Transport and Storage of Metals in Fractured and Karstic Rock Aquifers.

摘要

The objective of this project was to evaluate the movement of metals in karst aquifers, including metal accumulation, release, and transport under low flow and storm conditions. Metals investigated include aluminum, arsenic, chromium, lead, and nickel. Measurements were made of variations in metal concentration from base flow to storm flow using three springs before, during, and after storm events to study metal transport and release. Sediment samples from 10 springs were analyzed for metals and characterized by bulk mineral identification. The metals were subjected to a selective extraction procedure that evaluated the form of the accumulated metal, which in turn controls the availability of the metal to humans and ecological receptors. Results indicate that metals are transported as adsorbates on clays and other small particles which are mobilized during storms, leading to a peak in metal concentration coincident with the peak of the storm hydrograph. Trace metals are stored in the spring sediments mainly bound onto iron or manganese oxide coatings on the silicate grains. Appendixes contain the following research papers by Dorothy J. Vesper and William B. White: 'Storm Pulse Chemographs of Saturation Index and Carbon Dioxide Pressure: Implications for Shifting Recharge Sources During Storm Events in Karst Aquifers'; Metal Transport to Karst Springs During Storm Flow: An Example from Fort Campbell, Kentucky/Tennessee, U.S.A.'; Comparative Storm Response of Ground Water and Contaminant Chemistry in a Carbonate Aquifer, Fort Campbell, Kentucky-Tennessee, U.S.A.'; and 'Spring and Conduit Sediments as Storage Reservoirs for Metal Contaminants in Karst Aquifers.' (12 tables, 38 figures, numerous refs.).