Human Impact on the Environment.

Page 1

The Atmosphere and Climate Change.

Climate: refers to the long-term weather conditions of an area.

Atmosphere:

made up of nitrogen, oxygen and other gases.

Green house gases:

- Carbon Dioxide and Methane

- Green house gases absorb infrared long wave radiation emitted from the earth and prevents it from escaping back into the atmosphere.

- Known as the green house affect.

The green house effect is important to keep the earth warm enough to sustain life.

The increase in the concentration of the greenhouse gases leads to an 'enhanced green house effect'.

This enhanced greenhouse effect then causes a rise in the average temperature of the earth for a period of time, which then becomes known as 'global warming'.

Carbon Dioxide Increase:

Burning of fossil fuels: Combustion of carbon-rich fuels, such as coal and plants, releases carbon that was stored in them, as carbon dioxide. (used for electricity, power vehicles, and for industrial processes.)

Deforestation: Cutting down trees and removing vegetation decreases the amount of carbon dioxide taken up by plants furing photosynthesis. This then increases the level of carbon dioxide in the air.

Methane Increase:

More landfills: Decaying organic matter and waterlogged soils such as landfills releases methane.

More livestock: Ruminants such as cows release methane gas through their digestive tracts.

Mining of coal.

Increased temperature consequences:

Increased temperature leads to more evaporation, leading to more precipitation, which ultimately leads to a higher threat of flooding.

The melting of glaciers will cause a rise in sea levels, which causes a potential flooding.

Increased wildfires causes more soil erosion, which can lead to desertification.

Species unable to adapt to the high temperature will cause a drop in biodiversity and ultimately desertification.

Droughts can lead to desertification and food insecurity.

Carbon Footprint:

A measure of the total amount of carbon dioxide emissions from an individual, a defined population, or a company per year.

Reduce Carbon Footprint:

- Reuse and Recycle

- Drive less

- Reduce required heating (insulated walls, energy efficiency).

- Carbon offsetting (using alternative energy sources and reforestations to act as carbon reservoirs)

- Technological developments (decrease the dependency of carbon emitting duels/reduce energy required for production)

Ozone layer destruction:

The ozone is a greenhouse gas that is found in a low concentration of 15-50 km above the Earth's surface.

It absorbs the ultraviolet waves from the sun. ( ultraviolet rays can damage dna and cause skin cancer)

The damage of the ozone layer is cause mainly by chemicals known as CFC's (chlorofluorocarbons), which are emitted from refrigerators, aerosol sprays and fast food packaging.

If reduction of damage is not made then:

- Skin cancer will increase.

- Ultraviolet rays will cause permanent eye damage.

Page 2

Water Quality and Water Availability.

It is estimated that 2 billion people will not have sufficient access to clean water by 2050.

Availability:

Factors include:

Construction of Dams: The construction of dams plays a major role in increasing the quantity of water stored and made available for later use by people and agriculture.

Destruction of Wetlands: Wetlands contribute to the availability and quality of water.

Water Wastage:

- A large amount of water, used my irrigation systems, is lost due to poor farming practices.

- Open drain irrigation systems causes a loss of water through irrigation systems.

- The use of water for irrigation systems further up the river causes a decrease in the availability for water uses in the lower river.

- Water can be wasted through leaking taps, toilets and faulty pipelines.

- REDUCED: this can occur by decreasing the pressure of water in the pipelines and educating people to use water wisely by maintaining a good plumbing condition.

Cost of Water:

- The cost of water is influenced by the availability and quality of water.

- The cost per kiloliter (kl) of water increases with the increased use of water. (discouraging waste)

- A certain amount of water is available free to citizens to ensure that even the poorest will have water.

Poor Farming Practices:

- Contamination of water by fertilizers and pesticides has decreased the availability of clean water, thus increasing the cost involved in purification.

- Over-grazing leads to soil erosion. Water then runs off quickly on eroded soil. The water is then not soaked up and used, which leads to wastage.

Droughts and Floods:

- During droughts water availability is decreased and the water from dams during droughts cannot be easily replaced.

- Natural vegetation can hold back water from floods. Therefore if vegetation is removed then flood waters are lost.

Boreholes:

- Boreholes can increase the availability of water in areas where there is no direct access to water.

- Over-use of boreholes can lead to the drying up of aquifers (water-banks for boreholes) which could ultimately lead to a decrease in water availability of water for the future.

Water Recycling:

- Water can be reused! (example, some household water can be used for the garden and sewage water can be restored)

Exotic Plantations:

- Some exotic plants soak up a huge amount of water, thus leaving other vegetation thirsty and depleting water availability.

