Cesium-137 and mercury contamination in lake sediments

The contribution of fluvial discharge and global fallout of Cs-137 and merc ury to sedimentation fluxes in Lake Shinji and Lake Nakaumi, Japan, was stu died. The fluvial flux through soil erosion accounted for 11 to 27% of accu mulated Cs-137 in the sediments in the 1950's and 1960's, which were the pe riods of the most extensive atmospheric input, and for 90 to 100 % in the 1 990's. The vertical profiles of mercury concentrations in the lake sediment s studied showed a maximum between 1959 and 1963, which was originated most ly from the extensive use of mercury-agrochemicals in paddyfieids of the wa tershed in the past. These findings are representative examples of long-ter m contamination of lake sediments caused by the contaminated ground soil er osion. (C) 1999 Elsevier Science Ltd. All rights reserved.