Projections of NH 3 emissions from manure generated by livestock production in China to 2030 under six mitigation scenarios.

China's rapid urbanization, large population, and increasing consumption of calorie-and meat-intensive diets, have resulted in China becoming the world's largest source of ammonia (NH ₃ ) emissions from livestock production. This is the first study to use provincial, condition-specific emission factors based on most recently available studies on Chinese manure management and environmental conditions. The estimated NH ₃ emission temporal trends and spatial patterns are interpreted in relation to government policies affecting livestock production. Scenario analysis is used to project emissions and estimate mitigation potential of NH ₃ emissions, to year 2030. We produce a 1km×1km gridded NH ₃ emission inventory for 2008 based on county-level activity data, which can help identify locations of highest NH ₃ emissions. The total NH ₃ emissions from manure generated by livestock production in 2008 were 7.3TgNH ₃ ·yr ^-1 (interquartile range from 6.1 to 8.6TgNH ₃ ·yr ^-1 ), and the major sources were poultry (29.9%), pigs (28.4%), other cattle (27.9%), and dairy cattle (7.0%), while sheep and goats (3.6%), donkeys (1.3%), horses (1.2%), and mules (0.7%) had smaller contributions. From 1978 to 2008, annual NH ₃ emissions fluctuated with two peaks (1996 and 2006), and total emissions increased from 2.2 to 7.3Tg·yr ^-1 increasing on average 4.4%·yr ^-1 . Under a business-as-usual (BAU) scenario, NH ₃ emissions in 2030 are expected to be 13.9TgNH ₃ ·yr ^-1 (11.5-16.3TgNH ₃ ·yr ^-1 ). Under mitigation scenarios, the projected emissions could be reduced by 18.9-37.3% compared to 2030 BAU emissions. This study improves our understanding of NH ₃ emissions from livestock production, which is needed to guide stakeholders and policymakers to make well informed mitigation decisions for NH ₃ emissions from livestock production at the country and regional levels.
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