Human influences on the Ecosystem.

The expanding demands of an increasing human population put great pressures on ecosystems. These pressures include the use of space, habitat destruction, use of raw materials and pollution. Some examples include

1. Tropical rain forests removal for agriculture (deforestation)Are exploited for timber and slash and burn agriculture. Soils are thin and poor quality and erode after logging or are exhausted of minerals after a shirt period of use for farming. When abandoned, the forest cannot regrow leading to habitat destruction, extinction of species.Plant roots and the tree canopy are very important in preventing the loss of soil due to wind and rain erosion. Overgrazing and agriculture can create bare areas of soil which will allow soil loss by rain causing flooding and wind rendering the area infertile and the regrowth of tress impossible and the lower rate of photosynthesis causes accumulation of carbon dioxide contributing to global warminghttp://www.landscapeplanet.com/maintenance-1-cause-of-erosion.htmhttp://www.rain-tree.com/facts.htm

2. FloodingMost of Bangladesh is less than 8 meters above sea level. There is a monsoon season, a lack of forests and overgrazing due to human activity and poor infrastructure. This leads to flooding, loss of habitat and loss of human life (200,000+ in 1991)http://www.tulane.edu/~sanelson/geol204/riversystems.htm

3. OceansThe “midnight zone” is the area of deep ocean with no light. It makes up almost 90% of the ocean. There are no plants and the animals present are predators and detritus feeders. Sewage pollution from boats and cities causes bacterial population growth which depletes the oxygen (anoxia) causing the animals to die from lack of oxygen, including part of the Mediterranean off the coast of the Peloponnese.http://library.thinkquest.org/CR0215471/ocean_pollution.htm

4. Eutrophication of riversThe Mississippi river is highly polluted by organic human and animal wastes. This had led to an increase in disease causing coliform bacteria respiring the organic chemicals. In some areas, the bacteria population exceed the permitted amount by 2000 times. There is also a considerable amount of non-biodegradable refuse in the water which kills water birds, often by asphyxiation.http://abcnews.go.com/Technology/mississippi-river-flooding-2011-pollution-waste-water-flood/story?id=13571053

5. Eutrophication due to fertilisersThe run off of nitrate and phosphate agricultural fertilisers into lake water causes considerable plant and algal growth (bloom). When these plants die, they sink to the bottom of the lake and are consumed by saprotrophs which increase in population, thereby using up oxygen. This leads to further die offs and the lake or inland sea (e.g. the Sea of Marmara) becomes anoxic (without oxygen) and unable to support life

http://www.eoearth.org/article/Eutrophication

6. Carbon dioxide and methane accumulationCO2 is formed by respiration and combustion of fossil fuels. It accumulates in a layer in the atmosphere which reflects heat back to the earth thereby causing global warming – “the greenhouse effect”. This can lead to loss of the ice shelf breeding and feeding areas for polar bears and penguins as well as flooding and habitat loss such as the increase in desertification in the Sahel.Methane accumulates in the atmosphere from cattle farming and also has a warming effect

7. Pollution due to pesticides and herbicides.Pesticides (kill pests) are chemicals that also damage animals other than pests. They can bio accumulate (increase in concentration as they rise up the food chain) and then become toxic to predators (e.g. reducing egg shell thickness in hawks) or humans (liver cancer).Herbicides (weed killers) can also have similar effects.Both can run-off into water systems and cause environmental damagehttp://en.wikipedia.org/wiki/Agricultural_pollution

8. Pollution due to nuclear fall-out.Nuclear fall-out is the release of radioactive minerals into the atmosphere or water sources due to power station melt-down or after the use of atomic weapons. The material released can cause death, mutations, cancer and liver damage depending on its potency and may remain in the environment for a considerable period if it has a long half-life. Short half-life materials are more potent but less persistent.http://www.environmentabout.com/799/radioactive-pollution-and-its-effects-on-human-beings

9. Acid rain

Conservationis the maintenance of raw materials, species diversity and habitats. It is of importance because:

Raw materials are in limited amounts and therefore need to be conserved or recycled e.g. aluminium

Species which become extinct or decrease in population may affect other members of the food chain leading to further extinctions or losses e.g. the bee population and pollination

Habitats are the environments in which species exist and they are adapted to theses environments, if they are destroyed, the species cannot survive e.g. bamboo forest/panda.

http://www.teara.govt.nz/en/conservation-a-history/page-1 Water is a resource which is extremely limited in many areas of the world. Conservation

measures can include: recycling of waste water for drinking, agriculture, limited, controlled agricultural watering, minimising domestic use e.g. double flush toilet cisterns, economical washing machines (turn the tap off when you brush your teeth!)

Fossil fuels such as coil, oil were formed millions of years ago by fossilisation and are being utilised and cannot be replaced. Despite controversy, at some point, they will become scarce. Conservation methods include: use of renewable energy sources (e.g. wind, wave, hydroelectric), hybrid cars and greater fuel efficiency e.t.c. There is, however, no form of energy that does not have an environmental cost e.g. the millions of bats and thousands of eagles killed annually by wind turbines.http://www.fort.usgs.gov/BatsWindmills/http://environment.nationalgeographic.com/environment/freshwater/water-conservation-tips/

S Other forms of pollution Non-biodegradable plastics are plastics which decompose extremely slowly, remain in the

environment and can cause damage by poisoning, asphyxiation e.t.c. – watch the video “Midway, a message from the gyre” by Chris Jordan.

Acid rain is caused by burning of fossil fuels. Sulphur is an impurity in oil and coal and forms SO2 on combustion. N2 is 80% of the atmosphere and forms NO and NO2 in the heat and pressure of the internal combustion engine. These gases deposit near the source of pollution or enter the atmosphere. In both cases, they dissolve in water and form acidic strong mineral acids. These acids can damage fish and amphibian eggs, prevent crop growth and damage leaves as well as human eyes and lungs.http://www.epa.gov/acidrain/what/

S Global warmingis thought to be caused by the accumulation of methane (cattle farming, swamps from anaerobic

respiration) and carbon dioxide (combustion of fossil fuels e.g. power stations) which form a layer in the atmosphere that reflects light and heat back towards the earth. The effects of this include: melting of ice-caps (breeding areas for penguins, feeding areas for Polar bears, flooding), desertification (Sahel south of the Sahara) and invasion of pestilential species in more Northern habitats (Nile fever mosquito in the Peloponnese). http://www.nrdc.org/globalwarming/

S Recycling of paper and waste water.are conservation measures to limit forest loss for paper manufacture and limit overuse of water

supplies.

Waste water is filtered to remove debris, allowed to settle (with the addition of Barium sulphate) to remove fine particles, sprayed over stones containing bacteria to respire organic material and chlorinated (or fluoride) to kill bacteria and is then fit to drink or return to water sources.

http://water.epa.gov/learn/kids/drinkingwater/watertreatmentplant_index.cfm

Paper waste is collected, separated into types, washed, pulped, rolled and dried.http://recycling-guide.org.uk/science-paper.html