  Iron study during a time series in the western Weddell pack ice; ; et al in Marine Chemistry (2008), 108(1-2), 85-95 Samples of sea ice, snow, brine and underlying seawater were collected in the western Weddell pack ice at the ISPOL drifting station (Ice Station POLarstern, 68 degrees S/55 degrees W) in spring-summer ... [more ▼] Samples of sea ice, snow, brine and underlying seawater were collected in the western Weddell pack ice at the ISPOL drifting station (Ice Station POLarstern, 68 degrees S/55 degrees W) in spring-summer period (November 2004-January 2005). Total-dissolvable, dissolved and particulate Fe concentrations in the sea ice environment were determined every 5 days during the time series, together with relevant physical, chemical and biological parameters. From 29 November to 30 December, a decrease in all forms of Fe measured was observed, likely to be the result of enhanced ice permeability as summer proceeds. At the beginning of the time series, melting of the upper ice layer took place together with brine drainage process. This would enable the seeding of Fe from the ice matrix towards the upper water column below. 70% of this Fe was supplied during the first 10 days of the survey, while the ice cover is still present. Flux estimates from the sampled area furthermore highlight the relevant role of the pack ice in the biogeochemical cycle of Fe in the western Weddell Sea. (C) 2007 Elsevier B.V. All rights reserved. [less ▲] Detailed reference viewed: 18 (2 ULg) High temporal coverage of carbon dioxide measurements in the Southern Bight of the North Sea; ; et al in Marine Chemistry (2007), 106(1-2), 161-173 A monthly survey of the partial pressure of CO2 (pCO2) was carried in the Southern Bight of the North Sea (SBNS) from June 2003 to May 2004. The spatial variability of the surface distribution of the pCO2 ... [more ▼] A monthly survey of the partial pressure of CO2 (pCO2) was carried in the Southern Bight of the North Sea (SBNS) from June 2003 to May 2004. The spatial variability of the surface distribution of the pCO2 was relatively small (within a range of 10–70 μatm) compared to the amplitude in the seasonal signal (∼260 μatm). On an annual scale, the pCO2 dynamics appeared to be controlled by biological processes (primary production in springtime and respiratory processes in summer), rather than temperature (in summer). The comparison with measurements carried out in 2001 and 2002 (13 cruises) shows that the inter-annual variability of pCO2 was close to the range of the spatial variability and mostly observed in spring, associated to biological processes (primary production). Net ecosystem production estimated from dissolved inorganic carbon (DIC) temporal variations showed that the SBNS is autotrophic, at an annual rate of 6.3 mol C m−2 yr−1. The decoupling in time between autotrophy in spring and heterotrophy in summer, associated to the relatively rapid flushing time of the water mass in the area (∼70 days), might allow the export of a fraction of the springtime synthesized organic matter to the adjacent areas of the North Sea. The SBNS was on a yearly basis a sink of atmospheric CO2 at a rate of −0.7 mol C m−2 yr−1. [less ▲] Detailed reference viewed: 21 (2 ULg)Barium distribution across the Southern Ocean frontal system in the Crozet-Kerguelen Basin; ; et al in Marine Chemistry (2005), 95(3-4), 149-162 We investigated the dissolved and excess particulate Ba distribution (Ba-xs, an estimate of biogenic Ba considered to consist mainly of barite [BaSO4]) across the complex frontal system of the Crozet ... [more ▼] We investigated the dissolved and excess particulate Ba distribution (Ba-xs, an estimate of biogenic Ba considered to consist mainly of barite [BaSO4]) across the complex frontal system of the Crozet-Kerguelen Basin (Southern Ocean; 42-47 degrees S, 62-65 degrees E). Ba-xs profiles show the characteristic mesopelagic maximum (depth range between 150 and 400 in) reaching up to 1000 pM in the Subantarctic Zone and Subtropical Front, the highest value observed for Southern Ocean mesopelagic waters. Dissolved Ba (concentrations between 38 and 104 nM) correlates with silicate and alkalinity, but the regression is not perfect, reflecting the involvement of different biogenic carriers in the control of the water column distribution of these compounds. Dissolved Ba in the upper 500 in appears strongly influenced by cross-frontal exchanges, involving both northward and southward transport of water masses. In the mesopelagic waters (150-400 m) of the Polar Front Zone, a dissolved Ba depletion faces the Ba, maximum. This depletion appears mainly maintained by cross-frontal advection of waters containing less Ba and originating north of the Subantarctic Front. Overall, no clear evidence that precipitation of barite reflected by the occurrence of Baxs maxima does measurably influence the distribution of dissolved Ba was found. (C) 2004 Elsevier B.V. All rights reserved. [less ▲] Detailed reference viewed: 14 (1 ULg)Metal fluxes through the Strait of Gibraltar: the influence of the Tinto and Odiel rivers (SW Spain); ; Beckers, Jean-Marie  et alin Marine Chemistry (2001), 73(3-4), 193-213 A large set of new data concerning dissolved metal concentrations has been acquired in the Gulf of Cadiz and in the Strait of Gibraltar from 1996 to 1999. These data, associated with models (hydrodynamic ... [more ▼] A large set of new data concerning dissolved metal concentrations has been acquired in the Gulf of Cadiz and in the Strait of Gibraltar from 1996 to 1999. These data, associated with models (hydrodynamic, tracer advection-dispersion and mixing), have been used to assess the influence of rivers draining the South Iberian Pyrite Belt on the Gulf of Cadiz and on the Atlantic inflow in the Strait of Gibraltar. Metal concentrations in surface waters from the Gulf of Cadiz are maximal near the mouth of the Tinto/Odiel rivers with values exceeding 50 nmol/kg (Mn), 5 nmol/kg (Ni), 30 nmol/kg (Cu), 100 nmol/kg (Zn), 0.9 nmol/kg (Cd) and 45 nmol/kg (As). From the Tinto/Odiel river, a plume of contamination follows the coast in the direction of the Strait of Gibraltar. The computation of a tracer advection-dispersion model confirms that the coastal currents carry the metals discharged from the Tinto and Odiel to the Strait of Gibraltar. From temperature-salinity and metal-salinity plots, four water masses can be recognised in the Gulf of Cadiz and in the Strait of Gibraltar: North Atlantic Surface Water (NASW), North Atlantic Central Water (NACW) and metal-enriched Spanish Shelf Waters from the Gulf of Cadiz (SSW). The Mediterranean Outflow Water (MOW) is also clearly seen at depths greater than 300 m. The chemical characteristics of these various water masses have been used in a mixing model to evaluate their relative contribution to the Atlantic inflow through the Strait of Gibraltar. These contributions are seasonally variable. in June 1997, the contribution was: 80 +/- 20%, 5 +/- 5% and 15 +/- 10% for NASW, NACW and SSW, respectively. In September, the SSW contribution was apparently negligible. Finally, these relative contributions allow the evaluation of the metal fluxes in the Strait of Gibraltar. The presence of SSW in the Strait increases the metal flux to the Mediterranean Sea by a factor of 2.3 (Cu), 2.4 (Cd), 3 (Zn) and 7 (Mn). It does not modify significantly As and Ni fluxes. (C) 2001 Published by Elsevier Science B.V. [less ▲] Detailed reference viewed: 28 (1 ULg) |
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