Pollution Characteristics And Ecological Risks Of Emerging Pollutant Organophosphorus Flame Retardants In Typical Areas Of The Yellow Sea And East China Sea

In recent years,bromine-based flame retardants(BFRs)have been restricted and banned,and organophosphate esters(OPEs)have become a good substitute for them,which are widely used in textiles,plastics,electronic equipment,building materials,lubricants,paints,and other products.As an Emerging Contaminant,OPEs have become a hot topic of global environmental pollution because of their increased production and release,frequent detection in the environment,and strong biological toxicity.The inshore sea is the sink of terrigenous pollutants.The coastal areas such as Jiangsu,Shandong,and Shanghai are the main production and consumption areas of OPEs.The variation characteristics and differences of pollution sources of OPEs in the adjacent sea areas are not clear.In this study,we selected the Yellow Sea,Jiaozhou Bay,and the Yangtze River Estuary for investigation,which are typical areas of the Yellow Sea and the East China Sea,and selected OPEs widely detected in the environment as the target compounds.The occurrence and distribution of OPEs in typical sea areas,bays,and estuaries were explored,the spatial and temporal changes of OPEs in the marine environment were analyzed,the main pollution sources of OPEs were analyzed,and the potential ecological risk of OPEs in the Yellow Sea and the East China Sea was assessed.The main findings of the study are as follows:(1)On the whole,the concentration of water in the Yellow Sea and the East China Sea was low,the mean values of ΣOPEs in the surface,20 m depth layer,and bottom seawater in the Yellow Sea were 66.73 ng/L,27.2 ng/L,and 72.03 ng/L,respectively,the concentration of Jiaozhou Bay seawater was 37.76 ng/L,but significantly lower than those in the inflowing river water of Jiaozhou Bay(median:940.61 ng/L)and the Yangtze River Estuary in spring(surface seawater:467.04 ng/L):467.04 ng/L,bottom seawater:462.16 ng/L)and summer seawater(surface seawater:390.3 ng/L,bottom seawater:398.0 ng/L).The concentration of ΣOPEs in sediments from the Yangtze River Estuary in spring(median:167.60 ng/L)was significantly higher than in summer(median:60.61 ng/L).Due to the difference in pollution sources in different regions,the pollutants in different regions have different composition structures.Halogenated OPEs were the main contributors to seawater in the Yellow Sea and Jiaozhou Bay,accounting for 74.44%and 60.55%of ΣOPEs respectively,with TCPP being the most dominant OPE.In contrast,alkyl OPEs were the first contributor in the Yangtze River Estuary,with TnBP and TiBP as the main components,where the contribution of alkyl OPEs had exceeded 75%in both seawater and sediment in spring,the contribution rate of alkyl OPEs in summer seawater reaches 60%,and even more than 80%in sediments.(2)The spatial distribution of OPEs in the Yellow Sea and the East China Sea decreased gradually from south to north,and the OPEs were mainly distributed in estuaries,bays,and coastal areas affected by human activities.In 2019,the high-value areas of OPEs in Yellow Sea seawater were found in the nearshore and offshore areas of the South Yellow Sea.Compared with 2015,the distribution area spread from nearshore to offshore areas,and the halogenated OPEs increased by 1-2 times in the seawater,respectively,with the proportion of TCPP in halogenated OPEs increasing from 56.49%in 2015 to 79.95%in 2019.The OPEs in Jiaozhou Bay are mainly distributed in the nearshore areas and the inflowing rivers,especially in the eastern coastal areas.The spatial distribution characteristics of OPEs in the water bodies of the Yangtze River Estuary,which are mainly distributed in the southern branch of the estuary and the central and southern nearshore areas,are heavily influenced by runoff,monsoons,and ocean currents.In spring,OPEs peak in the central to southern regions of the nearshore Yangtze River Estuary;in summer,OPEs are concentrated in the south branch channel of the estuary and the southern nearshore zone and show a decreasing trend towards the northeast.OPEs in sediments of the Yangtze Estuary showed high concentrations in the Yangtze River Mud Area and the ZheMin Coastal Mud Area and were significantly lower in summer than in spring.(3)The main sources of OPEs in the Yellow Sea and the East China Sea include endogenous and exogenous sources.The endogenous source is the release and diffusion of sediments,and the exogenous sources are closely related to the region’s degree of urbanization and industrial level.The exogenous sources mainly include municipal and industrial sewage discharge sources,urban and marine traffic discharge sources,and atmospheric deposition sources,among which municipal and industrial sewage discharge sources are the most important sources of OPEs in the Yellow Sea and the East China Sea.However,due to differences in industrial structure,there are also differences in the major pollutants in different regions,such as CDPP,TCPP,TDCP,and TBEP being the major contributors to the effluent sources in Jiaozhou Bay,while TMP,TPrP,TCPP,and TPhP are the major contributors to the industrial discharge sources in the Yangtze River Estuary.Transportation emission sources in Jiaozhou Bay are dominated by TPhP,TiBP,and TPrP.EHDPP and TEP are the main contributors to atmospheric deposition sources in Jiaozhou Bay.However,TnBP and TiBP dominate the second source of pollution in the Yangtze River Estuary,representing the combined impact of industrial discharges and marine traffic sources.The atmospheric deposition sources in the Yangtze River Estuary are dominated by TEP in spring;while TEHP and TBEP have the highest contribution in summer and are the combined effect of leakage of anti-corrosion coatings from ships and atmospheric deposition.The results show that OPEs in the Yellow Sea and the East China Sea are influenced by multiple sources of pollution and are closely related to the industrial characteristics,the degree of urbanization,and the seasonality of human activities in the region.(4)OPEs showed no ecological risk in the seawater of the Yellow Sea and the East China Sea,but exhibit low-risk levels in parts of the South Yellow Sea and the nearshore areas of Jiaozhou Bay.Even moderate ecological risk was found in the inflowing river water of Jiaozhou Bay and the Yangtze River Estuary.In addition,the contribution of OPEs to different typical areas in the Yellow Sea and the East China Sea was also different.TCPP,TDCP,and the highly toxic TCrP and EHDPP were the main contributors to the Yellow Sea.TCPP,TDCP,TCrP,and EHDPP were the main contributors to the ecological risk in Jiaozhou Bay.While the ecological risk in the Yangtze River Estuary was mainly caused by TnBP,TiBP,and TDCP.OPEs had caused a certain impact on the aquatic life in the bays and estuaries of the Yellow Sea and the East China Sea,and the ecological risk was showing an increasing trend year by year,and the scope of its impact is constantly expanding.Therefore,the ecological risk of OPEs in the region still needs continuous attention.