Physical and chemical characteristics of sediment deposits in Meander Creek Reservoir

Abstract

Variations in physical and chemical properties of sediment deposits in Meander Creek Reservoir were investigated in this study. Three sediment cores were extracted from northern end of the reservoir, one on March 14, 2005 and two on July 11, 2005. The sediment was cored, transported to the laboratory, and sliced. Physical analyses included pore water content, moisture content, and specific gravity, were carried out immediately. The other sediments were air dried, pulverized and analyzed from grain size distribution, dry specific gravity, and metal concentrations. The grain size distribution was performed by a hydrometer (ASTM -152H), and the Inductively Coupled Plasma - Atomic Emission Spectrometer (ICP-AES) was used for heavy metal analysis. An attempt was made to correlate variation with depth to activities in the surrounding area. The physical properties were affected by changes in land use and land development. Silt was the most prominent particle size in the sediment, followed by sand and clay respectively. Even though the watershed did not have heavy industries, the study revealed that the sediment is contaminated with heavy metals like iron (569 mg/kg), manganese (429 mg/kg), nickel (7.25 mg/kg) and chromium (2.67 mg/kg). These are below the Threshold Effect Level (TEL). Hence, the sediment does not directly post any threat to the Meander Creek Reservoir, which is used as a public water supply. Peaks in zinc and chromium just below mid-depth of the core appear to correspond to peak production of the local steel industry in the 1940's and 1950's. These patterns are consistent with a fairly uniform rate of sediment deposition since the reservoir's construction in 1932.