某聚氯乙烯树脂厂退役场地土壤汞污染特征分析

场地重金属污染是工业化进程的产物，污染来源多为原料及副产物的泄漏或不达标排放，给人类和环境造成不同程度的危害。本文以武汉某退役聚氯乙烯（PVC）树脂厂为研究对象，结合氯化汞催化工艺特点，探究场地土壤重金属汞的污染来源及分布特征，为同类型场地土壤重金属汞的污染调查、防治、修复提供案例支撑。研究结果表明：1）参与调查的33个点位中有27.3%已达到相当严重的污染水平，潜在生态风险单项指数Ei值最高达57 900，污染分布范围主要集中于氯化汞催化乙炔生产氯乙烯（VCM）工艺段，水平迁移扩散能力不强；2）重金属汞的垂直迁移受土壤性质影响，粘土对重金属汞的截留效果佳，粘土层中0.8~1.0 m至1.8~2.0 m最大汞浓度衰减量达2 040 mg·（kg·m）-1，衰减率达97.2%，而疏松的杂填土则有利于汞的垂直下渗；3）调查区域受重金属汞污染呈现典型点源污染特征。

Soil mercury pollution characteristics in a retired polyvinyl chloride resin factory

Site heavy metal pollution is the product of the industrialization process, and the pollution sources are leakage or non-compliance emissions of the raw materials and by-products, causing harm to humans and the environment. The study on the pollution sources and distribution characteristics of mercury in the soil combining with the mercuric chloride catalyst technology of a selected retired polyvinyl chloride (PVC) resin factory provides a case support of mercury pollution investigation, prevention and remediation for the same field soil. The results shows that, 1) 27.3% of the 33 points in the survey reached a considerable level of pollution, the highest potential ecological risk index Ei was up to 57900, and pollution distribution was mainly concentrated in mercuric chloride catalytic acetylene production of vinyl chloride (VCM) process segment, but horizontal migration and diffusion capacity was not obvious. 2) The vertical migration of heavy metal mercury was affected by soil properties. The original clay layer had high intercept effectively for the mercury contamination with the highest decrement was 2 040 mg·(kg·m)-1 at the ratio of 97.2% between 0.8~1.0 m layer and 1.8~2.0 m layer, nevertheless the loose miscellaneous fill was conducive to the vertical infiltration of mercury. 3) The investigation area was characterized by typical point source pollution due to the mercury.