`Hot spot' v `hot moment' regulation of catchment-scale aquatic greenhouse gas (CO2, CH4, N2O) emissions
Abstract
The d iscrete reactive zones and events that regulate carbon and nitrogen fluxes from land to sea also l ikely regulate aquatic carbon (CO2 , CH4 ) and nitrogen (N2 O) greenhouse gas emissions . But while increasing attention is paid to small inland waterways a s greenhouse gas emission `hot spots', quantifying emissions due to stochastic `hot moments' remains challenging. Here we aimed to redress this gap by combining empirical dissolved N2 O, CO2 , and CH4 measurements, spatial mapping, and hydrodynamic modelling to assess total emissions from across a lowland aquatic landscape. S ites included farm drains, ponds, creeks, rivers, and the receiving coastal waters across the Peel-Harvey catchment in Western Australia. T he estuary accounted for 87% of the catchment's aquatic surface area, but only 30% of emissions. In contrast, small farm drains ( <1% of the aquatic surface area ) produced 20% of emissions. However, a winter storm, when high winds ( ~100 km h -1 ) increased estuary greenhouse gas emissions 40 x, inverted this balance . Increase d emissions w ere due to physical factors: wind-generated turbulence increase d g as transfer velocities and enhanced porewater flushing ( CH4 concentrations increas ed from 2 μ M to 30 μ M during the highest wind period ) . This suggests a split between production-driven hot spots and emission-driven hot moments. Greenhouse gas emissions from aquatic networks will thus depend o n both drainage system management and future storm frequency and intensity.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMB018.0016W
- Keywords:
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- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0458 Limnology;
- BIOGEOSCIENCES;
- 0495 Water/energy interactions;
- BIOGEOSCIENCES