Estimation of non-point source pollution loads caused by soil erosion in China.

摘要

With point-source pollution generated by industries gradually coming under control, non-point source (NPS) pollution in China nowadays poses a severe threat to water quality and river basin ecosystem. Thus, it is significant to carry out integrative evaluation on NPS pollution loading from soil erosion. Pollutants nitrogen (N), phosphorus (P) and Chemical Oxygen Demand (COD) were chosen as assessment indices, and the method of export coefficient model was adopted for statistical calculation of the pollutants loading distribution across the country. The results showed that the total NPS pollution loading in 2007 achieved 2.44x1010 kg in the country, of which COD contributed the largest proportion (83.3%), followed by total N and P. There were huge differences existed on the 31 provinces, autonomous regions and municipalities. Spatial variability of pollutants loading and intensity was caused by many influencing factors including regional social economy levels, agriculture conservation practices, climate, hydrological factors and so on. Our study showed that it was much more rigorous in the west than in the east of China, especially in the northwestern Loess Plateau. This study is the first national scale evaluation of the main non-point source pollution loads, and provides some references on environmental protection and sustainable development.