COMPARATIVE RESEARCH ON PHYSICOHEMICAL FACTORS BETWEEN XIANGXI BAY AND THE FRONT REGION OF THREE GORGES RESERVOIR

Based on the routine monitoring in Xiangxi Bay after the initial impounding in Three Gorges Reservoir in June, 2003,the physicochemical indices and the dynamics were analyzed and compared with the data of the front region of Three GorgesReservoir.The results indicated that the concentrations of TN, NO3-N in Xiangxi Bay were lower than those in the reservoir significantly.The biyearly averages of TN, NO3-N were 1.29mg/L, 0.88mg/L in Xiangxi Bay and 1.62mg/L, 1.22mg/L in thefront reservoir.However, PO4-Pwas higher in Xiangxi Bay than in the front reservoir, and monthly averages of TP/PO4-P in thefront reservoir were significantly higher than those in Xinagxi Bay during July to September.The results also showed that therewere heavy soil erosion in the reservoir, while soil and water were kept better in Xiangxi Bay.Based on the evaluation of thetrophic state indices (TSIM), Three Gorges Reservoir was middle eutrophical (TSIM >37), and Xiangxi Bay was eutrophical(TSIM >53)due to high phosphorus and nitrogenous pollution.