湛江红树林湿地沉积物中多溴联苯醚(PBDEs)的污染特征与生态风险评价

近年来,红树林有机污染物(POPs)污染逐渐加重,其生态环境保护压力日趋加大。湛江红树林保护区是中国面积最大的红树林自然保护区,对生态系统稳定具有重要作用,准确评估湛江红树林湿地多溴联苯醚(PBDEs)的污染现状及潜在生态风险,对了解湛江红树林有机污染物的污染状况、红树林的生态环境保护等具有重要意义。采用索氏抽提法和气相色谱-质谱法测定了湛江红树林湿地12个采样位点沉积物中的PBDEs质量分数,分析了多溴联苯醚(PBDEs)的污染水平、空间分布特征及其潜在风险。结果表明,湛江红树林表层沉积物中共检测到14种PBDEs,BDE-209质量分数占比最高,为53.58%—77.66%。12个采样点的∑PBDEs质量分数均值为23.30 ng·g^?1。按地理位置划分为6个研究区域,各研究区域的∑PBDEs质量分数均值变化为:湛江市区(33.06 ng·g^?1)>廉江西(29.68 ng·g^?1)>徐闻(19.29 ng·g^?1)>雷州东(16.47 ng·g^?1)>遂溪(15.72 ng·g^?1)>雷州西(11.92 ng·g^?1);BDE-209、∑13PBDEs(除BDE-209外)质量分数的分布规律与∑PBDEs质量分数的变化趋势一致。与国内外其他红树林湿地沉积物相比,湛江红树林沉积物中∑PBDEs质量分数处于中等水平。湛江红树林沉积物中的PBDEs污染主要源自商业五溴、八溴及十溴联苯醚产品的使用,高溴联苯醚的降解也是其来源之一。环境中的降雨量、TOC、pH值等对沉积物中PBDEs的影响不大。风险熵数法的生态风险评价结果表明,湛江红树林沉积物中PBDEs的综合生态风险水平较高,尤其是penta-BDEs和deca-BDEs处于高风险水平,应引起关注。

Pollution Characteristics and Ecological Risk Assessment of PolybrominatedDiphenyl Ethers (PBDEs) in Sediments of Zhanjiang Mangrove Wetland

In recent years,the pollution of persistent organic pollutants(POPs)in mangrove sediments is increasing year by year,causing more and more pressure on ecological environment.As the largest mangrove nature reserve in China,Zhanjiang Mangrove Reserve plays an important role in the ecosystem stability.It is important to accurately evaluate the status and potential ecological risks of the polybrominated diphenyl ethers(PBDEs)to protect the mangrove resource in Zhanjiang Mangrove Reserve,and it is also important to explore their distribution characteristics and the corresponding factors.In this study,the contents of PBDEs in 12 sampling sites of Zhanjiang Mangrove Wetland were determined by Soxhlet extraction method and gas chromatography-mass spectrometry(GCMS).The results showed that up to 14 homologues of PBDEs were detected in mangrove sediments of Zhanjiang.BDE-209 accounted for the highest proportion with 53.58%–77.66%.The average mass fraction of ∑PBDEs in 12 sampling sites was 23.30 ng·g^?1,and the highest value existed in ZJ12(67.90 ng·g^?1),followed by ZJ2(50.60 ng·g^?1),and ZJ10 was the lowest(2.27 ng·g^?1).According to the geographical location,the 12 sampling points were divided into six research areas,Urban area(33.06 ng·g^?1)>Lianjiang west(29.68 ng·g^?1)>Xuwen(19.29 ng·g^?1)>Leizhou East(16.47 ng·g^?1)>Suixi(15.72 ng·g^?1)>Leizhou West(11.92 ng·g^?1);the distribution of BDE-209 and ∑13PBDEs(except BDE-209)were consistent with that of ∑PBDEs.Compared with other mangrove sediments in domestic and foreign mangrove wetlands,the content of ∑PBDEs in mangrove sediments in Zhanjiang were in the medium level.The main source of PBDEs pollution in Zhanjiang mangrove sediments were penta bromine,octa-bromo and deca-bromo products,and the degradation of PBDEs was also one of the sources.Rainfall,TOC and pH in the environment had little impact on the content and composition of PBDEs in the sediments.The ecological risks in terms of risk quotient(RQ)for PBDEs were also assessed in Zhanjiang mangrove wetlands,the comprehensive ecological risk level of PBDEs in mangrove sediments in Zhanjiang was relatively high,especially for penta-BDEs and deca-BDEs.