Titration Curves: A Useful Instrument for Assessing the Buffer Systems of Acidic Mining Waters (10 pp) |
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Authors: | Oliver Totsche Andrew Fyson Margarete Kalin Christian Steinberg |
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Institution: | (1) Dr. Oliver Totsche Leibniz Institute of Freshwater Ecology and Inland Fisheries Post Box 850119 12561 Berlin Germany totsche@igb-berlin.de, , ,;(2) Andrew Fyson Leibniz Institute of Freshwater Ecology and Inland Fisheries Post Box 850119 12561 Berlin Germany, , ,;(3) Margarete Kalin Boojum Research, Ltd. 468 Queen St. Toronto M5A 1T7 Ontario, Canada, , ,;(4) Prof. Dr. Christian E.W. Steinberg Institute of Biology Freshwater Ecology Humboldt University at Berlin Arboretum Spaethstr. 80/81 D-12437 Berlin, , , |
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Abstract: | Background, Aims and Scope The acidification of mine waters is generally caused by metal sulfide oxidation, related to mining activities. These waters
are characterized by low pH and high acidity due to strong buffering systems. The standard acidity parameter, the Base Neutralization
Capacity (BNC) is determined by endpoint titration, and reflects a cumulative parameter of both hydrogen ions and all buffering
systems, but does not give information on the individual buffer systems. We demonstrate that a detailed interpretation of
titration curves can provide information about the strength of the buffering systems. The buffering systems are of importance
for environmental studies and treatment of acidic mining waters.
Methods Titrations were carried out by means of an automatic titrator using acidic mining waters from Germany and Canada. The curves
were interpreted, compared with each other, to endpoint titration results and to elemental concentrations contained therein.
Results and Discussion The titration curves were highly reproducible, and contained information about the strength of the buffer systems present.
Interpretations are given, and the classification and comparison of acidic mining waters, by the nature and strength of their
buffering systems derived from titration curves are discussed. The BNC-values calculated from the curves were more precise
than the ones determined by the standard endpoint titration method. Due to the complex buffer mechanisms in acidic mining
waters, the calculation of major metal concentrations from the shape of the titration curve resulted in estimates, which should
not be confused with precise elemental analysis results.
Conclusion Titration curves provide an inexpensive, valuable and versatile tool, by which to obtain sophisticated information of the
acidity in acidic water. The information about the strength of the present buffer systems can help to understand and document
the complex nature of acidic mining water buffer systems. Finally, the interpretation of titration curves could help to improve
treatment measurements and the ecological understanding of these acidic waters. |
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Keywords: | pH-buffering acidity acid mine drainage base neutralization capacity (BNC) acid-base titration mine waters |
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