铅锌矿区农田土壤重金属有效态空间分布及其影响因子分析

利用地统计学方法,研究了广西岩溶地区某铅锌矿区农田土壤中Cd、Zn、Pb、Cu四种重金属有效态含量的空间分布特征及其影响因子.结果表明:研究区域不同程度地受到Cd、Zn、Pb、Cu的污染,且水田污染较旱地严重;与广西土壤背景值相比,污染程度最严重的是Cd,在水田和旱地中超标率均为100%,平均超标倍数分别为312.94和33.67;其次是Zn,在水田和早地中超标率分别为100%和34%,平均超标倍数分别为38.34和2.11;污染最轻的为Cu,超标率仅为7%.空间分析表明,有效态Cd、Zn、Pb、Cu的块金系数分别为2.7%、0.2%、6.5%、0.13%,体现了强烈的空间自相关性,且四种重金属空间分布特征相似,在离原铅锌选矿厂较近的西北偏西面有效态Cd、Zn、Pb、Cu含量最高,沿着西北偏西至东南偏东的灌溉渠流向,有效态Cd、Zn、Pb、Cu的含量呈递减趋势,东部旱地有效态Cd、Zn、Pb、Cu含量相对较低.土壤有效态Cd、Zn、Pb、Cu在污染区的空间分布与土壤基本理化性质关系密切,有效态Cd、Zn、Pb、Cu与pH、阳离子交换量、粘粒都呈极显著负相关,与有机质含量则呈极显著正相关.

Analysis on spatial distribution of soil available heavy metals and its influential factors in a lead-zinc mining area of Guangxi, China

By means of geostatistics, a study was carried out to investigate spatial distribution of available heavy metals (Cu, Zn, Pb, Cd) in agricultural soils in a Lead-zinc mining area of Guangxi Zhuang Autonomous Region, China. At the same time, the factors which influence the distribution of available heavy metals were analyzed. Results showed that the soil was polluted by Cd, Zn, Pb, Cu in different degrees. And the contamination in paddy soil is more serious than that in arid land soil. Contrast to the background value of heavy metals in soil at Guangxi, the contaminated degree of Cd in soil is most serious that exceeding standard rate of Cd is 100% and the mean exceeding standard are 312.94 and 33.67 times of Cd in the paddy soils and arid land soils, respectively. The exceeding standard rates of Zn are 100% and 34% in the paddy soils and arid land soils, respectively. The contaminated degree of Cu is slight and the exceeding standard rate of Cu is only 7%. The ratios of nugget to sill of available Cd, Zn, Pb, Cu are 2.7%, 0.2%, 6.5%, 0.13%, respectively, indicating the spatial distribution of available Cd, Zn, Pb, Cu are similar and autocorrelated. The contents of available Cd, Zn, Pb, Cu showed obvious directional characteristics from west northwest to east southeast, and the contents of available Cd, Zn, Pb, Cu reduced gradually along the irrigation ditches from WNW to ESE. The contents of available Cd, Zn, Pb, Cu of arid land soils in west were lower. The correlation analysis showed that spatial distribution of available Cd, Zn, Pb, Cu had been effected significantly by the soil basic physical chemistry character. It is positive correlation between available Cd, Zn, Pb, Cu with organic matter, while that is significantly negative correlation with pH, cation exchange capacity and clay.