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天津市武清区农田土壤和蔬菜中重金属污染特征及来源解析

彭皓1,2,马杰2,马玉玲2,陈雅丽2*   

  1. 1吉林农业大学资源与环境学院, 长春 130118;2农业农村部环境保护科研监测所, 天津 300191)
  • 出版日期:2019-07-10 发布日期:2019-07-10

Characteristics and source identification of heavy metal pollution in agricultural soils and vegetables in Wuqing District, Tianjin City, China.

PENG Hao1,2, MA Jie2, MA Yu-ling2, CHEN Ya-li2*   

  1. (1College of Resources and Environmental Science, Jilin Agricultural University, Changchun 130118, China; 2AgroEnvironmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China).
  • Online:2019-07-10 Published:2019-07-10

摘要: 为评价中国北方典型农田土壤和蔬菜重金属污染特征,从天津市武清区分别采集45个农田表层土壤及对应的叶类蔬菜、32个农用畜禽粪便样品和4组土壤剖面,测定了Cd、Cr、Cu、Ni、Pb和Zn共6种重金属的含量和形态,〖JP2〗并利用相关性分析和主成分分析判断土壤中重金属污染的可能来源。结果表明:表层土壤6种重金属的累积程度依次为Cd>Cr>〖JP〗Cu>Zn>Pb>Ni,其中26.7%的Cd超过了土壤环境质量二级标准(GB 15618—2018);叶类蔬菜根部存在重金属累积(尤其是Cd),但蔬菜叶片中并不存在重金属超标;研究区所施用的畜禽粪便中Cd的超标率为16%(参照NY 525—2012),其长期施用会造成表层土壤中重金属的累积;同时,表层土壤中高的可交换态Cd、Cu和Zn会增加作物吸收土壤中重金属的风险,是造成当地叶类蔬菜根部和叶片中重金属累积的原因之一。结合主成分分析结果:Cr和Ni主要来自于成土母质;Zn主要受农业活动影响,如畜禽粪便的施用;Cd和Pb主要受工业活动影响;Cu为复合污染,受工业和农业活动共同影响。综上所述,研究区土壤和畜禽粪便中存在Cd超标现象,虽然目前蔬菜叶片中重金属未超标,但应该注意控制或减少农业和工业污染对蔬菜地重金属的影响,以确保农田土壤和蔬菜的安全。

Abstract: To evaluate heavy metal pollution in agricultural soils and vegetables in North China, 45 surface agricultural soil samples and corresponding vegetable samples, 32 livestock manure samples, and four soil profiles were collected in Wuqing District, Tianjin City. For all samples, heavy metal (Cd, Cr, Cu, Ni, Pb, Zn) concentrations and their fractions were analyzed. The correlation analysis and principal component analysis were used to determine the potential pollution sources. The results showed that the accumulation (relative to soil background value) of heavy metals in surface soils decreased in the order of Cd>Cr>Cu>Zn>Pb>Ni. The concentration of Cd in 26.7% of samples exceeded the Second Standards of Soil Environment (GB 15618-2018). Heavy metal concentrations in vegetable roots were relatively enriched (especially for Cd), while those in leaves did not exceed the standards (GB 2762-2017). In the study area, 16% of samples for Cd in applied livestock manures exceeded the industry standards of organic fertilizer of China (NY 525-2012), which could lead to the accumulation of heavy metals in surface soils after longterm application. Relatively high proportion of exchangeable Cd, Cu and Zn in the surface soil might increase the potential risk of heavy metals absorbed by crops and lead to the accumulation of heavy metals in roots and leaves of vegetables. Results from the principal component analysis showed that Cr and Ni may derive from soil parent material, Zn from agricultural activities (such as the application of livestock manures), Cd and Pb from industrial activities, and Cu from both agricultural and industrial activities. In summary, Cd in some soil and livestock manure samples exceeded the standard in this area. More attention should be paid to control or reduce the impacts of agricultural and industrial pollution on metal concentrations in soils and vegetables, although no heavy metal concentrations in leaves exceed the limit of stan dards at present.