The marine nitrogen (N) cycle controls the productivity of the oceans. This cycle is driven by complex biogeochemical transformations, including nitrogen fixation, denitrification, and assimilation and anaerobic ammonia oxidation, mediated by microorganisms. New processes and organisms continue to be discovered, complicating the already complex picture of oceanic N cycling. Genomics research ha...

In Inner Mongolia, steppe grasslands face desertification or degradation because of human overuse and abandonment after inappropriate agricultural management. The soils in these abandoned croplands exist in heterogeneous environments characterized by widely fluctuating microbial growth. Quantitative polymerase chain reaction analysis of microbial genes encoding proteins involved in the nitrogen...

As crucial terrestrial ecosystems, temperate forests play an important role in global soil carbon dioxide flux, and this process can be sensitive to atmospheric nitrogen deposition. It is often reported that the nitrogen addition induces a change in soil carbon dioxide emission in growing season. However, the important effects of interactions between nitrogen deposition and the freeze-thaw-cycl...

The human alteration of the nitrogen cycle has evolved from minimal in the mid-19th century to extensive in the present time. The consequences to human and environmental health are significant. While much attention has been given to the extent and impacts of the alteration, little attention has been given to those entities (i.e., consumers, institutions) that use the resources that result in ex...

Version 1 of the Community Earth SystemModel, in the configurationwhere its full carbon cycle is enabled, is introduced and documented. In this configuration, the terrestrial biogeochemical model, which includes carbon– nitrogen dynamics and is present in earlier model versions, is coupled to an ocean biogeochemical model and atmospheric CO2 tracers. The authors provide a description of the mod...

Over the last 10 years, during the lifetime of the nitrogen cycle meetings, structural biology, coupled with spectroscopy, has had a major impact of our understanding enzymology of the nitrogen cycle. The three-dimensional structures for many of the key enzymes have now been resolved and have provided a wealth of information regarding the architecture of redox active metal sites, as well as rev...

This paper reviews the current array of complexes of relevance to achieving lanthanide mediated nitrogen fixation. A brief history of nitrogen fixation is described, including a limited discussion of successful transition metal facilitated nitrogen fixation systems. A detailed discussion of the numerous lanthanide-nitrogen species relevant to nitrogen fixation are discussed and are related to t...

Deposition of reactive nitrogen (N) from human activities has large effects on temperate forests where low natural N availability limits productivity but is not known to affect tropical forests where natural N availability is often much greater. Leaf N and the ratio of N isotopes (δ(15)N) increased substantially in a moist forest in Panama between ~1968 and 2007, as did tree-ring δ(15)N in a dr...

the Marine Environment # 2008 16/B978-0-12-372522-6.00035-9 All rig Else hts 1537 1 .1. N itrogen in the preoxygenated world/oceans 1537 1 .2. O xygenation of the early atmosphere: The influence of shelf area and nitrogen fixation rates 1538 2. N itrogen-Fixation, Nitrogenase, and Oxygen. Evolutionary Constraints, Adaptations of Cellular Pathways and Organisms, Feedbacks to Global Nitrogen, Car...