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Spatial Distribution of CO 2 , CH 4 , and N 2 O in the Great Barrier Reef Revealed Through High Resolution Sampling and Isotopic Analysis
Author(s) -
Reading Michael J.,
Maher Damien T.,
Santos Isaac R.,
Jeffrey Luke C.,
Cyronak Tyler J.,
McMahon Ashly,
Tait Douglas R.
Publication year - 2021
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2021gl092534
Subject(s) - carbon dioxide , spatial distribution , environmental science , methane , tonne , nitrous oxide , isotopes of carbon , environmental chemistry , greenhouse gas , atmospheric sciences , reef , oceanography , chemistry , total organic carbon , geology , remote sensing , organic chemistry
Methane (CH 4 ) and nitrous oxide (N 2 O) dynamics in coastal coral reef areas are poorly understood. We measured dissolved carbon dioxide (CO 2 ) and CH 4 (with δ 13 C‐CO 2 and δ 13 C‐CH 4 isotope fractions) and N 2 O in the Great Barrier Reef (GBR) to determine spatial distributions and emissions. CO 2 (379–589 μatm) was oversaturated due to calcification and riverine sources, as indicated by depleted δ 13 C‐CO 2 values. CH 4 (1.5–13.5 nM) was also oversaturated from nearshore biogenic sources indicated by depleted δ 13 C‐CH 4 and probable offshore aerobic production. N 2 O (5.5–6.6 nM) was generally undersaturated, with uptake highest near the coast. Daily CO 2 emissions were 5826 ± 1191 tonnes, with CO 2 equivalent ( eq ) N 2 O uptake (191 ± 44 tonnes) offsetting 3.3% of CO 2 or 89% of CH 4 eq (214 ± 45 tonnes) emissions based on 20‐year global warming potentials. The GBR was a slight CO 2 and CH 4 source and N 2 O sink during our study. However, further work is required to constrain diurnal, seasonal, and spatial dynamics.