Derivation Of Water Quality Criteria For Nonylphenol And Its Application In Ecological Risk Assessment

Nonylphenol (NP) is an endocrine disruptor and causes feminization andcarcinogenesis in various organisms.China accounts for approximately10%of thetotal NP usage in the world. Consequently, the environmental distribution andecological risks of NP have received wide concern.But the water quality criteria of NPhave not been established in China and the ecological risk of this pollutant cannot beproperly assessed.Current national aquatic environmental quality standards in Chinaare derived from and/or based on those of developed countries, which may not fit theregional eco-environment and current needs ofenvironmental management in China.Therefore,it is necessary to undertake researches on water quality criteria andecological risk assessment. This study aimed to determine the acute and chronic waterquality criteria of NP in Chinabased on species sensitivity distribution (SSD)modeland to assess the ecological risk of NP in coastal waters of China.In addition,aschronic toxicity values of NP were limited, theacute to chronic ratio (ACR)methodologywasemployed to make extrapolation fromacute to chronic values.Main conclusions were as follows: based on the ACR method and with9acute-chronic data sets selected from US Environmental Protection Agency (USEPA)ECOTOX database, the final acute to chronic ratio (FACR) of NP was calculated as10.3, which can be used for the extrapolation from acute to chronic toxicity data inseawater to overcome the problem of seawater toxicity data shortage.This study adopted the SSD methodology to derive water quality criteria forNP.Toxicity data of NP tested with Chinese native species were screened frompublished literature. The datasets included13acute toxicity data and12chronictoxicity data in freshwater,8acute toxicity data and2chronic toxicity data inseawater. The screened chronic toxicity data in freshwater were sufficient for the establishment of SSD models, whereas those in seawater were not.Two acute toxicitytests with two marine species (Platymonas subcordiformis and Chlamys farreri) weretherefore undertaken in our lab to supplement toxicity data for seawater species.Besides two chronic toxicity data screened from literature, additional ten chronicvalues were achieved through the ACR method for seawater species. Based on theacute and chronic toxicity data, SSD models were built for both freshwater andseawater species with4best fit models.Results showed that for freshwater, the acutewater quality criteria for NP was calculated as22.4μg/L and chronic criteriawas2.4μg/L; for seawater, the acute water quality criteria was1.0μg/L and chroniccriteria was0.2μg/L。The risk quotient (RQ) method and margin of safety (MOS10) method were usedfor the quantitative characterization of ecological risk of NP in coastal waters ofChina. a) RQ values ranging from0.008-13.8in freshwater and0.013-3.81inseawater.The highest value in freshwater was recorded in the urban riverine water ofPearl River Delta and the lowest value was in adjacent rivers of northern South ChinaSea. The highest value in seawater was recorded inNorth Yellow Sea and the lowestinSishiliBay and TaoziBay. All the waters investigated in Haihe River and NorthYellow Sea were at low risk level (RQ<0.1); medium risk (0.1<RQ<1) occurred inPearl River Delta and adjacent northern South China Sea, Yangtze River Estuary,Haihe River and Bohai Bay. High risk level (RQ1.0) were recorded at6%,33%and28%in Jiaozhou Bay and its surrounding rivers, Urban riverine water of the PearlRiver Delta and Daliao River Estuary, respectively. Urban riverine water of the PearlRiver Delta was proved as the most polluted area by NP. b) MOS10in most waterswere at low risk level (MOS10>1) except some maximum values in freshwater. Risklevel in seawater was lower than freshwater, hazardous concentration in seawater andfreshwater for5%of the species accounted for9.1%and17.6%, respectively。NP wastherefore widely distributed in coastal waters of China and its ecological risk warrantsfurther investigation.