scholarly journals Defoliation Tolerance and Ammonium Uptake Rate in Perennial Tussock Grasses

2004 ◽  
Vol 57 (1) ◽  
pp. 82 ◽  
Author(s):  
Carolina Saint Pierre ◽  
Carlos Alberto Busso ◽  
Oscar Montenegro ◽  
Gustavo D. Rodriguez ◽  
Hugo D. Giorgetti ◽  
...  
Keyword(s):  
Uptake Rate ◽  
Ammonium Uptake ◽  
Tussock Grasses

scholarly journals Defoliation tolerance and ammonium uptake rate in perennial tussock grasses

2011 ◽  
Vol 57 (1) ◽  
Author(s):  
Saint Pierre Carolina ◽  
Carlos Busso ◽  
Oscar Montenegro ◽  
Gustavo Rodriguez ◽  
Hugo Giorgetti ◽  
...  
Keyword(s):  
Uptake Rate ◽  
Ammonium Uptake ◽  
Tussock Grasses

scholarly journals Defoliation tolerance and ammonium uptake rate in perennial tussock grasses

2004 ◽  
Vol 57 (1) ◽  
pp. 82-88
Author(s):  
CAROLINA SAINT PIERRE ◽  
CARLOS ALBERTO BUSSO ◽  
OSCAR MONTENEGRO ◽  
GUSTAVO D. RODRIGUEZ ◽  
HUGO D. GIORGETTI ◽  
...  
Keyword(s):  
Uptake Rate ◽  
Ammonium Uptake ◽  
Tussock Grasses

scholarly journals Crocosphaera as a major consumer of fixed nitrogen despite its capability of nitrogen fixation

2021 ◽  
Author(s):  
Takako Masuda ◽  
Keisuke Inomura ◽  
Taketoshi Kodama ◽  
Takuhei Shiozaki ◽  
Satoshi Kitajima ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Growth Rates ◽  
Uptake Rate ◽  
Ecological Model ◽  
Model Analysis ◽  
Ammonium Uptake ◽  
Fixed Nitrogen ◽  
Potential Significance ◽  
Diazotrophic Cyanobacteria

Crocosphaera watsonii (hereafter Crocosphaera) is a key nitrogen (N) fixer in the ocean, but its ability to consume combined N sources is still unclear. Using in situ microcosm incubations with an ecological model, we show that Crocosphaera has high competitive capability both under low and moderately high combined N concentrations. In field incubations, Crocosphaera accounted for the highest consumption of ammonium and nitrate, followed by pico-eukaryotes. The model analysis shows that cells have a high ammonium uptake rate (~7 mol N (mol N)-1 d-1 at the maximum), which allows them to compete against pico-eukaryotes and non-diazotrophic cyanobacteria when combined N is sufficiently available. Even when combined N is depleted, their capability of nitrogen fixation allows higher growth rates compared to potential competitors. These results suggest the high fitness of Crocosphaera in combined N limiting, oligotrophic oceans, and thus heightens its potential significance in its ecosystem and in biogeochemical cycling.

scholarly journals A geographical and seasonal comparison of nitrogen uptake by phytoplankton in the Southern Ocean

2014 ◽  
Vol 11 (4) ◽  
pp. 1829-1869
Author(s):  
R. Philibert ◽  
H. Waldron ◽  
D. Clark
Keyword(s):  
Southern Ocean ◽  
Primary Production ◽  
Nitrogen Uptake ◽  
Uptake Rate ◽  
Nitrate Uptake ◽  
Day Length ◽  
Ammonium Uptake ◽  
Ammonium Concentration ◽  
Uptake Rates ◽  
The Impact

