Downward fluxes of particulate carbon, nitrogen and phosphorus in the north-western Adriatic Sea

Downward fluxes of particles, organic carbon, total nitrogen and total phos phorus and the composition of the settled particulate matter were determine d in the north-western Adriatic Sea at two coastal sites influenced by the outflows of the Po and Adige rivers and one offshore site. Vertical fluxes were strongly influenced by resuspension processes in addition to the prima ry flux and advection. The resuspended material contributed on average 34-4 3% of the total matter sedimented in the near bottom traps in coastal water s. Net annual vertical fluxes (due to primary flux and advection) of organi c carbon, total nitrogen and phosphorus in the coastal stations were: 71-97 g C m(-2) year(-1) 8-14 g N m(-2) year(-1) and 2.1-2.3 g P m(-2) year(-1), with the highest values recorded at the station off the Po river delta. Th e offshore site was characterised by net annual fluxes of particulates, C, N and P approximately one order of magnitude lower than the above. The carb on export to the bottom was limited in the warm seasons when it constituted only 2-9% of primary production, due to high recycling and utilisation in the upper layer of the water column, increasing up to 8-18% in winter becau se of the instability of the water column and low biological utilisation. ( C) 2001 Elsevier Science B.V. All rights reserved.