GAC008 Assessment Event 4: Academic Research Essay
Definition: Man-made Environmental Issues
20 September 2013
Question: What is meant by ‘hypoxia’? Explain with reference to the severity of the problem in your own country. In China, as the economy develops rapidly, the environment is going worse and worse because of various pollutions. Hypoxia is one of these. It has been a serious environmental issue that mainly caused by human activities for many decades and may have severe effects to people’s life if people still find no effective ways of dealing with it. Hypoxia occurs when water in a lake, river, or a sea contains low level of dissolved oxygen that cannot sustain the survival of most aquatic animals. It can be caused by many reasons combined. Generally, physical and biological processes and human activities can both result in oxygen depletion, but the process would be far longer when the former one serve as the dominant cause. Hypoxia mainly occurs in estuarine and coastal areas in wet seasons, between May and September. The poor capability of vertical mixing in shallow water leads to the existence of a strong stratification which influence the normal biological processes in water significantly, such as photosynthesis and respiration action. Therefore, the regular nutrient pattern would be changed, and phytoplankton would overgrowth to diminish the oxygen in water, giving rise to the hypoxia. Nevertheless, despite of natural processes, human activities are the chief culprit of water hypoxic pollution. Lots of industrial effluents and leachate from fertilized field that contains abundant chemical elements such as nitrogen and phosphorus flux into rivers or seas and caused a phenomenon called eutrophication, which means nutrient enrichment. Those chemical wastes feed phytoplankton in water as a nutrient and enable them to grow rapidly, eventually sucking out the...
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