Bioaccumulation Of OCPs, PCBs And OPEs In Coral Reef Fish From Weizhou Island

Coral reef ecosystem,especially the coastal coral reef ecosystem,is the most abundant and vulnerable ecosystem in marine ecosystem,and is more susceptible to human activities.In view of the deficiency of persistent organic pollutants（POPs）research in coral reef ecosystem,the legacy POPs,including organochlorine pesticides（OCPs）and polychlorinated biphenyls（PCBs）,and emerging organic pollutants,organophosphate esters（OPEs）in the coastal coral reef fish from Weizhou Island,South China Sea were determined in the present study.The residue levels and compositional profiles of the target compounds in coral reef fishes were analyzed to understand the contaminant status,and bioaccumulation and trophic biomagnification of OCPs,PCBs and OPEs in the coastal coral reef ecosystem were studied using coral reef fish as bioindicator.The potential health risks of the target compounds via fish consumption by residents were also discussed.Furhermore,the maternal transfer of OCPs and PCBs in breeding fish were also studied.The main conclusions of this thesis were summarized as follows:（1）.The detection frequencies of OCPs,PCBs and OPEs were 95.7–100%,76.1–100%and 34.5–100%in the muscle tissues of eight of coral reef fish species in Weizhou Island（i.e.Selaroides leptolepis,Siganus fuscescens,Chaetodon octofasciatus,Labracinus cyclophthalmus,Terapon theraps,Diploprion bifasciatum,Cephalopholis boenak and Sebastiscus marmoratus）,which indicated that these compounds were ubiquitous in these fishes.The concentrations of∑₁₈OCPs,∑₂₂PCBs and∑₁₁OPEs were 24.5–452,0.87–19.8and 255–1132 ng/g lw,respectively,which were at the low levels in worldwide.Cephalopholis boenak and Sebastiscus marmoratus had the highest contaminant level of target compounds,respectively,which were closely related to their different living and feeding habits.（2）.DDTs and MXC were predominant in all coral reef fishes from Weizhou Island,accounting for 89.9–96.4%of∑₁₈OCPs;hexa-CBs（50.1%）and penta-CBs（19.5%）were primary homologues of PCBs;overall patterns of OPEs showed highest contribution of TCPP,accounting for 23.7–48.2%of∑₁₁OPEs,and followed by TBEP and TDCPP.Composition profiles and source analysis showed that the composition patterns of target compounds were similar to each other in eight coral reef fish species;the historical residues of industrial pollution were the main sources of DDTs,HCHs,CHLs and PCBs at present,and the contaminant pattern of OPEs was governed by the discharge of daily sewage and industrial wastewater.（3）.The concentration of OCPs,PCBs and OPEs exhibited species-specific values in eight fish species.The concentration of target compounds in carnivorous fishes was higher than that in phytophagous and omnivorous fishes,and the benthic fishes were generally higher than other fishes.However,the level of OPEs in Labracinus cyclophthalmus was higher than that in the Cephalopholis boenak,which may be related to its pregnant period.The correlation analysis between biological parameters（body length,body weight and fat content）and wet weight concentration of target compounds showed that the accumulation of DDTs,HCHs,CHLs,HCB and PCBs in fish was positive growth-dependent and fat-dependent,while the accumulation of Drins and OPEs has negative growth dependence and does not have fat dependence.（4）.Bioaccumulation of different compounds in fish was different.In terms of bioaccumulation factors（BAF）,DDTs and MXC had bioaccumulation(Log BAF（>3.7）with Log BAFs ranged from 3.54 to 5.22 and 3.39 to 4.47,respectively;PCBs and HCB had potential bioaccumulation（3.3 to Log BAF<3.7）in some fish samples;other compounds（including HCHs,CHLs and Drins）were not bioaccumulative.Most of compounds,except for Drins and OPEs,exhibited biomagnification trend with trophic biomagnification factor（TMF）greater than one,while Drins and OPEs were still biodiluted in coral reef fish food chain.（5）.The ECR of 40 OCPs and PCBs homologues ranged from 0–89.2%,and only 27.5%of these homologues with ECR lower than 50%were PCBs monomers with higher molecular weight.This was mainly due to the specific transfer of these compounds in gonads,which was affecteded by the maturity of gonads,physical and chemical properties of compounds,background concentration and other factors.（6）.Risk analysis found that the consumption of five major economic fish from Weizhou Island would not lead to non-carcinogenic and carcinogenic health risks for resident.The present study indicated that there were some OCPs,PCBs and OPEs pollution in the coral reef ecosystem of Weizhou Island.The levels of these compounds were at the low levels in the worldwide,though they were ubiquitous in all samples and continuous accumulation.Therefore,the ecological threats of traditional POPs and emerging organic pollutants in the coral reef ecosystem of Weizhou Island cannot be ignored and the long-term comprehensive monitoring for OCs is still warranted.