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| Schmidt, K.; De La Rocha, C. L.; Gallinari, Morgane; Cortese, G.. |
| Correlation between particulate organic carbon (POC) and calcium carbonate sinking through the deep ocean has led to the idea that ballast provided by calcium carbonate is important for the export of POC from the surface ocean. While this idea is certainly to some extent true, it is worth considering in more nuance, for example, examining the different effects on the aggregation and sinking of POC of small, non-sinking calcite particles like coccoliths and large, rapidly sinking calcite like planktonic foraminiferan tests. We have done that here in a simple experiment carried out in roller tanks that allow particles to sink continuously without being impeded by container walls. Coccoliths were efficiently incorporated into aggregates that formed during the... |
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| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00176/28728/27193.pdf |
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| Le Moigne, F. A. C.; Gallinari, Morgane; Laurenceau, E.; De La Rocha, C. L.. |
| To examine the potentially competing influences of microzooplankton and calcite mineral ballast on organic matter remineralization, we incubated diatoms in darkness in rolling tanks with and without added calcite minerals (coccoliths) and microzooplankton (rotifers). Concentrations of particulate organic matter (POM in suspension or in aggregates), of dissolved organic matter (DOM), and of dissolved inorganic nutrients were monitored over 8 days. The presence of rotifers enhanced the remineralization of ammonium and phosphate, but not dissolved silicon, from the biogenic particulate matter, up to 40% of which became incorporated into aggregates early in the experiment. Added calcite resulted in rates of excretion of ammonium and phosphate by rotifers that... |
| Tipo: Text |
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| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00157/26836/24957.pdf |
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| Coffineau, N.; De La Rocha, C. L.; Pondaven, Philippe. |
| This study presents six new water column profiles of the silicon isotopic composition (delta Si-30) of dissolved silicon (DSi) from the Atlantic and Indian sectors of the Southern Ocean and a variable depth box model of silica cycling in the mixed layer that was constructed to illuminate the evolution of surface ocean delta Si-30 over the full course of a year. In keeping with previous observations, delta Si-30 values ranged from +1.9 to +2.4% in the mixed layer (ML), +1.2 to +1.7 parts per thousand in Winter Water (WW), and +0.9 to +1.4 parts per thousand in Circumpolar Deep Water (CDW). These data also confirmed the occurrence of diminished values for ML delta Si-30 at low DSi concentrations in early austral autumn on the Kerguelen Plateau. The box model... |
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| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00260/37171/35691.pdf |
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