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| Registros recuperados: 23 | |
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| Eaucea,; Prou, Jean. |
| L'objet de l'étude est de décrire les liens principaux entre l'hydrologie de la Charente et les constats qualitatifs dans le bassin de Marennes, ainsi que l'estimation des flux continentaux, sur la base des données des stations de Fontenelles et de Boyard entre 1977 et 2006. Du fait de l'influence de la marée, il n'est pas possible de mesurer les débits de la Charente dans sa partie aval. Ils ont donc été reconstitués à partir des stations de Saint-Savinien, du pont de Beillant, de Carillon, du Moulin de Chatre, de la Lijardière, de Jarnac, de Vindelle et de Foulpougne, en fonction de la disponibilité et de la fiabilité des données. Les mesures à Fontenelles et Boyard ont été réalisées de façon à disposer d'une gamme variée de situations par rapport au... |
| Tipo: Text |
Palavras-chave: Hydrologie; Flux continentaux; Cycle de marée; Nitrates; Phosphates; Production primaire; Marennes Oléron; Charente. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/00083/19419/17030.pdf |
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| Herbert, R. |
| Seasonal data and depth profiles using super(15)N-labelled NO sub(3)u- show that denitrification (77-90% of NO sub(3)u- respired) rather than NO sub(3)u- dissimilation to NH sub(4)u+ was the principal route of nitrate reduction in Kingoodie Bay sediments. Populations of both groups of NO sub(3)u- reducing bacteria were highest in the 0-20 mm horizon in those sediments where highest rates of NO sub(3)u- respiration were recorded (28.56 mu g N.d super(-1) dry wt. sediment super(-1)). Autotrophic nitrification rates shared a marked seasonality with highest rates (0.92 mu g N.d super(-1).g dry wt. sediment super(-1)) occurring during the summer. Maximum populations of autotrophic nitrifying bacteria were also found in the 0-20 mm sediment horizon and these... |
| Tipo: Text |
Palavras-chave: Seasonal variations; Bacteria; Estuaries; Sediment chemistry; Biogeochemistry; Ammonia; Nitrates; Nitrogen cycle. |
| Ano: 1984 |
URL: http://archimer.ifremer.fr/doc/1984/acte-971.pdf |
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| Purvina, S; Béchemin, Christian; Balode, M; Verite, Celine; Arnaud, Christophe; Maestrini, Serge Y. |
| The use of riverine dissolved organic matter by the heterotrophic bacteria associated with a culture of the cyanobacterium Microcystis aeruginosa and release of simple nitrogen compounds were studied in an experimental series. Bacteria reduced the bulk of dissolved organic nitrogen (DON) by half, but when associated with M. aeruginosa, DON was excreted and its concentration rose by 13%. During the stationary growth phase bacteria released ammonium, doubling the concentration of ammonia as well as of nitrates. Bacteria associated with M. aeruginosa consumed riverine DON and joined the ammonification and nitrification process, supplying cyanobacteria with simple nitrogen compounds. |
| Tipo: Text |
Palavras-chave: Microcystis aeruginosa; Heterotrophic bacteria; DOM; DON; Nitrates; Ammonia. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00353/46408/46122.pdf |
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| In the urban area of Dakar, excessive nitrate concentrations beyond the OMS standards of 50 mg/l were recorded in the wells and bore holes catching the underground aquifer of the quaternary sands, thus endangering the peninsula water resources. |
| Tipo: Report |
Palavras-chave: Water pollution; Nitrates. |
| Ano: 2002 |
URL: http://hdl.handle.net/1834/668 |
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| Mensi, F.; Ksouri, J.; Seale, E. G.; Romdhane, M.S.. |
| L'exploitation des algues rouges appartenant au genre Gracilaria pour l'extraction de l'agar a considérablement augmenté au cours des dernières décennies. En Tunisie Gracilaria verrucosa (Hudson) Papenfuss 1950 (Rhodophyta), est candidate pour la culture dans la lagune de Bizerte (Nord de la Tunisie) où ne pousse que sur une courte période de l’année. Ainsi, le but de cette étude est de recueillir des informations de base sur sa croissance dans cette région. Les effets de la salinité des sources d’azote et du phosphore ainsi que leurs concentrations sur la croissance de cette algue ont été étudiés à l'échelle de laboratoire en utilisant la méthodologie de surface des réponses. Afin de déterminer les interactions entre les variables et les niveaux optimaux... |
| Tipo: Journal Contribution |
Palavras-chave: Algae; Ammonium; Red algae; Salinity; Growth; Nitrates. |
| Ano: 2011 |
URL: http://hdl.handle.net/1834/4734 |
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| Mertens, J.; Massart, D.L.. |
