Nitrogen speciation and nitrification potential in the Skagerrak area during the SKAGEX IV experiment

Enoksson, V.; Fogelqvist, Elisabet; Fonselius, Stig

doi:10.1016/0967-0637(96)00050-7

Cited by 6 publications

(4 citation statements)

References 14 publications

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“…The annual average content of phosphate 0.11±0.1 µmol l −1 is much lower than that recorded by Abdel-Halim and Khairy (2007) in Eastern Harbor which was 0.51 µmol l −1 . The strongly negative correlations between inorganic phosphate and oxidizable organic matter (r = -0.98) revealed the phosphorous replenishment as a result of microbial decomposition of organic matter (Enoksson et al, 1996).…”

Section: Discussionmentioning

confidence: 99%

Ecological Studies of Epiphytic Microalgae and Epiphytic Zooplankton on Seaweeds of the Eastern Harbor, Alexandria, Egypt

El-Din¹,

Shaltout²,

Nassar³

et al. 2015

American Journal of Environmental Sciences

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Abstract:A qualitative and quantitative study on the epiphytic microalgae and epiphytic zooplankton were conducted in order to follow up their community structures on seaweeds in relation to some physicochemical variables in the coastal waters of the Eastern Harbor of Alexandria. Water and macroalgal samples were collected seasonally during two years successively: Winter, summer, autumn (2012) and spring (2013). The collected seaweeds were Ulva fasciata (green alga), Corallina mediterranea, Corallina officinalis, Gelidium sp., Pterocladiella capillacea, Hypnea musciformis and Grateloupia doryphora (red algae). The studied water quality parameters were pH, salinity, dissolved oxygen, oxidizable organic matter and nutrient salts. The abundance of epiphytes were significantly different between morphotypes (two-way ANOVA), p≤0.05; ranking the branched thalli as the first preference for microalgal epihytes, sheet-like thalli with a smooth surface as the second one, while the lowest rank was for the mucilaginous species. The same result was found for epiphytic zooplankton. The results of the statistics revealed insignificant seasonal variations in the epiphytic microalgae and very weak correlations between the abundance of microalgae and the physico-chemical parameters. In contrast, there were significant differences for epiphytic zooplanktonic seasonal variations. Whereas, the zooplankton count was correlated preferably with environmental water salinity, followed by nutrients.

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Section: Discussionmentioning

confidence: 99%

Ecological Studies of Epiphytic Microalgae and Epiphytic Zooplankton on Seaweeds of the Eastern Harbor, Alexandria, Egypt

El-Din¹,

Shaltout²,

Nassar³

et al. 2015

American Journal of Environmental Sciences

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“…incomplete assimilatory reduction of nitrate by phytoplankton and bacteria (Vaccaro & Ruyther 1960, Wada & Hattori, 1971, Miyazzaki et al 1973, Miyazzaki et al 1975, Kiefer et al 1976, Herbland & Voituriez 1979, Olson 1981a, Dore & Karl, 1996b, Collos 1998. (2) Ammonium oxidation to nitrite by autotrophic nitrifying bacteria (Brandhorst 1959, Miyazzaki et al 1975, Olson 1981a,b, Ward 1986, Dore & Karl 1996b, Enoksson et al 1996. (3) Nitrite assimilation by phytoplankton and bacteria (Ward et al 1989).…”

Section: Abstract: Nutrients · Nitrogen Species · Nitrite · Phytoplamentioning

confidence: 99%

Phytoplankton drives nitrite dynamics in the Gulf of Aqaba, Red Sea

Al-Qutob¹,

Häse²,

Tilzer³

et al. 2002

Mar. Ecol. Prog. Ser.

