METALS AND OTHER COMPONENTS OF COAL MINE DRAINAGE AS RELATED TO AQUATIC LIFE STANDARDS

Abstract

The objective of this study was to characterize the occurrences of various metals and other contaminants in 128 different water samples from untreated coal mine drainage (CMD) as related to aquatic life water quality criteria. The water quality analyses were of untreated drainage from active, reclaimed, and abandoned surface and underground mines, as well as coal waste materials. About 75% of the study sample set had pH values less than 4.5, and the remaining samples had pH values ranging from 4.5 to 6.9. The following metals were included in the chemical analyses: ferrous and ferric iron, aluminum, manganese, arsenic, beryllium, cadmium, cobalt, chromium copper, antimony, and zinc. As would be expected by pH-controlled solubility relationships, higher metal concentrations were generally associated with lower pH values. Water hardness values were somewhat independent of pH over the range of the study sample set, but were generally very hard. This is significant since hardness usually raises the aquatic toxicity threshold for most metals (e.g., cadmium chromium, copper, lead, manganese, nickel, and zinc). No clear correlations were found between the occurrence of manganese, which has been used as a CMD treatment surrogate, and other more toxic metals. Potentially toxic concentrations of some of thesemore » metals were found at manganese concentrations less than 2 mg/L, which is the normal effluent standard for CMD discharges. Traditional active and abandoned mine land reclamation practices have focused on discharge water quality parameters that conform to usual National Pollution Discharge Elimination System (NPDES) standards. This particularly applies to the use of manganese levels as a surrogate for threshold concentrations of toxic and heavy metals in discharge waters.« less