scholarly journals Nitrogen Cycle: Impact on Global Environment

2018 ◽  
pp. 42-52
Author(s):  
Yul Ho
Keyword(s):  
Nitrogen Cycle ◽  
Marine Ecosystems ◽  
Global Environment ◽  
Biogeochemical Cycle ◽  
Nitrogen Compounds ◽  
Chemical Forms ◽  
Atmospheric Nitrogen ◽  
Physical Processes ◽  
Schematic Representation ◽  
Multiple Chemical

Schematic representation of the flow of nitrogen through the ecosystem. The importance of bacteria in the cycle is immediately recognized as being a key element in the cycle, providing different forms of nitrogen compounds assailable by higher organisms. The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmosphere, terrestrial, and marine ecosystems. The conversion of nitrogen can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation, ammonification, nitrification, and denitrification. The majority of Earth's atmosphere (78%) is atmosphere nitrogen, making it the largest source of nitrogen. However, atmospheric nitrogen has limited availability for biological use, leading to a scarcity of usable nitrogen in many types of ecosystems.

Oleacin and oleocanthal: Two olive oil bioactives in multiple chemical forms

Planta Medica ◽  
2012 ◽  
Vol 78 (11) ◽  
Author(s):  
T Michel ◽  
A Termentzi ◽  
E Gikas ◽  
M Halabalaki ◽  
AB Smith ◽  
...  
Keyword(s):  
Olive Oil ◽  
Chemical Forms ◽  
Multiple Chemical

scholarly journals Isotopic measurement of atmospheric nitrogen compounds

Tellus ◽  
1974 ◽  
Vol 26 (1-2) ◽  
pp. 169-174 ◽  
Author(s):  
Howard Moore
Keyword(s):  
Nitrogen Compounds ◽  
Atmospheric Nitrogen

Iron-Only and Vanadium Nitrogenases: Fail-Safe Enzymes or Something More?

2020 ◽  
Vol 74 (1) ◽  
pp. 247-266 ◽  
Author(s):  
Caroline S. Harwood
Keyword(s):  
Microbial Community ◽  
Nitrogen Cycle ◽  
Active Sites ◽  
Atmospheric Nitrogen ◽  
Critical Importance ◽  
Community Interactions ◽  
Nitrogen Gas ◽  
Vanadium Nitrogenase ◽  
Fail Safe ◽  
Biological Nitrogen

The enzyme molybdenum nitrogenase converts atmospheric nitrogen gas to ammonia and is of critical importance for the cycling of nitrogen in the biosphere and for the sustainability of life. Alternative vanadium and iron-only nitrogenases that are homologous to molybdenum nitrogenases are also found in archaea and bacteria, but they have a different transition metal, either vanadium or iron, at their active sites. So far alternative nitrogenases have only been found in microbes that also have molybdenum nitrogenase. They are less widespread than molybdenum nitrogenase in bacteria and archaea, and they are less efficient. The presumption has been that alternative nitrogenases are fail-safe enzymes that are used in situations where molybdenum is limiting. Recent work indicates that vanadium nitrogenase may play a role in the global biological nitrogen cycle and iron-only nitrogenase may contribute products that shape microbial community interactions in nature.

scholarly journals The role of air-sea exchange in the marine nitrogen cycle

2006 ◽  
Vol 3 (3) ◽  
pp. 271-280 ◽  
Author(s):  
T. Jickells
Keyword(s):  
Nitrogen Cycle ◽  
Coastal Waters ◽  
Algal Blooms ◽  
Long Range Transport ◽  
Atmospheric Nitrogen ◽  
Ocean Productivity ◽  
Nitrogen Inputs ◽  
Range Transport ◽  
Atmospheric Inputs

Abstract. This contribution to the Spot-On volume considers the magnitude and composition of atmospheric nitrogen inputs to the oceans and then goes on to consider the impacts of these inputs. Effects in open ocean and coastal areas are probably different. Offshore atmospheric inputs may produce a small enhancement of overall ocean productivity and hence CO2 drawdown. In coastal waters atmospheric inputs contribute significantly to overall eutrophication pressure, but evidence that they trigger algal blooms is limited. Management of atmospheric inputs to coastal waters to mitigate eutrophication pressures requires that emissions be managed over a wide area reflecting the efficient long range transport of atmospheric nitrogen. Strategies for management of oxidised and reduced nitrogen deposition will be different reflecting their different rates of deposition.

