Abstract:
BACKGROUND The exploitation of minerals releases heavy metals into the surrounding soil, which can cause health hazards when biological entities are exposed to contaminated soil. Iron ore is one of the most widely distributed minerals in China, but there are few studies on the health risk of soil heavy metals in iron mines, especially in arid areas. The ecosystem of the arid area is fragile and difficult to repair once it has been polluted.
OBJECTIVES To perform environmental health risk assessment for topsoil surrounding iron deposits from Guyang County, Baotou City.
METHODS 101 topsoil samples were collected from an iron mine in Guyang County, Baotou City. Heavy metals were measured by inductively coupled plasma-mass spectrometry/optical emission spectrometry and atomic fluorescence spectrometry, to study element characteristics. The health risk assessment method was used to evaluate and calculate the screening value.
RESULTS The results showed that the variation coefficients of copper, chromium, and nickel in the study area were higher than 0.5, and the average contents of these elements were significantly higher than that in the Hetao Plain. The high value areas of copper were mainly distributed around tailings ponds and concentrators, while the high value areas of chromium or nickel were mainly distributed in bedrock mountains. The assessment of health hazards showed that the hazard quotient of all elements was less than 1, and the order was As>Cr>Ni>Cu>Cd>Zn>Hg. The average of total hazard quotient was 0.542. There was a sample in the bedrock mountain south of the iron mine, which had a total hazard quotient exceeding 1, and the contribution rates of chromium, nickel and arsenicwere 59%, 25%, and 15%, respectively. The carcinogenic hazard index of all elements was below 10-4. Soil screening levels of chromium, nickel and arsenic in the study area were 579mg/kg, 622mg/kg and 32.8mg/kg base on human health.
CONCLUSIONS Chromium and nickel in the study soil are mainly affected by parent materials of soil formation, while copper is mainly affected by mineral processing activities. In general, the health hazard of heavy metals in soil is relatively low, and is greatly influenced by the parent materials of soil formation. However, it is still necessary to pay attention to the accumulation of polluted elements in the areas around tailings ponds, and to avoid oral intake of pollutants. And it is also necessary to further study the feature of soil heavy metals from different kinds of iron mines and different regions that have not been studied before, because the associated elements of iron ore in different regions or types are not the same.
下载: