杭州市典型茶园土壤与茶叶中重金属的积累与来源分析

为了解杭州市茶园土壤与茶叶中重金属的污染状况及其重金属的可能污染来源,选择杭州市典型茶园20个,按区位与施肥的不同分为城郊-化肥、城郊-有机肥、山区-化肥和山区有机肥等4种类型,采集了0~15、45~60 cm分层土样及茶树新叶和老叶样品,分析土样和茶叶样品中Pb、Zn、Cu、Cd、Hg、Cr和Co等重金属含量。结果表明,研究土壤Pb、Zn、Cu、Cd、Hg、Cr和Co污染程度较轻,其含量均低于土壤环境质量二级标准。除老叶样中Pb有25%样品超标外,新叶及老叶的其他重金属元素都在限值以下。城郊区茶园土壤的Pb、Cd和Hg含量普遍高于山区茶园。施用化肥的茶园土壤Cd略高于施用有机肥的茶园,施有机肥的茶园土壤Hg略高于施用化肥的茶园。施用有机肥的茶园土壤Zn和Cu明显高于施化肥的茶园。施用有机肥可轻微提高茶园土壤中Cr的积累;土壤中Co的积累受人为影响较小。研究认为,研究区茶园土壤中重金属Pb、Cd和Hg的积累主要与大气沉降有关,而Zn和Cu的积累主要与有机肥料的施用有关。

Accumulation and Sources of Heavy Metals in Soil and Tea-leaf in Typical Tea Gardens in Hangzhou

In order to study the pollution situation caused by heavy metals in both soil and tea-leaf in tea gardens in Hangzhou and its possible sources, the author chose 20 typical tea gardens in Hangzhou and divided them as gardens of suburb-chemical fertilizer, suburb-organic fertilizer, mountainous area-chemical fertilizer and mountainous area-organic fertilizer according to the location and fertilization. The author collected 0-15 cm (surface soil) and 45-60 cm (bottom soil) soil samples and both new and old tea-leaf samples for analyzing Pb, Zn, Cu, Cd, Hg, Cr and Co content. The results showed that the pollution of Pb, Zn, Cu, Cd, Hg, Cr and Co in soil were not obvious, concentrations of those metals were lower than The Second Level Standard of Soil Environmental Quality. Except Pb in 25% samples of old leaves exceeded the safety standard, other elements in both new and old leaves were within the limiting value. The soil concentrations of Pb, Cd and Hg in suburb tea gardens were generally higher than those in mountain tea gardens. The soil concentration of Cd in chemical fertilizer tea gardens was slightly higher than that in organic fertilizer tea gardens. The soil concentration of Hg in organic fertilizer tea gardens was slightly higher than that in chemical fertilizer tea gardens. The soil concentrations of Zn and Cu in organic fertilizer were much higher than those in chemical fertilizer tea gardens. Application of organic fertilizer could slightly increase Cr concentration in soil. Concentration of Co was not related to human activity. It was concluded that the accumulations of Pb, Cd, and Hg in soil were mainly related to atmospheric deposition, and the accumulations of Cu and Zn in soil were mainly related to the application of organic fertilizer.