| 新疆哈密地区有机氯农药大气、土壤残留特征、气-土交换及潜在生态风险 |
| 摘要点击 2442 全文点击 1352 投稿时间：2012-05-20 修订日期：2012-08-13 |
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| 中文关键词 哈密地区 大气 土壤 OCPs污染 气-土交换 生态风险 |
| 英文关键词 Hami region air soils organochlorine pesticides(OCPs) pollutions air-soil exchange ecological risk |
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| 中文摘要 |
| 应用大气被动采样技术对新疆哈密地区城市、农村及林场点位大气和土壤中主要有机氯农药:HCHs和DDTs进行了1 a的观测分析,对其大气、土壤残留现状和气-土交换进行了分析研究,并对其潜在生态风险进行了初步评估,结果表明,哈密地区大气中 HCHs和 DDTs在1a观测期的平均浓度分别为107.1 pg·m-3和43.9 pg·m-3; 大气中HCHs和DDTs浓度呈现季节性变化:夏、秋两季HCHs和DDTs的浓度普遍高于冬、春两季,推测为夏、秋季较高的温度造成更多的HCHs和DDTs挥发到空气中; 大气中两类OCPs污染以HCHs为主,HCHs各类异构体残留以α-HCH为主,DDTs残留以p,p'-DDE为主. 研究区大气中α-HCH/γ-HCH的值普遍在3~7之间,推测工业HCHs的使用或HCHs的大气长距离传输对该地区大气中HCHs含量有较为明显的影响; 大气中(DDD+DDE)/DDTs的值在0.4~0.9之间,有71.4%的比值大于0.5,表明大气中DDTs主要来自于环境中的残留,近期没有新源输入. 土壤中HCHs和DDTs含量范围分别为0.344~6.954 ng·g-1和0.104~26.397 ng·g-1,均未超过国家土壤环境质量标准规定的一级自然背景值; 土壤中两类OCPs污染以DDTs为主, HCHs各异构体残留以β-HCH为主,DDTs残留以o,p'-DDT为主,根据(DDD+DDE)/DDTs<0.5,近期土壤中有新的HCHs和DDTs输入. 土壤和大气中HCHs和DDTs的来源不一致,主要是由土壤和大气本身的不同特性以及哈密地区复杂的地理和气候条件导致的. 气-土交换研究表明:哈密地区HCHs各异构体和p,p'-DDE的气-土交换主要以土壤向大气挥发为主; 而o,p'-DDE、o,p'-DDD、p,p'-DDD、o,p'-DDT、p,p'-DDT的气-土交换则主要是由大气向土壤沉降. 大部分DDTs的汇是土壤,源是大气; 而HCHs和p,p'-DDE的汇则是大气,源是土壤. 哈密地区土壤中HCHs的生态风险较低,哈密城市和林场土壤中DDTs可能对该地区鸟类和土壤生物具有一定的潜在生态风险. |
| 英文摘要 |
| The concentrations of HCHs and DDTs in soil and air of urban/rural/forestry centre locations in the Hami region of Xinjiang were monitored for a year by passive atmospheric sampling in order to study the residual levels and air-soil exchange and evaluate ecological risk. The study results showed that the annual average concentrations of HCHs and DDTs in the air of Hami were 107.1 pg·m-3 and 43.9 pg·m-3, respectively, and the concentrations of HCHs and DDTs in summer and autumn were generally higher than those in winter and spring. It was deduced that the HCHs and DDTs tended to evaporate into the air because of the higher temperatures in summer and autumn. For OCPs in the air of study area, HCHs were dominanted the main pollution compared with DDTs. Meanwhile, α-HCH contributed the largest portion among all HCHs isomers, and p,p'-DDE dominated the residual levels of DDTs. Moreover, the values of α-HCH/γ-HCH were in the range of 3 to 7, which indicated that the use of technical HCHs or the long distance atmosphere transport of HCHs may play a significant role for HCHs in the air of Hami region. Furthermore, ratios of (DDD+DDE)/DDTs were in the range of 0.4-0.9, 71.4% of which were higher than 0.5, indicating that DDTs in the air were mainly from historical usage and no new DDTs sources emerged in Hami recently. The concentrations of HCHs and DDTs in soil were between 0.344-6.954 ng·g-1and 0.104-26.397 ng·g-1, respectively, which did not exceed the National Soil Quality Standard Level I. In addition, DDTs predominated in soil OCPs, in which β-HCH accounting for a huge percentage in HCHs isomers, while o,p'-DDT predominated in pollution caused by DDTs isomers. From study results, it was also suggested that the important cause of DDTs residues in soil of Hami area could be the recent inputs of new sources since the value of (DDD+DDE)/DDTs were lower than 0.5.The sources of HCHs and DDTs in soil and atmosphere were not consistent, which was mainly caused by the different characteristics of soil and atmosphere and the complex geographical environment and climatic conditions in Hami region. The study on air-soil exchange showed that the escaping tendency of the various isomers of HCHs and p, p'-DDE was mainly from the soil to the air, on the contrary, the escaping tendency of o,p'-DDE,o,p'-DDD,p,p'-DDD,o,p'-DDT,p,p'-DDT was mainly from the air to the soil in Hami, which indicated that the soil was the sink of most of DDTs, and the air was the source of most of DDTs; while the air was the sink of HCHs and p,p'-DDE,and the soil was the source of HCHs and p,p'-DDE. There were potential risks of DDTs to birds and soil organisms in urban soil and forestry centre soil of Hami region, while the ecological risk of HCHs was light in Hami surface soil. |
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