|
|
|
| Registros recuperados: 58 | |
|
|
| Merceron, Michel. |
| The 1998 survey of green tides on the Brittany coast was performed in the same way as that of 1997 in order to allow comparison. 11 includes an inventory ofail the concerned sites, and a precise assessment ofthirteen ofthem, the most loaded. On these ones, nitrogen fluxes were surveyed during the critical period, and the green seaweed stock on the beach and in the first waves was quantified. The climatic conditions were opposite between the two years, very dry in spring and summer 1997, and wet in 1998. The irradiance contrast was inverse, and less pronounced. The nitrate contents and mostly the flows were more important in 1998. They generated nitrogen fluxes about 3.3 times those of 1997. The total number of sites concerned in 1998 is clearly higher than... |
| Tipo: Text |
Palavras-chave: Bretagne; Nitrate; Prolifération; Ulve; Eutrophisation; Brittany; Nitrate; Proliferation; Ulva; Eutrophication. |
| Ano: 1999 |
URL: http://archimer.ifremer.fr/doc/1999/rapport-2665.pdf |
| |
|
|
| Longo, Sébastien; Sibat, Manoella; Taiana Darius, Hélène; Hess, Philipp; Chinain, Mireille. |
| Ciguatera poisoning is a foodborne disease caused by the consumption of seafood contaminated with ciguatoxins (CTXs) produced by dinoflagellates in the genera Gambierdiscus and Fukuyoa. Ciguatera outbreaks are expected to increase worldwide with global change, in particular as a function of its main drivers, including changes in sea surface temperature, acidification, and coastal eutrophication. In French Polynesia, G. polynesiensis is regarded as the dominant source of CTXs entering the food web. The effects of pH (8.4, 8.2, and 7.9), Nitrogen:Phosphorus ratios (24N:1P vs. 48N:1P), and nitrogen source (nitrates vs. urea) on growth rate, biomass, CTX levels, and profiles were examined in four clones of G. polynesiensis at different culture age (D10, D21,... |
| Tipo: Text |
Palavras-chave: Gambierdiscus polynesiensis; French Polynesia; Ciguatera; Ciguatoxins; LC-MS; MS; Toxin profile; Nitrate; Urea; Culture medium acidification. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00662/77382/78981.pdf |
| |
|
| |
|
|
| Collos, Yves; Hadjadji, Imene; Plisson, Benoit; Cecchi, Philippe; Laabir, Mohamed; Bechemin, Christian; Masseret, Estelle. |
| Alexandrium tamarense (M. Lebour) Balech strains isolated in spring 2007 from a single bloom in Thau lagoon have been grown in nonaxenic artificial media. For three strains showing large oscillations in biomass (crashes followed by recoveries) on a scale of several days, a significant relationship was observed between changes in cell densities (as in vivo fluorescence) and changes in nitrate concentrations. Increases in cell densities were accompanied by decreases in nitrate, while decreases in cell densities corresponded to increases in nitrate, presumably due to nitrification. Net increases in nitrate could reach up to 15 mu mol N . L(-1) . d(-1) indicating a very active nitrifying archaeal/bacterial population. However, following population crashes,... |
| Tipo: Text |
Palavras-chave: Alexandrium tamarense; Archaea; Bacteria; Decay; Growth; Nitrate; Nitrification; Oscillations. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00049/16046/13585.pdf |
| |
|
| |
|
|
| Merceron, Michel. |
| The yearly study of Ulva in Brittany aims at building a time series of its proliferations and corresponding nutrient loadings. The goal is to detect results of wilful loading reductions, and to distinguish them from natural variations. This first actually quantified study is the starting bench-mark of the process. Forty-five concerned sites were listed in 1997. They are nearly the same as in 1988, 1991 and 1994 (previous rough census). The Côtes d'Armor and then the Finistère are the most affected departments. The Morbihan is less and file et Vilaine not at all. Ulva biomass was precisely quantified in about fifteen locations during the growing season, along with nitrogen loadings of local streams (mostly nitrate). The fluxes of nitrogen - the limiting... |
| Tipo: Text |
Palavras-chave: Bretagne; Nitrate; Prolifération; Ulve; Eutrophisation; Brittany; Nitrate; Proliferation; Ulva; Eutrophication. |
| Ano: 1998 |
URL: http://archimer.ifremer.fr/doc/1998/rapport-1580.pdf |
| |
|
| |
|
|
