IMPACTS OF COAL PILE LEACHATE ON A FORESTED WETLAND IN SOUTH-CAROLINA

This study was conducted to: (1) determine the probable cause of sever al areas of stressed and dead vegetation adjacent to a 15-yr-old rejec t coal pile in western South Carolina and (2) identify the factors lim iting successful revegetation of the site. Data from an earlier study suggested that solution pH, total dissolved solids (TDS) and electrica l conductivity (EC), and/or elevated trace element concentrations may have contributed to the stress and dieback. Soil water in the two vege tation kill zones is saline (TDS > 10000 mg L(-1) and EC > 4 dS m(-1)) , highly acidic (soil pH < 3.5), and high in Al and Mn (Al conc. > 200 mg L(-1) and Mn conc. > 10 mg L(-1)). Soil water in areas of sparse v egetation is brackish (TDS > 1000 mg L(-1) and EC > 2 dS m(-1)) and ac idic (soil pH < 4.0), with elevated Al values (> 40.5 mg Al L(-1)). Ti ssue samples were collected from volunteer loblolly pine (Pinus taeda L.) seedlings growing in the study area and analyzed for essential and non-essential elements. Seedling tissues did not contain abnormal con centrations of nutrients or trace elements. The strong relationship be tween the zones of vegetation stress and dieback and solution pH and s oluble salt concentrations, and the lack of excessive metal accumulati ons by tree seedlings which have become established in the less toxic portions of the study area, suggest that low solution pH and high solu ble salts are more important factors limiting plant establishment on t his site than solution metal concentrations. The results of this study demonstrate the importance of site hydrology in determining the impac ts of coal waste disposal on adjacent ecosystems.