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Wyświetlanie 1-2 z 2
Tytuł:
Influence of bacterial activities on nitrogen uptake rates determined by the application of antibiotics
Autorzy:
Tungaraza, C.
Brion, N.
Rousseau, V.
Baeyens, W.
Goeyens, L.
Powiązania:
https://bibliotekanauki.pl/articles/48700.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
bacterial activity
inorganic nutrient
antibiotic
bacteria
nitrogenous nutrient
phytoplankton
Opis:
The influence of bacterial activities on inorganic nutrients has always affected total phytoplankton uptake rates owing to the absence of a reliable method that can exclude these effects. The use of natural samples to determine the contribution of bacterial activities has been based on the size fractionation method which, unfortunately, is encumbered with uncertainties, especially because of the size overlap between bacteria and phytoplankton communities. In this paper, the results are reported of an estimation of bacterial activities by the use of inhibitors (antibiotics). It was shown that the contribution of bacterial activities to the uptake of nitrogenous nutrients was highest for ammonium (79%), followed by nitrate (72%) and urea (62%). In a second set of experiments the concentration of ammonium was raised by 5 μM. This was done to avoid nutrient limitation resulting from the absence of recycled nutrients following the addition of antibiotics and the maximum contribution of bacterial activity to the uptake rate of ammonium increased to 87%. It can be concluded that the use of inhibitors is a good method, a reliable alternative to the fractionation method. However, it is important to note that inhibitors can affect both phytoplankton growth and the nutrient recycling process. Our results indicate that the application of antibiotics had measurable effects not only on the target bacteria but also on the uptake behaviour of phytoplankton. Our observations were therefore limited to the period when there was no effect on the phytoplankton, as was demonstrated by a carbon protein incorporation experiment.
Źródło:
Oceanologia; 2003, 45, 3
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of two models in the estimation of nitrogen uptake rates using data from 15-N incubation experiments
Autorzy:
Tungaraza, C.
Brion, N.
Baeyens, W.
Powiązania:
https://bibliotekanauki.pl/articles/48263.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
marine environment
nitrogen isotope
Elskens' model
phytoplankton
nitrogenous nutrient
comparison
Opis:
This paper compares two uptake rate models, Dugdale & Goering’s (D&G) model and Elskens’ model. The aim is to provide an insight into how estimates of uptake processes, i.e. regeneration and loss rates from both dissolved and particulate nitrogen pools, influence the total uptake rates when the two models are compared. The uptake rates of three nitrogenous nutrients (nitrate, ammonium and urea) from 15-N incubation experimental data were compared. The comparison indicated that the D&G model underestimated nitrate uptake rates by about 34%, implying a significant regeneration and loss rates of the nutrient. Elskens’ model further showed that the loss rates from the dissolved phase were about 40% and 25% for the ammonium and urea pools, respectively, indicating that the D&G model underestimated the experimental uptake rates of the nutrients. On average, nitrification made up about 30% of the total ammonium uptake flux, whereas the sinks from particulate nitrogen and dissolved nitrogen were estimated at 36% and 56%, respectively. The D&G model sometimes overestimated the f-ratio values to about 60% and higher as a result of ammonium and urea uptake rates underestimation. This paper also shows that detritus adsorption, bacterial uptake and cell lysis are equally important processes.
Źródło:
Oceanologia; 2005, 47, 3
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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