Carbon regeneration in cariaco trenchs water, Venezuela, during the period January 2002-September 2003 | Regeneración del carbono en el agua de la fosa cariaco, Venezuela, durante el perido enero 2002-septiembre 2003

Poster.-- Workshop on "Oxygen Minimum Systems in the Ocean: Distribution, Diversity and Dynamics", 2006

In this investigation the regeneration of carbon in waters of the Cariaco Trench is studied following Broecker & Peng's model (1982). This model uses the slope generated from the AT curve and CO2, where CO2 is the concentration of carbon dioxide and AT the total alkalinity. Additionally the primary productivity (PP) is estimated as a measurement of carbon produced by biological activity. The results indicate that the CO2 levels are minimum (1,962 µmol/kg) in the surface layer increasing through the anoxic threshold until a value of 2,451 µmol/kg is reached. At the same time, the primary productivity, was maximum in the first 7 m, with a seasonal cycle that increases the values up to 17 mgC/m3/h in the months of maximum upwelling, i.e., January-April. These increases are reflected in the integrated values, which surpass the 600 g C/m2/año. The regeneration model indicates that, 82% of carbon distribution is controlled by organic carbon from the soft material of the photosynthetic organisms, whereas 18% is of inorganic origin, from the chalky skeletons. Vertically, the regeneration of organic carbon (81-84%) is maximum in the surface layer in agreement with PP values; nevertheless, in the oxic-anoxic interface a second maximum of smaller intensity (70-80%) is detected, which is generated by bacterial processes of decomposition of organic matter that using chemoautotrophic mechanisms. The values regenerated in the anoxic zone are lower than those in the oxic zone because the decomposition under the aerobic conditions is more effective than those under the anaerobic ones

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