In order to investigate total organic carbon TOC exchange through the Strait of Gibraltar, samples were taken along two Ž. Ž. sections from the western Gulf of Cadiz and eastern Western Alboran Sea entrances of the Strait and at the middle of thé Strait in April 1998. TOC was measured by using a high-temperature catalytic oxidation method. The results referenced here are based on a three-layer model of water mass exchange through the Strait, which includes the Atlantic inflow, Mediterranean outflow and an interface layer in between. All layers were characterised by a decrease of TOC concentrations from the Gulf of Cadiz to the Western Alboran Sea: from 60-79 to 59-66 mM C in the Atlantic inflow and from 40-60 tó 38-52 mM C in the Mediterranean waters, respectively. TOC concentrations in the modified North Atlantic Central Water Ž. varied from 43 to 55 mM C. Intermediate TOC values were measured in the interface layer 43-60 mM C. TOC concentrations increased from the middle of the Strait towards continents indicating a contribution of organic carbon of photosynthetic origin along Spain and Morocco coasts or TOC accumulation due to upwelling in the northeastern part of the Strait. Our results indicate that the short-term variability caused by the tide greatly impacts the TOC distribution, particularly in the Gulf of Cadiz. The TOC input from the Atlantic Ocean to the Mediterranean Sea through the Strait of Gibraltar varieś 4 4 y 1 Ž 12 12 y 1. from 0.9 = 10 to 1.0 = 10 mol C s or 0.28 = 10 to 0.35 = 10 mol C year , respectively. This estimate suggests that the TOC inflow and outflow through the Strait of Gibraltar are two and three orders of magnitude higher than reported via the Turkish Straits and Mediterranean River inputs.

The total organic carbon (TOC) and total inorganic carbon (C 2) exchange between the Atlantic Ocean and the Mediterranean Sea was studied in the Strait of Gibraltar in September 1997. Samples were taken at eight stations from western and eastern entrances of the Strait and at the middle of the Strait (Tarifa Narrows). TOC was analyzed by a high-temperature catalytic oxidation method, and C 2 was calculated from alkalinity}pH 2 pairs and appropriate thermodynamic relationships. The results are used in a two-layer model of water mass exchange through the Strait, which includes the Atlantic in#ow, the Mediterranean out#ow and the interface layer in between. Our observations show a decrease of TOC and an increase of C 2 concentrations from the surface to the bottom: 71}132 M C and 2068}2150 mol kg\ in the Surface Atlantic Water, 74 }95 M C and 2119}214 8 mol kg\ in the North Atlantic Central Water, 63}116 M C and 2123}2312 mol kg\ in the interface layer, and 61}78 M C and 2307}2325 mol kg\ in the Mediterranean waters. However, within the Mediterranean out#ow, we found that the concentrations of carbon were higher at the western side of the Strait (75}78 M C, 2068}2318 mol kg\) than at the eastern side (61}69 M C, 2082}2324 mol kg\). This di!erence is due to the mixing between the Atlantic in#ow and the Mediterranean out#ow on the west of the Strait, which results in a #ux of organic carbon from the in#ow to the out#ow and an opposite #ux of inorganic carbon. We estimate that the TOC input from the Atlantic Ocean to the Mediterranean Sea through the Strait of Gibraltar varies from (0.97$0.8)10 to (1.81$0.90)10 mol C s\ (0.3;10 to 0.56;10 mol C yr\), while out#ow of inorganic carbon ranges from (12.5$0.4)10 to (15.6$0.4)10 mol C s\ (3.99}4 .90;10 mol C yr\). The high variability of carbon exchange within the Strait is due to the variability of vertical mixing between in#ow and out#ow along the Strait. The prevalence of organic carbon in#ow and inorganic carbon out#ow shows the

[1] In the eastern North Atlantic, carbon dioxide fugacity (fCO 2 ) in the upper mixed layer and discrete pH and total alkalinity measurements in the upper 2000 m were studied during three cruises (winter, spring, and summer 2001) within the framework of the Programme Océan Multidisciplinaire Méso Echelle (POMME) project. This extensive region is located between 39°and 45°N and 16°and 21°W. The mesoscale variability of fCO 2 on the sea surface and in the atmosphere during each season was determined to understand the mechanisms of evolution that control the spatial and temporal variability of fCO 2 together with an estimation of the fluxes of CO 2 between the atmosphere and the ocean. If we consider the observation to be 22 days per cruise, the region was in-taking 0.30 Tg C during the winter cruise and 0.36 Tg C during the spring cruise, whereas it was out-gassing 0.07 Tg C during the summer cruise. These values are clear indications that the area is acting as a sink of CO 2 on an annual scale, with an estimated flux value of À1.1 mol m À2 yr À1 , which is over twice as much as the mean global flux of À0.5 mol m À2 yr À1 (Takahashi et al., 2002). The changes with time observed in the fCO 2 values over the surface layer between the winter and the spring cruises have been described considering thermodynamics, gas exchange, water transport, and biological activity in the area. The estimation of the subduction of inorganic carbon yielded a value of 0.25 Pg C yr À1 , which is approximately 10% of the global net oceanic CO 2 sink flux.Citation: González Dávila, M., J. M. Santana-Casiano, L. Merlivat, L. Barbero-Muñoz, and E. V. Dafner (2005), Fluxes of CO 2 between the atmosphere and the ocean during the POMME project in the northeast Atlantic Ocean during 2001,