Studies On Persistent Organic Pollutants In Chinese Alligators

Persistent organic pollutants (POPs) are of great concern due to their environmentalpersistence, bioaccumulative properties, and potentially adverse effects on both wildlife andhumans. Hexachlorocyclohexane (HCHs), dichlorodiphenyltrichloroethanes (DDTs),polychlorinated biphenyls (PCBs), hexabromobiphenyl (hexa-BB) and components of thepenta-BDE and octa-BDE mixtures have been in the list of POPs under the StockholmConvention. Although the production and use of these POPs have been officially banned, they arestill present in most environmental matrices and have a potential risk to ecosystems. The Chinesealligator (Alligator sinensis) as one of only two alligator species in the world was listed as acritically endangered species by the International Union for Conservation of Nature (IUCN),which may be attribute to environmental pollution. Although a number of studies have reportedthe pollution characteristics of POPs in crocodilia, there is still a dearth of information on theChinese alligator.In the present study, we examined the levels and patterns of several POPs including OCPs,PCBs, PBDEs, DBDPE, and PBB153in the adult tissues, neonates, and eggs of captive Chinesealligators (Alligator sinensis) from the Anhui Research Center for Chinese AlligatorReproduction. Furthermore, we assessed the potential toxicological effects of these chemicals onChinese alligators. These results could contribute to a better understanding of pollutioncharacteristics of these compounds in crocodilia and provide the theory basis for protecting wildChinese alligator population. The main results were as the followings:1. The detected OCPs consisted of HCHs and DDTs with concentrations in Chinesealligators ranging from9.86to1038ng g-1wet weight. The concentrations of HCHs and DDTsranged from0.56to29.3and6.03to1020ng g-1wet weight, respectively. Compared with DDTslevels in other alligators or crocodiles, DDTs levels in Chinese alligators were higher and theseelevated DDTs levels indicated high DDTs contamination in the habitats of Chinese alligators.Except for the larger contributions of p,p’-DDMU in muscle tissues, the composition profiles forDDTs were similar across all the Chinese alligator samples. p,p’-DDE was the dominantcompound followed by p,p’-DDD and p,p’-DDT. For HCHs, the composition profiles were alsosimilar across all the Chinese alligator samples and β-HCH was the dominant compound followed by α-HCH and γ-HCH.2. The concentrations of ΣPCBs, the sum of52PCB congeners, in Chinese alligators rangedfrom1.12to22.2ng g-1wet weight. The concentrations of ΣPCBs in Chinese alligators were atthe middle of reported ranges from crocodilia in previous studies. PCB153/132and138were themajor contributing congeners and collectively constituted9-50%of the ΣPCBs. Hexa-CB was thedominant PCB homologue, followed by tetra-, penta-, and hepta-CB.3. The concentrations of ΣPBDEs, the sum of17PBDE congeners, in Chinese alligatorsranged from0.11to16.1ng g-1wet weight. Compared with ΣPBDEs concentrations in otherreptiles such as water snakes and turtles, the concentrations of ΣPBDEs in Chinese alligatorswere lower, indicating that Chinese alligators were only slightly contaminated by PBDEs. ThePBDE congener profiles observed in the neonates and eggs of Chinese alligators were similar, butwere different from that observed in the muscle tissues. PBDE209was the most abundant PBDEcongener in the adult tissues, neonates, and eggs of Chinese alligators, accounting for more than50%of the ΣPBDEs. Compared with the muscle tissues, both the neonates and eggs showedlower contributions of nona-and deca-BDE, but higher proportions of tri-, tetra-, and hepta-BDE.4. DBDPE and PBB153were detected in all Chinese alligator samples with concentrationsranging from0.01to17.7ng g-1wet weight and0.21to4.69pg g-1wet weight. Compared withthe concentrations of ΣDDTs and ΣPCBs in the present study, the concentrations of DBDPE andPBB153in Chinese alligators were lower, indicating that DBDPE and PBB153contaminationswere limited in Chinese alligators.5. The concentrations of ΣPCBs and ΣDDTs found in both the neonates and eggs weresignificantly higher than those detected in the muscle tissues of adults. Additionally, with theexception of PBDEs99,100, and208, PCBs207and208, and p,p’-DDM, all of the PBDE andPCB congeners, HCHs, DDTs, DBDPE and PBB153detected in adult female Chinese alligatorswere also detected in the neonates and eggs, implicating the maternal transfer of these chemicalsin Chinese alligators.6. In the present study, DDE concentrations in four of the five Chinese alligator eggs werehigher than the threshold level (100ng g-1wet weight) resulting in a female-biased sex ratio,indicating that DDE in Chinese alligator eggs could cause sex reversal.