Environmental Distribution Of Organophosphate Esters In The Bohai And Yellow Seas And The Toxicological Effects Of Tris-(Chloropropyl) Phosphate On Mussel (Mytilus Galloprovincialis)

Organophosphate esters(OPEs)are organic compounds with a phosphorus atom center that are mainly used as flame retardants and plasticizers,as well as antifoaming agents and hydraulic fluids.With the global phasing out of brominated flame retardants in the 21 st century,production and usage of OPEs have increased significantly.Meanwhile,OPEs,being emerging organic pollutants,noncovalently bond to the added materials,which makes them easily leach into the environment and pose threats on ecosystem and even human health.In this study,concentrations and distributions and their influential factors of 8 OPE compounds [tri-n-butyl phosphate(Tn BP),tri-isobutyl phosphate(Ti BP),tris-(2-chloroethyl)phosphate(TCEP),tris-(chloropropyl)phosphate(TCPP),tris-(1,3-dichloro-2-propyl)phosphate(TDCPP),triphenyl phosphate(TPh P),tripentyl phosphate(TPe P),tris-(2-ethylhexyl)phosphate(TEHP)] and triphenylphosphine oxide(TPPO)(TPPO would be viewed as a special OPE compound and discussed together with other OPE compounds in later chapters)in the Bohai and Yellow seas were analyzed and discussed.The distributional characteristics of OPEs both in seawaters and sea sediments were also explored and discussed.The research showed:1.The highest and mean concentrations of total OPEs(7 OPEs: Tn BP,Ti BP,TPh P,TCEP,TCPP,TDCPP,and TPPO)in the seawater of the Bohai and Yellow Seas were 98.04 and 23.70 ng L-1,respectively.The distribution patterns of total OPEs and most individual OPEs were that the nearshore sites showed higher concentrations than those of the open sea and that sites of surface water showed higher concentrations than those of the bottom water.Riverine input,disturbance of ocean currents and water mass were main factors that influenced the concentrations and distributions of OPEs in this region.2.The highest and mean concentrations of total OPEs(8 OPEs: Tn BP,Ti BP,TPe P,TEHP,TPh P,TCEP,TCPP,and TDCPP)in the surface sediments of the Bohai and Yellow Seas were 4,552 and 516 pg g-1,respectively.The distribution patterns of total OPEs and most individual OPEs were that sites in the deposition areas showed higher concentrations than those outside the deposition areas.Riverine input and deposition effects were the main factors that influenced the concentrations and distributions of OPEs in this region.3.It was estimated that mean OPE reserves in seawater and surface sediments of the Bohai and Yellow Seas was 396,604 kg and 2,499 kg respectively.This indicated that surface sediments were not the main reservoir of OPEs in this region.Furthermore,based on the concentrations of the OPEs in the Bohai and Yellow Seas and the documented toxicity of OPEs,toxicological effects of TCPP(main OPEs of the region)toward the intertidal mussel(Mytilus galloprovincialis)were characterized.Levels of apoptosis,reactive oxygen species(ROS)and malondialdehyde(MDA),enzyme activity of superoxide dismutase(SOD),expressions of immune related genes(GLYZ,CLYZ,Caspase8,Caspase2,BD6,Mytimacin,My D88,Jun-like,LITAF,TLR2,Galectin,and PGRP)of hemocytes were analyzed for mussels after chronic(42 days)exposure for different concentrations(10 and 100 nmol L-1)of TCPP.Meanwhile,i TRAQ-based proteomics was also employed to detect gender-specific responses of mussels toward chronic(42 days)TCPP(100 nmol L-1)exposure in the whole tissues(except shells and byssuses).The research showed:1.The low concentration(10 nmol L-1)of TCPP exposure(42 days)showed significant influence on the ROS levels and the expression of immune related genes(CLYZ,Caspase8,Mytimacin,LITAF,Galectin,and PGRP)of the hemocytes of mussels.2.The high concentration(100 nmol L-1)of TCPP exposure(42 days)showed significant influence on the levels of apoptosis,ROS,and MDA,the enzyme activity of SOD and the expression of immune related genes(CLYZ,Caspase8,Caspsae2,BD6,Mytimacin,My D88,LITAF,TLR2,Galectin,and PGRP).3.The high concentration(100 nmol L-1)of TCPP exposure(42 days)influenced multiple biological processes(energy metabolism,protein synthesis,contraction of adductor muscles,and reproduction)in the whole tissues of mussels.In summary,both the seawater and surface sediments of the Bohai and Yellow Seas presented relatively high OPE concentrations and the distribution patterns were that higher concentrations occurred in the nearshore and surface seawater and in the sediments of deposition areas.Riverine input,disturbance of ocean currents,water mass and deposition effects were the main factors that influenced the distributions of OPEs in this region.The mean OPE reserve in surface sediments of the Bohai and Yellow Seas was relatively low,which indicated surface sediments were not the main reservoir of OPEs in this region.By choosing TCPP as representative OPEs,multi-level exploration towards toxicological effects of TCPP to mussels were conducted and gender diffence of mussels were taken into consideration as well.Levels of apoptosis,ROS,MDA,enzyme activity of SOD,and expression of immunity related genes of mussel hemocytes were influenced by chronic TCPP exposure.Meanwhile,energy metabolism,protein synthesis,contraction of adductor muscles,and reproduction were also influenced by chronic TCPP exposure in the whole tissues of mussels.This research might shed important light on the environmental behavior and toxicological effects of OPEs both theoretically and practically.