Abstract:

Hongfeng Lake is one of the great lakes in Yunnan and Guizhou provinces，and the water pollution caused by agriculture production is a serious problem in environment conservation of Guiyang city.Monitoring studies about rainfall,runoff,TN,TP and CODcr were continuously conducted in a typical agricultural watershed,Dachong in the upper reach of Hongfeng Lake,to reveal the characteristics of nonpoint source pollutants during 2010.The concentration of these nonpoint source pollutants and output amount to water system of the watershed was also tested.The results showed that concentration of TN and CODcr in runoff water were much higher than national standard.Total of runoff,TN,TP,and CODcr in 2010 were 414×105 m3,2 546.7 kg,856 kg,and 10 883.2 kg，and outputs of TN,TP and CODcr from the Dachong watershed to lake were 577,019 and 1451 kg/(km2·d).Concentrations of TN,TP and CODcr in surface runoff from Jun.to Sep.were much higher than those in other months,and their quantity flowing to Hongfeng Lake during the five months in the summer took about 948%,733% and 943% of their total.The pollutants TN,TP,CODcr generated from cultivation land on slope,forests and young stand took 1338,1329 and 1354% of total in the watershed.Concentration of TN,TP,CODcr in surface runoff in rice land and vegetable land respectively ranged from 084~1032,007~018,2050~6800 mg/L and 216~754,001~004,450~2240 mg/L.TN,TP and CODcr in living sewage even got up to 1384~5011,320~510 and 357~2070 mg/L,and those in the sewage from the area livestock lived got up to 4510~7262,450~1850 and 2200~8500 mg/L.The pollution load in surface runoff at the outlet of the watershed was significantly correlated with runoff volume of watershed