Distribution Characteristics And Ecological Risk Assessment Of Priority Organic Pollutants In Typical Rivers Of Shenyang

Although the integrated water quality index (CODCr, BOD5, ammonia, etc.) has been improved year by year in Liao River Basin (LRB), the pollution in some tributaries were still severe. Toxic and hazardous materials from different industries have caused great harm to aquatic life and human health. Shenyang was the economic center and also the largest industrial city in Northeast China. Due to the rapid development of city, the emissions of industrial wastewater and domestic sewage increased dramatically, causing serious pollution of rivers receiving wastewater discharge. According to incomplete statistics,562 enterprises, accounting for 37.1% of the total number of enterprises in Shenyang City, discharged the wastewater into the Xi River; there were 253 enterprises that released the wastewater into the Pu River, accounting for 16.7% of the total number of enterprises in Shenyang City.Using improved potential hazardous index method,52 organic pollutants in the Xi and Pu Rivers were scored and sequenced. It was shown that phthalic acid esters(PAEs) and phenols were identified as priority organic pollutants. The distribution characteristics and ecological risk assessment of these organic pollutants in the water and surface sediment of Xi and Pu Rivers were investigated. The main results were showed as follows:(1) In the water of Xi River, the total concentration of 6 PAEs (Σ6PAEs) and 8 phenols (Σ8Phenols) ranged from 3.04 to 35.5 μg/L and from 5.51 to 5970 μg/L, respectively. The predominant pollutants were dimethyl phthalate (DMP), dibutyl phthalate (DBP), diisobutyl phthalate (DIBP), phenol,3,5-dimethylphenol and 4-methylphenol. The top 3 sampling sites with higher concentration of Σ66PAEs and Σ8Phenols in different sampling seasons were Dawula> Aijin> Ganguanqiaoand and Aijin> Ganguanqiao> Jiliqiao, respectively. In the water of Pu River, the concentration of Σ6PAEs and Σ8Phenols ranged from 2.23 to 76.1μg/L and from 4.05 to 230 μg/L, respectively; the predominant contaminants were DBP, DIBP, Bis(2-ethylhexyl) phthalate (DEHP), phenol and 4-methylphenol; the top 3 sampling sites with higher mean concentration of Σ6PAEs and Σ8Phenols in different sampling seasons were Guodao 102 bridge> Puheyan> Heiyugou and Hefeng> Puheyan> Mengjiatun. The seasonal distribution in Xi and Pu Rivers showed that the mean concentrations of Σ6PAEs and Σ8Phenols followed the sequence of flood season> dry season> normal season.(2) In surface sediment of Xi River, the concentrations of Σ6PAEs and Σ8sPhenols ranged from 22372 to 36155 ng/g and from 2724 to 105466 ng/g, respectively; the predominant pollutants were DEHP, DNOP, phenol and 4-methylphenol; the pollution level of Σ6PAEs and Σ8Phenols were upstream> midstream> downstream, upper and middle reaches> downstream, respectively. In surface sediment of Pu River, the concentration of Σ66PAEs and Σ8sPhenols ranged from 6804 to 46907 ng/g and from 812 to 24987 ng/g, respectively; the predominant pollutants were DEHP, DNOP, phenol,4-methylphenol and 2,4-di-tert- butylphenol; the sampling sites with top 3 high concentration of Σ6PAEs were Guodao 102 bridge> Hefeng> Shengliqiao; the concentration of Σ8Phenols in the sampling site of Hefeng was much higher than those of other sites.(3) The extrapolation method of the effects evaluation combined with quotient method was adopted to evaluate the ecological risk of PAEs and phenols. The results indicated that in the Xi River, the ecological risk of DBP, phenol,4-methylphenol,2,4-dimethylphenol and 2,4,6-trimethylphenol were high; in the Pu River, the risk of DBP, DEHP and 4 phenol congeners were in a relatively high level.