Arsenic and mercury concentrations in major landscape components of an intensively cultivated watershed

To provide an understanding of arsenic (As) and mercury (Hg) concentrations in soil, sediment, water, and fish tissues, samples were collected from a Mississippi River alluvial floodplain located in northwest Mississippi. As concentrations increased approximately an order of magnitude from water (5. 12 mu g/l) to fish tissues (36.99 mu g/kg) and an additional two orders of magnitude in soils, lake sediments, and wetland sediments (5728. 5614, and 6746 mu g/kg), respectively. Average Hg concentrations in water, soils, lak e sediments, and fish were 2.16 mu g/l, 55.1, 14.5 and 125 mu g/kg, respect ively. As and Hg concentrations were within published ranges for uncontamin ated soil, water, and sediments. As concentrations represented a lour risk. Hg concentrations were also low but showed a greater tendency to concentra te in fish tissue. The dominant mode of entry of these materials into aquat ic systems is through storm-generated runoff Since both metals accompany se diments, agricultural conservation practices such as reduced tillage, buffe r riparian strips, and bordering sediment ponds or drainage wetlands will m inimize watershed input to aquatic systems. Crown Copyright (C) 2000 Publis hed by Elsevier Science Ltd. All rights reserved.