The abandoned Phillips sulfide mine in the critical Highlands watershed in New York has been shown to produce strongly acidic mine drainage (AMD) with anomalous metal contaminants in first-order streams that exceeded local water standards by up to several orders of magnitude (Gilchrist et al., 2009). The metal-sulfide-rich tailings also produce contaminated soils with pH < 4, organic matter < 2.5% and trace metals sequestered in soil oxides. A geochemical transect to test worst-case soil contamination showed that Cr, Co and Ni correlated positively with Mn, (r = 0.72, r= 0.89, r = 0.80, respectively), suggesting Mn-oxide sequestration and that Cu and Pb correlated with Fe (r = 0.76, r = 0.83, respectively), suggesting sequestration in goethite. Ubiquitous, yellow coating on the mine wastes, including jarosite and goethite, is a carrier of the metals. Geochemical and μ -SXRF analyses determined Cu to be the major soil contaminant. μ-SXRF also demonstrated that the heterogeneous nature of the soil chemistry at the micro-meter scale is self-similar to those in the bulk soil samples. Generally metals decreased, with some fluctuations, rapidly downslope through suspension of fines and dissolution in AMD leaving the area of substantial contamination « 0.5 km from the source.
- Metal contamination
- Mine tailings