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ASSESSING MINE DRAINAGE WATER QUALITY FROM THE COLOR AND SPECTRAL REFLECTANCE OF CHEMICAL PRECIPITATES
Citation:
Williams, D J., J. M. Bigham, C. A. Cravotta III, S. J. Traina, J. Anderson, AND J G. Lyon. ASSESSING MINE DRAINAGE WATER QUALITY FROM THE COLOR AND SPECTRAL REFLECTANCE OF CHEMICAL PRECIPITATES. APPLIED GEOCHEMISTRY 17(10):1273-1286, (2002).
Impact/Purpose:
The objectives of this task are to:
Assess new remote sensing technology for applicability to landscape characterization; Integrate multiple sensor systems data for improved landscape characterization;
Coordinate future technological needs with other agencies' sensor development programs;
Apply existing remote sensing systems to varied landscape characterization needs; and
Conduct remote sensing applications research for habitat suitability, water resources, and terrestrial condition indicators.
Description:
The pH and dissolved sulfate concentrations of mine impacted waters were estimated on the basis of the spectral reflectance of resident sediments composed mostly of chemical precipitates. Mine drainage sediments were collected from sites in the Anthracite Region of eastern Pennsylvania, representing acid to near neutral pH. The mineralogy of sediments occurring in acidic waters was primarily schwertmannite and goethite while near neutral waters produced ferrihydrite. The minerals comprising the sediments occurring at each pH mode were spectrally separable. Spectral angle difference mapping was used to correlate sediment color with stream water pH, and resulted in an r2 of 0.76. Band-center and band-depth analysis of mineral spectral absorption features was used to discriminate ferrihydrite rich and goethitic (sediments having a mixture of goethite and schwertmannite) chemical precipitates. Sediment mineralogy was determined by analyzing the 4T1 6A1 crystal field transition (900 - 1000 nm). The presence of these minerals accurately predicted stream water pH (r2 = 0.87) and provided a qualitative estimate of dissolved sulfate concentrations. Spectral analysis results were used to analyze airborne Digital MultiSpectral Video (DMSV) imagery for several sites in the region. The high spatial resolution of the DMSV sensor allowed for precise mapping of the mine drainage sediments. Spectroscopy results from this study can be used by airborne and space-borne imaging spectrometers to accurately predict water quality.