Assignment four.

Factors affecting the Earth and its environment.

 

4.1 The evolution of Earth’s atmosphere.

The early atmosphere.

Scientists believe that the Earth was formed about 4 ½ billion years ago.

The early atmosphere of the Earth was probably formed from the gases given out by volcanoes. It is believed that there was intense volcanic activity for the first billion years of the Earth’s existence. There were also important gases put into the Earth’s atmosphere from the impact of asteroids.

The early atmosphere was probably mostly carbon dioxide, with little or no oxygen. There were smaller proportions of water vapour, and ammonia and methane. As the Earth cooled down, most the water vapour condensed and formed the oceans. The amount of oxygen in the atmosphere has changed quite a lot over the last 600 million years. About 280 million years ago, the amount of oxygen in the atmosphere was 30%, this is a lot higher than the current level of 21%. This high level of oxygen is the reason why we can find giant insects preserved as fossils from that time. These animals cannot exist today, because the amount of oxygen in the air is very much lower.

Many scientists think that the atmospheres of Mars and Venus today, which contain mostly carbon dioxide, very similar to the early atmosphere of the Earth.

Changes in the atmosphere.

What happened to make the amount of carbon dioxide in the atmosphere go down and the amount of oxygen in the atmosphere to go up?

The amount of oxygen went up because of photosynthesis by plants.

The amount of carbon dioxide went down because:

It was locked up in sedimentary rocks, such as limestone and in fossil fuels.

It was absorbed by plants for photosynthesis.

It dissolved into the water of the oceans.

The burning of fossil fuels and is carbon dioxide to the atmosphere faster than it can be removed. This means that the level of carbon dioxide in the atmosphere is increasing.

The very earliest atmosphere of the Earth would have been mostly hydrogen.

The greatest changes in the Earth’s atmosphere over these millions of years, took place because of natural processes.

4.2 The coal industry, its effects on the environment.

The mining of coal causes many effects on the environment, it has a very large effect on the land where the coal is mined, the waste that is produced by the mining causes problems, and water and air are both polluted by taking the coal out of the ground getting it ready to be used and then when it is actually used. When the coal is burned hundreds of millions of tonnes of solid waste is produced this includes ash and a poisonous mud which contains heavy metals such as mercury, thorium, arsenic and uranium.

Air pollution from coal-fired power stations includes sulphur dioxide and nitrogen oxides, particulate matter and heavy metals. This leads to smog, acid rain, toxins in the environment and long and breathing diseases.

The water that flows out of coalmines often has acid in it this can wash into nearby rivers and streams and kill fish and other animals.

Coal fires can happen in abandoned coal mines and coal waste pits. Across the world thousands of underground coal fires are burning now.

The ash that has left behind after coal has been burnt is often stored in deep holes called landfills. As rain trickles through these ash pits poisonous metals are washed out into the local environment.

After it has been mined and before it can be used coal has to be washed. The dirty water left behind is called coal sludge or slurry and is usually placed in ponds near coalmines. As this contains poisonous metals such as lead if it leaks into the local water supply it can cause poisoning to fish and other animals.

In some cases to reach the coal layers the miners will remove the top part of a mountain which can lead to floods.

 

 

 

 

 

 

 

 

 

 

 

4.3 The coal industry, three cures, which is best.

Carbon capture and storage, one of the best ideas for using coal in a clean way, involves keeping hold of the carbon dioxide that is produced by the power stations. Because the carbon dioxide contributes to global warming, if we can find a way to keep hold of the carbon dioxide and not let it out into the environment, it will not contribute to global warming. It uses a method called’ flue gas separation’and this captures the carbon dioxide with a solvent and collects the carbon dioxide into a product which can be sold. Another process is Oxy fuel combustion, this burns the fuel, coal, impure or enriched oxygen atmospheres to create a flue gas composed primarily of carbon dioxide and water. A 3^rd method, pre-combustion capture removes the carbon dioxide before it burned as part of a gasification process. After collecting the carbon dioxide there are 2 options for storage geological and oceanic. Geological storage is a way of injecting carbon dioxide into the Earth, empty oil and gas wells can safely contain carbon dioxide. Ocean storage involves injecting carbon dioxide into the water between 503,000 m deep where it dissolves under pressure.

