Pollution loads variation of agricultural source in upstream of Huairou Reservoir

Abstract: Increased nutrient (i.e., nitrogen and phosphorus) concentrations have been observed in the surface water bodies inmany counties. Agricultural non-point source (NPS) pollution has been identified as one of the most important factors in causing water quality deterioration. To control NPS pollution effectively, it is necessary to quantifying agricultural pollution loads and understanding contribution of the pollution sources. Furthermore, watershed-based analysis can provide scientific basis for agricultural practices and water pollution control. In this paper, the general export coefficient model was used to estimate the loads of total nitrogen (TN) and total phosphorus (TP) from the upper Lianghuai basin of Huairou Reservoir for year 2000 and 2011. The model results showed that the total nitrogen and total phosphorus loads in 2000 were mainly contributed from the farmland planting, livestock and poultry breeding., while aquatic agriculture mainly contributed the total nitrogen and total phosphorus loads in 2011. Agricultural nitrogen and phosphorus loads increased in the study area during two year period. The nitrogen load increased from 454.029 ton in 2000 to 485.961 ton in 2011, while phosphorus load increased from 51.014 ton in 2000 to 58.437 ton in 2011. The nitrogen and phosphorus loads from aquatic agriculture took account of the largest percentage among the agricultural pollution sources. The agricultural land use and industrial structure changes caused nitrogen and phosphorus loads changed from 2000 to 2011 in the study basin. In the future, the corresponding control measures are recommended according to different pollution sources in order to reducing their pollution discharges. Moreover, recycling economy pattern is encouraged to achieve the resource utilization and reuse of planting, breeding and rural life waste.