State Key Laboratory of Soil and Sustainable Agriculture, Changshu National Agro-Ecosystem Observation and Research Station, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China; University of Chinese Academy of Sciences, Beijing, 100049, China; University of Chinese Academy of Sciences, Nanjing, 211135, China.
College of Resources and Environment, Hunan Agricultural University, Changsha, 410128, China.
J Environ Manage. 2024 Jul;364:121472. doi: 10.1016/j.jenvman.2024.121472. Epub 2024 Jun 15.
Aquaculture systems are expected to act as potential hotspots for nitrous oxide (NO) emissions, largely attributed to substantial nutrient loading from aquafeed applications. However, the specific patterns and contributions of NO fluxes from these systems to the global emissions inventory are not well characterized due to limited data. This study investigates the patterns of NO flux across 127 freshwater systems in China to elucidate the role of aquaculture ponds and lakes/reservoirs in landscape NO emission. Our findings show that the average NO flux from aquaculture ponds was 3.63 times higher (28.73 μg NO m h) than that from non-aquaculture ponds. Additionally, the average NO flux from aquaculture lakes/reservoirs (15.65 μg NO m h) increased 3.05 times compared to non-aquaculture lakes/reservoirs. The transition from non-aquaculture to aquaculture practices has resulted in a net annual increase of 7589 ± 2409 Mg NO emissions in China's freshwater systems from 2003 to 2022, equivalent to 20% of total NO emissions from China's inland water. Particularly, the robust negative regression relationship between NO emission intensity and water area suggests that small ponds are hotspots of NO emissions, a result of both elevated nutrient concentrations and more vigorous biogeochemical cycles. This indicates that NO emissions from smaller aquaculture ponds are larger per unit area compared to equivalent larger water bodies. Our findings highlight that NO emissions from aquaculture systems can not be proxied by those from natural water bodies, especially small water bodies exhibiting significant but largely unquantified NO emissions. In the context of the rapid global expansion of aquaculture, this underscores the critical need to integrate aquaculture into global assessments of inland water NO emissions to advance towards a low-carbon future.
水产养殖系统预计将成为氧化亚氮（NO）排放的潜在热点，这主要归因于水产养殖中大量使用饲料所带来的大量养分负荷。然而，由于数据有限，这些系统中 NO 通量对全球排放清单的具体模式和贡献仍未得到很好的描述。本研究调查了中国 127 个淡水系统中 NO 通量的模式，以阐明水产养殖池塘和湖泊/水库在景观 NO 排放中的作用。我们的研究结果表明，水产养殖池塘的平均 NO 通量（28.73μg NO m h）比非水产养殖池塘高 3.63 倍。此外，水产养殖湖泊/水库的平均 NO 通量（15.65μg NO m h）比非水产养殖湖泊/水库增加了 3.05 倍。从非水产养殖到水产养殖的转变，导致 2003 年至 2022 年中国淡水系统中每年净增加 7589±2409 Mg NO 排放量，相当于中国内陆水域总 NO 排放量的 20%。特别是，NO 排放强度与水域面积之间的强负回归关系表明，小池塘是 NO 排放的热点，这是由于营养浓度升高和更活跃的生物地球化学循环所致。这表明，与同等大的水体相比，较小的水产养殖池塘每单位面积的 NO 排放量更大。我们的研究结果表明，水产养殖系统的 NO 排放不能用自然水体的排放来替代，特别是那些表现出显著但在很大程度上未量化的 NO 排放的小水体。在全球水产养殖快速扩张的背景下，这突显了将水产养殖纳入内陆水 NO 排放的全球评估以迈向低碳未来的迫切需要。
