Selenite-selenate speciation in mine soils and salt solutions: A comparison of atomic absorption spectroscopy and ion chromatography
- Univ. of Wyoming, Laramie, WY (United States)
Coal mining activities may enhance bioavailability of selenium (Se) species in soils, which can subsequently cause toxicity and contamination problems. Information on comparative applications of spectroscopy and chromatography for selenite (SeO{sub 3}{sup -2}) - selenate (SeO{sub 4}{sup -2}) speciation in coal mine soils is limited. Aqueous extracts (triplicates) of five soil samples, collected from reclaimed coal mine sites in the Powder River Basin, Wyoming, and a set of SeO{sub 3}{sup -2}-SeO{sub 4}{sup -2} salt solutions (0.5, 1, 5, 10 and 25 mg/L., in triplicates) were speciated using atomic absorption spectroscopy with hydride generation (AAS-HG) and in chromatography (IC). The objective of this study was to compare these two methods for Se speciation. The results indicated that AAS-HG was capable of analyzing very low Se concentrations of SO{sub 4}{sup -2} affected chromatographic Se speciation, either by shifting or overlapping Se peaks. For such cases, AAS-HG was more useful than IC. However, IC was capable of speciating aqueous SeO{sub 3}{sup -2} - SeO{sub 4}{sup -2} directly without any sample pretreatment, whereas AAS-HG measured SeO{sub 3}{sup -2} + SeO{sub 4}{sup -2}, and SeO{sub 3}{sup -2} in separate runs and SeO{sub 4}{sup -2} was calculated from the difference, i.e., spectroscopic speciation was an indirect method. For both Se species, AAS-HG and IC data were comparable within the limit of standard deviation, indicating the reliability of both methods for Se speciation. Thus, chromatographic and spectroscopic techniques could be applied to speciate solution Se; however, each had its own analytical limitations. For some of the speciation data there were some discrepancies, which could be due to mutual interconversions between SeO{sub 3}{sup -2} and SeO{sub 4}{sup -2} in the solutions, or integrational error during analysis, or some impurity in the original salts used to prepare the Se solutions.
- OSTI ID:
- 588812
- Report Number(s):
- CONF-9605286--
- Country of Publication:
- United States
- Language:
- English
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