Source_data.xlsx

Aquaculture systems are expected to act as potential hotspots for nitrous oxide (N₂O) emissions, largely attributed to substantial nutrient loading from aquafeed applications. However, the specific dynamics and contributions of N₂O fluxes from these systems to the global emissions inventory are not well characterized due to limited data. This study delves into the N₂O flux patterns across 127 freshwater systems to elucidate the role of aquaculture ponds and lakes/reservoirs in the N₂O emission landscape. Our findings reveal that the average N₂O flux from aquaculture ponds, at 28.73 μg N₂O m^‒2 h^‒1, is markedly elevated compared to that from lakes/reservoirs, which average 15.65 μg N₂O m^‒2 h^‒1. This translates to an increase of 3.63 and 3.05 times, respectively, over their non-aquaculture counterparts. Smaller aquaculture ponds, in particular, stand out as significant N₂O emission hotspots, disproportionately emitting higher N₂O fluxes relative to their area, a result of both elevated nutrient concentrations and more vigorous biogeochemical cycles. By integrating data from 40 published literature with our field measurements, we estimated China's freshwater aquaculture contributes 9,562 ± 3,061 Mg N₂O per year (an increase of 35% from 2003 to 2022), equivalent to 25.2% of total N₂O emissions from China’s inland water. After subtracting background emissions from natural water bodies, the net N₂O emissions arising from aquaculture in China freshwater reach as high as 7,589 ± 2,409 Mg N₂O per year, highlighting the significant impact of in situ aquaculture as a hotspot for freshwater N₂O fluxes. In the context of the rapid global expansion of freshwater aquaculture, our findings underscore the critical need to factor in aquaculture's contribution to global N₂O emissions from inland water bodies and its implications for achieving a low-carbon future.