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

Michael J. Reading, Damien T. Maher, Isaac R. Santos, Luke C. Jeffrey, Tyler J. Cyronak, Ashly McMahon, Douglas R. Tait

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Methane (CH4) and nitrous oxide (N2O) dynamics in coastal coral reef areas are poorly understood. We measured dissolved carbon dioxide (CO2) and CH4 (with δ13C-CO2 and δ13C-CH4 isotope fractions) and N2O in the Great Barrier Reef (GBR) to determine spatial distributions and emissions. CO2 (379–589 μatm) was oversaturated due to calcification and riverine sources, as indicated by depleted δ13C-CO2 values. CH4 (1.5–13.5 nM) was also oversaturated from nearshore biogenic sources indicated by depleted δ13C-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.

Original languageEnglish
Article numbere2021GL092534
JournalGeophysical Research Letters
Volume48
Issue number15
DOIs
StatePublished - Aug 16 2021

Scopus Subject Areas

  • Geophysics
  • General Earth and Planetary Sciences

Keywords

  • carbon dioxide
  • continental shelf
  • coral reef
  • greenhouse gas
  • methane
  • nitrous oxide

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