GEOCHEMICAL AND ISOTOPIC INVESTIGATIONS OF THE EFFECT OF MINE DRAINAGE ON A SMALL STREAM (WEST LITTLE SUGAR CREEK) IN THE GREEN VALLEY MINE AREA, INDIANA USA

The disposal of waste from mining activities near water sources can have long term effects on the environment from heavy metal concentrations and groundwater quality in a locality. Studies of the water and sediments can provide insights into the quality and extent of contamination. Geochemical analysis was conducted on samples collected from locations along the West Little Sugar Creek in the Green Valley mine area in Indiana. The samples were obtained from acid mine drainage contaminated undiluted effluent sources, contaminated diluted sources and uncontaminated sources. Sediment samples colonized by algae were also collected along the stream reach. The goal is to determine the chemical composition of water and sediment samples and characterize changes in water quality from the source to the mouth of the creek. Environmental parameters (temperature, conductivity, alkalinity, pH, ORP, DO) were measured in the field. Water samples were analyzed for cations and anions and sediment samples were analyzed for elemental content and mineralogical composition. The algal colony was identified. The dissolved inorganic carbon (DIC) and stable carbon isotope ratios of the DIC were also determined. Results show that the average water temperature was 13.2°C. The pH ranged from 3.1-6.6. Where values were present alkalinity averaged 173 mg/L. For anions, sulfate concentrations were highest and measured between 1328.0 and 29821.0 mg/L, while for cations calcium concentrations were highest and measured between 391.0 and 616.0 mg/L. Heavy metal content showed high values for lead, mercury and iron. Among these, iron had the highest content ranging between 0 and 11259.0 mg/L. Aqueous carbon dioxide calculated from DIC ranged between 0.1 and 18.3 mmol/L and the d13C DIC varied between -9.8 and -1.7‰. The algal colony was identified as the acid tolerant blue-green algae Eugena Mutabilis. It is known to synthesize its food by photosynthesis, which uses carbon dioxide and releases oxygen. The oxidation of sulfide minerals such as pyrite leads to highly acidic mine waters with high trace element concentrations. Understanding the geochemistry of water and sediments contaminated with mine waste is important for our efforts to remediate the effects that contaminants have on surface and groundwater.