scholarly journals The role of air-sea exchange in the marine nitrogen cycle

2006 ◽  
Vol 3 (1) ◽  
pp. 183-210 ◽  
Author(s):  
T. Jickells
Keyword(s):  
Nitrogen Cycle ◽  
Coastal Waters ◽  
Algal Blooms ◽  
Long Range Transport ◽  
Atmospheric Nitrogen ◽  
Ocean Productivity ◽  
Nitrogen Inputs ◽  
Range Transport ◽  
Atmospheric Inputs

Abstract. This contribution to the Spot-On volume considers the magnitude and composition of atmospheric nitrogen inputs to the oceans and then goes on to consider the impacts of these inputs. Effects in open ocean and coastal areas are probably different. Offshore atmospheric inputs may produce a small enhancement of overall ocean productivity and hence CO2 drawdown. In coastal waters atmospheric inputs contribute significantly to overall eutrophication pressure, but evidence that they trigger algal blooms is limited. Management of atmospheric inputs to coastal waters to mitigate eutrophication pressures requires that emissions be managed over a wide area reflecting the efficient long range transport of atmospheric nitrogen. Strategies for management of oxidised and reduced nitrogen deposition will be different reflecting their different rates of deposition.

scholarly journals The Warming Climate Aggravates Atmospheric Nitrogen Pollution in Australia

Research ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Yi Sun ◽  
Baojing Gu ◽  
Hans J. M. van Grinsven ◽  
Stefan Reis ◽  
Shu Kee Lam ◽  
...  
Keyword(s):  
Economic Growth ◽  
European Union ◽  
Sustainable Development ◽  
Human Health ◽  
Nitrogen Cycle ◽  
Atmospheric Nitrogen ◽  
The European Union ◽  
Health Cost ◽  
Warming Climate ◽  
The Usa

Australia is a warm country with well-developed agriculture and a highly urbanized population. How these specific features impact the nitrogen cycle, emissions, and consequently affect environmental and human health is not well understood. Here, we find that the ratio of reactive nitrogen (Nr) losses to air over losses to water in Australia is 1.6 as compared to values less than 1.1 in the USA, the European Union, and China. Australian Nr emissions to air increased by more than 70% between 1961 and 2013, from 1.2 Tg N yr-1 to 2.1 Tg N yr-1. Previous emissions were substantially underestimated mainly due to neglecting the warming climate. The estimated health cost from atmospheric Nr emissions in Australia is 4.6 billion US dollars per year. Emissions of Nr to the environment are closely correlated with economic growth, and reduction of Nr losses to air is a priority for sustainable development in Australia.

scholarly journals Box-modeling of the impacts of atmospheric nitrogen deposition and benthic remineralization on the nitrogen cycle of the eastern tropical South Pacific

2015 ◽  
Vol 12 (17) ◽  
pp. 14441-14479
Author(s):  
B. Su ◽  
M. Pahlow ◽  
A. Oschlies
Keyword(s):  
Nitrogen Fixation ◽  
Primary Production ◽  
Atmospheric Deposition ◽  
Water Column ◽  
Nitrogen Deposition ◽  
Nitrogen Cycle ◽  
South Pacific ◽  
Atmospheric Nitrogen Deposition ◽  
Atmospheric Nitrogen ◽  
Model Domain

Abstract. Both atmospheric deposition and benthic remineralization influence the marine nitrogen cycle, and hence ultimately also marine primary production. The biological and biogeochemical relations of the eastern tropical South Pacific (ETSP) to nitrogen deposition, benthic denitrification and phosphate regeneration are analysed in a prognostic box model of the oxygen, nitrogen and phosphorus cycles in the ETSP. In the model, atmospheric nitrogen deposition based on estimates for the years 2000–2009 is offset by half by reduced N2 fixation, with the other half transported out of the model domain. Both model- and data-based benthic denitrification are found to trigger nitrogen fixation, partly compensating for the NO3− loss. Since phosphate is the ultimate limiting nutrient in the model, enhanced sedimentary phosphate regeneration under suboxic conditions stimulates primary production and subsequent export production and NO3− loss in the oxygen minimum zone (OMZ). A sensitivity analysis of the local response to both atmospheric deposition and benthic remineralization indicates dominant stabilizing feedbacks in the ETSP, which tend to keep a balanced nitrogen inventory, i.e., nitrogen input by atmospheric deposition is counteracted by decreasing nitrogen fixation; NO3− loss via benthic denitrification is partly compensated by increased nitrogen fixation; enhanced nitrogen fixation stimulated by phosphate regeneration is partly removed by the stronger water-column denitrification. Even though the water column in our model domain acts as a NO3− source, the ETSP including benthic denitrification might become a NO3− sink.

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