Net source or sink? Direct air-sea flux measurements of greenhouse gases and volatile organic carbon on the coast
Abstract
The coastal seas, connecting land with the open ocean, are regions of intensive trace gas cycling. Influenced by riverine input and other terrestrial run offs, coastal seas can be significant sources of greenhouse gases (GHGs) to the atmosphere. Many gaseous volatile organic carbon (VOC) compounds are emitted from terrestrial biogenic and anthropogenic sources into the air, and these gases may be absorbed by the coastal seas during periods of offshore wind flow. Due to the heterogeneity of the coastal environment, the multitude of emission sources, and the large variability in physical forcing, the directions (let alone magnitudes) of the air-sea fluxes of many trace gases are poorly known. Here we describe a year-long dataset of air-sea methane and carbon dioxide fluxes, as well as a month-long dataset of VOC fluxes. These fluxes were measured directly with the eddy covariance technique at the coastal Penlee Point Atmospheric Observatory in the Southwest UK. The GHG fluxes show large seasonal variability and some diurnal/semi-diurnal variability. VOC fluxes were largely from air to water, except for dimethyl sulfide which originates from marine biota. Concurrent dissolved concentration measurements of these gases in the nearby coastal seas allow us to assess their spatial heterogeneity and also derive their gas transfer velocities.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMB023...02Y
- Keywords:
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- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0458 Limnology;
- BIOGEOSCIENCES;
- 0495 Water/energy interactions;
- BIOGEOSCIENCES