Pollution Levels And Risk Assessment Of6Priority Phthalate Esters In Water And Sediments From Estuaries Of The Pearl River Delta

Phthalate esters (PAEs) are teratogenic, carcinogenic and mutagenic compounds withendocrine disrupting effects. With the development of the plastics industry and the usage ofphthalates, there are many global environmental issues about the residues level, distributioncharacteristics and ecological risk of PAEs. Rapid developments of the Pearl River Delta regionin recent dacades have resulted in the increasingly serious environmental pollution in and aroundthe region. The Pearl River estuary is the most direct and important source of fresh water for thePearl River Delta citizens and industrial and agricultural life. Therefore, it is great significant tothe study of the distribution and health and ecological risk assessment of the environment ofphthalate esters in Pearl River outlets for providing basic data for environmental hormonesresearch.In this study, six USA Environment Protection Agency (US EPA) priority controlledphthalate esters (dimethyl phthalate, diethyl phthalate, dibutyl phthalate, butyl benzyl phthalate,di-2-ethylhexyl phthalate and di-n-octylo-phthalate) were chose as target compounds. Weinvestigated the concentration and distribution of the6PAEs in water and sediment from PearlRiver outlets (Humen1, Humen2, Jiaomen, Hongqimen, Maodaomen, Jitimen, Yamen), thenpreliminary health and ecological risk assessment had been discussed. The main findings asfollows:The Σ6PAEs concentration in water from the outlets ranged from0.50to28.1μg/L, DBP andDEHP were predominant pollutants. As compared to the results for other studies, the PAEsconcentration of the study area was in a middle level. The seasonal distribution showed PAEsconcentration in summer was highest, which was due to rainfall, surface runoff and atmosphericwet deposition. It was higher than that in spring, autumn and winter. The spatial distributionshowed the mean concentration of Σ6PAEs at different outlets was in descending order as Yamen> Humen2> Humen1> Jitimen> Modaomen> Jiaomen> Hongqimen. The Pearsoncorrelation coefficient of BBP and DnOP, DEP and DnOP, DBP and DEHP were0.884(P<0.01),0.814(P<0.05),0.779(P<0.05), respectively, indicating BBP and DnOP, DEP and DnOP, DBPand DEHP might be from the common source. The Σ6PAEs concentration in surface sediment ranged from1.22to13.6μg/g, DBP andDEHP were also predominant pollutants. As compared to the results for other studies, the PAEsconcentration of the study area was in a lower middle level. Compared the PAEs composition inwater, DEHP which was of long/branched chain was more inclined to adsorbed in sediment,because of the higher Kowvalue, the stronger hydrophobic property. The spatial distributionshowed that the mean concentration of Σ6PAEs in surface sediment at different outlets was indescending order as Humen1> Hongqimen> Modaomen> Humen2> Jiaomen> Jitimen>Yamen. The vertical distribution of PAEs in core sediments from Humen, Jiaomen andModaomen showed PAEs content was decreased by years at Jiaomen and Modaomen, while itwas increased at Humen because of extensive use of plastic products in cities located theupstream.According to the health risk assessment model of US EPA, the total non-carcinogenic riskof6PAEs to the individual person per year ranged from3.80×10-5to2.38×10-4, it was higherthan the maximum tolerable value (5.0×10-5a-1) recommended by the US EPA and the ICRP. Ascompared to the results for other studies, the carcinogenic risk of DEHP in the study area was ina relatively high level. According to the ecological risk assessment methods of risk quotients andmargin of safety, the RQ values of DEHP ranged from0.813to45.8, indicated DEHP was themost adverse effect on the sensitive aquatic organism (Pseudokirchneriella subcapitata、Daphniamagna、Oncorhynchus mykiss). The MOS10values of4PAEs (DMP, DEP, DBP, DEHP) withhigher detection frequency were11378.1,11424.1,23.40,19.68; the risk of them as followsDEHP> DBP> DMP> DEP.Surface sediment’s ecological risk was assessed with the methods of sediment qualityguidelines (SQGs) and risk quotients. The SQGs result showed DEHP was present in excess ofthe lower ERL and might pose adverse biological effects. All RQ values of5PAEs were lowerthan10and followed by BBP> DBP> DEHP> DMP> DEP, indicating the ecological risk insediment was in a low level.