Bioaccumulation Of Organochlorine Pesticides (OCPs) And Polycyclic Aromatic Hydrocarbons (PAHs) For Corbicula Fluminea From Sediment In Sewer Channel Of Tianjin

Well-developed industry made southwest of Tianjing polluted heavily,and the sewer Channel of Tianjin immediately or mediately undertook industry sewage and life sewage from Beijing and Tianjing.The main sewer chnannels were Dagusewer chnannel,Beitang sewer chnannel and Beijing sewer chnannel.More and more contaminants inputted to sewer channel and the water and sediment condition were heavily polluted by industry sewages.Many pesticides and organic contaminants are organic and have hydrophobic properties.These hydrophobic contaminants tend to bind to suspended particulate matter and to accumulate in the bottom sediments of rivers,once entered to the water ecosystems.Organochlorine pesticides and polycyclic aromatic hydrocarbons have been detected in aquatic sediments and organism tissues many years after a ban and usage stop of that particular pesticide in one country,due to both their persistence as well as dispersal from other countries where these compounds are still in use.However,Bioaccumulation from sediment is a dominant process,especially at lower trophic levels,where benthic invertebrates play an ecologically crucial role when remobilizing contaminants into aquatic food webs by sediment ingestion.Contamination usually mediate and immediate contaminated from sediment to aquatic organisms,then bio-accumulated to organisms and transferred higher step of the food chain,even imperiled the human been.Sediment contaminate effect is an important part for water research.Bioaccumulation and bioavailability of sediment-associated organochlorine pesticides(OCPs) and polycyclic aromatic hydrocarbons(PAHs)in nine sewer channels,Tianjin,were assessed using a benthic organism Asiatic clam(Corbicula fluminea)collected from clean water.The results showed that:(1)Concentration of organochlorine pesticides(OCPs)and polycyclic aromatic hydrocarbons (PAHs)of sediment:Determined OCPs mainly included HCHs and DDTs,the total concentrations of HCHs,DDTs and OCPs in sediment samples were 1.2 to57.8 ng/g dry weight,9.3 to 27.9 ng/g dry weight,and 17.1 to 83.6 ng/g dry weight,respectively.The average concentrations of HCHs, DDTs and organochlorine pesticides were 29.7,17.2 and 46.8 ng/g dry weight,respectively.All of the a-HCH,β-HCH,γ-HCH and d-HCH were detected over nine samples.The detected DDTs including p,p' -DDE,p,p'-DDT and p,p'-DDD.There was no new loading to channel sediments. In the pesticides HCHs might not be inputted from new pollution sources.Compared with HCHs and DDTs contents in sediments of different water surfaces reported in China,the content of the pesticides in the sediment of Tianjin River was higher.The 16 PAHs were determined from sediments of Tianjin River,and the totle concentrations of PAHs were 1523.4 to 42480.7 ng/g dry weight(the average was17726.3 ng/g dry weight).Most of the determined PAHs in sediments were 3- and 4- ring PAHs and the proportion to total PAHs were 28.3%and 37.7%respectively.The proportion of 2-,5- and 6- ring PAHs to total PAHs were less.There were positive correlations between contamination concentrations and sediment's total organic carbon(TOC)and black carbon (BC)content.(2)Bioaccumulation of OCPs and PAHs using Asiatic clam(Corbicula fluminea):The total bioaccumulation of HCHs,DDTs and OCPs in Asiatic clam's muscle increased significantly with exposure time and were 2.6 to 85.9 ng/g dry weigh,36.4 to 83.5 ng/g dry weigh and 38.9 to 163.2 ng/g dry weigh,respectively at 28d.The average bioaccumulation of HCHs,DDTs and OCPs were 59.3 ng/g dry weigh,58.8 ng/g dry weigh and 118.1 ng/g dry weigh,respectively.Compared with HCHs and DDTs contents in organisms of different water organisms reported in China,the content of the pesticides in Asiatic clam's muscle of Tianjin River was higher.Bioaccumulations of PAHs were ranged from 1169.1 to 2145.2 ng/g dry weigh after 28 d exposed.Most of the determined PAHs in Asiatic clam were 3- and 4- ring PAHs.The bioaccumulations of fluoranthene and pyrene were relative higher than other PAHs,and the proportion to total PAHs in organisms were 16.1%±2.4%,16.5%±2.2%respectively.(3)Bioaccumulation of OCPs and PAHs in different tissues:Bioaccumulation of OCPs in gill, muscle and gut were 82.0±28.7 ng/g dry weigh,115.3±36.4 ng/g dry weigh and 117.8±29.8 ng/g dry weigh,respectively.The bioaccumulation trend about HCHs was muscle＞gill＞gut.The bioaccumulation trend about DDTs was gut＞muscle＞gill and were 78.1±14.2 ng/g dry weigh, 58.5±14.4 ng/g dry weigh,and 31.3±9.1ng/g dry Weigh,respectively.The bioaccumulation trend about DDTs was gut＞muscle＞gill and were 78.1±14.2 ng/g dry weigh,58.5±14.4 ng/g dry weigh, and 31.3±9.1ng/g dry weigh,respectively.Most of the bio-accumulated PAHs in Asiatic clam gill were 2- and 3- ring PAHs,and the proportion to total PAHs in organisms were 32.3%and 39.6%. 4- ring PAHs were the major part in muscle and gut,and the proportion to total PAHs in muscle and gut were 43.6%and 54.9%.3- ring PAHs were the subordinate part in muscle and gut,and the proportion to total PAHs in muscle and gut were 32.9%and 20.0%,respectively.(4)Bioaccumulation kinetics about OCPs and PAHs with Asiatic clam(Corbicula fluminea): The Bioaccumulation kinetics test was made using four representative sites during 28 d exposed. The results showed that the concentrations of OCPs and PAHs in organism might trend to temporal equilibrium,significant positive correlation were found between bioaccumulation in Asiatic clam tissues and exposed time(1d,3 d,7 d,14 d,21 d and 28 d).(5)The biota-sediment accumulation factors(BSAFs):The biota-sediment accumulation factors(BSAFs)were calculated for OCPs and PAHs respectively.BSAFs of HCHs,DDTs,and OCPs were 1.43±0.29,2.46±0.27 and 1.79±0.22,respectively.Significant positive correlation was observed between Biota-Sediment Accumulation Factors(BSAFs)and octanol and water partitioning coefficients(Kows)for both HCHs and DDTs(r=0.878,p=0.009).The biota-sediment accumulation factors(BSAFs)calculated for Corbicula fluminea to PAHs were ranged from 0.021 to 0.147,and the BSAF for Low-Weight-PAHs,High-Weight-PAHs and Total PAHs were 0.085±0.018,0.046±0.018 and 0.066±0.017,respectively.Significant negative correlation was observed between Biota-Sediment Accumulation Factors(BSAFs)for PAHs and content of sediment total organic carbon(TOC)as well as black carbon(BC).(6)Bioaccumulation and bioavailability:Significant negative correlation was observed between Biota-Sediment Accumulation Factors(BSAFs)for PAHs and content of sediment total organic carbon(TOC)as well as black carbon(BC).Total organic carbon(TOC)or black carbon (BC)and sediment grain size can affect the bioavailability and the bioaccumulation of OCPs and PAHs.