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Environmental Degradation.docx

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McMaster University
Life Sciences
Luc Bernier

March 11 , 2013 Life Sci 2H03: Environmental Life Sciences Environmental Degradation What is Environmental Degradation? - deterioration of the environment - impacts of disturbance of change in the environment leading to negative impacts - quality of air, soils, sensitive ecosystem (wetlands), wildlife Soil Degradation: Many Causes - over the past 50 years: has reduced global grain production by 13% - serious concern as the global population is increasing - happening at unusually high rates - too much agriculture, overgrazing (supporting growth of live stocks) and deforestation - if we remove the root system of plants there is an acceleration in the rates of erosion Soil Erosion: A Global Problem - top soil (rich in organic material) is disturbed by increasing winds - erosion by the movement of water due to loss of plant cover - sheet erosion - rill erosion carve trenches bringing soils away from areas that require this soil - gully erosion - storm will increase in intensity, higher precipitation and will cause more rill and gully erosion due to more water movement - areas that are expected to become dryer are those that are already dry, wind action Global Soil Erosion - Africa: lead to reduction of 50% of crops if these issues persist - Short fall in crop reduction would become even more problamatic Millions of Acres of Cropland Lost Each Year - between 5-7 million ha of productive cropland lost annually - intensification of agriculture due to increasing population - climate change Salinization and Warming - accumulation of salts in and on the soil to the point that plant growth is suppressed - salt draines the water out of the plants - how can it occur:  conventional irrigation uses a lot of water, there is usually too much water being used  in dry climate the water ends up leaving quickly causing a crust of salt  90% of global consumptive water use is irrigation  land impacted by salinization  soils are no longer usable for crop production  expected to worsen in drier areas Increased Desertification - deterioration of land in arid, semi-arid and dry subhumid areas - loss of more than 10% productivity - wind erosion, water erosion, chemical problems and soil structure problems World Desertification - expected to worsen by climate change - prairies, middle east and Sahara - Sahel: region that is bordering the Sahara desert leading to changes in precipitation - Below is less precipitation - Since the 1960s there is a trend of low precipitation, extended drought has lead to repeated famines (especially in the early 1970s) Freshwater Availability and Ecosystems - less water in certain areas to replenish the flow (discharge) - if there are areas that are creating reservoirs it leads to situations where there is less water availability - expectations in terms of reduced river flows in different river basins in western Europe - occurrence of droughts - impacts on aquatic ecosystems as some species depend on specific water flow - more rain falling in Northern Europe leading to decrease of droughts Smog and Urban Air Quality - industrial smog combined with water vapour in the atmosphere - photochemical smog: reaction between nitrogen oxides and various organic compounds reacting with vapour in the atmosphere and sunlight leads to brown photochemical smog Worldwide Differences in Air Quality - China and India are above WHO air quality s
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