Rapid Removal of Toxicity of Acid Mine Drainage Contaminated Sediments in a Clean Stream: Relative Contribution of Acidity Vs Metals

Laboratory bioassays using Ctenodaphnia magna (Order: Cladocera) were performed to test the toxicity of acid mine drainage (AMD) contaminated sediments at four heavily impacted streams around Athens with reduced mean pH, visible metal precipitates and elevated water column concentrations of iron, aluminum and manganese.Bioassays showed that sediments from all of the AMD impacted sites were highly toxic to Daphnia.Toxicity was correlated to reduced pH but not with any specific metal content.In another experiment, AMD contaminated sediments were placed in baskets and transplanted into the bed of a healthy stream for 5 days.They were collected on the 2 nd and 5 th day and tested for toxicity.After 5 days in the clean stream, aluminum and ironcontaminated substrates were no longer toxic to the Daphnia.These results suggest that sediments at these sites will not retain toxicity after remediation of the AMD input.