Study On Trophic Level Amplification Effect Of Organochlorine Pesticides In The Food Web Of Dalian Bay

Organochlorine pesticides(OCPs)are typical persistent organic pollutants,characterized with lipophilicity,poor degradation,semi volatility,etc.Most OCPs have carcinogenic,teratogenic and mutagenic effects.Therefore,these substances do great harm to human health and ecological environment.Due to the persistence and bioaccumulation,OCPs accumulate in organisms and transfer in the food chain after entering the ocean,and the concentration will increases with the increase in trophic levels.Therefore,the human health risk caused by eating seafood contaminated by OCPs has attracted extensive attention.In this study,Dalian Bay was selected as the study area to study the levels,composition,possible sources and human health risks assessment of OCPs in 23 species of marine organisms(including 9 species of fish,3 species of shrimp,2 species of crabs,8 species of shellfish and snails and 1 species of plankton).The trophic structure of marine organisms in the study area was determined by the method of stable isotope,the trophic magnification of OCPs in food chain was studied and the factors influencing trophic magnification were discussed.The main results of this study are as follows:(1)Dichlorodiphenyltrichloroethane(DDTs),chlordane(CHLs),hexachlorobenzene(HCHs),hexachlorobenzene(HCB)and endosulfan(ENDs)were detectable in 23 species of organisms in Dalian Bay.In all samples,DDTs had the highest concentrations,followed by HCHs and ENDs had the lowest concentrations.Composition and source analysis of OCPs in organisms from Dalian Bay show that the main sources of HCHs are historical residues,and new sources existed for DDTs and CHLs.The usage of dicofol may be the new source of DDTs and the external inputs of ENDs were considered to be the sources of these compounds.(2)The organisms in the food web in the sea area of Dalian Bay existed across 3 trophic levels,and each trophic level spanned 1 to 2 layers.Especially,the trophic levels of fish fluctuate in different years to some extent.(3)The trophic magnification factor(TMF)of the 17 OCPs was significant greater than one(p < 0.01),indicating significant trophic magnification of these compounds in the study area.p,p’-DDE and p’-DDT had the largest trophic magnification factor.The metabolic conversion capacity,fat content and individual size of organisms are the main factors,affecting the trophic magnification.(4)Human health risk assessments of OCPs showed that the estimated daily intake of OCPs in all biological samples was lower than the Chinese standard for food hygiene,and also lower than the daily acceptable daily intake given by the World Health Organization,which indicated that there was no safety risk in eating seafood from Dalian Bay.The impact of consumer species on the estimated daily intake results showed that the exposed population will be exposed to more OCPs through seafood.The results of cancer risk and risk factor showed that long-term consumption of seafood contaminated by OCPs will cause potential cancer risk to human health.In this study,these findings from the results of OCPs in 303 marine biological samples are helpful to master the pollution level of these compounds in the sea area of Dalian Bay,which provide theoretical basis and technical support for the restoration and management of high-risk ecological environment areas.Human health risk assessment of OCPs based on experimental data,provide basis for relevant departments to formulate pollutant limit standards,raise reasonable suggestions and measures for pollutant control and emission reduction,and put forward support for comprehensive assessment of OCPs in Dalian Bay.