Effect of pump-gateway engineering on water quality of Bailianjing River.

The investigation on water quality of Bailianjing reach in Shanghai was carried out from April 2007 to April 2009.One cross-section at South Ferry of Huangpu River and three cross-sections at Bailianjing River were chosen and the survey covered both the spring and neap tides throughout the years.The damming of pump-gateway engineering on Bailianjing River was started in October 2007.Five water quality parameters which were dissolved oxygen(DO),biochemical oxygen demand(BOD5),permanganate index(CODMn),total nitrogen(TN) and total phosphorous(TP),were used to calculate the standard category index of 4 cross-sections.The results showed that the most important pollutants were TN and TP.Weight coefficients of TN in excess of 40% or even 50%,were over V grade and didn't meet the corresponding water quality standard.Weight coefficients of TP were more than 10% or even 30%,and TP content was 0.8~5.6 times as high as National Grade IV.In general,water quality of three sites at Bailianjing River was inferior to that of Huangpu River,but the pre-construction water quality was better than building sluiced.Before pump-gateway was constructed,the proportion of IV grade water in Bailianjing River during spring tide period was 29%,21% above that during neap tide period(8%).After pump-gateway engineering started,the percentage of the water grade worse than V during spring and neap tide periods was 87% and 88%,showing that tides did not have any noticeable effect on Bailianjing River.