Space-time evolution of China's agricultural ammonia emission and emission reduction potential

The causes of haze in China are more complicated than those in developed countries. Artificial ammonia (NH₃) pollution is an important factor driving the continuous increase in PM_2.5 index in China, but so widely ignored by the entire society. Existing research shows that artificial NH₃ emission come mainly from agriculture. Thus, agricultural NH₃ emission reduction is the most economic and effective method of haze governance. Therefore, research on agricultural NH₃ emission reduction potential has significant practical significance for the governance of haze in China. Based on the related data (statistical yearbook and research results), referred to as "Technical Guidelines for Preparation of Atmospheric Ammonia Emission Inventory (for Trial Implementation)", we built an analytical model of agricultural NH₃ emission reduction potential, calculated and analyzed temporal evolution of China's agricultural NH₃ emission for the period from 2004 to 2013 and the reduction potential of agricultural NH₃ emission for the period from 2020 to 2030 using emission factor method and scenario analysis. The results showed that:1) total agricultural NH₃ emission was 11.939 2 million tons in 2013, up 18.59% compared to 2004. 2) The provinces and cities where total amount of agricultural NH₃ emission was 0.6 million t·a^-1 or more in 2004 were Henan, Shandong, Hebei and Inner Mongolia provinces. By 2013, this had expanded to six provinces-Henan, Inner Mongolia, Hebei, Shandong, Xinjiang and Sichuan. 3) Under business-as-usual (BAU) scenario, China's agricultural NH₃ emissions in 2020, 2025 and 2030 increased by 15.26%, 23.60% and 30.23%, respectively, over that in 2013. 4) Under abatement scenario, China's agricultural NH₃ emissions in 2020, 2025 and 2030 reduced by 3.194 million tons, 5.013 million tons and 6.604 million tons, respectively, compared with BAU scenario, which were respectively 11.49%, 18.39%, and 25.08% lower than the 2013 levels. 5) For the future, the key to China's agricultural NH₃ emission reduction depended on the quantity and consumption structure of China's household consumption of livestock and poultry products. Next, it depended on the changes in feed nutrient levels in China's livestock and poultry farming. 6) The key potential agricultural NH₃ emission reduction provinces were Henan, Shandong, Hebei, Inner Mongolia and Sichuan. Thus for future control of China's agricultural NH₃ emissions under BAU scenario, the implementation of China's agricultural NH₃ emissions reduction must be done by vigorously cutting down emissions in key areas and accelerating the transformation of consumer behavior in livestock and poultry products.