Assessment of heavy metal pollution in abandoned Giap Lai pyrite mine (Phu Tho Province)

Abstract

Giap Lai pyrite mine had been exploited in the period 1975 - 1999, and abandoned after the mine became closed. This work is conducted with the aim to evaluate the impacts of the abandoned mine to the environment. 23 surface water, 15 ground water and 20 soil samples from the mining area were collected for experiments. Acid production potential and metal leaching of waste materials from tailings were tested. Results show that acid rock drainage (ARD) in the old mining area still occurs, with sulfide-rich tailings and waste rocks being sources of ARD, causing elevated metal concentrations in downstream water bodies. Surface water shows significant pollution of Fe, Mn, Ni and partially As. In the rainy season, the percentage of surface water samples having low pH values as well as metal contents in samples is higher than in the dry season. Metal concentrations in ground water are generally low, but many samples have low pH values, indicating the influence of the ARD. The geo-accumulation index reveals that soil from mining area is moderately contaminated with Ni, Cu, Hg and partially As. Most of the polluted samples are located near old mining pits, waste dumps and tailing ponds. The study also shows that negative effect of Giap Lai pyrite mine on the surrounding water and soil has been ongoing. However, no post-closure remediation measures have been applied at the mine, so there must be appropriate solutions for the acid mine drainage treatment before its being discharged to the environment. Given the facts revealed by this study, it is recommended that the Environmental Protection Law should be fully implemented at mining sites not only during the exploitation but also after their closures.References AMIRA, 2002. ARD Test Handbook. Project P387A Prediction & Kinetic Control of Acid Mine Drainage. AMIRA international May 2002, 42p. Çevik, F., Göksu, M. Z. L., Derici, O. B., Fındık, Ö., 2009. 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