Experimental Ecosystem Eutrophication Causes Offsetting Effects on Emissions of CO2, CH4, and N2O from Agricultural Reservoirs

• DOI: 10.1021/acs.est.3c07520
• Publication Date: 2024-04-08T15:55:20Z
• Authors: Chun Ngai Chan; Cale A. C. Gushulak; Peter R. Leavitt; Laura A. Logozzo; Kerri Finlay; Matthew J. Bogard
• Keywords: Biogeochemical Cycle; Nitrous oxide; Nutrient pollution

Despite decades of research and management efforts, eutrophication remains a persistent threat to inland waters. As nutrient pollution intensifies in the coming decades, implications for aquatic greenhouse gas (GHG) emissions are poorly defined, particularly responses individual GHGs: carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O). The biogeochemical controls each can differ, making it difficult predict overall effect on net radiative forcing ecosystems. Here, we induced small nitrogen (N)-limited agricultural reservoirs measured changes diffusive GHG within before-after-control-impact (BACI) study design during June September 2021. Each exhibited unique response 300% increases primary production, with shift from an CO2 source sink, modest increase N2O flux, and, unexpectedly, no significant change CH4 emissions. lack directional CO2-equivalent fertilized summer contrasts findings empirical studies eutrophic lakes. Our illustrate difficulty extrapolating among different sized ecosystems suggest that forecast 2-fold N fertilization by 2050 may not result consistently elevated summer, at least continental grassland regions.