| Raimonet, Melanie; Guillou, Gael; Mornet, Francoise; Richard, Pierre. |
| Although nitrogen stable isotope ratio (delta N-15) in macroalgae is widely used as a bioindicator of anthropogenic nitrogen inputs to the coastal zone, recent studies suggest the possible role of macroalgae metabolism in delta N-15 variability. Simultaneous determinations of delta N-15 of dissolved inorganic nitrogen (DIN) along the land sea continuum, inter-species variability of delta N-15 and its sensitivity to environmental factors are necessary to confirm the efficiency of macroalgae delta N-15 in monitoring nitrogen origin in mixed-use watersheds. In this study, delta N-15 of annual and perennial macroalgae (Ulva sp., Enterommpha sp., Fucus vesiculosus and Fucus serratus) are compared to delta N-15-DIN along the Charente Estuary, after... |
| Tipo: Text |
Palavras-chave: Nitrogen isotopes; Nitrate; Ammonium; Primary producers; Indicators; Land-sea continuum. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00134/24558/23645.pdf |
| |
|
|
| Qui-minet, Zujaila Nohemy; Coudret, Jérôme; Davoult, Dominique; Grall, Jacques; Mendez‐sandin, Miguel; Cariou, Thierry; Martin, Sophie. |
| Made up of calcareous coralline algae, maerl beds play a major role as ecosystem engineers in coastal areas throughout the world. They undergo strong anthropogenic pressures, which may threaten their survival. The aim of this study was to gain insight into the future of maerl beds in the context of global and local changes. We examined the effects of rising temperatures (+3°C) and ocean acidification (−0.3 pH units) according to temperature and pH projections (i.e., the RCP 8.5 scenario), and nutrient (N and P) availability on three temperate maerl species (Lithothamnion corallioides, Phymatolithon calcareum, and Lithophyllum incrustans) in the laboratory in winter and summer conditions. Physiological rates of primary production, respiration, and... |
| Tipo: Text |
Palavras-chave: Calcification; Maerl; Nitrate; Ocean acidification; Ocean warming; Phosphate; Photosynthesis; Respiration. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00595/70722/68955.pdf |
| |
|
| |
|
|
| Kienast, M.; Lehmann, M. F.; Timmermann, A.; Galbraith, E.; Bolliet, T.; Holboum, A.; Normandeau, C.; Laj, C.. |
| Sedimentary delta(15)N records from the oligotrophic western equatorial Pacific (WEP) off Mindanao show that late Holocene sedimentary delta(15)N is substantially lower than that of the early Holocene, following a gradual >3 parts per thousand decrease that occurred between 7 and 3 kyrs ago. Analyses of modem day nitrate isotope profiles from the same region indicate the sensitivity of the WEP N pools towards (1) the advection of (15)N-enriched nitrate from the Eastern Equatorial Pacific (EEP) by the North Equatorial Current (NEC) and the Mindanao Current in subsurface waters and, (2) at shallow depths, the input of new and (15)N-depleted nitrate through N, fixation. We suggest that the Holocene decrease in sedimentary delta(15)N reflects a diminished... |
| Tipo: Text |
Palavras-chave: Tropical Pacific; El Nino; Surface temperature; Fresh water; Nitrate; Mindanao; Ocean; Variability; Holocene; Seawater. |
| Ano: 2008 |
URL: https://archimer.ifremer.fr/doc/00207/31843/30257.pdf |
| |
|
|
| Menesguen, Alain. |
| Since 25 years, an increasing number of beaches and coves along the Britanny coast are invaded from spring until autumn by proliferating green macroalgae (free ulvae, fixed enteromorphae). This typical case of eutrophication, which has been well studied in the bays of Saint-Brieuc, Lannion, Douarnenez and Brest, could be explained by the conjunction of a natural containment of shallow water masses with a recent enrichment of them by nitrate river loadings. In the naturally confined sites, field measurements of summer biomass showed a good correlation with the spring nitrate river loadings ; furthermore, the summer rarefaction of these loadings explains the fall of the nitrogen content of the ulvae, which induces the summer stop of the algal growth. The... |
| Tipo: Text |
Palavras-chave: Intensive farming; Biogeochemical models; Coastal eutrophication; Nitrate; Ulva; Green tide; Agriculture intensive; Modèles biogéochimiques; Eutrophisation côtière; Nitrate; Ulve; Marée verte. |
| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/2003/rapport-143.pdf |
