Cet article établit l'expression du flux de particules, émises dans le vide par unesource ponctuelle à travers une surface plane. Cette équation est alors comparée auxrésultats numériques obtenus par utilisation de symétries sur des exemples. Uneapplication est proposée pour un détecteur cylindrique (surface non plane). Descompléments sont donnés en conclusion.

Fluxes of dissolved oxygen and nutrients and vertical fluxes of particulate organic elements were investigated in the subtidal benthic environment of Marian Cove, King George Island, Antarctica, using in situ benthic chambers and near-bottom sediment traps. Fluxes of dissolved oxygen, ammonium, phosphate, and silicate were comparable to those measured in temperate regions. Sediment oxygen consumption was a good indicator of organic respiration and elemental efflux at the benthic boundary layer of Marian Cove, with good positive correlations with ammonia (r2 = 0.67), phosphate (r2 = 0.57), and the C:N:P ratio (106:11.5:1.15) in the chamber water. A positive relationship (r2 = 0.58) between settling particulate organic carbon flux and chl a concentration suggests that water column biomass and production are direct sources of settling particles. According to element budgets in summer assessed using the fluxes, Jin and the sum of Jout and Jburial were 15.9 ± 8.1 and 22.6 ± 8.2 mmol m-2 d-1 for carbon, 2.02 ± 0.54 and 2.46 ± 0.82 mmol m-2 d-1 for nitrogen, 0.07 ± 0.03 and 0.23 ± 0.08 mmol m-2 d-1 for phosphorus, and 12.4 ± 2.7 and 13.5 ± 5.0 mmol m-2 d-1 for silicon, respectively. There was a broad balance between sediment organic input and remineralized output for carbon and nitrogen at the benthic boundary layer of Marian Cove.

The flux and composition of settling particles were measured in a subtidal benthic environment of Marian Cove, King George Island, from February 1998–January 2000. The total mass flux ranged between 2.47 g m−2 d−1 (August and September 1998) and 21.97 g m−2 d−1 (February 1999), and showed distinct seasonal variation: high in the summer and low in winter. Lithogenic particles constituted 70–95% of the total particles, while biogenic particles represented only 10%, except in spring when biogenic particles made up more than 30%. The fluxes of organic carbon, biogenic silica, nitrogen, and organic phosphorus all peaked in spring rather than in summer, with ranges of 4.4–34.0, 1.2–23.5, 0.48–5.56, and 0.01–0.15 mmol m−2 d−1, respectively. Fluxes of metals (Al, Ti, Cu, Cd, and Pb) showed temporal variability, similar to that of the total mass flux, but each metal had different enrichment factor (EF) values. The EF value of Cu correlated positively with fluxes in lithogenic components, while the EF value of Cd correlated with biogenic particle fluxes. The Cu flux is mainly related to substantial inflows of melt water laden with Cu- enriched lithogenic particles. The Cd flux is probably associated with organic matter deposition following phytoplankton blooms in the water column.

Time-series sediment traps were deployed to investigate the temporal evolution of particle fluxes in eastern and central Bransfield Strait, from December 1999–December 2000. Particle fluxes showed large seasonal variation at both trap sites. In eastern Bransfield Strait, summer mass fluxes were two orders of magnitude higher than winter mass fluxes, while in central Bransfield Strait, almost 99% of the annual mass flux (33 g m−2) was collected in a 40-day period from December–January. Export flux also exhibited a high regional variability. This regional variability is probably due to central Bransfield Strait's strong surface current, which carries most settling particles produced in the surface waters away from the mooring site during the low summer flux period. The relatively low biogenic silica to organic carbon ratios (a range of 0.29–1.4) and high lithogenic fluxes (41% of total mass flux) indicate that the growth of phytoplankton is not limited by the micronutrient iron in eastern Bransfield Strait. The annual flux of organic carbon in eastern Bransfield Strait was 6.8 g C −2, which is three times higher than the flux measured in central Bransfield Strait (2.2 g C −2). Organic carbon flux in eastern Bransfield Strait is relatively high for the Southern Ocean, possibly due to fast-sinking faecal pellets that lead to less decomposition of organic material in the water column. Calculations suggest that approximately 7.2% of the organic carbon produced at the surface in eastern Bransfield Strait is exported to a depth of 678 m. This exceeds the maximum calculated export of primary production to a depth of 1000 m in the Atlantic and Southern oceans.