THE EFFECTS OF THE POPULATION EXPLOSION
There are increasing numbers of people on the planet. The world population is currently around 7 billion. Many people demand a better standard of living, so we are using up more raw materials and those that aren't renewable cannot be replaced. When goods are produced, there is a lot of industrial waste. We are producing more waste and the pollution that goes with it. Humans reduce the amount of land available for plants and animals by building, quarrying, farming and dumping waste. The continuing increase of the world's population is affecting the ecology of the Earth. We pollute waterways with sewage, fertiliser and toxic chemicals. We pollute air with smoke and gases such as sulfur dioxide, which contributes to acid rain. We pollute the land with toxic chemicals such as pesticides and herbicides and these can get washed into the water.
LAND AND WATER POLLUTION
People pollute the land in many different ways. Sewage contains human body waste and waste water from our homes. Sewage must be treated properly to remove gut parasites and toxic chemicals or these can get onto the land. Large quantities of household and industrial waste are placed in landfill and toxic chemicals leak out. Farming methods can pollute the land. Herbicides (weedkillers) and pesticides (which kill insects) are poisonous and the poisons sprayed on crops can get into the soil and into the food chain. Eventually they are washed away into rivers. Farmers use chemical fertilisers to keep the soil fertile, and these can also be washed into rivers.
Fertilisers and untreated sewage can leave high levels of nitrates in the water. Toxic chemicals from landfill leak into the water and pollute it, killing organisms such as fish.
Burning fuels can release sulfur dioxide and other acidic gases into the atmosphere. Power stations and cars release acidic gases. The sulfur dioxide dissolves in water in the air, forming acidic solutions. The solutions then fall as acid rain, sometimes a long distance away from where the gases were produced. Acid rain kills organisms and trees are damaged if the leaves are soaked in acid for long periods. Acid rain can change the soil pH, damaging roots and releasing toxic minerals which damage organisms. Enzymes are very sensitive to pH. When trees are damaged, food and habitats for many other organisms are lost.
DEFORESTATION AND PEAT DESTRUCTION
Deforestation is the cutting down of trees. Large scale deforestation in tropical areas is due to the need for timber and to provide land for agriculture. Deforestation has increased the release of carbon dioxide into the atmosphere due to the burning of trees (where the carbon dioxide stored in them is released) or decay of the wood by microorganisms. It has reduced the rate at which carbon dioxide is removed from the atmosphere by photosynthesis and reduced biodiversity due to loss of food and habitats…