ENVIRONMENTAL-IMPACT OF METALS DERIVED FROM MINING ACTIVITIES - PROCESSES, PREDICTIONS, PREVENTION

Mining activities affect relatively small areas but can have a large local impact on the environment. Release of metals from mining sites occurs primarily through acid mine drainage and erosion of waste dumps and tailings deposits. The available methods for predicting acid mine drainage the fate of released metals are briefly reviewed. Results of one case study, a geochemical model was used to predict copper concentrations in a river system affected by acid mine drainage and tailings inputs, showed good agreement between measured and predicted values. For large scale commercial mining operations, tools to predict and prevent environmental impact are available. However, mining operations involving a large number of small-scale activities are difficult to control. Gold-mining activities in Brazil, in which mercury is used to concentrate gold have already resulted in high concentrations of mercury in fish and may have long-lasting effects due to the mechanisms of metal cycling in tropical forest ecosystems.