饲养环境中土壤对牛饲料重金属元素含量影响

Effect of Soil on Levels of Heavy Metal Elements in Cattle Feeds in Rearing Environment

通过设立研究区的方法,研究了贵州不同污染条件下土壤和牛饲料中Cu、Zn、Pb、Cd污染状况和饲料与土壤重金属含量的相关性。结果表明:(1)贵州地表介质具有高Cd含量的背景分布特征,3个研究区内土壤中Cd的含量均超过我国《土壤环境质量标准》中三级土壤的最高限量值,非污染区、中度污染区和污染区土壤Cd含量分别是一级土壤的15.10倍、23.15倍和50.70倍,4种重金属的污染程度为Cd>Pb>Zn>Cu。(2)除非污染区外,牛饲料存在着Pb、Cd元素的污染,污染区饲料中Pb、Cd的含量分别是限量标准的16.50倍和13.16倍。(3)饲料中Zn、Pb、Cd含量与土壤元素之间呈显著的正相关,r>0.95,饲料中Cu元素与土壤元素之间含量呈负相关,相关系数r=-0.69。(4)随污染程度的增加,Cu元素在土壤-饲料之间的迁移系数逐步降低,Zn元素随污染程度的增加迁移系数逐步增加,而Pb、Cd两元素的迁移系数在中度污染区最高,在污染区中有所下降。

Through setting up a research area, the concentrations of heave metals, copper （Cu）, zinc （Zn）, lead （Pb） and cadmium （Cd） in soil and feed samples and their relations were studied under different pollution levels in Guizhou. The results showed that high cadmium concentration existed in Guizhou earth surface, and the mean concentration of Cd in soil samples were over the highest limit quantity of the Soil Environment Quality Standard Class III, around research areas. The Cd concentrations in non-polluted area, moderate polluted area and polluted area were 15.10, 23.15 and 50.70 times of Class I soil, respectively. The pollution levels of four heavy metals in the soil samples were in an order： Cd〉Pb〉Zn〉Cu. In moderate polluted area and polluted area, there existed the pollution of Cd and Pb in cattle feed, the Cd and Pb concentrations in cattle feed in polluted area were 16.50 times and 13.16 times of limit quantity value of the standard. The concentration of Zn, Pb and Cd in feed closely correlated to those in soil （r〉0.95）. There was negative correlation between the concentration of Cu in feed and in soil. With pollution degree increasing, the migration coefficient of Cu elements from soil to feeds decreased, but that of Zn increased. The migration coefficients of Pb and Cd were highest in moderate polluted area and decreased somewhat in polluted area.