Using Equivalent Standard Pollution method to evaluate impacts of agricultural non-point pollution resources on water environment in Shandong Province

A comprehensive evaluation of impacts of different pollution resources on water environment is a prerequisite for controlling total amount of pollutants. This forms an important basis for prevention of agricultural non-point source pollution. The amount of total nitrogen and phosphorus loss from agricultural sources (chemical fertilizer, livestock and poultry manure, and live sewage), equivalent standard pollution loads (ESPL) and equivalent standard pollution indices (ESPI) of 17 cities in Shandong Province were calculated in this study. The results show that chemical fertilizer and livestock and poultry manure are the biggest sources of total nitrogen and phosphorus, respectively. Livestock and poultry manure, chemical fertilizer and live sewage account for 49.3%, 42.6% and 8.1% of the total nutrients loss respectively. Total ESPL of nitrogen is slightly higher than total ESPL of phosphorus in Shandong Province. Of the investigated cities, Weifang has the highest ESPLs of chemical fertilizer, livestock and poultry manure, as well as nitrogen and phosphorus. Linyi exhibits the highest ESPL of live sewage. Livestock and poultry manure has the strongest impact on water environment in Shandong Province. ESPL ratio for live sewage, chemical fertilizer and livestock and poultry manure is 1∶4∶7. Based on comprehensive ESPL effect and water resources, Dezhou has the highest ESPI and potential threat to water environment in Shandong Province. This is followed by Liaocheng, Heze, Binzhou, and Tai’an. In order to reduce water pollution, it is important to implement different prevention and control strategies based on key pollution sources in different regions.