Water Purification:

- The quality of water can be increased through purification methods. Therefore, undrinkable water can be made drinkable.

Quality of Water:

Factors include:

Eutrophication and algal bloom:

- Fertilizers, pesticides and herbicides used for agriculture can pollute the water of dams, rivers and lakes, which causes eutrophication.

- Eutrophication is when an over growth of algae (algal bloom) occurs due to an increase of nutrients, which depletes the oxygen in the water and ultimately reduces the potential for life in the water.

Thermal Pollution:

- Thermal pollution refers to the heating of water due to the use of water for cooling in power stations and factories.

- This affects the quality of water because heated water has a lower oxygen content, thus reducing the support of life.

Domestic/ Agricultural/ Industry:

- Often water that is used for a domestic purpose contains detergents (washing) or sewage. This water then first has to be treated before it can be used again.

- Water used in industry often contains heavy metals, oils, fertilizers, and heat. This then affects the quality of the water that all life depends on.

- Fertilizers and pesticides can run-off into dams, lakes, and rivers, thus causing pollution of the water.

Mining:

- Water returned from mines is often toxic and acidic. It is also hot, which contributes to thermal pollution.

Alien Plants:

- Alien invasive water plants often blocks waterways for other plants, reducing light for other aquatic plants. These plants then die and decompose. The bacteria then from the decomposed plants depletes the oxygen supply in the water.

Page 3

Food Security

Food security refers to the access of all people to nutritious food for a healthy and productive life.

Factors influencing food security:

Human population growth:

- The human population is increasing at an exponential rate and many countries cannot produce enough food for the growing population.

- Therefore food production needs to correlate with the growth of the population or many countries will suffer from food insecurity.

Droughts and Floods:

- Climate change has caused more frequent droughts and floods.

- Droughts causes crop losses and livestock death, which decreases food availability.

- Floods cause excessive damage and decreases the amount of farmland available to grow crops.

- People often also lose their homes, possessions and economic security during floods and droughts which causes a decrease in food security.

Alien plants and reduction of agricultural land:

- Alien plants deplete topsoil of water and nutrients.

- They out-compete indigenous plants due to no natural predators and invade natural land that could be used to grow crops.

Varieties and Gene Pools:

- Crop plants have replaces wild varieties.

- The preservation of wild varieties is important, because if environmental conditions destroy crop plants then wild varieties can be used as a source of food.

- If wild varieties are wiped out then it will reduce genetic diversity and thus the gene pool.

Genetically Engineered Food:

- Genetic food is produced by Genetically modified organisms (GMO's).

- Genetic engineering involves inserting a desired gene from one organism into another to increase the yield.

- A gene for drought resistance can be inserted in to a crop that grows in areas where water is scarce.

Food Wastage:

- Can occur in storage, production and processing of food.

- Food thrown away and not eaten.

- Food wastage will increase the price of food in a country, which then reduces food security.

Poor Farming Practices:

Mono-culture: Growing of one crop over large areas of land year, after year.

- It depletes nutrients and water, which then impacts negatively on the quality of topsoil.

Pest control: Usage of pesticides against pests that compete with humans for food.

- Pesticides may kill or get into the tissues of the healthy plant, this then reduces crop production and increase the price of food thus decreasing the availability of food to poor consumers.

- Farmers now use biological control, which is using natural predators to get rid of pests. (such as lady bugs)

Topsoil: The top 1.5 meters of soil that contains the nutrients plants require for growth.

- Tiling between planting and heavy rainfall causes much of the topsoil to be lost.

- This decreases the nutrients for the plants to grow, which ultimately decreases the crop yield for plants.

Fertilizers: Both inorganic (chemical) and organic (compost/manure) can be used to increase the nutrients available in the soil and to keep the soil fertile.

- This replaces the nutrients that are lost in the soil when the crops absorb them.

- Fertilizers are often expensive, which increases the price of food, thus decreasing the availability of food to poor consumers.

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Biodiversity

Refers to the variety of plant and animal species on the earth.

Ensures:

food

fresh water

fuels

medicine

climate regulation

controlled floods

disease control (predators eat sick animals)

purified water (wetlands)

seeds dispersed

nutrients cycled

oxygen and soil formation.

ecotourism and recreation

Factors reducing Biodiversity:

Farming Methods:

- Monoculture

* replaces indigenous plants

* Insects invade due to no natural predators

* Intensive use of agrochemicals in the plants and soil run off into the water causing eutrophication.

