| Nonylphenol (NP) and Octylphenol (OP) are persistent organic pollutant and typicalphenolic endocrine disrupting chemicals. They are resistant to biodegradation, toxic,bioaccumlative and estrogenic active. NP and OP are two synthetic compounds that are widelyused in industrial production, both of which are one of the most common commercially availablelong chain alkylphenols and the main biodegradation products of alkylphenol polyethoxylates. Inrecent years, much more concern has been focused on the distribution, transport andtransformation of NP and OP in addition with their ecological risk assessment is of urgent need.The Pearl River estuaries, as an economically developed region, were characterized by complexnature environment, densely populated, human interference huge impact on the ecologicalenvironment of the estury and the main channel of land-sourced pollutants enter to the SouthChina Sea (SCS) connecting to the Pacific Ocean. However, reports about distribution of NP andOP in China are still very limited, and there are even less report in Pearl River estuaryenvironment. This paper took Pearl River estuaries as a study area. NP and OP are quantified byHPLC-MS with external standard. The spatial-temporal distribution of NP and OP in surfacewater and sediments are analyzed, and the possible biological effects are also discussed. Basedon the occurrence study of NP and OP mentioned above, a risk assessment of NP and OP in PearlRiver Estuaries were evaluated by the calculation of risk quotient (RQ).Main results were as follows:(1) the mean concentrations of NP and OP in surface water ofthe riverine outlets of the Pearl River Delta were30.4-16.2×103ng/L and1.7-15.7×103ng/L,respectively. Seasonally, NP and OP concentrations in summer were higher than winter, springand antumn. It possibly attribute to higer water temperature accelerating the biodegradation rateof NPEs and OPEs. The mean concentrations for NP and OP varied spatially, with the highconcentrations being found at Humen. It mainly affected by the discharge of industrial waste,municipal and domestic wastewater. The mean concentrations of NP and OP in surface sedimentsof the study area were1.2-91.7ng/g dw and <LOD-8.8ng/g dw, respectively. The seasonalvariations of NP and OP concentrations in surface sediments were similar to that in surface water.The highest concentrations of NP was found at Modaomen, which mainly affected by river input.However, the highest levels of OP were detected in Yamen probably due to higher consumption of OPEs surfactants. Compared with other areas from the world, NP and OP concentrations inriverine outlets of the Pearl River Delta were moderate pollution levels.(2) NP and OP concentrations in both water and sediment of the study area mostly didexceed the threshold limit for undesirable biological effects. According to the EU assessmentreport on NP, the value of NP RQwaterin surface water and sediment were in the rangs of0.11-49and0.03-2.4, respectively. The risk of NP in water was higher than that in sediment. Furtherinvestigation and risk mitigation measures for NP should be taken in this area.(3) A risk assessment model for NP and OP was built based on species sensitivitydistribution (SSD). NP and OP of RQwatervalues in water were caculated as0.082-44and0.0059-55, respectively. NP and OP of RQsedimentwere0.022-1.7and0.081-0.27, respectively.Most sites of RQsedimentwere0.1-1. Further investigation and risk mitigation measures for NPand OP were needed in this area.(4) In respect to human health risk, the risk index (RI) of adult and infant were exposed toNP were0.1and0.3, respectively. For OP, the RIs were0.0005for adult and0.002for infant,respectively. The values of RI were lower than1, showing the intake for NP and OP for PearlRiver Delta residents through drinking water and lower risk. |
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