The Effect of Soil on the Renovation of Acid Coal Mine Drainage Water

Abstract

This study was initiated to determine under field conditions the feasibility of using soil as a medium for the renovation of acid mine drainage water. Acid water from a stream was applied weekly at three levels (0, 12.5, and 25 cm/week) to an unlimed and a limed (20 metric tons/ha) floodplain soil. Soil water samples were collected weekly at soil depths of 25, 75, and 130 cm. The soil water samples and the acid water were analyzed for pH, total acidity, Al, Fe, Mn, K, Ca, Mg, Na, and SO4. The effect of liming, levels of acid water irrigation, and depth in the soil profile on the soil water quality were determined.Initially both the unlimed and limed areas had considerable capacity for renovating the applied acid water. However, with time, lower pH values and higher levels of acidity, Al, Fe, and Mn were found at the 25‐ and 75‐cm soil depths in the unlimed areas. When the soil was limed, the soil water at the 25‐cm depth was nearly neutral or alkaline throughout the study and practically devoid of Al, Fe, and Mn. At the 130‐cm depth on both unlimed and limed areas the pH, total acidity, Al, Fe, and Mn of the soil water remained relatively unchanged even after 525 cm of acid water had been applied. Growth of ryegrass and tall fescue was not adversely affected by irrigation with the acid water, but was significantly increased by liming. Only the tall fescue yielded significantly more with increased levels of acid water irrigation.