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  1. 1. Human Impact on the Environment Mary Rodriguez
  2. 2. Mexico
  3. 3. Problems • scarcity of hazardous waste disposal facilities • natural freshwater resources scarce and polluted in north, inaccessible and poor quality in center and extreme southeast • raw sewage and industrial effluents polluting rivers in urban areas • Deforestation • widespread erosion • desertification deteriorating agricultural lands • serious air and water pollution in the national capital and urban centers along US-Mexico border • land subsidence in Valley of Mexico caused by groundwater depletion
  4. 4. Deforestation • • • warming/deforestation-overview/ • Forms: – fires – clear-cutting for agriculture – ranching and development – unsustainable logging for timber – degradation due to climate change • Facts: – The world’s rain forests could completely vanish in a hundred years at the current rate of deforestation – Seventy percent of Earth’s land animals and plants live in forests, and many cannot survive the deforestation that destroys their homes. – Forest soils are moist, but without protection from sun- blocking tree cover they quickly dry out. Trees also help perpetuate the water cycle by returning water vapor back into the atmosphere.
  5. 5. Extinction • • • CAUSES: – Neglect – Excessive hunting – Threatening Conditions in Environment • Animals Become – Vulnerable – Threatened – Endangered – Extinct • It is necessary that the organic and inorganic elements of the environment be in balance. If some being or factor undergoes some type of alteration (absence, mutation, decrease or increase) in the long run, the whole habitat will suffer from it, and in turn, be at risk of disappearing. • Extinct: – The Mexican wolf – The Imperial Woodpecker – The Passenger Pigeon – The Trumpeter Swan – The Elf Owl – The Caribbean Monk Seal • Threatened Species: – The jaguar – The black bear – The Socorro Dove – The Volcano Rabbit – The crocodile – The Harpy Eagle – The Antelope
  6. 6. EXTINCT
  7. 7. Loss of Soil • old/isco99/pdf/ISCOdisc/SustainingTheGlobalFarm/P109-Ventura.pdf • Soil Erosion is a result of intensive maize cultivation on areas with steep slopes • Soil Erosion is a result of deforestation for agriculture • If the rate of erosion exceeds the rate of soil formation (from rock and decomposing organic matter), then the land will become infertile. • Deforestation or other vegetation often leads to serious soil erosion, because plant roots bind soil, and without them the soil is free to wash or blow away,
  8. 8. Flooding • • Deforestation has allowed silt to fill in rivers thereby reducing their capacity and making floods more likely • Causes of Flooding: – The constant extraction of petroleum and gas – the construction of dams in the zone – the erosion of land and deforestation
  9. 9. Water Pollution (Sewage) • • • egion/ • Sewage, manure, and chemical fertilizers, contain "nutrients" such as nitrates and phosphates. Deposition of atmospheric nitrogen (from nitrogen oxides) also causes nutrient-type water pollution. • Direct sources include effluent outfalls from factories, refineries, waste treatment plants etc.. that emit fluids of varying quality directly into urban water supplies. • Indirect sources include contaminants that enter the water supply from soils/groundwater systems and from the atmosphere via rain water. Soils and groundwaters contain the residue of human agricultural practices (fertilizers, pesticides, etc..) and improperly disposed of industrial wastes.
  10. 10. CO2 Build Up • • • Autotrophs draw in Carbon Dioxide for Photosynthesis and with deforestation a great amount of it • The clearing and burning of tropical forests and peat lands releases more than a billion metric tons of carbon • Greenhouse Effect: – Greenhouse gases (CO2) are transparent to incoming solar radiation. This radiation reaches the earth's surface and heats it. Greenhouse gasses trap heat in the atmosphere. As greenhouse gases build up, more heat is trapped in the atmosphere.
  11. 11. AIR POLLUTION • • Exhaust fumes from Mexico City's 3 million cars are the main source of air pollutants • Mexico is home to many assembly plants "maquiladoras" that are responsible for the release of dangerous substances into the environment. • The most important air pollutants of Mexico City are ozone (O3), sulfur dioxide (SO2), precursors like nitrogen oxides (NOX), hydrocarbons (HC), and carbon monoxide (CO), that originate from the incomplete combustion of fossil fuels.
  12. 12. Mexico City Air Pollution