Variability of metals in reservoir sediment from two adjacent basins in the central Great Plains

Reservoir-sediment cores were used to investigate sediment quality in two adjacent basins in the central Great Plains. A total of 18 metals were analyzed to determine and compare concentration magnitudes and trends within and between the two basins. Temporal patterns (bottom to top of core) and ranges in metal concentrations were similar between the two basins; spatial patterns (upstream to downstream), however, showed no similarities. Sediment quality was assessed for eight metals that have federally established sediment-quality guidelines. Of the eight metals, several had concentrations that exceeded threshold effect levels for aquatic organisms. However, the concentrations were less than established probable effect levels. For both basins, increasing trends were indicated for As, Sr, and Se. The trends may be related to both natural conditions and increased irrigation activities in both basins.