- Overgrazing

* If livestock is kept in one area for too long, the vegetation grazed on is eaten to such a point that it will no longer grow back.

* Causes soil erosion by removing plants that bind the soil together with their roots.

* Topsoil lost through heavy rainfall, which could lead to desertification causing a loss in biodiversity.

* Sometimes alien invaders use the over-grazed land destroying habitats and taking over the land.

Golf Estates:

- A form of monoculture, which uses land, water, fertilizer, and pesticides.

- Such often runs off into aquatic ecosystems poisoning them.

- Housing often replaces large areas of natural vegetation.

Mining:

- Mining often alters the environment thus affecting the biodiversity.

- Pollutants in the form of dust and smoke are released into the air.

- Natural vegetation is often replaced with rock and wast dumps

- Underground water may be polluted due to the sulphates and heavy metals released into them.

Urbanization:

- Growth of large cities.

- Surfaces are covered with concrete and natural habitats are destroyed.

- Habitat fragmentation then causes the loss of biodiversity.

- Natural plants are often replaced by exotic trees and plants.

Deforestation:

- Permanent destruction of indigenous forests and woodlands areas.

- Caused by human activities such as agriculture, logging, and firewood.

- Destruction of habitats for organisms (insects and frogs) decreasing the biodiversity.

Wetlands and Grasslands:

- Both have unique plants and wildlife, which provides many ecological services to humans

- Destruction of these habitats will drop biodiversity.

Poaching:

- Poaching refers to the illegal hunting of animals. (for food or money)

- Can also apply to plants that are illegally removed and sold for profit. (medicinal plants)

- Many animals are hunted for food and are on the verge of extinction.

- Elephants are killed for their tusks to make carvings and jewelry

- Rhinos are killed for the horns in Far East medicine.

Alien Plant Invasions:

- Plants, which have been introduced into a new area that competes with natural plants in that area.

- Often out-compete the indigenous plants, which decreases biodiversity.

Maintaining Biodiversity:

Control of alien plant invasions:

- Can be controlled by mechanical, chemical and biological methods.

* Mechanical: physically removing them. (time consuming)

* Chemical: Spraying herbicides. (harmful to the environment and expensive)

* Biological: Introducing a natural enemy of the alien plant from it's environment and letting it feed on the invasive plant.

Sustainable use of the environment:

- Using resources without harming the ability for future generations to use it.

- Substances from indigenous plants (devil's claw, rooibos, african potato, hoodia) all have economical and medicinal value.

- Encouraging traditional healers to grow these plants rather than collect from the wild can cause them to be used in a sustainable manner.

- Encouraging traditional healers be become apart of formal medicinal programs can help establish the sustainable use of medicial plants and can encourage consistent training.

- Legislation on a harvest limit should be implemented.

- Seeds of medicinal plants should be collected and distributed to increase plant numbers.

Page 5

Solid Waste Disposal

Solid waste is any solid material that is of no use to humans and which needs to be disposed of in a safe and environmentally friendly way.

Dump-sites:

The most simple and cost-effective way of disposing solid material is burying it in landfill sights.

Landfill site: A hole where solid waste is dumped and then covered by soil.

This causes soil and groundwater pollution, because rain will seep through the waste to form a toxic substance called leachate.

To prevent the leachate from polluting the soil a plastic liner is placed under the dump-site area.

Rehabilitation of a dump-site often occurs before they are closed down.

This involves covering of the old landfill site with clay-soil, which is impermeable to water, and then it is covered with topsoil.

Grasses or other vegetation is then planted and growth stabilizes the area.

It can then be used for recreation (golf, park..etc)

Recycling:

Solid waste can be managed through recycling, re-using and reducing.

Reusing: reusing shopping bags, glass bottles, plastic containers, this reduces waste.

Recycling: A process whereby used materials/waste products are recycled to make new products. (glass, tin, and paper)

Advantage:

- Provides employment

- Reduces the use of raw materials and energy

- Reduces air, ground and water pollution.

Heating and Lighting:

Methane is a gas produced as a result of decomposing organic waste.

This gas can be used as fuel.

Is can be collected from landfill sites and generated into electricity for domestic use. - heat (cooking) and electricity (lighting)

Safe Disposal of Nuclear Waste:

SA uses radioactive material such as uranium to power its nuclear power station at Koeberg in WC.

A by-product of this is then nuclear waste which is radioactive and dangerous.

This is then stored in thick steel drums and buried in trenches at protected sites.