Pollutant concentration variation and analysis of causes in Eight Major Outlet of Pearl Rive

According to the statistics of 20 year monitoring data of pollutant concentration in the Eight Major Outlet of the Pearl River,the annual concentration variations of DIN、PO4-P,heavy metals such as Hg,Cu,Pb and Cd,oils and COD were analyzed.The results show that the concentration of DIN and PO4-P which related to domestic sewage tends to continuously go up,but the concentration of heavy metals and oils which related to industrial waste water tends to go down and the concentration of COD which related to living and industrial pollutants shows the trend of first going up but later going down.Analyzing the pollutant date in dry,rainy and intermediate seasons,the concentrated and regulation distributions of pollutants were not found at the seasons.The causes of concentration variations of different pollutants were analyzed.