Nitrous oxide emissions from Chinese aquaculture since the Reform and Opening-up: An inventory-based estimate

Abstract:

China became the largest producer of global aquaculture since 1990. The nitrous oxide (N₂O) emission from Chinese aquaculture production has raised increasing concern amid the challenges from environment and resources. In this paper, we quantify N₂O emission from Chinese aquaculture systems in the past four decades (1979-2018) at species-, provincial-, and national-level using annual aquaculture production data from China Fishery Statistics Yearbook. Our calculation is based on an empirical analysis in which considered nitrogen in feed types and amounts, feed conversion ratio, and emission factors. We found that decadal changes in N₂O emissions from Chinese aquaculture were divergent in freshwater and marine aquaculture despite both exhibited a rapid emission increase from the 1980s to the 2010s. Freshwater fish dominated the total increase of aquaculture N₂O emission rising from 1.78 to 20.0 Gg N yr^-1. This increase was mostly from the two provinces (Guangdong and Hubei) with freshwater fish farming. Our estimates are vital to guide Chinese government to implement an effective management practice to mitigate future aquaculture N₂O emissions while meeting the global growing demand for fishery products.