Preliminary Assessment on Contamination and Potential Ecological Risk of Thallium in Cultivated Soils around the Ni-Mo Mining Area in Songlin,Zunyi

The Ni-Mo mining area in Songlin,Zunyi,Guizhou,is a typical one within the lower Cambrian Ni-Mo mineralization zone of South China.Therefore,assessing the environmental quality of soils around the mining area is of important scientific and practical significance.The concentrations of thallium in the cultivated soils around the Ni-Mo mining area in Songlin were analyzed by inductively coupled plasma mass spectrometry(ICP-MS) in this study.The result shows that the thallium contents(with an average of 1.84 mg/kg) in the soils are higher than the background value of thallium in the topsoil of Guizhou Province.It is preliminarily suggested that the black shales,Ni-Mo ores and Ni-Mo tailings exposed on the surface environment are major sources of thallium in the soils.In the present study,we evaluated the degree of contamination and potential ecological risk of thallium in the soils in terms of geoaccumulation index and potential ecological risk index,respectively.It is revealed that the soils around the Ni-Mo mining area in Songlin,Zunyi,Guizhou,have been contaminated by thallium(most of the samples with slight to moderate heavy pollution levels).It is also indicated that the studied soils have an obvious potential ecological risk caused by thallium(with low to moderate potential ecological risk levels).Therefore,further research on remediation for the contaminated soils deserves to be carried out.