Spatial Distribution of CO2, CH4, and N2O in the Great Barrier Reef Revealed Through High Resolution Sampling and Isotopic Analysis

• Methane (CH4) and nitrous oxide (N2O) dynamics in coastal coral reef areas are poorly understood. We measured dissolved carbon dioxide (CO2) and CH4 (with delta C-13-CO2 and delta C-13-CH4 isotope fractions) and N2O in the Great Barrier Reef (GBR) to determine spatial distributions and emissions. CO2 (379-589 mu atm) was oversaturated due to calcification and riverine sources, as indicated by depleted delta C-13-CO2 values. CH4 (1.5-13.5 nM) was also oversaturated from nearshore biogenic sources indicated by depleted delta C-13-CH4 and probable offshore aerobic production. N2O (5.5-6.6 nM) was generally undersaturated, with uptake highest near the coast. Daily CO2 emissions were 5826 +/- 1191 tonnes, with CO2 equivalent ((eq)) N2O uptake (191 +/- 44 tonnes) offsetting 3.3% of CO2 or 89% of CH4eq (214 +/- 45 tonnes) emissions based on 20-year global warming potentials. The GBR was a slight CO2 and CH4 source and N2O sink during our study. However, further work is required to constrain diurnal, seasonal, and spatial dynamics.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Geofysik (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Geophysics (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Geologi (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Geology (hsv//eng)

Nyckelord

carbon dioxide

methane

nitrous oxide

greenhouse gas

coral reef

continental shelf

nitrous-oxide emissions

submarine groundwater discharge

ring-down

spectroscopy

brisbane river estuary

carbon-dioxide

oxygen dynamics

methane budget

coastal zone

fresh-water

denitrification

Geology

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)