Abstract. Primary production in the Southern Ocean has been shown to be regulated by light and nutrients (such as silicate and iron) availability. However, the impact of these factors vary seasonally and differ from region to region. The seasonal cycle of primary production in this region is not fully resolved over an annual scale due to the lack of winter in situ measurements. In this study, nitrate and ammonium uptake rates were measured using 15N tracers during a winter cruise in July 2012 and a summer cruise in February/March 2013. In winter, nitrogen uptake rates were measured at 55% and 1% of the surface photosynthetically active radiation (sPAR). The summer uptake rates were measured at 4 light depths corresponding to 55, 30, 10 and 3% sPAR. The integrated nitrate uptake rates during the winter cruise ranged from 0.16–5.20 (average 1.14) mmol N m−2 d−1 while the ammonium uptake rates ranged from 0.6–32.8 (average 6.72) mmol N m−2 d−1. During the summer cruise, the mean integrated nitrate uptake rate was 0.34 mmol N m−2 d−1 with a range between 0.16–0.65 mmol N m−2 d−1. The integrated ammonium uptake rate averaged 5.61 mmol N m−2 d−1 and ranged from 1.44–11.28 mmol N m−2 d−1. The factors controlling primary production in winter and summer were investigated. During the winter cruise, it was found the different nitrogen uptake regimes were not separated by fronts. Light (in terms of day length) and ammonium concentration had the most influence on the nitrogen uptake regime. In the summer, increases in the mixed layer depth (MLD) resulted in increased nitrogen uptake rates. This suggests that the increases in the MLD could be alleviating nutrient limitations experienced by the phytoplankton at the end of summer.

Determination of the impact of toxic inflows on the performance of activated sludge by wastewater characterization

1997 ◽  
Vol 36 (2-3) ◽  
pp. 45-52 ◽  
Author(s):  
A. D. Andreadakis ◽  
C. M. Kalergis ◽  
N. Kartsonas ◽  
D. Anagnostopoulos
Keyword(s):  
Activated Sludge ◽  
Uptake Rate ◽  
Industrial Wastewater ◽  
Treatment Plant ◽  
Domestic Sewage ◽  
Ammonium Uptake ◽  
Rational Approach ◽  
Biomass Characterization ◽  
Inhibition Of Nitrification ◽  
The Impact

A rational approach for the design of the activated sludge process based on wastewater and biomass characterization techniques as applied to the upgrading of the treatment plant of Volos, a city in the central part of Greece, is presented. The study investigates possible nitrification inhibition and carbon inadequacy, due to high salinity, industrial inflows and pre-precipitation by iron salts. The experimentation was carried out by means of batch Ammonium Uptake Rate (AUR) and Nitrates Uptake Rate (NUR) tests. The results show that within the studied range, 900-4000 mg l−1, chlorides did not inhibit nitrification. Contrary to this, the industrial wastewater entering the plant was found to be toxic. With the existing 1:15 ratio of industrial to total wastewater flow a 50% inhibition to the nitrification process was observed, which is higher than the 25 - 30% inhibition caused by typical domestic sewage. Industrial contributions exceeding 20% resulted in complete inhibition of nitrification. With respect to denitrification it was found that the industrial wastewater provided a suitable source of carbon, without any adverse effects on denitrification. Pre-precipitation removed about 25% of the filtered COD, thus reducing the amount of nitrates which could be rapidly denitrified. Design of the biological reactors on the basis of the findings indicate that a significant under-design may result if typical nitrification and denitrification rates obtained from the literature and practice concerning typical domestic sewage are adopted.

scholarly journals A geographical and seasonal comparison of nitrogen uptake by phytoplankton in the Southern Ocean

Ocean Science ◽  
2015 ◽  
Vol 11 (2) ◽  
pp. 251-267 ◽  
Author(s):  
R. Philibert ◽  
H. Waldron ◽  
D. Clark
Keyword(s):  
Southern Ocean ◽  
Nitrogen Uptake ◽  
Uptake Rate ◽  
Nitrate Uptake ◽  
Day Length ◽  
Ammonium Uptake ◽  
Ammonium Concentration ◽  
Atlantic Sector ◽  
Uptake Rates ◽  
The Impact

