Study Of Bioaccumulation Behavior Of Hydroxylated Polybrominated Diphenyl Ethers In Common Carp

Recently, hydroxylated polybrominated diphenyl ethers (OH-PBDEs), as emerging organic pollutants, have been detected in various environmental media and even human body. They attracted considerable concern due to their strong biological toxic effects. In order to greatly evaluate ecological risk and ultimate fate of OH-PBDEs, in the present study, bioacumulation behavior in aquatic organism(common carp) was investigated. Function mechanisms of bioaccumulation effect in liver, kidney, brain and muscle of common carp were also unveiled.Firstly, analytical methods of OH-PBDEs to biotic and natural water samples were established and optimized, based on previous reported methods in environmental samples. The result showed that method detection limits were0.35-10.13ng/g (lipid weight) and4.2～10.13ng/mL, respectively. OH-PBDEs congeners spiked recoveries were62.6-118.2%with good reproductivity.Secondly, acute toxicities (96h-LC50) of OH-PBDEs (2’-OH-BDE7,4’-OH-BDE17,2’-OH-BDE28,2’-OH-BDE68,4’-OH-BDE90and2’-OH-BDE123) to common carp were determined. Except that4’-OH-BDE17was highly toxic with LC50=1130ng/mL, the other five OH-PBDEs (2’-OH-BDE7,2’-OH-BDE28,2’-OH-BDE68,4’-OH-BDE90and2’-OH-BDE123) were virulent and the LC50values were697、854、550、644and522ng/mL, respectively. By using octanol-water partition coefficient and quantum chemical parameters as descriptors, the quantitative structure activity relationships between them and96h-lgLC50values were studied. The results showed that linear relationships were good with correlation coefficient square greater than0.96and the predicted96h-LC50values of OH-PBDEs by the obtained equations were consistent with the experimental values.Lastly, absorption and elimination of OH-PBDEs (2’-OH-BDE68and4’-OH-BDE90) in liver, kidney, brain and muscle of common carp were studied, using two-compartment kinetic model. A semi-static system was maintained throughout30-day exposure and60-day depuration periods. And kinetic parameters of bioaccumulation including uptake rate constant (K1), elimination rate constant (K2), bioconcentration factor (BCF) and half-life (T1/2) were obtained by linear fitting. The results showed:(1) The biaccumulation effects of2’-OH-BDE68and4’-OH-BDE90in each tissue of common carp followed first order reaction kinetics. Four parameters (BCF, K1, K2and T1/2) of 2’-OH-BDE68were as high as1.4×102～8.0×103(L/Kg),357.1(d-1),0.030～0.101(d-1),6.9～23.1(d), respectively.35～2.2×103(L/Kg),0.39～49.0(d-1),0.022～0.074(d-1) and9.4～31.5(d) were BCF, K1, K2and T1/2values of4’-OH-BDE90, respectively.(2) Exposure concentration had a significant impact on four kinetic parameters (BCF, K1, K2and T1/2). When it increased, BCF, K1and T1/2of2’-OH-BDE68and4’-OH-BDE90decreased, K2for2’-OH-BDE68enhanced and had no remarkable law for4’-OH-BDE90instead. The positive correlation relationship between lgBCF of OH-PBDEs congeners (nBr=4and5) in different tissues of common carp and their lgKow may be not notable.(3) The orders of distribution for2’-OH-BDE68and4’-OH-BDE90in different tissues were basically liver>kidney>brain>muscle, liver>brain>kidney>muscle, respectively. This was probably caused owing to liver and kidney being biological metabolic target organs, muscle with a large amounts and widely distributed in fish, blood brain barrier in common carp having a function to reject exogenous compounds passing into central nervous system. Perhaps there was great neurotoxicity of4’-OH-BDE90to common carp. And diversity of lipid content in tissues may be another reason.