『Abstract
Weathering of heavy metal enriched black shales may be one of
the most important sources of environmental contamination in areas
where black shales are distributed. Heavy metal release during
weathering of the Lower Cambrian Black Shales (LCBS) in western
Hunan, China, was investigated using traditional geochemical methods
and the ICP-MS analytical technique. Concentrations of 16 heavy
metals, 8 trace elements and P were measured for sampling from
selected weathering profiles at the Taiping vanadium ore mine
(TP), the Matian phosphorous ore mine (MT), and Taojiang stone-coal
mine (TJ). The results show that the bedrock at these three profiles
is enriched with Sc, V, Cr, Co, Ni, Cu, Zn, Pb, Th, U, Mo, Cd,
Sb, Tl, and P. Based on mass-balance calculation, the percentages
of heavy metals released (in % loss) relative to immobile element
Nb were estimated. The results show significant rates of release
during weathering of : V, Cr, Co, Ni, Cu, Zn, U, Mo, Cd, Sn, Sb,
and Tl for the TP profile; Sc, Cr, Mn, Co, Ni, Cu, Zn, Pb, Th,
Cd, and Sn for the MT profile; and Sc, Mn, Co, Ni, Zn, Th, Cd,
Sn, and Tl for the TJ profile. Among these heavy metals, Co, Ni,
Zn, Cd, and Sn show very similar features of release from each
of the three weathering profiles. The heavy metals released during
weathering may affect the environment (especially topsoil and
surface waters) and are possibly related to an observed high incidence
of endemic diseases in the area.
Keywords: Heavy metals; Weathering; Release; The Lower Cambrian
Black Shales; Western Hunan; China』
Introduction
Materials and methods
Results and discussion
Distribution of heavy metals
Heavy metal release
Possible environmental effects
Acknowledgements
References