[Distribution characteristic and assessment of soil heavy metal pollution in the iron mining of Baotou in Inner Mongolia].
The pollution status and total concentration of soil heavy metals were analyzed around tailing reservoir of Baotou and iron mining of Bayan Obo located in Inner Mongolia grassland ecosystem. Aim of the study is to control soil heavy metal pollution of grassland mining area and provide the basic information. The results indicated that the soils from different directions of the tailing reservoir were contaminated by Pb, Cu, Zn and Mn. According to the single factor pollution index, the pollution degree was Mn > Zn > Pb > Cu. According to Nemerow integrated pollution index, the indexes of the northeast, southeast, southwest, and northwest of the tailing reservoir, were 2.43, 10.2, 1.88, 1.64. Soils from the southeast had the most serious heavy metal contamination because of the dominant wind of northwest. Within 50 m from the edge of tailing reservoir, heavy metal contamination was most serious except Cu. With regard to Bayan Obo iron mining, the single factor pollution index indicated that the soils from the six surveyed regions were contaminated by Pb, Cu, Zn and Mn. The integrated pollution index indicated that the indexes of the six regions, such as the mining area, the dump, outside the dump, outside the urban area, east region of the railway, and west region of the railway, were 14.3, 4.30, 2.69, 3.41, 2.88, and 2.20, respectively. The soil pollution degree of the mining area was the highest. Additionally, the transport of ore resulted in soil heavy metal pollution along railway. In general, soils of the two studied areas had the similar pollution characteristic, and the elements of heavy metal contamination were corresponding with the concentrations of tailings. The health and stabilization of grassland ecosystem are being threatened by soil heavy metals.