural Research Service, National Sedimentation Laboratory, PO Box 1157,Oxford, MS 38655
Arsenic (As) and mercury (Hg) concentrations in soil, sediment, water, and fish tissues were measured from samples collected from a Mississippi River alluvial floodplain located in northwest Mississippi. Arsenic concentrations increased approximately an order of magnitude from water (5.12 mg/L) to fish tissues (36.99 mg/kg) and an additional 2 orders of magnitude in soils, lake sediments, and wetland sediments (5728, 5614, and 6746 mg/kg), respectively. Average mercury concentrations in water, soils, lake sediments, and fish were 2.16 mg/L, 55.1 mg/kg, 14.5 mg/kg and 125 mg/kg, respectively. Arsenic and mercury concentrations were within published ranges for uncontaminated soil, water, and sediments. Arsenic concentrations represented a low risk. Mercury concentrations were also low but showed a greater tendency to concentrate in fish tissue. Presence of these metals is from natural concentrations in alluvial soils, agricultural application for over a century, and continuing atmospheric deposition. The dominant mode of entry of these materials into aquatic systems is through storm-generated runoff. Since both metals accompany sediments, agricultural conservation practices such as reduced tillage, buffer riparian strips, and bordering sediment ponds or drainage wetlands will minimize watershed input to aquatic systems.
Presented at 1:00 PM on Wednesday, May 31, 2000 in Ecotoxicology / Toxicity Testing
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