Environmental Implications of Elements Associated with Pyrite Concentrates from Coal in the Sydney Coalfield (Upper Carboniferous), Nova Scotia, Canada

Abstract

Pyrite concentrates were obtained from seven successive coal seams of Upper Carboniferous age in the Sydney Coalfield of Nova Scotia. These concentrates were analyzed for forty-nine trace metals and oxides using INAA and ICPES. The data indicate that trace amounts of other sulphide phases (inclusions as arsenopyrile, galena, chalcopyrite), presumed epigenetic clay minerals, and zircon inclusions are associated with pyrite concentrates. The content of rare earths and actinides in these pyrites are age dependent and tend to be more highly concentrated in the younger seams. Pyritic oxidation in coal and resultant formation and dissolution of secondary sulphate minerals are one mechanism for trace-metal dispersion into the surface-water environment. The pyrite concentrates on average are arsenic-rich (range 240-2900 ppm, mean 1556 ppm). However, this As may form insoluble, stable organic-complexes, which remain as As-rich sediments in situ.