Biogeochemical Cycles - Assignment Example

Biogeochemical cycles A biogeochemical cycle is a cyclical pathway through which all nutrients stream in to the living components from the nonliving and then back to them. Bio means living, geo means rocks and soil and chemical means the involved processes. Out of the gaseous and sedimentary cycles, the two basic types, the former is global. The reason being its major nutrient pools are the atmosphere and the oceans, hence making it so. “The three most important gases for life are nitrogen, oxygen and carbon dioxide. They are present in steady quantities of 78, 21 and 0.03 percents respectively, in atmosphere” (Smith, pp. 475). (Figure: Smith, pp.475) A nitrogen cycle consists of a gas phase and a mineral phase. Since plants require nitrogen as a mineral rather than as gas, they receive their requisite via biological nitrogen fixation, aided by bacteria. Legumes play an important role by giving them a home and transferring the fixed organic nitrogen, thus produced, in the ecosystem through food chains. Animals, for the purposes of energy, breakdown proteins and organic compounds and excretes the ammonium ion form of nitrogen. Either the plants reabsorb it or bacteria convert it into nitrate, hence creating an organic cycle (Nebel and Wright, pp.62-64). (Nebel and Wright, pp.64) “The key processes in a carbon cycle are of respiration and photosynthesis. During the process of respiration, carbohydrates and oxygen in a combination, produces carbon dioxide, water and energy” (Ibanez et al, pp.148-150). Whereas, during the process of photosynthesis, carbon dioxide produces the carbohydrates and oxygen, back again. Besides being liberated by plant, either the carbon remains in them when they die or animals eats plant and respire them back into the atmosphere through respiration. Moreover, either decomposer decompose actively cycled carbon in dead organic matter to release it back in atmosphere or the dead matter stays intact to form coal, oil or natural gas (fossil fuels). As per hydrogen cycle, since, largest reservoir for hydrogen is water; electrons from H2O, H2S and low-molecular weight organic compounds reduce CO2 whereas the electrons from reduced organic compounds travels through the respiratory chain to ultimately form water from dioxygen reduction. Moreover, anaerobic fermentation, photosynthesis and nitrogen fixation produces and releases free gaseous H2 (Ibanez et al, pp.148-150). The life supporting oxygen has three sources, atmosphere, water and carbon dioxide. The atmospheric oxygen has two sources; breakup of water through sunlight into its constituents and the process of photosynthesis. However, some fraction of oxygen present today is a consequence of past disproportion of respiration-photosynthesis that has occurred at some point in the Earth’s history (Smith, pp.490). There are number of ways through which human have been interfering and disturbing these cycles and has resulted in changes in the climate, global warming, depletion of ozone layer, and increase in the oxidative capacity of troposphere etc. Keeling Curve by Charles Keeling, an oceanographer at the Scripps Institute of Oceanography (Harrison, 2009), found that human alterations are highly affecting the natural carbon cycle. About 150 years ago, with the inception of the industrial alterations, the two major activities of human have paced up and unfortunately had lead to the long-term acceleration of atmospheric carbon dioxide. These are burning of fossil fuels and deforestation. Smoldering of fossil fuels liberates carbon into the atmosphere because of the burning of oil and coal. Its speed of releasing carbon into the air is far greater than any means of eliminating it. Such imbalance thus results in concentrated quantities of carbon dioxide. The process of deforestation further worsens the scenario because then the ability of forests to remove CO2 from the atmosphere goes down even more, thereby, also resulting in the same result as in case of burning, that is a net increase of CO2. This is why the amount of carbon dioxide in the atmosphere today is much more than it was half a million years ago. The overall impact of this increase is the ‘green house effect’, because CO2 has the ability to hold heat and cause warmth, therefore another of its name is the greenhouse gas. Moreover, “with an average increase of 0.6 degree C in global temperature, average sea level is likely to rise from 0.09 meters to 0.88meters” (Harrison, 2009), thereby, escalating the probability of severe floods. Yet another resultant of such changes is their impact on the growth patterns of plants all over the world. According to scientists, it is likely that shrubby species are going to raise, reason being they are amongst those plants, which respond favorably to the increased concentration of CO2 (Harrison, 2009). Another factor to lead to the climatic changes is the formation of aerosol clouds. Human use of perfumes and sprays containing chlorofluorocarbons and the production of sulfur gases are the reasons to it (Charlson et al, pp. 355). The chlorofluorocarbons result in ultimate depletion of ozone layer that in turn leads to increased passage for ultraviolet rays to reach humanity on earth thereby accelerating the chances of skin cancer. Besides, the production of sulfur gases results in appearance of its particles in to the air. These cause harmful effects of contributing to the polluting smog, acidic rain, increasing the cause of respiratory diseases (CSUMB, 2009), while also creating a haze layer that reflects radiation from the sun and may result in cooling down of the earth’s surface (CSUMB, 2009). The following figure depicts how the green house effect and arousal/cloud formation affect the different cycles in ecosystem. (Charlson et al, pp.354) Some other factors that have caused irrevocable damage to the ecosystem include pollution and exploitation of natural resources for the sake of money. All types of pollution be it air, water or sound, have harmful effects on the atmosphere. However, the air and water pollution are the lead destroyer because of their direct effects on the livening creatures on earth and water while interfering the biogeochemical cycles. Exploitation of natural resources has also led to the same effects. These have resulted in extinction of both animal and plant species and in fact has wiped out a number of potential herbs and medicines without having been discovered (Think Quest, 2009). Conclusively, the paper has discussed some of the significant aspects of biogeochemical cycles. It is an expectation that the paper will be beneficial for students, teachers, and professionals in better understanding of the topic. Works Cited Biogeochemical cycles, Astrobiology, the living universe. 2009. Retrieved on October 17, 2009: http://library.thinkquest.org/C003763/index.php?page=planet03 Charlson, Robert J., Orians, Gordon H., Wolfe, Gordon V. and Butcher, Samuel S. Human Modifications of Global Biogeochemical Cycles. Global biogeochemical cycles, Vol. 50, 1992, pp.353-358. Ecosystem Services, California State University Monterey Bay. 2009. Retrieved on October 17, 2009: http://essp.csumb.edu/esse/climate/climatebiogeo.html Harrison, John Arthur. The carbon cycle, 2009. Retrieved on October 17, 2009: http://www.visionlearning.com/library/module_viewer.php?mid=95&mcid=&l= Ibanez, Jorge G., Esparza, Margarita Hernandez, Serrano, Carmen Doria & Singh, Mono Mohan. Environmental chemistry: fundamentals. Springer. 2007. Nebel, Bernard J. and Wright, Richard T. Environment science: the way the world works. Prentice Hall, 1993. Smith, Robert. Elements of Ecology. Pearson Education India. 2000. Read More