| |
|
|
| Berg, Gm; Balode, M; Purina, I; Bekere, S; Bechemin, Christian; Maestrini, Serge. |
| Trends in nitrogen utilization, determined with N-15-labeled substrates, were related to blooms of distinct phytoplankton groups in the Gulf of Riga, Baltic Sea, during May, June and July 1999. The dominant phytoplankton groups included diatoms, cryptophytes, dinoflagellates, and filamentous cyanobacteria. As the water column became progressively more stratified over the growing season, diatoms comprised a smaller proportion of the total phytoplankton assemblage and almost disappeared by late summer. Their disappearance correlated with undetectable surface-water nitrate concentrations and low nitrate uptake rates (5 to 8% of total nitrogen uptake). Diatoms were the only phytoplankton group significantly associated with the uptake of oxidized nitrogen... |
| Tipo: Text |
Palavras-chave: Nitrogen uptake; DON; Nitrate; Diatoms; Cyanobacteria; Cryptophytes; Baltic Sea; Gulf of Riga. |
| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/00000/10207/7595.pdf |
| |
|
| |
|
|
| Poli,M.N; López Miranda,L.A; Fernández Iriarte,P.J; Zanier,G.J; Iúdica,C.E. |
| Previous research has shown connections between the exposure to different agents and mutations in germinal and somatic cells. One of such agents, nitrate (NO3), can be potentially genotoxic for individuals who drink high nitrate well water, and may cause a subsequent impact on their health and on the whole ecosystem. The aim of this research was to conduct genotoxicity assays in somatic cells from people living in the northern area of Mar del Plata city, Argentina. The purpose of these experiments was, in turn, to establish the possible relationships between mutagenic effects and high nitrate water consumption. To this end, different diagnostic tests were carried out to detect potential genetic and/or chromosomal alterations. A non-exposed population equal... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Mutagenic agents; Nitrate; Chromosomal aberrations; Genotoxicity; Micronuclei. |
| Ano: 2012 |
URL: http://www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S1852-62332012000100001 |
| |
|
| |
|
|
| Dias Filho,M.B.. |
| Understanding how weed seed germination and emergence respond to environmental factors is critical to determining their adaptive capabilities and potential for infestations, and could also aid in the development of effective control practices. Germination of Ipomoea asarifolia (Desr.) Roem. & Schultz and Stachytarpheta cayennensis (Rich) Vahl. decreased linearly with decreasing osmotic potentials. Also, increasing osmotic stress delayed germination of Ipomoea more than that of Stachytarpheta. Ipomoea germination was insensitive to light, while Stachytarpheta showed a positive photoblastic behavior. Nitrate had a negative effect on germination of Ipomoea seed under both light and dark conditions but stimulated dark germination of Stachytarpheta.... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Nitrate; Light; Osmotic stress; Depth of planting. |
| Ano: 1996 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83581996000200005 |
| |
|
|
| Kanwar, Ramesh S.; Reungsang, Pipat; Jha, Manoj K.; Gassman, Philip W.; Ahmad, Khalil; Saleh, Ali. |
| A validation study has been performed using the Soil and Water Assessment Tool (SWAT) model with data collected for the Upper Maquoketa River Watershed (UMRW), which drains over 16,000 ha in northeast Iowa. This validation assessment builds on a previous study with nested modeling for the UMRW that required both the Agricultural Policy EXtender (APEX) model and SWAT. In the nested modeling approach, edge-of-field flows and pollutant load estimates were generated for manure application fields with APEX and were then subsequently routed to the watershed outlet in SWAT, along with flows and pollutant loadings estimated for the rest of the watershed routed to the watershed outlet. In the current study, the entire UMRW cropland area was simulated in SWAT, which... |
| Tipo: Working or Discussion Paper |
Palavras-chave: Calibration; Modeling; Nitrate; SWAT; Validation; Water quality; Resource /Energy Economics and Policy. |
| Ano: 2005 |
URL: http://purl.umn.edu/18440 |
| |
|
| |
|
| |
| Registros recuperados: 58 | |
|
|
|
