GENERAL-ASPECTS OF CARBON BIOGEOCHEMISTRY IN THE RIA OF VIGO, NORTHWESTERN SPAIN

The rias of Galicia in northwestern Spain are local areas of high prim ary production. In this article, the fluxes of organic and inorganic c arbon and the processes of photosynthesis, remineralization, and sedim entation of particulate organic carbon in one of these, the ria of Vig o, are quantified using the box model method. In 1986 the mean photosy nthesis rate in the ria of Vigo was 350 mgC m-2 d-1; on average, 40% o f this quantity was remineralized; 140 mgC m-2 d-1 passed into the sed iment; and the remaining 65 MgC m-2 d-1 ( 18%) was exported to the coa stal waters. Such budgets are very sensitive to meteorologic condition s; 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 moIC s-1. During the rest of the year the ria behaves l ike a carbon trap, with most of the 27 molC s-1 that is trapped being lost to sedimentation.