Abstract. The impact of light and nutrients (such as silicate and iron) availability on nitrogen uptake and primary production vary seasonally and regionally in the Southern Ocean. The seasonal cycle of nitrogen uptake by phytoplankton in the Southern Ocean is not fully resolved over an annual scale due to the lack of winter in situ measurements. In this study, nitrate and ammonium uptake rates were measured using 15N tracers during a winter cruise in July 2012 and a summer cruise in February–March 2013. The winter cruise consisted of two legs: leg 1 extended from Cape Town to the ice margin along the GoodHope line and leg 2 stretched from the ice margin to Marion Island. The summer cruise was mostly focused on the subantarctic zone of the Atlantic sector. In winter, nitrogen uptake rates were measured at 55 and 1% of the surface photosynthetically active radiation (sPAR). The summer uptake rates were measured at four light depths corresponding to 55, 30, 10 and 3% sPAR. The integrated nitrate uptake rates during the winter cruise ranged from 0.17 to 5.20 mmol N m−2 d−1 (average 1.14 mmol N m−2 d−1) while the ammonium uptake rates ranged from 0.60 to 32.86 mmol N m−2 d−1 (average 6.73 mmol N m−2 d−1). During the summer cruise, the mean-integrated nitrate uptake rate was 0.20 mmol N m−2 d−1 with a range between 0.10 and 0.38 mmol N m−2 d−1. The integrated ammonium uptake rate averaged 4.39 mmol N m−2 d−1 and ranged from 1.12 to 9.05 mmol N m−2 d−1. The factors controlling nitrogen uptake in winter and summer were investigated. During the winter cruise, it was found that the different nitrogen uptake regimes were not separated by the fronts of the Antarctic Circumpolar Current (ACC). Light (in terms of day length) and ammonium concentration had the most influence on the nitrogen uptake. In the summer, increases in the mixed layer depth (MLD) resulted in increased nitrogen uptake rates. This suggests that the increases in the MLD could be alleviating nutrient limitations experienced by the phytoplankton at the end of summer.

Uptake of ammonium by four species of macroalgae in Port Phillip Bay, Victoria, Australia

1999 ◽  
Vol 50 (6) ◽  
pp. 515 ◽  
Author(s):  
Stuart J. Campbell
Keyword(s):  
Competitive Advantage ◽  
Nutrient Uptake ◽  
Uptake Rate ◽  
Undaria Pinnatifida ◽  
Ammonium Uptake ◽  
N Availability ◽  
Low Concentrations ◽  
Uptake Rates ◽  
Maximum Uptake Rate ◽  
Saturation Rate

The uptake rates of ammonium were determined for three species of native macroalgae and an exotic macroalga from Port Phillip Bay. All species exhibited rate-saturated mechanisms of uptake described by Michaelis–Menten uptake kinetics. At the highest concentration examined (28.6 µmol NH4-N) Hincksia sordida had a higher rate of uptake (435 µmol NH4 -N g dry wt–1 h–1) than Ulva sp. (108 µmol NH4-N g dry wt–1 h–1) or Polysiphonia decipiens (53 µmol NH4 -N g dry wt–1 h–1). Maximum surge uptake rate was highest for H. sordida and lowest for P. decipiens (802 and 57 µmol NH4 -N g dry wt–1 h–1 respectively). The introduced phaeophyte Undaria pinnatifida had an intermediate capacity for ammonium uptake which was dependent on blade maturity. Differences in the ratio of maximum uptake rate to half-saturation rate between surge and assimilation uptake phases suggest a propensity for some species to take up ammonium at low concentrations. The relationships between nutrient uptake and growth among species would afford mature U. pinnatifida, H. sordida and Ulva sp. a competitive advantage for ammonium uptake in winter during high N availability, whereas P. decipiens would be able to exploit low N concentrations in spring and summer.

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