The Influence of Human Activity on the Environment

Improvements in agriculture health and medicine have produced a dramatic rise in the human population This increase in population size leads to an increase in pollution and higher demand for the world’s resources

Humans are using up the earth’s resources, including fossil fuels.

Burning fossil fuels in cars and power stations produces carbon dioxide, sulphur dioxide and other greenhouse gases Carbon dioxide traps heat in the atmosphere and causes the temperature of the earth to rise. This leads to disruption of the weather patterns eg drought, floods. Some weeds may thrive on the extra carbon dioxide while other plants are killed

Sulphur dioxide will dissolve in rain producing Acid Rain Acid rain damages trees and pollutes rivers and lakes.

Acid rain causes erosion of buildings and statues particularly if they are made of limestone

Deforestation In may countries people are chopping down forests to provide timber or space for agriculture for the growing population

This causes several problems 1.Burning the timber increases the level of carbon dioxide in the air 2.Less trees means less carbon dioxide absorbed for photosynthesis 3.Soil is eroded as it is exposed to the wind and rain 4.Less water is transpired into the atmosphere 5.Many animal and plant habitats are destroyed causing extinction of species

Intensive Farming Farming has become more intensive to provide a higher % yield from land Many people regard intensive farming of animals to be cruel In order to produce more food from the land farmers have to use more fertilisers and pesticides

Intensive Farming

Problems with Fertilizers Fertilizers enable farmers to grow more food as they are replacing the nutrients removed from the soil by plants However, if too much fertilizer is added and it then rains, the fertilizer finds its way into rivers and lakes This causes the water plants to grow and as there is competition for light, some will die

Bacteria decompose the dead plants and in so doing use up oxygen from the water This means the fish suffocate and die This process is called Eutrophication Raw sewage pumped into rivers has the same effect

Pesticides Pesticides kill insects that will damage crops They also kill harmless insects or can get washed into rivers and pollute the water They may even end up in the food chain

In the 1960s, DDT in the food chain threatened bird populations. Many birds of prey came close to extinction Silent Spring Reading Supplement Activity

Bio magnification DDT becomes concentrated in the tissues of organisms representing four successive trophic levels in a food chain.trophic levels in a food chain The concentration effect occurs because DDT is metabolized and excreted much more slowly than the nutrients that are passed from one trophic level to the next. So DDT accumulates in the bodies (especially in fat). This is why the hazard of DDT to non -target animals is particularly acute for those species living at the top of food chains.

What can we Do?

Organic Farming? This produces less food and is more expensive but it does not produce the pollution problems of intensive farming

Use farmyard manure as a fertilizer and set aside land for growth of wild plants

Biological Control of Pests This means using natural predators to eat pests instead of pesticides It does not have harmful effects

Develop alternative energy sources Conserve our rapidly diminishing fossil fuel reserves by using solar power or wind power

Benefits of conserving endangered species Ecotourism Agricultural benefits Species indicators Maintaining diversity in gene pool

How Does the BP Oil Spill Impact Wildlife and Habitat? Scientists are still assessing the effects of the estimated 170 million gallons of oil that flooded into the Gulf after the explosion of BP's Deep-water Horizon oil rig. More than 8,000 birds, sea turtles, and marine mammals were found injured or dead in the six months after the spill. The long-term damage caused by the oil and the nearly 2 million gallons of chemical dispersants used on the spill may not be known for years. Impacts of the Gulf oil disaster will be unfolding for years, and they will take even longer to understand. IS deep sea drilling worth the cost to our environment? Justify your Answer

Human Impact Matching Brainstorming as many combinations as they can between a human impact (column 1), an ecological community (column 2), and a natural resource (column 3). Describe how the human action impacts the community and how the natural resource is threatened. For example, you might choose “parking lot built with impervious material,” “conifer forest,” and “clean air.” In order to link these together, you could pretend that the parking lot is uphill from the edge of the forest. In the winter, ice trucks spread salt on the parking lot often, and the snow melt runs off down to the forest. Because of osmosis, the tree roots lose too much water to the salty run-off, the trees die, and therefore are not available to filter the air from the city.