نتایج جستجو برای: nitrogen dynamics

تعداد نتایج: 554220  

Journal: :Science 2008
R Hanson V V Dobrovitski A E Feiguin O Gywat D D Awschalom

Phase coherence is a fundamental concept in quantum mechanics. Understanding the loss of coherence is paramount for future quantum information processing. We studied the coherent dynamics of a single central spin (a nitrogen-vacancy center) coupled to a bath of spins (nitrogen impurities) in diamond. Our experiments show that both the internal interactions of the bath and the coupling between t...

2015
Christopher J. Somes Andreas Oschlies

Dissolved organic nitrogen (DON) and phosphorus (DOP) represent themost abundant formof their respective nutrient pool in the surface layer of the oligotrophic oceans and play an important role in nutrient cycling and productivity. Since DOP is generally more labile than DON, it provides additional P that may stimulate growth of nitrogen-fixing diazotrophs that supply fixed nitrogen to balance ...

2004
HEATHER L . THROOP

Atmospheric nitrogen deposition may indirectly affect ecosystems through depositioninduced changes in the rates of insect herbivory. Plant nitrogen (N) status can affect the consumption rates and population dynamics of herbivorous insects, but the extent to which N deposition-induced changes in herbivory might lead to changes in ecosystemlevel carbon (C) and N dynamics is unknown. We created th...

2010
Harold A. Mooney

Estimating the additional amount of global photosynthetic arbon influx into terrestrial ecosystems (PG) becomes possible with a leaf-level factor (Y) developed by Luo & Mooney only when an increase in atmospheric CO2 concentration (Ca) is small. Applying the Y factor to study long-term stimulation of PG with a large increase in Ca needs understanding of adjustments in leaf properties, canopy st...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 1997
D S Schimel B H Braswell W J Parton

Recent advances in biologically based ecosystem models of the coupled terrestrial, hydrological, carbon, and nutrient cycles have provided new perspectives on the terrestrial biosphere's behavior globally, over a range of time scales. We used the terrestrial ecosystem model Century to examine relationships between carbon, nitrogen, and water dynamics. The model, run to a quasi-steady-state, sho...

2012
Min Chen Qianlai Zhuang

The authors use a spatially explicit parameterization method and the Terrestrial Ecosystem Model (TEM) to quantify the carbon dynamics of forest ecosystems in the conterminous United States. Six key parameters that govern the rates of carbon and nitrogen dynamics in TEM are selected for calibration. Spatially explicit data for carbon and nitrogen pools and fluxes are used to calibrate the six k...

Journal: :Environmental science & technology 2010
Carla Cherchi April Z Gu

This study comprehensively investigated the impact of titanium dioxide nanomaterials (nTiO(2)) exposure on cell growth, nitrogen fixation activity, and nitrogen storage dynamics in the primary producer cyanobacteria Anabaena variabilis at various dose concentrations and exposure time lengths. The results indicated that both growth rate (EC(50)-96 h of 0.62 mgTiO(2)/L) and nitrogen fixation acti...

2016
Johannes Cairns Sebastián Coloma Kaarina Sivonen Teppo Hiltunen

Interactions between nitrogen-fixing (i.e. diazotrophic) cyanobacteria and their viruses, cyanophages, can have large-scale ecosystem effects. These effects are mediated by temporal alterations in nutrient availability in aquatic systems owing to the release of nitrogen and carbon sources from cells lysed by phages, as well as by ecologically important changes in the diversity and fitness of cy...

2017
Claudia Pogoreutz Nils Rädecker Anny Cárdenas Astrid Gärdes Christian Wild Christian R. Voolstra

Microbial nitrogen fixation (diazotrophy) is a functional trait widely associated with tropical reef-building (scleractinian) corals. While the integral role of nitrogen fixation in coral nutrient dynamics is recognized, its ecological significance across different coral functional groups remains yet to be evaluated. Here we set out to compare molecular and physiological patterns of diazotrophy...

2015
Sylvia Gierlinger

Taking an urban metabolism perspective, this article investigates food and feed consumption as well as flows of nitrogen in the city of Vienna during the industrial transformation. It addresses the question of the amount of agricultural products consumed in the city and their nitrogen content, their origin and their fate after consumption. Changes in dietary nitrogen flows in nineteenth century...

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