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Direct Versus Indirect Determination Of Suspended Sediment Associated Metals In A Mining-Influenced Watershed
Citation:
BUTLER, B. A., J. F. Ranville, AND P. E. Ross. Direct Versus Indirect Determination Of Suspended Sediment Associated Metals In A Mining-Influenced Watershed. R. Fuge (ed.), APPLIED GEOCHEMISTRY. Elsevier Science Ltd, New York, NY, 23(5):1218-1231, (2008).
Impact/Purpose:
The validity of this assumption (published water quality data include only concentrations of total and dissolved metals, with particulate concentrations assumed equal to the difference between the two) for mining-influenced waters is addressed in this paper by comparing data determined from the subtraction of total (acid-soluble) and dissolved (operationally defined as less than 0.45-µm) metal concentrations (difference method) with data obtained from acid-digestion of the particles retained on the filters used for filtering the dissolved fraction (digestion method).
Description:
The differentiation between the concentration of metals associated with suspended sediments and those in the dissolved phase is often of importance in aquatic ecosystems, for such reasons as toxicity evaluation, total maximum daily load calculations, and a better understanding of metal transport. Often, published water quality data include only concentrations of total and dissolved metals, with particulate concentrations assumed equal to the difference between the two. The validity of this assumption for mining-influenced waters is addressed in this paper by comparing data determined from the subtraction of total (acid-soluble) and dissolved (operationally defined as less than 0.45-µm) metal concentrations (difference method) with data obtained from acid-digestion of the particles retained on the filters used for filtering the dissolved fraction (digestion method). Greater than fifty water samples containing suspended sediment were collected from each of three sites in the Clear Creek Watershed in Colorado during a two and one-half year study on the fate and transport of metals in the watershed. Volumes of water filtered ranged from 50 to 250 ml, representative of typical volumes used for the determination of dissolved metal concentrations. The particulate-associated concentrations of Al, Cu, Fe, Mn, and Zn determined from the difference method compared well with the concentrations determined by the digestion method. Statistical analyses indicated that there is not a statistically significant difference between the two methods at the 95% confidence level, with p-values of 0.65, 0.88, 0.39, 0.67, and 0.75, for Al, Cu, Fe, Mn, and Zn, respectively, over the three sites.
URLs/Downloads:
DIRECT VERSUS INDIRECT DETERMINATION OF SUSPENDED SEDIMENT ASSOCIATED METALS IN A MINING-INFLUENCED WATERSHED