Distribution Characteristics And Ecological Risk Assessment Of Typical Phenolic Endocrine Disrupting Chemicals In Daliao River Estuary

Endocrine disrupting chemicals (EDCs) are chemicals that interfere with theendocrine system in animals, including humans. Nonylphenol (NP) and bisphenol A(BPA) are two synthetic compounds that are widely used in industrial production,both of which are typical phenolic endocrine disrupting chemicals. The extensiveproduction, usage and endocrine disrupting effects of NP and BPA have causedwidespread concern. The distribution, transport and transformation of NP and BPAin addition with their ecological risk have become a research hotspot in recent years.However, researches about distribution of NP and BPA in China are still very limited,and there are even less research in estuarine and marine environment. This paper tookDaliao River Estuary as a study area. NP and BPA are quantified by GC-MS withinternal standard. The spatial and temporal distribution of NP and BPA in surfacewater and sediments are studied. A risk assessment model was built based onspecies sensitivity distribution (SSD) and the risk assessment of NP and BPA inDaliao River Estuary were evaluated.Main conclusions were as follows: the concentration of NP in surface water andsediments of Daliao River Estuary were25.7-777ng/L and6.40-456ng/g dwrespectively, the concentration of which in river section were83.6-777ng/L and21.5-456ng/g dw respectively. The average concentration in both surface water andsediments in the wet period (August) were higher than the normal period (June). Theconcentration distribution in the river section in June was determined by the distanceaway from the source, but no obvious trend was found in concentration distribution inAugust. The spatial distributions of sediment in river section were similar in twosurveys, and the concentrations were gradually declined. The concentrations of NP insurface water and sediment coastal area were25.6-593ng/L and6.4-41.7ng/g dw respectively. The concentration in surface water in August was higher than that inJune, but the concentration in surface sediment in two investigations was comparable.The concentration in both surface water and sediment generally showed a decreasingtrend from the river mouth to offshore. The annual flux of NP from the Daliao RiverEstuary into the sea was estimated as753kg and the main pollution sources werefrom the upper reaches, domestic sewage, in addition with agricultural and industrialeffluents.The concentration of BPA in surface water and sediments of Daliao RiverEstuary were12.5-248ng/L and1.22-24.0ng/g dw respectively, the concentration ofwhich in river section were29.2-248ng/L and3.42-24ng/g dw respectively.Temporal and spatial distributions in surface water were similar on the upper sectionof the river in June and August, but showed difference in the middle-down section.The spatial distributions in surface sediment were sililar in two surveys, while thepollutant level in August was lower than that in June. The concentrations of BPA insurface water and sediment in coastal area were12.5-137ng/L and1.22-15.3ng/g dwrespectively, and the temporal and spatial distributions in surface water and sedimentwere similar to that in NP.NP and BPA concentrations in the Daliao River Estuary were moderate andcomparable to those in other areas of the world. The concentrations in both waterand sediment of the study area did, however, exceed the threshold limit forundesirable biological effects.A risk assessment model for NP and BPA was built based on species sensitivitydistribution (SSD). The predicted no effect concentration (PNEC) of NP in freshwaterand seawater was calculated as0.475μg/L and0.281μg/L respectively. PNEC of NPin freshwater sediment and marine sediment was0.056μg/g (wet weight) and0.033μg/g (wet weight) respectively. PNEC of BPA in freshwater and seawater wascalculated as0.592μg/L and2.82μg/L respectively. PNEC of BPA in freshwatersediment and marine sediment was0.010μg/g (wet weight) and0.0461μg/g (wetweight) respectively.The value of NP RQwaterin the river section and coastal area were caculated as 0.176-1.64and0.091-2.40respectively, RQsedimentin the river section and coastal areawere0.607-21.8and0.305-3.99respectively. Further investigation and risk mitigationmeasures for NP were needed in this area.RQwaterof BPA in the river section was0.053-0.418,showing potential ecologicalrisk; RQwaterin coastal area was0.004-0.048, and no risk was detected yet. RQsedimentin the river section and coastal area were0.549-5.83and0.041-1.07respectively.Further investigation and risk mitigation measures for BPA were needed in this area.