Feasibility Study On Biomarkers Indicating The Distribution And Source Of Organochlorine Pesticides(OCPs) In Sediment From Southern Yellow Sea(SYS)

The Southern Yellow Sea (SYS) is a marginal sea of the northwest Pacific.Surrounding advanced industry/agriculture and then pollutants discharges havetrenmendous repercussions on its eco-environments. Study on the distributions ofsedimentary organochlorine (OCPs) from SYS is favourable for understanding thedistributions and future trends of terrestrial organic pollutants in this region.Compared with other marginal seas of China, there are no direct larger riverine inputsand the distribution and deposit mechanism of organic matter is also unclear. In thispaper, the spatial distributions and the records of biomarkers (the indicators ofterrestrial and marine organic matter) and organic pollutants have been studied fordiscussing the source and burial mechanism of these anthropogenic contaminants. Thecontents of15kinds of OCPs (-HCH、β-HCH、γ-HCH、o,p’-DDT、p,p’-DDT、o,p’-DDE、p,p’-DDE、o,p’-DDD、p,p’-DDD、Aldrin、Endrin、Heptachlor、Heptachlorepoxide (Isomer A)、Heptachlor epoxide (Isomer B)、Methoxychlor) and organicmatter indexes (TOC、C37-alkenones、Brassicasterol、Dinosterol、C27+C29+C31n-alkanes、Branched-GDGTs、Pr、Ph) have been involved and the main results are asfollows:(1) The results presented that contents of∑OCPs were in ranges of0.5-7.6ng/gd.w., with a mean value of3.2±2.3ng/g d.w.. The areas with higher values weremainly located at H6-H12and H43, while the lowest value was located at H15.Among these15contaminants, the detection frequency of DDTs was the highest andthe contents ranged between ND-5.1ng/g d.w., with a mean of0.8±1.0ng/g d.w..The highest and lowest contents of∑DDTs emerged at H9and H11respectively. Thespatial distribution of∑OCPs showed an obvious decreasing trend from the middlearea to nearshore and southward. Compared with other marginal seas on the earth, the contents of surface sediementary∑OCPs was at lower levels. As for core N02, thecontents of∑OCPs in the upper layer (0-19cm) were from1.2to5.6ng/g d.w., withtwo peaks in1940s and1990s respectively. After2000s,∑OCPs rose slightly while∑DDTs rose rapidly, suggesting the occurrence of continuous inputs of freshpestcides.(2) The homologue characteristics (DDTs, HCHs,(DDE+DDD)/DDT) of DDTsalso indicated the fresh OCPs inputs into the SYS. Sedimentary records of∑OCPsand the ratios of∑OCPs to biomarkers present similar increasing trend, which alsoindicated the possible fresh pesticides inputs in recent years.(3) Marine biomarker indexes of C37alkenones (nd-443.5(average,155.5) ng/gd.w.), brassicasterol (77.7-998.6(439.6) ng/g d.w.) and dinosterol (160.0-1622.7(668.3) ng/g d.w.), all presented the same spatial distribution patterns, with low valuesin the middle mud area and higher values around. Terrigenous organic matter index ofC27+C29+C31n-alkanes (119.7-799.5(377.3) ng/g d.w.) also displayed the samepatterns to that of marine biomarkers. The records of zooplankton biomass (chlosterol)and phytoplankton primary productivity (brassicasterol、dinosterol) presented anrapidly increasing trend in the past90years. The contents of terrigenous organicmatter showed no significant change, but their contributions presented a decreasingtrend.(4) There were obvious positive correlations between∑OCPs and terrestrialbiomarkers/indexes. The results may be attributed to their same source, migrationpathway and burial mechanisms, such as riverine/atomsphere input, grain size effect,and hydrodynamic conditions.∑OCPs normalized TOC presented a seawardincreasing tendency, opposite to that of∑OCPs, indicated that a majority oforganochlorine pesticides may be from the nearshore runoff input. The characteristicsof DDD and DDE (0-19cm) indicated the redox nature of depositional environment,consistent with Pr/Ph index (0.58-0.94(average,0.80)).All the investigations in the thesis would gain pollution status and input recordsof OCPs in the sediment from SYS. Further understanding of the POPs depositionmechanism also has been got based on the spatial and temporal distribution of OCPs, meanwhile apply as the scientific pollutant control and management.