Abstract: As an important source of nitrous oxide (N₂O), the aquaculture water has aroused extensive attention in the past decades. Here, we characterized the spatial and temporal distribution of dissolved concentrations and the emission fluxes of N₂O in the aquaculture waters in China, and summarized the factors that potentially influence N₂O production. It is shown that N₂O in the aquaculture waters is generally between saturated and supersaturated. Its emission fluxes at the water-air interface range from -9.82×10^-3 to 143.25×10^-3 mg·m^-2·h^-1, and thus is an important contribution to atmospheric N₂O. Spatially, N₂O emission fluxes in the aquaculture waters are significantly higher in South China than in North China. The emission fluxes are much higher in the aquaculture waters than in the natural waters in North China, with an opposite pattern for South China. In general, the temporal variations in N₂O emission fluxes are similar among different sites, with higher fluxes in the middle culture period and lower fluxes in the late and early culture periods. As for the seasonal variation, the N₂O emission fluxes are higher in summer than that in winter and spring. The mechanisms of N₂O production in aquaculture waters are similar to those in other aquatic ecosystems, with nitrification and denitrification being the primary processes. The main factors influencing the production and emissions of N₂O in the aquaculture waters are temperature, pH, nutrients, salinity, and chlorophyll a. In addition, human activities such as artificial aeration, feed inputs, drainage activities, and cultured species, can also affect the production and emission of N₂O.

Key words: aquaculture water, N₂O, dissolved concentration, emission flux, influencing factor.