The Pollution Characteristics And Preliminary Source Apportionment Of Polycyclic Aromatic Hydrocarbons And Polychlorinated Biphenyls In Surface Sediments From The Western Sea Of Shenzhen

Polycyclic aromatic hydrocarbons(PAHs) and polychlorinated biphenyls(PCBs) are two kinds of typical persistent organic pollutants, regulated by the laws and regulations of many countries because of their severe damage to environment and animal health. The western sea of Shenzhen is one of heavily polluted seas, however researches on the pollution status of PAHs and PCBs in this sea are reported rarely. As a consequence, taking the western sea of Shenzhen as the study area, we collected 76 surface sediment samples altogether, which come from 4 sampling areas, rivers into the sea, Shenzhen bay, Moon bay and the Pearl River Estuary-Shenzhen sea, respectively. The contents of 15 PAHs monomers and 7 indictive PCBs monomers in surface sediments from 4 sampling areas have been analyzed comprehensively for the first time and their composition profiles, source apportionment and ecological risk assessment have been discussed in this work. Based on the investigation, Shenzhen government and relevant departments can manage the input fluxes of terrigenous pollutants and formulate various policies related with marine environment protection.The results of this paper could be summarized as follows:1. The average concentrations of 15 total PAHs in surface sediments from rivers into the sea, Shenzhen bay, Moon bay and the Pearl River Estuary-Shenzhen sea are 706.2ng/g 、498.90 ng/g、733.54 ng/g and 212.12 ng/g, respectively. The pollution level of total PAHs in sediments is moderate or slightly lower in comparison with other areas, however the propotion of high molecular weight PAHs(4~6 rings) is relatively great. There is a significant correlation between the contents of TOC and PAHs as well as between the contents of oil and PAHs in sediments(R=0.667,0.566, respectively, p<0.01), which indicates that TOC and oil are two important factors affecting PAHs distribution.2. Preliminary source apportionment by ratios of w(Fla)/w(Fla +Pyr) and w(Ba A)/w(Chr+ Ba A) reflects that PAHs in sediments from the western sea of Shenzhen all derive from the combustion of wood, coal and oil as well as the oil spill. However, the proportion of PAHs from combustion source is higher than that from oil spill.3. By means of effects range low(ERL), effects range median(ERM) and toxic equivalent quantity relative to BaP to assess the ecological risk of PAHs in sediments, we findthatbenzo[b]fluoranthene(bbf),benzo[k]fluoranthene(bkf),indeno[1,2,3-cd]pyre-ne(icdp)andbenz[g,h,i]perylene(bghip)canbedetectedinallstations,havingseriousdamagetocreatures.acenaphthene(ace)andfluorene(flu)andphenanthrene(phe)incertainstationshaveadverseeffectsoncreaturesoccasionallyduetotheirconcentrationsbetweenerlanderm,howeverotherpahsinallstationsgenerateadverseeffectsoncreaturesrarelyonaccountoftheirconcentrationsbelowtheerl;fromtheperspectiveoftoxicequivalence,sedimentsfrommoonbayhavethehighestecologicalrisk,followedbysedimentsfromriversintothesea,andthensedimentsfromthepearlriverestuary-shenzhenseahavethelowestecologicalrisk.dibenz[a,h]anthracene(daha),benz[a]pyrene(bap)andbenzo[b]fluoranthene(bbf)arethemainsourceofecologicalriskofsediments.4.theaverageconcentrationsof7 totalpcbsinsurfacesedimentsfromriversintothesea,shenzhenbay,moonbayandthepearlriverestuary-shenzhenseaare610pg/g,1035pg/g,1017pg/gand350pg/g,respectively.thepollutionleveloftotalpcbsinsedimentsisrelativelylowincomparisonwithotherareas.3clcbsand6 clcbsarethemaincomponentsoftotalpcbs.thereisasignificantcorrelationbetweenthecontentsoftocandpcbsinsediments(r=0.569,p<0.01),whichindicatesthattocisanimportantfactoraffectingpcbsdistribution.5.bycomparingthepcbscompositonofindustrialcommoditieswiththatofmodernanthropogenicactivityproducts,itisconsideredpreliminarilythatthelowchlorinatedpcbs(3cl~5cl)mainlyderivefromindustrialcommoditiesandhighchlorinatedpcbs(6cl~7cl)mainlystemfrommodernanthropogenicactivities.exceptforindividualstation,pcbsinsedimentsfromthewesternseaofshenzhenderivefrombothindustrialcommoditiesandmodernanthropogenicactivities.insomestations,theratioofpcbsfromindustrialcommoditiesislarger,howeverthecaseisadversetootherstations.6.byuseofeffectsrangelow(erl),effectsrangemedian(erm)andsedimentqualityguidelines(sqgs)toaccesstheecologicalriskofpcbsinsediments,wefindthattheconcentrationsoftotalpcbsinallstationsarebelowtheerl(22.7ng/g)andisqg(21.6ng/g),havingadverseimpactsoncreaturesrarely.