Of these 3 technologies the Oxy fuel combustion is the one which is closest to being used on a commercial basis and therefore would be the method of choice, the other 2 methods although impressive are still experimental.

 

4.4 The coal industry, remedies, did they work?

Existing methods for cleaning the coal production and coal burning industries are mainly involved with cleaning up the gases produced when the coal is burned. When coal burns it releases carbon dioxide and other gases in what is called ‘flue gas’. Some technologies clean up the coal before it burns. One type of coal preparation, coal washing, removes unwanted minerals by mixing crushed coal with a liquid and allowing the impurities to separate and settle.

Other systems control the coal burn to minimise emissions of sulphur dioxide, nitrogen oxides and particles. Wet scrubbers, also called flue gas desulphurisation systems, remove sulphur dioxide, which is a major cause of acid rain, by spraying the flue gas with a limestone and water. The mixture reacts with the sulphur dioxide to form synthetic gypsum, which is an ingredient in cement.

Low nitrogen oxide burners: these reduce the creation of nitrogen oxides, which causes ground level ozone, they do this by restricting the oxygen supply and controlling the combustion process. Electrostatic precipitator’s remove the small particles that make people’s asthma worse, and this is done by using an electrostatic charge to catch the particles on metal plates.

These technologies have effectively reduced the worst environmental effects and cleaned up the use of coal and the emissions that it produces.

 

 

 

 

4.5 Fishing, its effects on the environment.

The environmental impact of fishing can be divided into issues that involve the availability of fish to be caught such as overfishing, sustainable fisheries, and fisheries management. The 2^nd category involves the impact of fishing on other parts of the environment.

Some kinds of fishing can damage the habitat. Dynamite fishing and cyanide fishing, which are illegal in many places, harm the surrounding habitat. Bottom trawling, the practice of pulling a fishing net along the sea bottom behind trailers, removes up to a quarter of an area’s seabed life in a single run.

Overfishing which is taking more fish from the population than can regenerate, can permanently damage the fish stocks. Overfishing may disrupt food webs by targeting specific, in demand species. There might be too much fishing of prey species such as sardines and anchovies, thus reducing the food supply for the predators. It may also cause the increase of prey species when the target fishes are predator species such as salmon and tuna. Because tuna are large predatory fish, heavy consumption of tuna as opposed to another fish low on the food chain is actually far more stressful for ocean ecosystems. Tunas place in the food chain also means that low tuna numbers in the ocean can lead to population shifts in other species as well.

By catch, this is when the fishing nets bring up species that are not the target species. This can cause great damage to the ecosystem.

 

 

4.6 Fishing, three cures, which is best.

A ban on bottom trawling fishing will remove a great deal of damage to environment.

Careful control of fishing quotas will help to reduce the danger of overfishing.

Fishfarming, has been suggested as the answer to overfishing in the open ocean.

Because fishfarming can have damaging effects on the wild fish, and a ban on bottom trawling is unlikely to work due to its being difficult to enforce, fisheries management policies and quotas to prevent overfishing will be the most successful method.

 

4.7 Fishing, remedies, did they work?

Up to the present date, the most successful policy in preventing overfishing and damage to the environment has been governmental fisheries management policies with quotas on the number of fish that can be taken regulation of net sizes and regulation of fishing grounds.

 

 

 

4.8 Hurricane: its effects on the environment.

Hurricanes can destroy the homes of many thousands of people and communities. They can also have a large effect on the environment especially rivers near the sea and coastal habitats. Hurricanes generates strong winds that can completely destroy forest canopies. They can cause dramatic structural changes in forest ecosystems. Animals can either be killed by the hurricanes or impacted indirectly through changes in habitat and food availability caused by high winds, storm surge and intense rainfall. To give an example, the hurricanes could destroy the trees in the forest which have the food for the animal population, for example nuts and berries. The animals would die from lack of food, not actually being killed by the wind itself.

