AN INVESTIGATION INTO THE EFFECTS OF ORGANIC AMENDMENTS ON
BERKELEY PIT LAKE WATER QUALITY UNDER VARIOUS ENVIRONMENTAL
CONDITIONS
1
Doug Cameron and Marge Willett
Chemistry and Geochemistry Department, Montana Tech of the University of Montana,
Butte, MT 59701; 1Phone: (406) 496-4247, 1E-mail: dcameron@mtech.edu.
Wetland studies to ameliorate acid mine drainage have shown 10-80% metal
removal by sorption to insoluble or slightly soluble organic matter. These works have
also demonstrated decreases in the aqueous Eh values resulting from organic oxidation,
increases in pH due to chemical reaction of the organic matter, and the organic matter
acting as a carbon source for sulfate-reducing bacteria (SRB). We have recently started
investigation of the effects added organic amendments have on the water quality of the
Berkeley Pit Lake. The added organic carbon comes from sewage sludge, local grass
clippings, local foliage, and sawdust. The sawdust, foliage, and grass represent
precursors to natural humic material and are often deposited in the local landfill. The
sewage sludge is a readily available and economic source of carbon. Each organic
amendment is mixed separately with the water in a 10% mass ratio, and the mixture is
stirred continuously. The experimental matrix is such that a replicate of each mixture is
exposed to the following conditions: sunlight and air, sunlight and no oxygen, oxygen
and no sunlight, or no oxygen and no sunlight. Small fractions of the mixture will be
removed as a function of time and then filtered and analyzed to monitor the amount of
dissolved metal ions, anions, and organic carbon. The pH of the mixture will be
monitored frequently, and the gases and volatile organic matter emitted from the mixture
will be collected and analyzed periodically. We will be reporting the results from these
experiments.
Key words: pit lake, organic carbon, acid mine drainage