重庆市某区果蔬基地土壤重金属污染及其风险评价研究

Evaluation of Heavy Metals Pollution Risk of Fruit and Vegetable Bases in the Suburbs of Chongqing

对农田土壤重金属污染的评价和控制,对发展绿色食品的果蔬基地来讲具有十分重要的意义。采选重庆市近郊某区的2个典型的绿色果蔬生产基地的土壤为研究对象,系统分析了土壤中Cd、As、Pb、Cr、Cu、Ni、Zn、Ti和Se等9种重金属元素的含量,并以《绿色食品产地环境技术条件》(NY/T 391-2000)的"土壤中各项污染物的含量限值"、《土壤环境质量农用地土壤污染风险管控标准(试行)》(GB 15618-2018)和重庆市土壤背景值为相应的评价标准,通过单因子和内梅罗污染指数法、地积累指数法和生态危害指数法对土壤的重金属污染状况进行了多方面的评价。单因子和内梅罗污染指数法的结果表明,2个基地土壤样品的5种重金属元素单因子指数Pi均小于1.0;内梅罗污染指数PN分别为0.6743和0.6091,接近0.70,这表明2个基地的土壤符合绿色食品产地环境技术条件。地积累指数评价的结果显示2个基地的土壤均未受Cd、Cu、Ni、Zn这4种金属的污染,已受As、Pb的轻度污染,这可能与该区域的地理环境和人为活动有关。土壤潜在生态危害指数及风险程度分析评价的研究结果显示,基地-XY和基地-KY的土壤风险系数最大的均是Cd,分别为26、19,总的潜在生态风险指数RI分别为64、54,这也说明了2个基地土壤的生态风险较低。该研究可为系统全面地评价研究区域的土壤健康状况奠定一定的基础。

In order to develop green food product in suburbs of Chongqing,it is crucial to evaluate and control the heavy metal pollution of farmland.By using the soils of 2 blocks of fruit and vegetable bases in suburb of Chongqing,the content of 9 kinds of heavy metals in the soils was investigated,namely Cd,As,Pb,Cr,Cu,Ni,Zn,Ti and Se.Using the green food-technical conditions for environmental area(NY/T 391-2000),soil environmental quality risk control standard for soil contamination of agricultural land(GB15618-2018)and the background value of Chongqing as reference assessment criteria of soil quality,current situation of heavy metal pollution to the soils and the degree of its potential risk were analyzed through some index methods such as single factor pollution index,Nemerow comprehensive pollution index,the geoaccumulation index as well as potential ecological risk index.The result of single factor and Nemerow comprehensive pollution index showed that the of Pb,As,Cu,Cd,Cr in the soils were less than 1.0,and the of the 2 blocks bases also were less than 0.70,and this indicates that the soil of the 2 bases meets the environmental and technical requirements of green food producing areas.The evaluation results of the geoaccumulation index revealed that the soils of the two bases were not polluted by Cd,Cu,Ni and Zn,but were slightly polluted by As and Pb,which may be related to the geographical environment and human activities in the region.The potential ecological risk index analysis showed that the value of Cd was the Maximum one in both of the two bases,while the soil risk coefficient of base-XY and base-KY,which are 26 and 19,respectively.The total potential ecological risk index RI of the two lands was 64 and 54,respectively,classified as light potential ecological hazards.These results could lay a foundation for a systematic and comprehensive assessment of soil health in the suburbs of Chongqing.