Thermal vs biological control of air-sea CO2 fluxes and pHT variability in a coastal region of the Northern Adriatic shelf from a tiem series analyses. (Abstract/Poster in convegno)

Type
Label
  • Thermal vs biological control of air-sea CO2 fluxes and pHT variability in a coastal region of the Northern Adriatic shelf from a tiem series analyses. (Abstract/Poster in convegno) (literal)
Anno
  • 2012-01-01T00:00:00+01:00 (literal)
Alternative label
  • Cantoni C., Luchetta A., Celio M:, Cozzi S., Sparnocchia S. (2012)
    Thermal vs biological control of air-sea CO2 fluxes and pHT variability in a coastal region of the Northern Adriatic shelf from a tiem series analyses.
    in EPOCA final meeting, Saint jean Cap Ferrat, Nice, France, 2-5 april 2012
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Cantoni C., Luchetta A., Celio M:, Cozzi S., Sparnocchia S. (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#url
  • http://www.epoca-project.eu (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#titoloVolume
  • EPOCA final meeting (literal)
Note
  • Poster (literal)
  • Abstract (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • ISMAR (literal)
Titolo
  • Thermal vs biological control of air-sea CO2 fluxes and pHT variability in a coastal region of the Northern Adriatic shelf from a tiem series analyses. (literal)
Abstract
  • The Gulf of Trieste (GoT) lies in the northernmost part of the Adriatic Sea and is a shallow bay (< 25 m), connected with the Adriatic on the SW side. Meteorological conditions in the region exhibit a pronounced seasonal cycle, which determines strong variations in seawater temperature, salinity and water column stratification during the year. The annual thermal stratification occurs from spring to autumn and is enhanced by the relatively high sea surface temperature and freshwater advection, by the water loads of the Isonzo river. In winter the water column is mostly homogeneous, due to surface cooling and frequent mixing induced by strong NE Bora wind events. Since January 2008 pHT, total alkalinity and the main physical and chemical parameters were acquired on monthly basis, on the water column at the site PALOMA (centre of the Gulf, 25 m depth). The data collected allowed the calculation of all the other carbonate system parameters and put in evidence the strong seasonal and vertical variability of inorganic carbon chemistry and water column biogeochemical properties (Cantoni et al. 2012). Takahashi et al. (2002) developed a simple model to estimate the effect of temperature changes on pCO2 for oceanic waters and to separate the \"thermal\" and \"non-thermal\" effect on annual pCO2 variability. We tested its applicability to the coastal waters of the GoT and we used the same conceptual approach to better analyse the seasonal variability of pHT and carbonate ion concentration (CO3=). The results showed that the annual cycle of surface pCO2 was mainly controlled by the strong seasonal variability of seawater temperature. From January to March of both years, surface seawater was undersaturated with CO2 with respect to the air and acted as a strong CO2 sink during high-wind events. From June to August, seawater temperature increase led to higher pCO2 values, however this thermodynamic effect was dampened by primary production processes that removed CO2 from the upper layer. Overall, the balance between the two processes made surface waters a weak source of CO2 to the atmosphere during this season. In deeper waters, intense remineralisation processes released CO2 that reinforced the temperature-driven pCO2 increase leading to values up to 1043 µatm during hypoxic periods. The pHT variability followed the same pattern with higher values in the upper water column during winter and lower during summer and was mostly controlled by seasonal temperature variation. However, the strong temperature cycle that is typical of the GoT does not influence all carbon chemistry parameters in the same way and the CO3= concentration was mainly controlled by variation of seawater bulk chemical composition. It showed lower values in winter, where the cold waters were enriched in CO2 and higher values in the upper water column during summer. This leaded to the apparent paradox that winter surface waters had the highest pHT values and were the least acidic considering only pHT. At the same time they were the least saturated with CO3= and, consequently, the most \"acidic\" with regard to CO3= concentrations and carbonate mineral saturation states. (literal)
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