东海近岸持久性有机污染物分布及其影响因素

A review on the distribution of persistent organic pollutants and their influencing factors along the nearshore of the East China Sea

收集分析近10a东海近岸海水和沉积物中全氟烷基物(PFASs)、多氯联苯(PCBs)、多溴联苯醚(PBDEs)、有机氯农药(OCPs)、邻苯二甲酸酯(PAEs)和多环芳烃(PAHs)等六种典型持久性有机污染物(POPs)的分布及其影响因素的研究数据.结果表明,基于半数效应浓度(EC50)或海洋沉积物质量标准对海水和沉积物中POPs的生态风险评估,表明东海近岸大部分海域的PCBs、PBDEs和OCPs生态风险较低,但在杭州湾附近海域处于轻微至中等生态风险水平.PAHs整体上处于中等偏低及以下风险,PAEs处于中等偏高风险.PFASs处于中等及以下风险,但其中的全氟辛烷磺酸(PFOS)在长江口附近的生态风险较高.来自陆源输入的POPs在东海近岸海水和沉积物中的分布主要受到长江冲淡水、大气干湿沉降、沿岸流和潮汐作用的影响,呈现出绝大多数污染物含量在长江口和杭州湾附近较高,且向外海和南部沿岸总体降低的趋势.在浙闽沿岸泥质区、东海陆架泥质区,沉积物中部分污染物含量明显较高,与泥质区细颗粒泥沙对POPs的结合能力较强密切相关.长江冲淡水与东海海水交汇过程中温盐差异形成的“大陆边缘过滤器”效应,使得沉积物中部分POPs含量在盐度1~5的海域较高.东海的季节性低氧使得DDTs和PCBs等POPs普遍发生还原降解作用.除生物降解作用之外,生物泵和生物扰动等也会影响POPs在东海的分布.虽然我国已加强了对POPs的管控,但目前东海近岸的局部海域的POPs污染仍然存在,有待未来进一步完善POPs的监测手段和风险评价标准,并继续加强对新污染物的监测和环境行为研究.

The present study collected and analyzed the published data in recent decade on the distribution and influencing factors of six typical persistent organic pollutants(POPs)in the nearshore seawater and sediments of the East China Sea,including perfluoroalkyl substances(PFASs),polychlorinated biphenyls(PCBs),polybrominated biphenyl ethers(PBDEs),organochlorine pesticides(OCPs),phthalates(PAEs),and polycyclic aromatic hydrocarbons(PAHs).Based on the median effect concentrations and marine sediment quality criteria on ecological risk assessments of POPs in seawater and sediments,it was observed that the ecological risks of PCBs,PBDEs and OCPs at most of the nearshore sites of the East China Sea were low,but their concentrations reached slight to moderate risk level near Hangzhou Bay.PAHs concentrations were at moderate to low or lower risk levels,while PAEs concentrations were at moderate to high risk level.The concentrations of PFASs were generally at moderate or lower risk level,except for PFOS which exhibited relatively higher risk level near the Yangtze estuary.The distribution of terrestrial-derived POPs in the nearshore seawater and sediments was mainly controlled by the impacts of the Yangtze River diluted water,atmospheric wet and dry deposition,coastal currents,and tidal action.The concentrations of most tested POPs were relatively higher near the Yangtze estuary and Hangzhou Bay,and showing a decreasing trend towards the open sea and the southern coast.Within the muddy area along the coast of Zhejiang and Fujian and the East China Sea shelf,some of the tested POPs were remarkably higher in sediments,which highly related with the strong binding affinity of POPs on fine particles.The"Marginal filter effect"driven by the temperature and salinity gradients during the mixing of fresh water derived from Yangtze River and seawater in the East China Sea,resulting in higher POPs concentrations in the surface sediments at regions where salinity ranges between 1to 5.The seasonal hypoxia in the East China Sea promotes the reductive degradation of POPs,such as DDTs and PCBs.In addition to biodegradation,the distribution of POPs in the East China Sea was also affected by biopumping and bioturbation processes.Although China has strengthened the management and control of POPs,the coastal East China Sea is still facing their associated ecological risks,which requires future efforts on the improving the monitoring methods and risk evaluation standards of POPs,and further strengthen researches on the monitoring and environmental behaviors of emerging contaminants.