GEOCHEMISTRY OF ACIDIC TAILINGS AND AMD AT PHILLIPS SULFIDE MINE, HUDSON HIGHLANDS, NY

Soil, sediment and surface water from the tailings dump at the abandoned Phillips Mine in Putnam County, New York, are highly acidic and contain anomalous amounts of leached metal and radioactive pollutants. The tailings (mine soil) are almost devoid of vegetation even after 125 years of inactivity and are primarily brownish-yellowish, reflecting the presence of Fe-oxides and hydroxides. The oxides may be the dominant secondary minerals for sorption of the metals at the mine dump. Mineralogical analysis of the mine tailings suggests that the anomalous abundance of sulfide minerals, particularly pyrite, pyrrhotite, chalcopyrite and marcasite, are the primary constituents generating acid mine drainage at Phillips Mine. Metal enrichment in waters appear to concentrate at pH< 3.0. Chemical analysis of the water (and sediment samples collected simultaneously) along a 1.4 km stretch of Copper Mine Brook located below the tailings pile, indicates strongly acidic water (pH 2.25 – 4.06) flowing from the lower adit into the brook. Consequently, anomalous metal concentrations, including REEs, are abundantly present in the waters. Dilution, due to the confluence downstream between a clean brook and the mine waters, resulted in increased pH that lowered the metal concentrations in waters but progressively elevated metal sequestration in the sediments. Arsenic, impoverished in the water samples, appeared in the sediments. Severely deficient in organic matter, mine soil samples, from the tailings dump, are chemically enriched in metal pollutants, La, Ce and Th. Phosphorous enrichment spiked greatly in both the soil and sediment samples. Analysis for metal bioavailability of the roots, twigs and leaves of the sparse vegetation indicates that white birch and mountain laurel are the most adaptable metal-accumulating plant species, storing detectable amounts of REEs + Y that were found in their roots.