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| Ambient Severity Evaluation and Toxicity Effect of Organic Pollutants in Liuxihe Reservoir, China |
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| KeyWord:Liuxihe reservoir; organic pollutants; ambient severity evaluation; toxicological effect |
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| Abstract: |
| The risk of water resources being contaminated by organic pollutants is of major concern. The Liuxihe reservoir is one of the most important fresh water resources for Guangzhou City, supplying nearly 60% of the city′s fresh water demands. Identification and monitoring of these pollutants in the Liuxihe reservoir is of critical importance in an attempt to protect ecological and human health. In this study, semi-volatile organic compounds（SOVCs） in Liuxihe reservoir were determined by a gas chromatography method with mass spectrometric（GC-MS）detection. Ambient severity due to exposure to these organic pollutants was evaluated with multimedia environmental goals（MEG）. MEG is the environmental capacity of chemicals and limit values of emission which was calculated by environmental industry laboratory of United States Environmental Protection Agency（EPA）. The environmental goals in the MEG, include air, water and soil, and each one is divided into health goals and ecological objectives. Ambient severity（AS） is the ratio of the measured concentration of a compound with the corresponding value of MEG, which is divided into health severity（ASI） and ecology severity（ASII）. Higher values of AS mean pollutants cause more influence on water. The results indicated that total contents of 23 different SVOCs from water samples were 6.078 μg·L-1 and 24.952 μg·L-1, respectively, and benzo（a） anthracene, dibutyl phthalate and 2, 4-nitrotoluene were the main SVOCs. The total ambient severity of both health and ecology was less than 1, which indicated that water in Liuxihe reservoir was still safe to health and ecology. Routine physical and chemical analysis was not sufficient to make comprehensive evaluation of water quality, so the establishment of an effective test method to evaluate the ecotoxicity of organic compounds in water was of importance to environmental monitoring. The potential toxicity of water samples on the microalgae Scenedesmus obliquus was measured. Organic extracts from the samples were found to promote the growth of S. obliquus, which could increase the content of photosynthetic pigments, especially the content of the chlorophyll a and protein. Activities of superoxide dismutase（SOD） and peroxidase（POD） increased significantly with the content of organic pollutants, when compared with the control, which indicated that POD and SOD activities in S. obliquus was sensitive to organic extracts from the water samples. This study contributes to research on the toxicological effects of these pollutants in water and can provide references for the risk assessments on issues concerning SVOCs research. |
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