title: Experimentally altered groundwater inflow remobilizes acidity from sediments of an iron rich and acidic lake.
abstract: To study the impact of changes in groundwater flow and chemistry on acidity export from sediments in acid mine drainage (AMD) polluted lakes, a column experiment was carried out. Schwertmannite rich sediment was subjected to three different flow rates (0, 5, and 20 L m(-2) a(-1)), two percolate chemistries (1/1 mmol L(-1) vs 10/15 mmol L(-1) sulfate/ferrous iron, pH 5), and DOC input (approximately 2.5 mmol C L(-1)). Percolation induced acidity export in all percolated treatments (8.8-40.4 mol m(-2) a(-1)) by accelerated proton generation from schwertmannite transformation (18.0-35.9 mol m(-2) a(-1)) and ferrous iron release (3.8-11.6 mol m(-2) a(-1)) from the sediment matrix. Mobilization increased with flow rate and decreased with sulfate and iron concentrations. Unspecifically bound ferrous iron contents increased within the sediment (up to 40.5 mol m(-2) a(-1)) when iron concentrations in the percolate were high. Reduced sulfur species formed following raises in pH, but acidity consumption through this process (0.3-6.6 mol m(-2) a(-1)) and the formation of carbonates (0.11-0.45 mol m(-2) a(-1)) remained small. The study thus suggests that increases in groundwater inflow remobilize acidity from AMD polluted sediments.
authors.affiliation: Limnological Research Station and Department of Hydrology, University of Bayreuth, D-95440 Bayreuth, Germany.
authors.forename: Klaus-Holger
authors.initials: KH
authors.lastname: Knorr
authors.forename: Christian
authors.initials: C
authors.lastname: Blodau
mesh_terms: D004784:Environmental Monitoring; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000378:metabolism*; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water; D014872:Water Movements; D014873:Water Pollutants; D014874:Water Pollutants, Chemical / Q000032:analysis; D014876:Water Pollution; D018508:Water Purification / Q000379:methods*
chemical_list: D014873:Water Pollutants; D014874:Water Pollutants, Chemical; D014867:Water; D007501:Iron