February 1st to 5th 2016
Olhão, Portugal
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Average pH variations in the Mediterranean Sea surface waters

Scientific Exhibition
Future Oceans
Wednesday, February 3, 2016 -
18:30 to 20:00

Gemayel, E. 1 Hassoun, A.E.R. 2 Goyet, C. 3 Abboud-Abi Saab, M. 4

1National Council for Scientific Research, National Center for Marines Sciences, P.O Box 534, Batroun, Lebanon
2National Council for Scientific Research, National Center for Marines Sciences, P.O Box 534, Batroun, Lebanon
3Université de Perpignan Via Domitia, IMAGES_ESPACE-DEV, 52 avenue Paul Alduy, 66860 Perpignan Cedex 9, France
4National Council for Scientific Research, National Center for Marines Sciences, P.O Box 534, Batroun, Lebanon

This study presents an estimate of the pH variations over a 7 years average (2005-2012) in the Mediterranean Sea surface waters. Using the CO2calc software, the pH was calculated at the seawater scale by choosing as input parameters the total alkalinity (AT), total dissolved inorganic carbon (CT), temperature, salinity, pressure and the relevant dissociation constants. The average fields of AT and CT were previously presented by Gemayel et al. (2015). The mapped fields at 1/4*1/4 degree resolution, show that the pH at in situ temperature (pHT) ranged from a minimum of 8.007 in the Levantine sub-basin, to a maximum of 8.098 in the Ligurian sub-basin. Moreover there was a general decreasing North-South gradient in surface pHT variations. In fact, all the water masses that are located south of the Balearic sub-basin and the Aegean Sea (at around 36ºN latitude), have a pHT lower than 8.06. With decreasing latitude, the pHT reaches its minimum around the coasts of Libya and Egypt. Low pHT values coincided with high AT and CT concentrations and vice-versa. This shows the effect of high carbon penetration on lowering the pHT in surface waters. Hence this study provides an estimate of current pHT variations in the Mediterranean Sea and could be useful in forecasts analyses and models validation.

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