Correlation of Electron Donor Concentration in Sediments with Sediment Properties: New Providence, Iowa. Technical Report No. ND09-01

摘要

The concentrations of electron donors in aquifer sediments are important in understanding the fate and transport of redox-sensitive constituents in ground water, such as nitrate. In this study, 50 sediment samples were collected from below the water table from 11 boreholes at the US Geological Survey Agricultural Chemicals Transport site near New Providence, Iowa. All samples were analyzed for gravel, sand (coarse, medium, and fine), silt, clay, inorganic carbon contents and for the following electron donors: organic carbon, ferrous iron, and inorganic sulfide. A subset of sediment samples was analyzed for organic sulfur, but all of the 14 samples were below detection; therefore this potential electron donor was not considered further. Nonparametric correlation analysis was done with the data for the other three electron donor concentrations, inorganic carbon concentrations, sediment grain sizes, and sediment depths. The major finding was that electron donor concentrations are positively correlated to the smaller grain sizes and to each other. These findings suggest that most aquifer denitrification at this site takes place in zones having lower hydraulic conductivities.