Fractionation of Metal Contaminants in Acid Mine Drainage-Impacted Soil and the Effects On the Surrounding Ecosystem.

Anthropogenic activity can adversely affect an environment even long after the harmful activity has ceased. Contrary Creek is an 8-km stream located in Louisa County, Virginia, and the site of a few abandoned pyrite mines that closed almost a century ago. The surrounding ecosystem is still exhibiting strong signs of acid mine drainage (AMD) impacts as a result of the mining operations and leftover waste piles. After three years of studying several parts of this ecosystem, it is clear that AMD continues to affect the soil, water, and the area as a whole with very little improvement despite past attempts of remediation. Streamwater, sediment, soil, and vegetation samples were collected from sites that extend upstream and downstream along Contrary Creek as well as at an abandoned mine shaft about 50 m away from the creek. The samples were analyzed for trace metals, pH, and other factors. The soil, sediment, and vegetation samples were acid digested to determine total metal content. A sequential extraction was also performed on the soil and sediment samples to differentiate the distribution of metals. Although the pyrite mines closed in the 1920s, pH values in the soil, water, and sediments are still very low and total and soluble trace metal concentrations are often above acceptable limits for a healthy ecosystem. High bioavailable concentrations do not always correspond with high total metal concentrations, but they do show correlations with certain ecosystem effects.