Importance of the Nitrogen Cycle, Human Activity and Impact on Environment

The Nitrogen cycle is the central to the biogeochemistry of the Earth, which occupies 79% within the air. Nitrogen is an essential element for plants and animals to grow and to survive. (Soetan, Olaiya & Oyewole, 2010). There are 7 atoms number of symbol of N. The life time of reactive nitrogen in atmosphere and in terrestrial are a few weeks and a few decades respectively. (Fowler et al., 2013) This essay would be focusing on the nitrogen cycle, human activity and impact on environment.

Nitrogen cannot be bio-used directly, which needs to be transferred by different process such as nitrogen cycle include fixation, assimilation, ammonification, nitrification, denitrification and anaerobic ammonia oxidation. Nitrogen fixation is to turn atmospheric nitrogen into a usable fixed form for plants. (Mior, JWB(editor)2011) Assimilation is the process of how plants absorb nitrogen from soil. (Smil, V. 2000) Ammonification is the process of converting organic nitrogen from expels waste to ammonium. Nitrification is the conversion of ammonium to nitrate. Denitrification is the process of turning nitrates to nitrogen gas, which is the final stage of completing the nitrogen cycle. The biological process of anaerobic ammonia oxidation is to convert nitrite and ammonia to molecular nitrogen. (Nitrogen cycle, 2017). For instance, nitrogen gas would process nitrogen-fixing bacteria in soil or root nodules or lightning, hence to become nitrate compounds. Ammonia can also be converted to nitrates after being converted to ammonia(NH3) (Nitrogen fixation) by the Haber process and converted in the soil or break down and return nitrogen to the air. Proteins would be built up after the plants absorb nitrates from the soil and wait for being eaten by animals, and become animal protein. The nitrogenous wastes in animal urine would become ammonia (process of decomposers or ammonification) and back into soil. Furthermore, the bead bodes of organisms would also being beak down to ammonia and back into soil. (BBC, 2006)

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In addition, human activities would change the nitrogen cycle base on different factors. Nitrogen would increase with the increases of fossil fuel combustion. Due to the process, would transfer fixed nitrogen from long-term geological reservoirs to the atmosphere. ( Vitousek, P, et al., 1997) Vitousek, P, et al. in 1997 state that “human activities increased the quantity of organic carbon stored within terrestrial ecosystems; accelerated losses of biological diversity, especially losses of plants adapted to efficient use of nitrogen, and losses of the animals and microorganisms that depend on them; and caused changes in the composition and functioning of estuarine and nearshore ecosystems, and contributed to long-term declines in coastal marine fisheries” Eichner (1990), Schlesinger and Hartley (1992) state that human has impacts on atmosphere and the concentration of volatile NH3 in soils by the agricultural fertilization increases, thus, increase the process of fixed nitrogen and the release more nitrogen gases from soils and groundwater.

Nitrogen is a key element that controlling different facets of the earth. Different level of available nitrogen would affect many original plant species and their predators. Therefore, combustion of fossil fuel and many other human activities that increase the level of nitrogen would have environment consequences. Nitrous oxide(N2O) are contributing to climate change. Nitrous oxide is naturally present in small quantities in the atmosphere, however, human activities are increasing the amount in the atmosphere. Nitrogen occupies a important position on climate change mitigation and adaptation. Although nitrogen can cool the effect on climate change, however, the contribution of aerosols makes greater carbon dioxide due to nitrogen fertilization. Furthermore, N2O is a powerful greenhouse gas that causes stratospheric ozone layer depletion. (“The nitrogen cascade excess nitrogen in the environment.” 2014)
In conclusion, ecosystem have own adjustment function to maintain the conditions precedent of organism. However, human activities, such as fossil fuel combustion, increase the level of nitrogen, thus, cause the influence of biodiversity and damages of ecosystem. Chain reaction occur after a significant rise of biosphere N₂ emissions, for instance: greenhouse gases, accelerated losses of biological diversity and losses of plants adapted to efficient use of nitrogen. Due to human growing population, decreasing the fixation of nitrogen will be a difficult challenge situation in the future. One the other hand, serval ways that can stop the loss of nitrogen from farmland and protect water courses, thus, contributes to plants eutrophication. This type of methods can contribute to the nitrogen-limited waters area. Furthermore, the improvements of the efficiency of burning fossil fuel can also reduce the emissions. The most important factor is to transfer knowledge to developing country.

Reference list

BBC. (2006, September 15). GCSE Bitesize: Nitrogen cycle. Retrieved from BBC, http://www.bbc.co.uk/schools/gcsebitesize/science/add_gateway_pre_2011/greenworld/recyclingrev2.shtml

Fowler D et al. 2013 The global nitrogen cycle in the twenty-first century. Phil Trans R Soc B 368: 20130164. http://dx.doi.org/10.1098/rstb.2013.0164

Nitrogen cycle. (2017, February 15). Retrieved February 18, 2017, from Wikipedia, https://en.wikipedia.org/wiki/Nitrogen_cycle

Schlesinger, W., & Hartley, A. (1992). A global budget for atmospheric NH3. Biogeochemistry, 15(3), . doi:10.1007/bf00002936

Smil,V (2000(. Cycles of life. Scientific American Library, New York

Soetan, K. O., Olaiya, C. O., & Oyewole, O. E. (2010). The importance of mineral elements for humans, domestic animals and plants: A review. African Journal of Food Science, 4(5), 200-222. Retrieved from http://www.academicjournals.org/article/article1380713863_Soetan%20et%20al.pdf

The nitrogen cascade excess nitrogen in the environment. (2014). . Retrieved from http://www.unep.org/yearbook/2014/PDF/chapt1.pdf

Vitousek, P. M. et al. (1997). HUMAN ALTERATION OF THE GLOBAL NITROGEN CYCLE: SOURCES AND CONSEQUENCES. Ecological Applications, 7: 737-750. doi:10.1890/1051-0761(1997)007[0737:HAOTGN]2.0.CO;2