pCO2 variability in the surface waters of the ultra-oligotrophic Levantine Sea: Exploring the air–sea CO2 fluxes in a fast warming region

Guy Sisma-Ventura, Or M. Bialik, Ruth Yam, Barak Herut, Jacob Silverman

Research output: Contribution to journalArticlepeer-review

Abstract

Seasonal pCO2 variability was studied in the Southeast Levantine (SE-Levantine) during 2009–2015 with the aim of quantifying air–sea CO2 fluxes in this ultra-oligotrophic, warm and highly evaporative marginal sea. Mixed layer pCO2 varied significantly between 560 ± 9.0 μatm in August (summer) and 350 ± 8.7 μatm in March (winter). Comparison of pCO2 to Sea Surface Temperature (SST) yielded a strong positive correlation (n = 135, r2 = 0.94), suggesting that the seasonal variations are the result of a thermodynamic effect on the carbonate system in seawater. Using the coupling between pCO2 and SST, we calculated the mean monthly values and the air-sea fluxes in this region. These calculations indicated that this region is a net source of CO2 to the atmosphere over an annual cycle, with an average flux of 845 ± 270 mmol C m2 y− 1 (~ 0.98 Tg C y− 1). Flux estimation for three other sub-basins of the East Mediterranean (South of Crete) with similar oceanographic conditions, were calculated from mean seasonal SST and wind data (MEDATLAS). The results suggest that these regions may either be a weak source or sink for atmospheric CO2. However, considering the relatively rapid warming trends (~+1 °C/decade) observed in the Levantine basin and the anticipated thermodynamic effect on pCO2 levels in seawater, these sub basins could become more pronounced sources for atmospheric CO2. Thus, with the fast warming and increased stratification of its surface water the CO2 source of the Eastern Mediterranean is expected to expend spatially.

Original languageEnglish
Pages (from-to)13-23
Number of pages11
JournalMarine Chemistry
Volume196
DOIs
StatePublished - 20 Nov 2017
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2017 Elsevier B.V.

Keywords

  • Air–sea CO flux
  • Mediterranean Sea
  • Recent warming
  • Southeast Levantine
  • Ultra-oligotrophic

ASJC Scopus subject areas

  • Oceanography
  • Chemistry (all)
  • Environmental Chemistry
  • Water Science and Technology

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