绿洲区土壤镍的吸附解吸特性

Study on Sorption and Desorption of Nickel in Soil Samples Collected from Oases

土壤重金属的移动性和生物有效性与重金属的吸附解吸及形态分布密切相关。通过序批试验、单步提取和连续提取的方法,研究绿洲区土壤镍(Ni)的吸附解吸特性。结果发现:①所研究的土壤呈现碱性,具低有机质含量和高碳酸盐含量特征,土壤未被镍所污染;②Freundlich可以用来模拟绿洲区土壤对镍的吸附行为。吸附能力与土壤粉粒、黏粒、全磷、有机质、CEC成显著正相关,而与砂粒成显著负相关,土壤pH并不是影响绿洲区土壤吸附镍的重要因子,绿洲区土壤对镍的吸附不是哪一个土壤理化参数所控制,而可能是土壤理化参数的联合控制;③绿洲区土壤镍的解吸量随土壤中镍吸附量的增加而增加,土壤镍解吸量与解吸前吸附量的关系可以用幂函数进行模拟;④在添加50mg/L镍的条件下,绿洲区土壤吸附的镍主要以铁-锰结合态、碳酸盐结合态和可交换态为主。

The mobility and bioavailability of heavy metals depend on the sorption,desorption and chemical forms. Laboratory experiments,single extraction procedure,sequential extraction and simple correlation analysis were carried out to study the sorption and desorption of nickel （ Ni） in soil samples collected from oases and the speciation of sorbbed Ni. Soil samples were characterized by the low organic matter content and high CaCO3 and could be considered uncontaminated. Sorption of Ni in soils was well described by the Freundlich equation. The correlation results reveal that the soils with higher silt,clay,total P and organic matter contents and CEC will retain Ni in greater amount than the sandy soils with lower total P and organic matter content and CEC. Soil pH value is not an important factor affecting Ni sorption. Sorption of Ni in oasis soils is likely to be affected by a combination of soil properties,such as pH value,CaCO3 and CEC. Sorption capacity of Ni is in an order of marshland soil ag-ricultural soil desert soil and shrub soil. Land use affects the sorption of Ni in oasis soils. Desorption of Ni in soil samples collected from oases varied in a range from 26. 79% to 99. 09% ,and bioavailability of Ni in oasis soils was high. Ni desorption was increased with the increase of Ni sorption in oasis soils. Power function can be used to simulate the relationship between desorption and sorption of Ni before desorption. Exchangeable Ni concentration in oasis soils was significantly decreased with the increase of soil pH value. There was a significant positive correlation between soil CEC and carbonate,Fe-Mn bound and residual nickel concentration,and also between total soil N content and Fe-Mn bound,organic bound and residual nickel concentration.