Occurrence And Prioritization Of Phenolic Pollutants In Nanjing Chemical Industrial Park And The Surrounding Environment

Phenolic compounds are a group of endocrine disrupters.They are also mutagenic and carcinogenic,and widely present in waters,soils and sediments.Therefore,they have been recognized as one category of the most important pollutants in the environment.Phenolic compounds are widely used,especially in chemical industries,such as the production of plastics,plasticizers,resins,colors,pesticides,detergents,stabilizers,antioxidants,explosives and drugs The Yangtze River is the main drinking water source for more than one-third of the population in China.Nanjing Chemical Industry Park is the largest industrial park in Jiangsu Province,and located along the Yangtze River.A variety of chemicals in Nanjing Chemical Industry Park may be introduced into the surrounding environment through volatilization,leakage and effluent discharge during transportation,production and use of chemicals,which will cause some negative impacts on human health and as well as ecological system.The objectives of this study were to investigate the levels and distribution of phenolic compounds in environment around Nanjing Chemical Industry Park,to clarify the correlation between the water quality parameters of the influent and effluent in a wastewater treatment plant in Nanjing Chemical Industry Park and their acute toxicity on zebrafish,and to screen the priority phenolic pollutants in Nanjing chemical industrial parkBased on the optimization of the pretreatment methods as well as the instrumental conditions,we developed a new analytical method for the determination of 16 various phenolic compounds(including phenol,2-chlorophenol,2,4-dichlorophenol,2,4,6-trichlorophenol,pentachlorophenol,4-nitrophenol,2,4-dinitrophenol,2,4-dimethylphenol,2-methyl-4,6-dinitrophenol,4-chloro-3-methylphenol,hydroquinone,chlorohydroquinone,bisphenol A,nonylphenol,m-cresol,2,6-di-tert-butyl-4-methylphenol)in water,soil and sediment.The recoveries of all the analytes ranged from 76.7%to 111.5%in water,and 70.7%to 122%in soil and sediment.The relative standard deviations were all below 16%.The newly developed methods can be adopted to determine a variety of phenolic compounds in various environmental matricesThe results of these phenolic compounds in Nanjing Chemical Industry Park are summarized as follows.The two main phenolic pollutants in the influents and effluents of the wastewater treatment plant were 4-nitrophenol and 2,4-dimethylphenol.The removal efficiencies during wastewater treatment was 69.7%～100%for 4-nitrophenol and 72.3%～97.9%for 2,4-dimethylphenol.The concentrations of the phenolic compounds in the effluent were lower than the relevant discharging standards,which indicated that the wastewater treatment process was satisfactory for the removal of these phenolic pollutants.The four major phenolic pollutants in Chuhe River were 2,4-dimethylphenol,chlorohydroquinone,2,4-dinitrophenol and 4-dinitrophenol.The total concentrations of the phenolic pollutants showed a decreasing trend from the upstream to the downstream along the river,and were different in different seasons with dry season>flow season>wet season.Similarly,the three primary phenolic pollutants in Yangtze River were 4-chloro-3-methylphenol,2-chlorophenol and 2,4-dimethylphenol.The total concentration of the phenolic pollutants closed the discharging point of the effluent and chemical industry park was much higher than that in the upstream.These results demonstrated that Nanjing Chemical Industry Park might contribute to phenolic pollutants in the surrounding rivers(Yangtze River and Chuhe River).Furthermore,the major phenolic pollutants were Phenol,2,4-dinitrophenol,4-nitrophenol and 4-chloro-3-methylphenol in the soils in Nanjing Chemical Industry Park and the surrounding areas.The concentrations of the phenolic pollutants in the soils were relatively low,and no significant spatial distribution.The acute toxicity tests on zebrafish were conducted to obtain the 48h LC50 values of different samples for toxicity comparison.According to the toxicity classification standard of industrial wastewater,the effluent from the wastewater treatment plant in Nanjing Chemical Industry Park was classified as non-toxic.However,the influent and effluent were classified as low toxicity or median toxicity after mixing with wastewater with high level of chloride,The toxicity of Influent and effluent which were collected from the same place in different time periods increased with the increasing concentrations of the phenolic pollutants.The toxicity of influent/effluent samples increased with the increasing concentrations of adsorbable organic halogens(AOX),and decreased with the decreasing concentrations of TOC,COD,ammonia nitrogen and total phosphorusFinally,four priority pollutants were screened based on the toxicity data and the measured concentrations.The most dominant priority phenolic pollutant in Nanjing Chemical Industry Park was nonylphenol,followed by 2-methyl-4,6-dinitrophenol,2,6-di-tert-butyl-4-methylphenol and 4-chloro-3-methylphenol.