[Estimation and allocation of water environmental capacity in nonpoint source polluted river].
Based on the investigation of the application and emission quantities (QAE) of total nitrogen (TN) and total phosphorus (TP) for nonpoint sources in river catchment' s area, included fertilizer applications, livestock and living pollutants emissions, the quantities of TN and TP entered the river were computed by means of export coefficient model in Changle River, southeast China. Self-purification capacities of TN and TP in the reach were also estimated in terms of input-output balance analysis method. According to the provisions of water function planning in the river, the water environment residual capacity (WERC) or the demand for reducing the application and emission (DRAE) of nitrogen and phosphorus in the corresponding catchment were monthly estimated, and WERC and DRAE were respectively allocated among the pollution sources. Results indicated that about 28.8% of TN loads and 51.2% of TP loads could be self-purified respectively in the reach, i. e., purification of 775.9 t a(-1) for TN and 30.9 t a(-1) for TP. Seasonal variations of the self-purification for the pollutants not only resulted from riverine hydrological and ecological conditions, but also affected by the pollution loading. According to the demand of the water quality protection in the reach, about 1581.0 t a(-1) QAE of TN had to reduce in Changle catchment. The maximum demand for the reducing QAE of TN was the fertilizer application (1047.4 t a(-1)), and the highest ratio for the reducing QAE of TN was livestock-poultry breeding (32.4%). There was about 2335.7 t a(-1) WERC for TP in the reach. The largest DRAE of nitrogen was during mid-water season and the least WERC of TP was during higher-water season.
Chen
Ding-jiang
DJ
Department of Natural Resources, College of Environmental Science and Resources, Zhejiang University, Hangzhou 310029, China. chendj@zju.edu.cn
Lü
Jun
J
Jin
Shu-quan
SQ
Shen
Ye-na
YN
D002681:China; D004784:Environmental Monitoring; D005618:Fresh Water / Q000032:analysis*; D009584:Nitrogen / Q000032:analysis*; D010758:Phosphorus / Q000032:analysis*; D045483:Rivers; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014881:Water Supply
D014874:Water Pollutants, Chemical; D010758:Phosphorus; D009584:Nitrogen