Human Impact on the Biosphere
Human activities depleting the ozone layer
Ozone is the layer of O3 molecules (ozone molecules) that surrounds the Earth absorbing harmful UV radiation, preventing much of it from contacting organisms in the biosphere. The loss of ozone is mainly from the accumulation of chlorofluorocarbons, the chemicals used for refrigeration, as propellants in aerosol cans, and in certain manufacturing processes.
Habitat destruction
Deforestation is the clearing of trees, transforming a forest into cleared land. In 2000, only 8% of the original forest remained, in the form of an archipelago of small forest islands. Habitat destruction is brought on by agriculture, urban development, forestry, mining, and environmental pollution.
Exotic species introduced into new geographic regions
New species to an area is that it will disrupt the food chain and contribute to many extinctions. For example, the European Red foxes were introduced for hunting, but by preying on medium sized mammals, foxes have managed to contribute several of these mammals becoming extinct.
Acid Precipitation
The burning of wood and the combustion of coal and other fossil fuels release oxides of sulfur and nitrogen that react with water in the atmosphere. Acid rain affects the nutrient content of soils by causing calcium and other nutrients to leach from the soil. The loss of nutrients affect the health of plants and limit their growth. Fish populations have declined in the thousands of such lakes in Norway and Sweden, where the pH of the water has dropped below 5.4 due to acid rain.
Carbon Cycle/Global warming
Carbon is a ubiquitous element on Earth. Most of the Earth’s carbon is stored in rocks, but this carbon is essentially inert on the 100’s to 1000’s year timescales of interest to humans. The warmth from the sun is returned from Earth to the atmosphere in the form of heat radiation. Adding more CO2 to the atmosphere means more heat radiation is captured by the atmosphere and radiated back to Earth (greenhouse effect). This in turn, leads to Global Warming.
Biological magnification of toxins
What is DDT? DDT are the chlorinated hydrocarbons. DDT has been used to control insects such as mosquitoes and agricultural pests. It was also used in World War II. DDT have been found in nearly every organism tested; it has even been found in human breast milk throughout the world. The first signs that DDT was a serious environmental problem was a decline in the population of pelicans, ospreys, and eagles. The build of DDT in the birds tissues caused the deposition of calcium in their eggshells.
helpful resources
Pictures Cited: https://www3.epa.gov/climatechange/images/basics/factorysmoke.jpg
https://climatechange75.files.wordpress.com/2015/12/p51-1.jpg?w=739
http://www.zo.utexas.edu/faculty/sjasper/images/udl9_51_07a.jpg
http://www.pestsmart.org.au/wp-content/uploads/2014/09/red-fox2cropped-1260x576.jpg
http://www.panna.org/sites/default/files/user1/ddt-spray-beach.jpg
https://climatechange75.files.wordpress.com/2015/12/p51-1.jpg?w=739
http://www.zo.utexas.edu/faculty/sjasper/images/udl9_51_07a.jpg
http://www.pestsmart.org.au/wp-content/uploads/2014/09/red-fox2cropped-1260x576.jpg
http://www.panna.org/sites/default/files/user1/ddt-spray-beach.jpg