Availability and Speciation of Cu, Zn, and Pb Added to Irrigated Desert Soil
Shengli Wang, Zhongren Nan, Xiaowen Liu, Guozhen Zhang, Zhuanjun Zhao
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Key Laboratory of Western China’s Environmental Systems, Ministry of Education, Lanzhou University,
Lanzhou 730000, Gansu, P. R .China
Pol. J. Environ. Stud. 2010;19(4):865–869
Potential risks for human health and adverse effects on soil quality caused by accumulation of Cu, Zn, and Pb arising from the mining and smelting of heavy metals in northwestern China have long been recognized. An incubation experiment was conducted to study the availability and speciation of Cu, Zn, and Pb in the irrigated desert soil from the oasis regions of northwestern China. The quantities of Cu, Zn, and Pb extracted by NH4NO3 extractant increased with the quantities of Cu, Zn, and Pb added. At every metal concentration added, the quantities of heavy metals extracted by the NH4NO3 extractant decreased in the order: Cu>Zn>Pb. The sorption mechanism of Cu, Zn, and Pb was mainly not ion exchange, but specific sorption or precipitation. In lower added concentrations (100 mg/kg), most Cu and Pb was extracted in their reducible fraction and oxidizable fraction, probably because Cu and Pb mainly were sorbed to high energy sites. In higher added concentrations, most Cu, Zn, and Pb was extracted in its more mobile fraction (acetic acid soluble fraction), possibly because the irrigated desert soil contains high CaCO3 and less organic matter. Acetic acid soluble fraction among Cu, Zn, and Pb at very initial concentrations was in the order: Zn>Cu>Pb; both reducible fraction and oxidizable fraction were in the order: Pb>Cu>Zn.