General aspects of carbon biogeochemistry in the ria of Vigo, northwestern Spain

Abstract

The rias of Galicia in northwestern Spain are local areas of high primary production. In this article, the fluxes of organic and inorganic carbon and the processes of photosynthesis, remineralization, and sedimentation of particulate organic carbon in one of these, the ria of Vigo, are quantified using the box model method. In 1986 the mean photosynthesis rate in the ria of Vigo was 350 mgC m-* d-' ; on average, 40% of this quantity was remineraliied; 140 mgC mm2 d-’ passed into the sediment; and the remaining 65 mgC me2 d-’ ( 18%) was exported to the coastal waters. Such budgets are very sensitive to meteorologic conditions; for during the April to October period when wind-induced upwelling is frequent, the processes mentioned increase greatly in the interior part of the ria. In winter a large quantity of carbon gets exported to the ocean, 78 molC SK’. During the rest of the year the ria behaves like a carbon trap, with most of the 27 molC s-’ that is trapped being lost to sedimentation.