Characterization of Arsenic and Uranium Pollution Surrounding a Uranium Mine in Southwestern China and Phytoremediation Potential

Heavy metal pollution by both uranium and arsenic has become a major environmental problem associated with uranium mining worldwide. At present, physical, chemical and biological technologies are available as the main remediation techniques. Among them, phytoremediation is relatively low cost, hinders more pollution and allows for fast recycling of the uranium as compared to other techniques. However, suitable phytoremediation depends critically on the better choice of plant species. In this study, field sampling of soils and plants surrounding a uranium mine was conducted, and atomic emission spectrometry of samples performed, in order to characterize the distribution of heavy metal pollution and to provide a scientific basis for the phytoremediation of uranium mining sites. Soil uranium concentrations were found to be highest in open-pit mine sites, followed by ore dressing investigation sites and also the river confluence sites. Uranium did not migrate from active mining areas and the highest uranium concentration measured 232.70 mgxkg(-1). In contrast, arsenic regularly migrated downstream, with soil concentrations averaging 47.26 mgxkg(-1), two times the limit set by the Three Grade Standard of Soil Quality in China (GB 15618-1995). Rumex nepalensis accumulated high levels of uranium, with a bioconcentration factor of 3.60 and a transfer factor of 3.61. Polygonum viviparum was able to accumulate arsenic, with a root transfer factor of 3.69, and also uranium as indicated by a bioconcentration factor greater than one. Thus, our investigations improved the understanding of the potential role of Polygonum viviparum and Rumex nepalensis involved in phytoremediation of uranium or uranium-arsenic pollution.