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.