珠江三角洲土壤Hg污染区生态地球化学评价

Appraise of environmental geochemistry in soil Hg polluted areas in the Pearl River Delta

通过系统的区域土壤地球化学调查,珠江三角洲部分地区土壤存在Hg高含量区,主要分布于广州市、佛山市等城市及周边地区。通过多种方法调查分析,认为Hg高含量区属人为污染引起。土壤垂直剖面测量显示:土壤Hg低含量区自地表往2m深处Hg含量变化甚微,而大部分Hg高含量区的土壤从表面往2m深处Hg含量则显著降低。通过相态分析和重砂分析等方法,证实土壤污染区Hg主要以硫化物存在,部分硫化物为结晶态(即辰砂);污染区土壤在酸性→弱酸性→中性→弱碱性环境下,活泼相态Hg含量极低且变化极小。通过壤中Hg气测量和模拟大气Hg试验,推测污染区土壤Hg极可能有部分进入大气层。通过对部分农作物Hg含量调查,显示土壤Hg污染对不同种类农作物的影响差异较大,初步表明土壤Hg污染已影响部分农产品的质量但对质量安全构成的威胁并不大。

Through the systematic regional soil geochemical survey and analysis, it shows that the soil areas with high mercury content arc mainly distributed in Guangzhou, Foshan city, et al. and their surrounding areas in parts of the Pearl River Delta region. Based on investigation and analysis synthetically using different methods, it is confirmed that those areas with high mercury content arc caused by artificial contamination. The vertical profiles of soil survey on Pearl River Delta region shows that mercury contents change little in soil areas with lower mercury content from the earth＇s surface to 2 m depth, whereas it is significantly reduced in the most of soil areas with high mercury content. Using phase analysis and placer analysis method, et al., we confirm that mercury in contaminated soil area mainly exists in the form of sulphide and parts of sulfides are crystal （namely cinnabar）, and in the contaminated soil areas, the content of active phase mercury is terribly low and the change is little in such environment of earth＇s property from acidity-weak acidity-neutral acidity-weak alkaline. Based on the measurement of gaseous mercury in soil and test of simulating atmosphere-mercury, we infer that some of mercury in contaminated soil area probably enters into the atmosphere. To analyze the mercury contents of some agricultural crops show that the impacts of mercury pollution of soil on different kinds of agricultural crop vary greatly, and initially indict that mercury pollution of soil have impacted on the quality of some agricultural production, but the threat to quality safety aren＇t serious.