| In recent decades, a large number of synthetic chemicals have been used in the manufacture of drugs, personal care products and so on. Since some of these chemicals generally contain with high carcinogenic, teratogenic and mutagenic properties and mostly seem hard to be decomposed but easy to spread in the environment, they can transfer and enrich through the food chain in the process and gradually cause significant biological metabolic disorders and ecological pollution, eventually lead to the damage and destruction of the whole population and ecosystem. On the whole, biological toxicity is the comprehensive and accurate characterization to express the harmful degree of pollution when dealing with the pollutants growing in number and type. Moreover, riverine environment is the resource that human live on, as well as the receiving stream of the point and non-point source pollution. Compared with western countries, China has large population and rapid economic growth as well as the increasing discharge of the pollutants to the environment every year. At present, it seems that the largest population density and prominent and sensitive area with contradiction between human and land is located in South China. Besides, the two major river systems of China, the Yangtze River and Pearl River system, are distributed in South China where nearly six hundred million people dwell, which means that the river environmental qualities of these two basins have close relationships to the health and life quality of local people. Some former researches showed that part of the basin river has been seriously polluted by exogenous pollutants, especially endocrine disrupting chemicals, while the pollution and situation of most typical rivers are still unclear. In conclusion, it is necessary to apply the toxicity assessment by bioassay combined with varieties of biochemical indicators to reasonably analyze and assess the riverine environmental quality of this region. We started from the receiving waters and sediments of two rivers, the middle and lower reaches of Yangtze River system and East River from Pearl River system, through analyzing the two most classic types of biological activities caused by the environment pollutant, environmental hormonal activities and genetic toxical activity, in combination with other chemical monitoring data to assess the environmental pollution from survey on the breadth. This study also aimed to try to realize the ecological risk assessment and find the main contribution compounds of the bio-toxicity through effect-directed analysis on the depth. The main results of this research are as follows:(1) According to the analysis of environmental hormonal activities of river water and sediment in two typical basins of southern China during two seasons which showed that: The estrogenic activity appear to the most common pollution in Yangtze River, with the detection frequencies higher than 50% in both surface water and sediment. The highest estrogenic activity was up to 2.05 ng/L estradiol equivalents(EEQ) in surface water and 0.43 ng EEQ/g in sediment. In contrast, the detection frequencies of the other three hormonal activities were generally lower than that of estrogen activity in the river. The overall detection frequencies of those three hormonal activities ranked as follows: anti-androgenic activity > androgenic activity ≈ anti-estrogenic activity, with the maximum detected concentrations of 144 μg/L flutamide equivalents(FEQ), 37.9 ng/L dihydrotestosterone equivalents(DEQ) and 103 μg/L tamoxifen equivalents(TEQ) in surface water, and 53.6 μg FEQ/g, 12.0 ng DEQ/g and 51.5 μg TEQ/g in sediments. Seasonal variations were observed for the four hormonal activities in surface water of Yangtze River. Sites with relatively higher estrogenic activity were located at Wuhan, Nanjing-Wuhu sections and the outlet of Poyang Lake. However no obvious regional differences were observed for the other three hormonal activities. The hormonal activities in the river were positively correlated to the general environmental parameters such as local population, organic matter, and ammonia nitrogen, suggesting that environmental hormones are mainly originated from the wastewater discharge due to human activities. A preliminary risk assessment showed a high estrogenic risk level at the site of Poyang Lake, with medium risk levels in the rest sites. For the all study sites, no high androgenic risks were found in surface water. The results of East River also confirmed that estrogenic activity was the most common pollution, with the detection frequencies higher than 65% in both surface water and sediment. The concentration of estrogenic activity ranged from ND to 136 ng EEQ /L in surface water and from ND to 8.23 ng EEQ/g in sediment. The overall detection frequencies of other three hormonal activities in East River ranked as the same as in Yangtze River, with the average detected concentrations of 140 μg FEQ/L, 2.87 ng DEQ/L and 11.8 μg TEQ/L in surface water, and 48.8 μg FEQ/g, ND and 17.4 μg TEQ/g in sediments. Moreover, seasonal variations and watershed distribution difference present in the environmental hormonal activities. Danshui River and Shima River were marked as heavy polluted zone overall, with high estrogenic risk in most of the sites.(2) Through using the effect-directed analysis and YES test, the quantitative analysis of target compounds and qualitative analysis of unknown compounds, this study aimed to find out the key compounds caused estrogenic activity in East River of south China. Our results showed higher EEQ for surface water in the dry season than in the wet season. Simple risks assessment suggested that higher estrogenic risks would be expected in the Shima River and Danshui River receiving discharge of effluents from cities in the region than Xizhijiang and Dongjiang River. Fractionation and effect-directed analysis showed that estrogenic activity mainly occurred in polar and moderately polar fractions. The seven target estrogenic compounds(bisphenol A, 4-nonylphenol, 4-tert-octylphenol, 17α-ethynyl estradiol, estrone, diethylstilbestrol and 17β-estradiol) only accounted for part of the measured estrogenic activity, with the rest contributions from other potential estrogenic chemicals such as the derivatives of naphthalenol, indol, benzaldehyde, acetophenone, benzopyran, benzodiazepine and pyrazole as well as phthalic acid esters and phenols. The findings from this study suggest that fish in the river could be affected by those estrogenic chemicals detected in water. Proper measures should be taken to reduce the estrogenic activity in the riverine system to protect aquatic organisms.(3) Followed by optimized the existing SOS/umu test method and the purification of the bacteria, we rebuilt the appropriate method and standard curve as well as the dose relation curves of the samples. By using IR values and toxicity equivalent concentration these two representation modes, we analyzed the direct genetic toxicity of surface water and sediment samples in East River during two seasons. The results of IR value showed that the detection rate of water environment was 3.6% in the overall(only one site), most of the sites were at about 1.0. However, higher detection rate was observed in sediments(15%) than surface water. The detection rate of sediment in wet season(25%) was five times higher than in dry season, with the highest IR value was both located in S9(Guanlan town). In addition, equivalent concentration analysis also confirmed other weaker sites besides the above detection results, and the concentration of genetic toxical activity ranged from ND to 0.55 ng/L 4-nitroquinoline-N-oxide equivalents(NEQ) in surface water and from ND to 0.84 ng NEQ/g in sediment. Research further suggested that genetic toxicity may easy to be detected around the chemical industries and untreated water and sediment, which lead to the conclusion that enough attention and protective measures should be paid in a timely manner. |
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