Temporal and spatial evolution of nitrous oxide emissions in China: Assessment, strategy and recommendation

Comprehensive assessments and mitigation potential of nitrous oxide (N2O) emissions are particularly important, especially in China. We report that the total N2O emissions in China increased by 140% from 1978 to 2015, with croplands being the major emitters accounting for 35-48% of the emissions. Over the last 15 years, N2O emissions from industry, aquaculture and waste management have grown rapidly, while those from cropland, livestock, grassland, and human consumption have grown slowly. The spatial differences in China make the assessments of N2O emission patterns complex. Compared with other greenhouse gas emissions (including carbon dioxide, methane, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride) reported by the World Bank, we found that N2O emissions contributed approximately 9-20% (carbon dioxide equivalent) of the major greenhouse gas emissions from 1978 to 2012 in China. The growth rate of N2O emissions in China was 1.8 times greater than that throughout the world between 1978 and 2012. Additionally, we assessed the mitigation potential for various measures from the perspectives of production and consumption. The results show that knowledge-based nitrogen management (including the application of controlled-release nitrogen fertilizer, nitrification inhibitor and urease inhibitor, and optimal nitrogen fertilizer rate based on soil nitrogen tests), large farm sizes, flue gas denitration and healthy diet habits are effective strategies to cope with the continued growth of N2O emissions. The results of these quantitative scenario simulations are critical for the formulation and implementation of corresponding policy measures. (C)2019 Published by Elsevier Ltd.