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This study focuses on the seasonal changes in the Gulf of Aquaba, Red Sea, in nitrite concentration and their relationship with phytoplankton activity, which is mainly controlled by an alternation of water-column stratification with vertical mixing. Within the euphotic zone, during thermal summer stratification, nutrient depletion was severe, and no nitrite could be detected in the upper 70 m. However, during stratification, nitrite was always associated with the nutriclines and formed a deep maximum at the bottom of the euphotic zone. In contrast, nitrite accumulated in the mixed water column during winter, closely paralleling the development of phytoplankton biomass. In the Gulf of Aqaba, maximum nitrite accumulation occurred when winter mixing reached its greatest depth, which in turn was coincident with the height of the phytoplankton spring bloom. Thus, our field data suggest that accumulation of nitrite is associated with nutrient-stimulated phytoplankton growth. This hypothesis was supported by nutrient-enrichment bioassays performed concomitantly: only when phytoplankton growth was stimulated by nutrient additions, did nitrite accumulate in the water. In the bioassays, the time-course of nitrite accumulation closely paralleled the development of phytoplankton biomass during the incubation period. We therefore suggest that the accumulation of nitrite in the mixed water column during winter is due to excretion by algal cells. Our field and experimental data show that between 10 and 15% of the total amount of nitrogen entering the mixed-water column is released as nitrite by phytoplankton. Further, our field and experimental data support the hypothesis that nitrite excretion by phytoplankton has a significant role in the formation of the deep nitrite maximum (DNM) during stratification in summer. In the bioassays, phytoplankton cells excreted nitrite even when ammonia was the nitrogen source. This indicates a so far unrecognised physiological pathway involved in nitrite excretion by phytoplankton cells. KEY WORDS: Nutrients · Nitrogen species · Nitrite · PhytoplanktonResale or republication not permitted without written consent of the publisher Mar Ecol Prog Ser 239: 233-239, 2002 In the well-oxygenated water column of the Gulf of Aqaba, the dissimilatory reduction of nitrate to nitrite by denitrifying bacteria is likely to be negligible. Thus, we consider the following processes as potentially responsible for the generation and consumption of ambient nitrite in the Gulf of Aqaba: (1) Excretion of nitrite during nitrate reduction, i.e. incomplete assimilatory reduction of nitrate by phytoplankton and bacteria (Vaccaro & Ruyther 1960, Wada & Hattori, 1971, Miyazzaki et al. 1973, Miyazzaki et al. 1975, Kiefer et al. 1976, Herbland & Voituriez 1979, Olson 1981a, Dore & Karl, 1996b, Collos 1998. (2) Ammonium oxidation to nitrite by autotrophic nitrifying bacteria (Brandhorst 1959, Miyazzaki et al. 1975, Olson 1981a,b, Ward 1986, Dore & Karl 1996b, Enoksson et al. 1996. (3) Nitrite assimilation by p...

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“…While samples derived from point sources such as tap water or pore water are relatively straightforward, 84 the sampling of water courses presents a problem in that the nitrite profile will vary considerably with depth and current flow. 33,54,[85][86][87][88] Tidal flushing within deep water will obviously lead to a lower nitrite concentration being recorded than a sample extracted from the upper most layer of a mud sediment where microbial activity will be higher and the immediate water layer less mobile. 34,37 Any aqueous sample must therefore be reconciled with the spatial position, depth and current flow at which it was collected.…”

Section: Sampling Strategiesmentioning

confidence: 99%

“…Additional factors such as temperature, salinity, dissolved oxygen, pH and date/period of sampling will also be required to provide a complete profile of the sample but also to place the nitrite concentration within context. 33,[85][86][87][88] It may well be that high concentrations of nitrite are the result of seasonal fluctuations (increased temperature and light) rather than from anthropogenic sources. 34,87…”

Section: Sampling Strategiesmentioning

confidence: 99%

Current strategies in nitrite detection and their application to field analysisThe opinions expressed in the following article are entirely those of the authors and do not necessarily represent the views of The Royal Society of Chemistry, the Editor or the Editorial Board of JEM.

Dutt

Davis

2002

J. Environ. Monitor.

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The various analytical protocols that have been developed to aid the measurement of nitrite within environmental samples have been critically appraised and their applicability to field measurement assessed. The present communication presents a perspective on current techniques and technologies encompassing spectroscopic, electrochemical and chromatographic methodologies and highlights those that are liable to emerge in the near future. Commercial devices have been included and where appropriate the advantages and limitations posed by their operation within field contexts have been described.

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Nitrogen speciation and nitrification potential in the Skagerrak area during the SKAGEX IV experiment

Cited by 6 publications

References 14 publications

Ecological Studies of Epiphytic Microalgae and Epiphytic Zooplankton on Seaweeds of the Eastern Harbor, Alexandria, Egypt

Ecological Studies of Epiphytic Microalgae and Epiphytic Zooplankton on Seaweeds of the Eastern Harbor, Alexandria, Egypt

Phytoplankton drives nitrite dynamics in the Gulf of Aqaba, Red Sea

Current strategies in nitrite detection and their application to field analysisThe opinions expressed in the following article are entirely those of the authors and do not necessarily represent the views of The Royal Society of Chemistry, the Editor or the Editorial Board of JEM.

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