南中国海海水中有机氯农药和多氯联苯的含量及分布特征

近年来,随着沿海化工生产基地的大量投入运营及海上危险化学品运输业的日益增长,海洋生态环境受到严重威胁,我国海洋环境中持久性有机污染物如有机氯农药及多氯联苯在近海环境中普遍检出。为了对南中国海水体中持久性有机污染物的污染现状有所了解,本文利用气相色谱-电子捕获检测器(GCECD)对南中国海海水中的15种有机氯农药和多氯联苯进行测定,两类化合物各检出6种。采用外标法进行定量分析,结果显示:调查海域表层海水中有机氯农药和多氯联苯类化合物的浓度范围分别为0~92.30ng/L和1.16~76.24 ng/L,200 m层海水中分别为0~69.85 ng/L和0~49.63 ng/L,500 m层海水中分别为0~56.68 ng/L和0~26.47 ng/L。由此可看出,该海域有机氯农药和多氯联苯的含量分布特征大致呈现为:表层200 m层500 m层,原因可能是污染源主要来自周围地表径流或大气输入,且随着时间的推移污染物吸附于悬浮体由表层向下层迁移。与国内外相关海洋环境中有机农药及多氯联苯含量水平相比较,南中国海海水中有机农药和多氯联苯的含量低于国内大部分水域,但高于国外已知海洋水体中的含量。南中国海中有机农药和多氯联苯含量和分布特征的取得为下一步对海洋环境的研究和保护工作提供了基础数据。

Concentrations and Distribution Characteristics of Organochlorine Pesticides and Polychlorinated Biphenyls in Seawaters of the South Sea

In recent years, with the operation of coastal chemical production bases and booming maritime transportation of dangerous chemicals, there are threats to the marine environment. Persistent organic pollutants, such as organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs), have been detected in the offshore marine environment. In order to understand the pollution status of persistent organic pollutants (POPs) in the South China Sea, 15 PCBs and OCPs in seawater from the South China Sea were quantitatively determined by using Gas Chromatography-Electron Capture Detector (GC-ECD). Six kinds of OCPs and six kinds of PCBs were detected in these seawater samples. Using an external standard method for quantitative analysis, the detection limits were 0.24-1.07 ng/L, the linear range of the method was 1.0-250 ng/L. The recoveries for blanks were in the range of 89.1% to 109.7% with the relative standard deviations of 2.3%-8.6% and the recoveries for the samples were in the range of 90.1% to 113.5% with the relative standard deviations of 3.1%-10.4%. The results show that the concentration ranges of OCPs and PCBs were 0-92.30 ng/L and 1.16-76.24 ng/L respectively in the surface seawater, 0-69.85 ng/L and 0-49.63 ng/L in seawater from the depth of 200 m, and 0-56.68 ng/L and 0-26.47 ng/L in seawater from the depth of 500 m. The distribution of the contents of OCPs and PCBs tend to be highest in surface water, and lower in 200 m depth layer, and lowest in 500 m depth layer. The main possible pollutant sources are nearby surface runoff and atmospheric input. The pollutants were absorbed by suspended substances and transported from surface to deep seawater column. The detected OCPs and PCBs levels in the South China Sea are lower than those in other offshore marine environments in China, but higher than those in other countries with published data. The concentrations and distribution characteristics of OCPs and PCBs in the South China Sea, provide basic data for future research.