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Natural Alkalinity Generation in Neutral Lakes Affected by Acid Mine Drainage
Author(s) -
Koschorreck Matthias,
Tittel Jörg
Publication year - 2007
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2006.0354
Subject(s) - alkalinity , sulfate , acid mine drainage , sediment , environmental science , environmental chemistry , acid neutralizing capacity , hydrology (agriculture) , denitrification , ecology , chemistry , soil science , geology , nitrogen , acid deposition , biology , geotechnical engineering , organic chemistry , soil water , paleontology
Abstract Lakes in surface mining areas are often subject to continuous loads of acid mine drainage. The knowledge of internal alkalinity generation in a lake is necessary to predict if the lake will stay circumneutral or may acidify. The most important processes of alkalinity production in lakes are sulfate reduction, denitrification, and the burial of N in the sediment. By summarizing data from the literature, we present probable rates of these different processes in circumneutral mining lakes. The critical acidity load that can probably be compensated for by internal processes, is 5.09 mmol(−) m −2 d −1 in productive lakes and 0.50 mmol(−) m −2 d −1 in less productive lakes. Under the assumption that methanogenesis is inhibited by high sulfate concentrations, the highest probable acidity loads in such lakes are 6.85 mmol(−) m −2 d −1 and 1.06 mmol(−) m −2 d −1 , respectively. Denitrification, sulfate reduction, and N burial contributed significantly to total alkalinity production. Sulfate reduction had the largest potential. However, existing models cannot predict alkalinity generation from sulfate concentrations alone because the long‐term stability of reduced S compounds in the sediment is crucial for a sustainable biological alkalinity generation. The larger acid‐neutralizing potential of higher trophic lakes is caused both by higher rates of microbial activity and by a greater stability of reduced reaction products in the sediment. The largest uncertainties in our knowledge with respect to the total alkalinity budget are related to microbial processes in sulfate‐rich freshwater lakes and the long‐term stability of reduced reaction products in the sediment.