| Autor: |
Chan CN; Department of Biological Sciences, University of Lethbridge, Lethbridge, Alberta T1K 3M4, Canada., Gushulak CAC; Department of Biology, University of Regina, Regina, Saskatchewan S4S 0A2, Canada.; Institute of Environmental Change and Society, University of Regina, Regina, Saskatchewan S4S 0A2, Canada., Leavitt PR; Department of Biology, University of Regina, Regina, Saskatchewan S4S 0A2, Canada.; Institute of Environmental Change and Society, University of Regina, Regina, Saskatchewan S4S 0A2, Canada., Logozzo LA; Department of Biological Sciences, University of Lethbridge, Lethbridge, Alberta T1K 3M4, Canada., Finlay K; Department of Biology, University of Regina, Regina, Saskatchewan S4S 0A2, Canada.; Institute of Environmental Change and Society, University of Regina, Regina, Saskatchewan S4S 0A2, Canada., Bogard MJ; Department of Biological Sciences, University of Lethbridge, Lethbridge, Alberta T1K 3M4, Canada. |
| Abstrakt: |
Despite decades of research and management efforts, eutrophication remains a persistent threat to inland waters. As nutrient pollution intensifies in the coming decades, the implications for aquatic greenhouse gas (GHG) emissions are poorly defined, particularly the responses of individual GHGs: carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O). The biogeochemical controls of each gas can differ, making it difficult to predict the overall effect of nutrient pollution on the net radiative forcing of aquatic ecosystems. Here, we induced eutrophication of small nitrogen (N)-limited agricultural reservoirs and measured changes in diffusive GHG emissions within a before-after-control-impact (BACI) study design during June to September 2021. Each gas exhibited a unique response to 300% increases in primary production, with a shift from an overall CO 2 source to a sink, a modest increase in N 2 O flux, and, unexpectedly, no significant change in CH 4 emissions. The lack of net directional change in CO 2 -equivalent GHG emissions in fertilized reservoirs during the summer contrasts findings from empirical studies of eutrophic lakes. Our findings illustrate the difficulty in extrapolating among different sized ecosystems and suggest that forecast 2-fold increases in agricultural N fertilization by 2050 may not result in consistently elevated GHG emissions during summer, at least from small reservoirs in continental grassland regions. |