The wind is not the only thing that can cause the damage from a hurricanes, the large amount of rain that they bring can cause great damage also, for example flooding. This can also be a good thing for some areas, which have a water shortage, the rainfall brought by a hurricanes can be a very welcome thing.

 

 

 

 

 

 

 

 

 

4.9 Hurricane, three cures, which is best?

The most important measures that people can take with regard to hurricanes are attempts to minimise the damage caused by the hurricanes it wins and rainfall.

Early warning systems, these will allow people to evacuate from areas where hurricanes are known to strike or take shelter.

Flood defences, these can be built to prevent rivers overflowing or high tides from coming inland and damaging farm land and property.

Land drainage systems, which allow flood water to escape rapidly from coastal regions so that salty water does not damage farmland.

Without a doubt the most effective of these methods is an early warning system, which in terms of its cost effectiveness alleviates the greatest amount of damage for the smallest amount of money invested.

4.10 Forest fires, its effects on the environment.

Wildfires are a common occurence in some parts of the world. They occur on every continent except Antarctica. They happen most frequently in hot areas where there are extended periods of drought. Fires need heat, fuel (eg. dried out vegetation) and oxygen to continue to burn.  High temperatures can preheat fuels in the fire's path so that they burn more readily. Strong winds can fan the flames, pushing them towards new fuel sources as well as transferring burning embers and sparks which can start spot-fires. During the day, the sunlight heats the ground and warm air rises. When hot air currents travel up sloped landscapes they can cause fires to start.

Primary effects of wildfires

 Loss of life and injury to people and animals who are caught in the flames.

Destruction of property and possessions (this is getting more severe as more and more people live in the urban-rural fringe)

Burning of vegetation and crops.

Huge amounts of smoke released.

 Secondary effects of wildfires

 Health problems for people as a result of the smoke and ash.

Loss of jobs and incomes for agricultural workers whose animals/crops are destroyed.

Decline in the tourist industry, leading to loss of jobs.

Homelessness.

Insurance premiums rise.

Access to recreational areas is restricted.

Soil erosion and landslides because there is less vegetation to bind the soil together.

Loss of habitats for animals may lead to extinction.

 

Forest fuels consist of ground, surface and aerial materials.

Ground fuels lie below the earth's surface eg. tree roots.

Surface fuels include twigs, grasses, wood and needles.

Aerial fuels include tree crowns, branches and hanging mosses.

 

 

4.11 Forest fires, three cures, which is best?

Preventing the wildfires from happening in the first place

 

1. Remove dead leaves and branches from areas at risk of wildfires.

2. Organise controlled burns to remove dead plant material before any fires start.

3. Educate the public about wildfires so they know how to avoid them from startiing.

4.12 Man or nature, which has the biggest effect on the environment?

It is the common understanding of natural environment that underlies environmentalism — a broad political, social, and philosophical movement that advocates various actions and policies in the interest of protecting what nature remains in the natural environment, or restoring or expanding the role of nature in this environment. While true wilderness is increasingly rare, wild nature (e.g., unmanaged forests, uncultivated grasslands, wildlife, wildflowers) can be found in many locations previously inhabited by humans.

Goals commonly expressed by environmental scientists include:

Reduction and clean up of pollution, with future goals of zero pollution;

Cleanly converting non-recyclable materials into energy through direct combustion or after conversion into secondary fuels;

Reducing societal consumption of non-renewable fuels;

Development of alternative, green, low-carbon or renewable energy sources;

Conservation and sustainable use of scarce resources such as water, land, and air;

Protection of representative or unique or pristine ecosystems;

Preservation of threatened and endangered species extinction;

The establishment of nature and biosphere reserves under various types of protection; and, most generally, the protection of biodiversity and ecosystems upon which all human and other life on earth depends.