华北平原地区某铅冶炼厂附近土壤重金属有效性研究(Heavy Metal Availability in Soil near a Lead Smelter in the North China Plain)

为研究华北平原地区某铅冶炼厂对附近农田土壤和居民点内土壤重金属有效性的影响,在距离冶炼厂烟囱1000m和2500m处设置A1和A2两个采样断面(两断面间有一居民点),采取0～20cm土样,测定DTPA-Ni、Cu、Pb、Zn和Cd含量.结果表明,A1断面DTPA-Ni、Cu、Pb、Zn和Cd平均含量均低于A2断面.A1断面土壤DTPA-Pb和Cd变化范围分别为7.18～37.8和0.250～0.950mg·kg-1,平均值分别为25.2和0.580mg·kg-1;A2断面DTPA-Pb和Cd变化范围分别为14.7～133和0.280～2.35mg·kg-1,平均值分别为59.9和1.16mg·kg-1.所有样品的DTPA-Ni、Cu和Zn含量均小于5.5mg·kg-1.随着采样点距离冶炼厂烟囱距离的增加,土壤中DTPA-Ni、Cu、Pb、Zn和Cd含量呈非线性下降,可用幂方程(Ni、Cu和Pb)或对数方程(Zn和Cd)拟合.用Pb和Cd的拟合方程计算得到的研究区内居民点中心位置土壤DTPA-Pb和Cd含量分别为30.0和0.731mg·kg-1,高于地带性土壤背景值.DTPA-Ni、Cu、Pb、Zn和Cd的含量之间均存在极显著线性正相关关系(p<0.01).以上结果表明,冶炼厂造成研究区内土壤Pb和Cd有效性远高于正常水平,并导致Ni、Cu和Zn有效性有一定程度的升高,附近居民点内居民受到土壤高铅和高镉有效性的威胁;土壤铅和镉升高的范围达到距离冶炼厂烟囱2.8km以外区域.

Heavy Metal Availability in Soil near a Lead Smelter in the North China Plain

In order to investigate the influence of lead smelting on the heavy metal availability in soil in the North China Plain, soil sample(0～20cm)were collected at two transects near a lead smelter in the North China Plain. The two transects were named A1 and A2. Distances between the centers of transect A1 and A2 to the smelter chimney were 2500 and 1000m, respectively. Forty-five and 20 samples were collected from transect A1 and A2, respectively. DTPA-nickel(Ni), copper(Cu), Pb, zinc(Zn)and cadmium(Cd)extracted from soil were measured. Average soil contents of DTPA-Ni, Cu, Pb, Zn and Cd of transect A2 were higher than soil of transect A1. The contents of DTPA-Pb and Cd in transect A1 were 7.18～37.8 and 0.250～0.950mg·kg-1, respectively and average contents were 25.2 and 0.780mg·kg-1, respectively; while those of transect A2 were 14.7～133 and 0.280～2.35mg·kg-1, average contents were 59.9 and 1.16mg·kg-1, respectively. The contents of DTPA-Ni, Cu and Zn of all the samples were all lower than 5.5mg·kg-1. The relationships between the contents of DTPA-Ni, Cu, Pb, Zn and Cd and the distance of samples to lead smelter could be best fitted to negative power models(Ni, Cu and Pb)and negative logarithm models and(Zn and Cd). Estimated the contents of DTPA-Pb and Cd at the center of the residential area with the above models were 30.0 and 0.731mg·kg-1, both were much higher than background values in local soil. Significant positive linear correlations were found between the contents of DTPA-Ni, Cu, Pb and Zn and that of Cd(p<0.01). The results indicate that the atmospheric deposition from the lead smelter makes the availability of Pb and Cd in soil increase to far more than normal levels, and makes availabilities of Ni, Cu and Zn increased too. The health threat of Pb and Cd to the nearby residents exists. Elevation of Pb and Cd availability in soil reaches a distamce farer than 2.8km from the smelter.