Estimation Of Bioaccumulation Potential For Hydrophobic Organic Contaminants By Polydimethylsiloxane-Based Passive Sampling

The environmental behavior and bioaccumulation process of hydrophobic organic contaminants(HOCs)have been extensively investigated,because of their persistence,bioaccumulative and toxicant.Bioaccumulation plays a significant role in the risk assessment of contaminants to ecological health.However,it is time-cost and labor-cost to determine the HOC concentrations in the biota by conducting bioassay test in lab or collecting the organisms from field.Therefore,it is essential to develop new technology to estimate the bioaccumulative concentrations by monitoring the environmental concentrations.The PDMS-based equilibrium passive samplers have been widely used to monitor the HOCs in various environmental matrices.When the thermodynamic equilibrium is reached,the fugacity of HOCs in environment,sampler and organism is equal.The equilibrium concentrations in organisms could be calculated from concentrations in sampler and biological phases-PDMS equilibrium partition coefficients.At present,however,biological components-PDMS equilibrium partition coefficients of HOCs are quite limited,especially for highly hydrophobic organic contaminants(HHOCs,log KOW > 9).In addition,though the lipid is the dominant partition phase in organisms,for the organisms with high content of protein,partitioning into protein might influence the bioaccumulation of HOCs,but the protein-PDMS equilibrium partition coefficients are absent.Lastly,the current researches mainly focus on the bioaccumulation in aquatic environment,but the bioaccumulation data under the atmosphere contaminants are relatively scarce.Therefore,this research began with determining the equilibrium partition coefficients between biological phases and PDMS,applying the equilibrium passive sampling in sediment to estimate the bioaccumulation concentrations in benthic invertebrates and investigating the influence of protein on the bioaccumulation.Then,homing pigeons were chosen as the biomonitor of atmosphere HOCs.The bioaccumulation concentrations in homing pigeons were measured and their relationship with age and atmosphere concentrations were studied.Finally,the viability of bioaccumulation estimation of HHOCs in biological tissues from PDMS equilibrium passive sampling were investigated.Firstly,the preloaded PDMS depletion method was designed to measure equilibrium partition coefficients between PDMS and storage lipid(KSL,PDMS),membrane lipid(KML,PDMS)and protein(Kpro,PDMS)for 21 polychlorinated biphenyls(PCBs),14 polybrominated diphenyl ethers(PBDEs),dechlorane plus(DP)and decabromodiphenyl ethane(DBDPE).Although the target compounds had wide range of hydrophobicity with log KOW covering from 5.07 to 11.6,the values of KSL,PDMS,KML,PDMS and Kpro,PDMS were in the ranges of 5.36–52.5,0.286–11.8 and 0.067–2.62 g/g,respectively,being relatively constant.The relative sorption capacity of the biological phases showed storage lipid was the dominant sorption phase in biota,followed by membrane lipid and protein was the lowest.The KPDMS,pro values of the compounds with log KOW < 9 were similar(0.382–14.9 g/g)and did not changed with the thickness of preloaded PDMS disks.For HHOCs,however,KPDMS,pro values were significantly affected by the thickness of preloaded PDMS disks because of slow diffusion in PDMS.The KPDMS,pro values of HHOCs dropped when the thickness of preloaded PDMS disks dropped form 209 ?m to 58 ?m.The KPDMS,pro values of HHOCs measured by 58-?m PDMS disks ranged from 1.78 to 6.85 g/g,which was consistent with compounds with log KOW < 9.This validated that partition coefficients between PDMS and biological phases were independent of chemical hydrophobicity,showing the advantage of using PDMS-based passive samplers to directly estimate bioaccumulation potential of HOCs.Secondly,Lumbriculus variegatus was chosen as the model organism of benthic invertebrates,and the bioaccumulation concentrations of HOCs in Lumbriculus variegatus were estimated by PDMS equilibrium passive sampling.The data of equilibrium concentrations in PDMS and bioaccumulation concentrations in Lumbriculus variegatus were searched and collected.Equilibrium concentrations in PDMS in literature and KSL,PDMS,KML,PDMS and Kpro,PDMS measured in this study