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| Naqvi,S.W.A. |
| The Indian Ocean contains one of the oceans' most pronounced oxygen minimum zones (OMZ), which, anomalously, is the most intense in the northwestern sector (Arabian Sea). It also contains the majority of the area of oceanic continental margins in contact with oxygen-depleted waters. Impacts of the oxygen deficiency on regional biogeochemistry, especially anaerobic nitrogen transformations, are described. A comparison of the perennial, mesopelagic OMZ in the open Northwestern Indian Ocean is made with a shallower oxygen deficient system that develops seasonally (during late summer and autumn) over the western Indian shelf. The latter appears to have intensified in recent years presumably due to anthropogenic nutrient loading from land. |
| Tipo: Journal article |
Palavras-chave: Indian Ocean; Nitrogen cycling; Denitrification; N2O; Eutrophication. |
| Ano: 2006 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-65382006000300011 |
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| Bacher, Cedric. |
| A model of the growth of cultivated oyster in the Marennes-Oléron bay was developped to assess the influence of the nutrients input and of the amount of oysters on the growth performance (Railiard. 1991). The ecosystem main characteristics are: - short residence time of the water. - high turbidity level, depending on the season, tidal level, bathymetry, currents and wind. The turbidity acts on the primary production through light limitation and on oyster production as a food dilution factor. - presence of high density cultivated areas on mid-tidal flats. The amount of oysters is ranging between 80 000 and 110 000 tons according to the year. - spatial variability of the biological and physical features. - coupling effects of the physic process (transport,... |
| Tipo: Text |
Palavras-chave: Ecosystem model; Oyster; Crassostrea gigas; Nitrogen cycling; Marennes Oleron Bay; Charente Maritime. |
| Ano: 1993 |
URL: http://archimer.ifremer.fr/doc/00102/21300/18914.pdf |
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| Pichevin, L; Martinez, P; Bertrand, P; Schneider, R; Giraudeau, J; Emeis, K. |
| In the light of new surface sediment delta(15)N data collected over the Namibian shelf and slope, we examined glacial-interglacial variations of N inventory in the area of Luderitz (25 degrees 6S) by deciphering delta(15)N signals of three cores distributed from the upper to the lower continental slope. The lower slope cores display low delta(15)N during cold periods and high delta(15)N during climatic optima, akin to many other records from the world ocean, whereas the upper slope core displays a high-frequency low-amplitude delta(15)N signal without obvious glacial-interglacial variability. This dissimilarity results from the segregation of the upwelling structure in two cells, decoupling nutrient dynamics of the shelf from those beyond the shelf-edge.... |
| Tipo: Text |
Palavras-chave: Nitrogen cycling; Benguela; Climatic cycles. |
| Ano: 2005 |
URL: https://archimer.ifremer.fr/doc/00232/34366/32796.pdf |
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| Kalansky, Julie F.; Robinson, Rebecca S.; Popp, Brian N.. |
| The nitrogen isotopic composition of organic matter contained within diatom frustules of different sediment size fractions from the Guaymas Basin, Gulf of California, suggests that multiple nutrient cycling processes can be examined from a single sediment sample. The diatom-bound delta(15)N values from the greater and less than 63 mu m size fractions were analyzed from six intervals of core MD02-2517, each representing similar to 30-40 years. The diatom-bound delta(15)N values are compared to bulk sedimentary delta(15)N values, weight percent biogenic opal, and weight percent organic carbon. Bulk sedimentary delta(15)N values range from 10 parts per thousand to 12.5 parts per thousand and diatom-bound delta(15)N values of the <63 mu m size fraction from... |
| Tipo: Text |
Palavras-chave: Gulf of California; Diatoms; Export flux; Nitrogen cycling; Nitrogen isotopes. |
| Ano: 2011 |
URL: https://archimer.ifremer.fr/doc/00227/33836/32444.pdf |
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| STAELENS,JEROEN; AMELOOT,NELE; ALMONACID,LEONARDO; PADILLA,EVELYN; BOECKX,PASCAL; HUYGENS,DRIES; VERHEYEN,KRIS; OYARZÚN,CARLOS; GODOY,ROBERTO. |
| South Chilean forest ecosystems represent one of the largest areas of old-growth temperate rainforests remaining in the Southern hemisphere and have a high ecological value, but suffer from deforestation, invasion by exotic species, fragmentation, and increasing atmospheric nitrogen (N) deposition. To support sustainable forest management, more knowledge is required on nutrient cycling of these ecosystems. Therefore, a descriptive study of nutrient dynamics was done in four Valdivian rainforests in the lower Andes range of south Chile: old-growth and altered evergreen stands and unmanaged and managed secondary deciduous stands. Time series were measured for (i) mass (four year) and nutrient content (N, K, Ca, and Mg; one year) of litterfall, (ii)... |
| Tipo: Journal article |
Palavras-chave: Andisol; Chile; Nitrogen cycling; Nutrient dynamics; Temperate rainforest. |
| Ano: 2011 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2011000100010 |
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