Assessment and Prediction of the Combined Pollution Risk of Heavy Metals in the Sulfide Tailings of a Mining Area, Northern Guangxi, China

It may be hard to make a reasonable assessment on the combined pollution risk of heavy metals in the sulfide tailings merely by using a single method (e.g. Nemerom index) based on element total content. This paper carries out the comprehensive assessment of the combined pollution risk of Pb, Zn, Cd and As in the sulfide tailings in a mine (northern Guangxi, China), integrating methods such as the geological accumulative index, the potential ecological risk evaluation, and BCR acid extraction procedure. The reference value is taken from the element abundance of the weathering crust of carbonate country rock nearby LTS ore body in the mine. The results display that: (1) Cadmium (strongest ecological risk and mobility in the four elements) and Arsenic (highest pollution level and stronger ecological risk) are major pollution factors in the mine, and should be prevented and controlled; while Zinc (weak ecological risk), and Pb (low pollution level, weak ecological risk and mobility) may be relatively minor. (2) The elements active-acid-extractable content, which is one of the main causes inducing environment damages, correlates variously or inconsistently with its total content. That may be one reason for the problems existing in the assessment methods only based on the factor of element total content.