نتایج جستجو برای: nitrogen fixation
تعداد نتایج: 165917 فیلتر نتایج به سال:
Alder plays an important role in the nitrogen (N) economy of boreal forests because of its high capacity for atmospheric N fixation. Range expansion and increased insect and/or pathogen attack are two potential consequences of climate change that may result in significant, albeit opposite, effects on these systems through influences on alder-mediated N inputs. This study contrasted the effects ...
[1] We use a geochemical box model to investigate the changes in marine N-fixation and denitrification required to match the observed sedimentary ı15N changes between 30 kyr B.P. and the late Holocene. This is achieved by optimizing a set of seven parameters that describe the strengths of three ocean-internal N feedbacks and the response of the oceanic N cycle to four external forcings. Scenari...
We report a new synthesis of best estimates of the inputs of fixed nitrogen to the world ocean via atmospheric deposition and compare this to fluvial inputs and dinitrogen fixation. We evaluate the scale of human perturbation of these fluxes. Fluvial inputs dominate inputs to the continental shelf, and we estimate that about 75% of this fluvial nitrogen escapes from the shelf to the open ocean....
Natural nitrogen isotopic composition (δ(15)N) of suspended particulate organic matter (POM) and nitrogen fixation rates via (15)N(2) assay were measured in surface waters along 120° E from 30° N to 30° S in the Asian marginal seas (the East/South China Seas and the Sulu/Celebes/Java Seas) and the northeastern Indian Ocean in November-December 2005 and March 2006. The POM δ(15)N values ranged f...
Hydrogen is a selective inhibitor for nitrogen fixation, the effect in aerobes being one of competition with nitrogen (Wilson, 1951; Rosenblum and Wilson, 1950; Pratt and Frenkel, 1959). Also, carbon monoxide and nitrous oxide are selective fixation inhibitors (Hino, 1955) in Clostridium pasteurianum. The present work was undertaken to provide additional examples of selective inhibitors for nit...
[1] Surface waters in upwelling regions are thought to be nutrient rich and hence inhibit nitrogen fixation (diazotrophy) because diazotrophs can preferentially assimilate nitrate and ammonia instead of expending energy to fix dinitrogen. We found average nitrogen fixation rates to be two to seven times higher in the surface waters of the upwelling region of the eastern equatorial Atlantic than...
On the contrast to the well known, that there are other different genes involved in symbiotic nitrogen fixation in addition to nod, nif and fix genes. In this review we will discuss up to date the function of genes that can play a significant role in symbiotic N fixation such as nodulation, nitrogen fixation, production of 2 exopolysaccharides, Type I to Type VI secretion systems and other diff...
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