Based on the routine monitoring in the front region of Three Gorges reservoir from 2002 to 2004, the physicochemical indices were analyzed, and the significant tests for the investigated data before and after the initial impounding were carried out. The results indicated that the major physicochemical indices were not significant differences spatially, but mainly vary with time. Some indices were significantly different before and after impounding. Among them, the annual averages of TN, TP reduced from 2.38mg/L, 0.274mg/L before impounding to 1.62mg/L, 0.132mg/L after impounding respectively. Among inorganic nitrogens, NO3-N was as high as 91.25%, while NO2-N was only 1.05%, indicating that the Three Gorges Reservoir has great self-purification capacity.The results also showed that monthly averages of transparency and turbidity changed great, the two indices were negatively related, and transparency decreased and turbidity increased significantly during July to September, which implied that there were heavy soil erosion during rainfall seasons in this area. Meanwhile, TP also increased significantly along with turbidity increase, indicating that phosphorus pollution is heavy in the soil erosion area. However, since PO4-P deceased at the same time, it also indicated that this phosphorus pollution could not be effectively changed to PO4-P.Based on the evaluation of the trophic state indices, the front region of the Three-Gorges reservoir was still middle eutrophical due to huge pollution basis (TSIm > 37), although the water pollution reduced much after the impounding.At last, we compared the major physicochemical indices with those of other large local reservoirs, the results showed that concentrations of TP, NO3-N in the studying area were much greater.
Cao Ming (email@example.com) ; Cai Qing-Hua (firstname.lastname@example.org) ; Liu Rui-Qiu; Qu Xiao-Dong; Ye Lin.Comparative research on physicochemical factors in the front of three gorges reservoir before and after the initiate impounding,Acta Hydrobiologica Sinica,2006,30(1):41262