| A simple and rapid method for the determination of nitrate in seawater of high nitrate content (>1 ppm) is proposed. The absorption of the nitrate ion is measured at 210 and 220 mµ. The sample is treated with a measured quantity of hydrochloric acid to eliminate the carbonate and bicarbonate interferences and measured against a nitrate free blank prepared by reduction of the nitrate to ammonia with Raney nickel. The addition of HCl permits also storage of the sample without special precautions and the use of the blank eliminates the most serious of the interferences (bromide) expected in seawater. The interference of organic matter limits however the applicability of the method to concentrations higher than 1 ppm. |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Marine environment; Nitrates; Spectroscopy. |
| Ano: 1971 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3424 |
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| Kolaitis, L.N.; Bruynseels, F.; Van Grieken, R.; Andreae, M.O.. |
| In open ocean waters the predominant volatile sulfur compound is dimethyl sulfide (DMS), representing almost 90% of the marine sulfur emissions. Methanesulfonic acid (MSA), one of the oxidation products of DMS, is consequently an important constituent of marine aerosols. Laser microprobe mass analysis (LAMMA) has been used for single-particle analysis of particles collected in the marine boundary layer. MSA, like the non-sea-salt sulfate, is mainly associated with the smallest aerosol particles, whose LAMMA spectra match the reference fingerprint spectra of MSA salts, sodium methanesulfonate and ammonium methanesulfonate. The presence of nitrate and heavy metal ions in the LAMMA spectra can reveal, to a certain extent, the degree of air pollution at the... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Aerosols; Air pollution; Boundary layers; Heavy metals; Marine environment; Nitrates; Particle size; Sulphates. |
| Ano: 1989 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3177 |
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| Premuzic,Z; Palmucci,HE; Tamborenea,J; Nakama,M. |
| The addition of chlorine constitutes an economical disinfection method for closed, soil-less systems. Three quantities of sodium hypochlorite (0.55, 5.5 and 11 ppm) were applied to closed, soil-less greenhouse- grown lettuce (Lactuca sativa), to study the effect on its production (fresh weight and dry matter) and some commercial and nutritional quality factors (phytotoxicity, Vitamin C, nitrates). Sodium hypochlorite was weekly added within the nutrient solution, and the chemical properties (pH, EC and chlorides) of the recycled solution were measured. Damage to leaves was evaluated 15 days before harvest. Chlorination produced different effects regarding both production and quality. All treatments presented plants with excellent commercial weight,... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Chlorination; Lactuca sativa; Nitrates; Phytotoxicity; Vitamin C. |
| Ano: 2007 |
URL: http://www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S1851-56572007000100010 |
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| Loomis, John B.; Bell, Paul; Cooney, Helen; Asmus, Cheryl. |
| We estimate adults’ willingness to pay (WTP) to reduce health risks to their own or other families’ infants to test for altruism. A conjoint analysis of adults paying for bottled water found marginal WTP for reduction in risk of shock, brain damage, and mortality in the cash treatment of $2, $3.70, and $9.43, respectively. In the hypothetical market these amounts were $14, $26, and $66, indicating substantial hypothetical bias, although not unexpected due to the topic of infant health. Statistical tests confirm a high degree of altruism in our WTP results, and altruism held even when real money was involved. |
| Tipo: Journal Article |
Palavras-chave: Altruism; Conjoint; Drinking water; Nitrates; Validity; Willingness to pay; Agricultural and Food Policy; Consumer/Household Economics; Food Consumption/Nutrition/Food Safety; Health Economics and Policy; Institutional and Behavioral Economics; I10; Q53. |
| Ano: 2009 |
URL: http://purl.umn.edu/56657 |
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| Crutchfield, Stephen R.; Cooper, Joseph C.; Hellerstein, Daniel. |
| Nitrates in drinking water, which may come from nitrogen fertilizers applied to crops, are a potential health risk. This report evaluates the potential benefits of reducing human exposure to nitrates in the drinking water supply. In a survey, respondents were asked a series of questions about their willingness to pay for a hypothetical water filter, which would reduce their risk of nitrate exposure. If nitrates in the respondent's drinking water were to exceed the EPA minimum safety standard, they would be willing to pay $45 to $60, per household, per month, to reduce nitrates in their drinking water to the minimum safety standard. There are 2.9 million households in the four regions studied (White River area of Indiana, Central Nebraska, Lower... |
| Tipo: Report |
Palavras-chave: Water quality; Drinking water; Nitrates; Benefits; Contingent valuation; Resource /Energy Economics and Policy. |
| Ano: 1997 |
URL: http://purl.umn.edu/34025 |
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| Registros recuperados: 23 | |
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