Management and restoration of river ecosystem and resources

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The purpose of this cooperative study is to assess potential risk of drinking water resources in terms of trihalomethane formation potential, mutagenecity, cytotoxicity and synthetic organic chemicals such as surfactants and to develop a computer-aided system for the comprehensive management of aquatic environment and quality of water resourcesbased on water use, wastewater management, agricultural and industrial activities in the Nakdong River basin.Water quality of the Nakdong river is surveyed at 13 sampling stations. The water parameters determined in this investigation were water temperature, PH, dissolved oxygen, BOD, COD, SS, TKN, NH4-N, NO2-N, NO3-N, DT-N, PO4-P, DT-P, Chlorophyll-a. The distribution of total BOD concentration in the Nakdong river and the Kumho river were ranged 0.9 to 6.8 and 1.0 to 48.2 mg/l, respectively. The concentration of chlorophyll-a in the Nakdong river was ranged from 1.423 to 15.36 mg/ and from 3.153 to 26.507 mg/l for the Kumho river.Total concentr … More ation of LAS and ABS in Nak Dong River and Kum Ho River were found at levels varying 0.1 8 to 1.5 mg/l and those in raw water in the sewage treatment plant was found at levels varying 1.0 to 3.2 mg/l, and that of treated water was found at levels varying 1.2 to 2.7 mg/l. Concentration of LAS decreased over 70 % within 5 days, whereas concentration of TOC decreased only about 40 % after 9 days. The concentration of THM in Kachang and Nae-Dang water supply system were about 10-20 mg/l and 5 mg/l, respectively. Also carbon-tetra-chloride and chloropicrin were identified.Mutagenicity of the recovered substances was estimated by the preincubation method of Ames test with Salmonella typhimurium TA 98 or 100 strain. The substances recovered gave significant amount of revertants, and the number of revertants was dose-dependent, indicating that the water contain direct mutagenic substances. Also, the recovered substances gave significant amount of revertants in the presence of S9mix, indicating that the metabolite of recovered substances from these points should be mutagenic. A sample showed weak positive mutagenicity in the absence of S9mix but not in the presence of S9mix. The facts suggest that the sample had indirect mutagen but its activity should be very weak. Mutagenic substances in Nakdong and Kumho River should be frame-shift type.The computer-aided system could estimate pollution loads from the basin including both point and non-point sources and to predict quality of the water bodies based on the present load and expected loads after alternative management plans are implemented. The major source of pollution was night soil and gray water discharged form City of Taegu. Also paddy fields, agricultural lands and forests contributed in rural areas. Less