Modeling the effects of nitrogen and hydroperiod on greenhouse gas emissions in Great Lakes coastal wetlands
Abstract
Wetlands impact global warming potential by regulating the exchange of carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O). These three key greenhouse gases (hereafter GHG) contribute to the anthropogenic greenhouse effect and global warming. Few studies have investigated the interactive effects of different environmental factors, such as water residence time and nutrient inflows, on GHG emissions. Here we investigate GHG emission in Great Lakes coastal wetlands across various hydrology, temperature, and N inflow regimes using a process-based simulation model Mondrian. We found the emission of CH 4 , N 2 O and sequestration of C (i.e. negative NEE) all increased with increasing water residence time and N inflow, primarily driven by increased plant productivity and N uptake, which indicated greater C and N cycling rates. The total comprehensive global warming potential (i.e. sum GWP of CH 4 , N 2 O, and NEE) of wetlands on 20-year and 100-year time horizons were both primarily driven by CH 4 emissions. Under most conditions, the global warming potential of NEE was negative, meaning wetlands were net sinks of carbon as wetland plants assimilated atmospheric CO 2 and plant litter becomes accreted in underlying anaerobic soil. Negative GWP of NEE partially offset the GWP of measured CH 4 and made the comprehensive GWP less than the GWP of CH 4 alone. GWP of N 2 O was negligible even though N 2 O has high radiative forcing because the amount of N 2 O emitted from these simulated wetlands was very small. The comprehensive global warming potential mainly depended on how much global warming potential of CH 4 could be offset by negative global warming potential of NEE (CO 2 ). Water level scenarios also had an effect on GHG exchanges by modulating conditions between aerobic and anaerobic states. Higher temperature promoted higher global warming potential but due to the modest range of temperature increases expected by the midcentury, compared to other factors, its effects were minimal.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMB048.0014Y
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0442 Estuarine and nearshore processes;
- BIOGEOSCIENCES;
- 0469 Nitrogen cycling;
- BIOGEOSCIENCES