Seasonal variability in carbonate chemistry and air-sea CO2 fluxes in the southern Great Barrier Reef

Shaw, Emily C. and McNeil, Ben I. (2014) Seasonal variability in carbonate chemistry and air-sea CO2 fluxes in the southern Great Barrier Reef. Marine Chemistry, 158 49-58. doi:10.1016/j.marchem.2013.11.007


 
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Author Shaw, Emily C.
McNeil, Ben I.
Title Seasonal variability in carbonate chemistry and air-sea CO2 fluxes in the southern Great Barrier Reef
Formatted title
Seasonal variability in carbonate chemistry and air-sea CO2 fluxes in the southern Great Barrier Reef
Journal name Marine Chemistry   Check publisher's open access policy
ISSN 0304-4203
1872-7581
Publication date 2014-01
Year available 2013
Sub-type Article (original research)
DOI 10.1016/j.marchem.2013.11.007
Open Access Status
Volume 158
Start page 49
End page 58
Total pages 10
Place of publication Amsterdam, Netherlands
Publisher Elsevier
Collection year 2014
Language eng
Formatted abstract
There is presently little known about temporal variability in CO2 and carbonate chemistry (pH and aragonite saturation state (Ωarag)) in the Great Barrier Reef (GBR) region. In this study we investigated both the seasonal variability of the carbonate system and the air-sea CO2 fluxes in waters offshore of Lady Elliot Island, southern GBR, between the austral spring of 2009 and winter 2010. During winter, the partial pressure of CO2 (pCO2) was found to be the lowest (343 μatm), rising by 61 μatm to nearly 404 μatm during summer. Much of the variance in pCO2 and pH could be described by sea surface temperature (SST) and its thermodynamic effect on CO2. Despite the relatively large seasonal pCO2 signal (~60 μatm), we found little seasonal variability in Ωarag, which maintained a level of 3.6 throughout the seasons. Seasonal changes in dissolved inorganic carbon (DIC) and total alkalinity (TA), were found to offset each other during the seasons, thereby resulting in little seasonal variability to Ωarag. These results suggest that within southern GBR waters, future ocean acidification changes can be accurately predicted using various high-CO2 future scenarios without the need to account for seasonal variability that has been found to modulate the timing or onset of future oceanic acidification elsewhere in the ocean. For CO2, we found these waters to be up to 50 μatm lower than the atmosphere for nine months of the year, implying an annual CO2 sink. Using the robust relationship between SST and pCO2, we calculate the region to be a weak sink for CO2 (flux of -665mmolCm-2y-1). If we extrapolate our results to the wider southern GBR south of 20°S, it would imply a net CO2 sink of ~1TgCy-1.
Keyword Air-sea CO2 flux
Carbonate chemistry
Great Barrier Reef
Ocean acidification
Seasonal variability
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Geography, Planning and Environmental Management Publications
Official 2014 Collection
 
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Citation counts: TR Web of Science Citation Count  Cited 6 times in Thomson Reuters Web of Science Article | Citations
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