云南凤庆茶园土壤中重金属元素的形态分布特征

Speciation Distribution Characteristics of Heavy Metals in Typical Tea Garden Soils in Fengqing County of Yunnan

土壤重金属是茶叶中重金属的主要来源之一,土壤重金属的植物有效性与赋存形态关系密切.因此,采用Tessier化学形态连续提取法对凤庆代表性茶园土壤中6种重金属的形态进行连续提取,并分析茶园嫩叶与土壤重金属总量和可交换态含量之间的相关性.结果表明,凤庆茶园土壤中Cu,Pb,Zn,Cd,Cr和As的含量均未超过我国农用地土壤污染风险管控值,各茶园土壤中各重金属主要以残渣态为主(74.80%~98.73%),除彭家社茶园的Cu以外(可交换态Cu含量高达46.27%),各茶园的各重金属元素的可交换态含量均较低(<5%).茶叶嫩叶中重金属的含量均未超过各级标准的限定值,茶园表层土壤中6种重金属的总量和可交换态含量与茶叶嫩叶含量之间无明显的相关关系.

Soil heavy metals are one of the important sources of heavy metals in tea leaves. The plant availability of heavy metals in soil is closely related to their speciation. A sequential extraction method (Tessier method) was adopted for the extractions of heavy metals (Cu, Pb, Zn, Cd, Cr and As) speciation in Fengqing typical tea gardens (Dawotuo, Daliangzi, Pengjiashe, Dasixiang and Luodangxiang). The correlations between the total amount and the exchangeable content of heavy metals in the tea plantation soils and young leaves were analyzed. The results showed that the contents of Cu, Pb, Zn, Cd, Cr and As in the soil of Fengqing tea gardens did not exceed the control value of soil pollution risk in agricultural land in China. The heavy metals in the soil of each tea garden were mainly residuals (74.80%-8.73%). The exchangeable content of each heavy metal elements in each tea garden is relatively low (<5%), except for Cu in Pengjiashe Tea Garden (the content of exchangeable Cu is up to 46.27%).The content of heavy metals in the young leaves of tea did not exceed the limit value of the standard at all levels. There was no significant correlation between the total and exchangeable content of Cu, Pb, Zn, Cd, Cr and As in the surface soil of tea gardens and the content of young tea leaves.