were used to calculate the equilibrium bioaccumulation concentrations in Lumbriculus variegatus.When only the storage lipid was considered as partition phase,the estimated equilibrium bioaccumulation concentrations and measured bioaccumulation concentrations showed good correlation,with logarithm linear fitting curve slope being 1.06 and r2 = 0.931.The difference between estimated and measured values was below 10 times for all chemicals,indicating this estimation was valid.Furthermore,the results of one phase estimation model,in which only the storage lipid was considered as partition phase,and multi-phases estimation model,in which the storage lipid,membrane lipid and protein were simultaneously considered as partition phases,were compared,revealing the membrane lipid and protein did not significantly improve the accuracy of prediction.This illustrated that one phase estimation model could satisfy the estimation of bioaccumulation of HOCs in benthic invertebrates.Thirdly,29 homing pigeons in Guangzhou urban area were collected.Concentrations of polycyclic aromatic hydrocarbons(PAHs),polychlorinated biphenyl(PCBs),organochlorine pesticides(OCPs)and halogenated flame retardants(HFRs)in lung,liver and fat tissues were measured.There was no significant difference between these HOC bioaccumulation in female and male.Contaminant concentrations in lung were significantly higher than those in liver and fat.Moreover,only low concentrations of PAHs were detected in the food and drinking water for homing pigeons,further supporting respiratory route was the dominant bioaccumulation source.The bioaccumulation concentrations in homing pigeons followed the order: PAHs > PBDEs > OCPs > PCBs > DP.The relative abundance of tricyclic PAHs,nona-and deta-BDEs,p,p'-DDE,low chlorinated PCBs and anti-DP were higher.The total concentrations and compositions of contaminants bioaccumulated in homing pigeons were in accordance with local atmosphere.Furthermore,the bioaccumulation in different age groups were investigated.For 1-year old homing pigeons,higher levels of PAHs and PCBs in lung and liver tissues were probably ascribed to more intense flying than 5-and 10-year groups.However,fat concentrations of PCBs and PAHs showed reverse trends with increasing age because of different biotransformation.The OCPs concentrations decreased in older homing pigeons.PBDEs and DBDPE concentrations in lung were higher in 5-and 10-year groups,but the concentrations in liver and lung showed no significant difference among three age groups,probably because highly hydrophobic flame retardants mainly attached in atmosphere particle phase,their bioavailability was low and difficult to transfer to other tissues,resulting in deposition at lung tissue as particle binding form.Different from field birds which had diverse bioaccumulation routes,homing pigeons accumulated contaminants by respiratory and presented significant lower bioaccumulation levels than field birds.Overall,homing pigeons could serve as a suitable biomonitor for urban atmospheric HOCs,and the bioaccumulation data in homing pigeons could provide a reference for assessing the respiration exposure risk of HOCs to the residents in cities.Lastly,the PDMS equilibrium passive sampling was conducted in fat tissues of homing pigeons.The estimated and measured concentrations of DDTs and PBDEs were near unity with linear slop being 0.885 and r2 = 0.868,indicating equilibrium passive sampling could determine the HOC bioaccumulation concentrations in fat tissues instead of solvent extraction.The most hydrophobic chemical which was determined by PDMS sampler in this research was BDE-209,reflecting that PDMS equilibrium passive sampling could be used to quantify HHOCs in biological tissues.To sum up,this thesis combined biological phases-PDMS equilibrium partition coefficients and PDMS equilibrium passive sampling to estimate the bioaccumulation concentrations of HOCs in different organisms,providing essential data and system approaches for the application of PDMS equilibrium passive sampling in bioaccumulation.Through incorporating environmental passive sampling and bioaccumulation process,the environmental monitoring concentrations could be linked to biological effect concentrations,offering a new method for environmental quality criteria development and ecological risk assessment.