中国蔬菜土壤重金属含量及来源分析

Heavy Metal Content in Soils of Vegetable-growing Lands in China and Source Analysis

【目的】为系统了解并客观评价中国菜地土壤的重金属含量状况,促进中国蔬菜生产向优质高效方向发展。【方法】系统收集了1989年以来中国蔬菜土壤重金属研究的相关资料,并利用相关方法对所收集到的数据进行了统计分析。【结果】中国菜地土壤重金属中以Zn含量最高,其次是Cr,再次是Cu;而毒性较大的元素As、Hg、Cd的含量相对较低,其平均含量分别为8.03、0.12、0.28mg·kg-1。与国家土壤质量II级标准GB15618-1995(6.5<pH<7.5)相比,Cd含量超标的问题较为突出,全国约24.1%的菜地样本超标;Hg含量其次,样本超标率为10.3%;As的超标率为9.2%。各种重金属按含量超标率排序为:Cd>Hg>As>Zn>Cu>Cr>Pb。若按地区比较,则东部地区Cd含量超标较为严重,其次是Hg和Zn;中部地区以As和Cd含量超标为主,亦存在少量的Hg、Zn、Cu超标;西部地区亦以As、Cd超标为主,并伴随有少量的Cu、Cr和Hg超标。不同类型菜地比较,工矿/污灌区菜地的As、Cd、Hg、Zn含量均最高,尤其是其Hg含量平均高达2.36mg·kg-1,超出其它类型菜地含量的10.5～21.1倍;设施菜地的Cu、Cr含量在所有类型中是最高的,而城市郊区菜地则Pb含量相对较高。对全国各地的蔬菜基地进行单独分析,发现除Pb含量稍高外,其它几种重金属的含量均较低,全国普通菜地的整体质量状况较好。【结论】在中国当前菜地利用方式下,除工矿/污灌菜地、市郊菜地土壤中个别重金属含量超标外,中国菜地土壤、特别是蔬菜基地土壤的重金属含量基本上未超过国家标准,整体质量状况较好。

[ Objective] The objective of this investigation was to study the content of heavy metals in soils of vegetable lands systematically through assessment objectively to promote the development of vegetable production with high quality and efficiency. [Method] Statistical analysis of reported data on the heavy metals in Chinese vegetable plantation soils, from previous literatures published since 1989 was carded out systematically in this investigation. [Result] It is concluded that Zn, Cr, Cu had relatively high concentrations while the mean concentrations of toxic metals, As, Hg, Cd was 8.03, 0.12, 0.28 mg-kgl separately with comparatively low concentrations in vegetable lands in China. Compared to Chinese Soil Quality Criterion GB 15618-1995 （6.5〈 pH〈7.5）, about 24.1%, 10.3%, 9.2% of the total samples was contaminated by Cd, Hg and As respectively, and the descending order of heavy metals was Cd 〉Hg 〉As 〉Zn 〉Cu 〉Cr〉Pb. When compared among different regions, the relatively serious heavy metal contamination was found in eastern China vegetable lands and the main contamination elements were Cd, Hg and Zn. In the mid region, vegetable plantation land soil was mainly polluted by As and Cd, as well as Hg, Zn and Cu in some extent. In the west region of China, Cd and As contamination was also observed in some degrees, along with few soil samples exceeding the grade II level of GB 15618-1995 （6.5〈pH〈7.5） for Cu, Cr and Hg content. Compared to the five vegetable plantation land patterns, the highest concentration of As, Cd, Hg and Zn occurred in the industrial/sewage irrigation vegetable lands, especially for Hg with 2.36 mg.kg^-1 content which is 10.5-21.1 times higher than other four types of vegetable lands in average. The highest concentration of Cu and Cr occurred in greenhouse vegetable land soils, and urban vegetable land soil had the highest Pb content comparing to other types of vegetable plantation land pattems. Through analysis of heavy metal content under different vegetable land pattems, it was found that vegetable producing base soil had relatively low heavy metal concentrations except for Pb with a little higher amount in city suburbs. The soil quality of common vegetable land was good with the lowest concentrations for most heavy metals. [Conclusion] Under present utilization pattems of vegetable land, the soil quality in Chinese vegetable base land was good with comparatively low concentrations of heavy metals and mostly not exceeding the grade II level of Chinese Soil Quality Criterion GB 15618-1995 （6.5〈 pH〈7.5）. However, comparatively serious contamination was found in industrial/sewage irrigation and city suburb vegetable land soils.