Thursday, January 21, 2010

Man's effect on the environment

Man has had many far-reaching effects on the environment over the years. Global warming, pollution and the damage to the ozone layer are a few of the major things that can be heard about in the news. Man has damaged the earth gradually over the years and this damage cannot be reversed, we are now trying to stop any more damage being caused to the environment. For example, hedgerows have been destroyed but now people have realised what effects this is having on the environment the government are paying farmers to replant them instead of fencing. Not all of man's effects on the environment are harmful some are beneficial. Conservation work is going on across the country and this is helping to preserve the wildlife and countryside that we have left. The expanding human population has placed a huge demand on the food production of the country. The resources are limited but the population is increasing quite rapidly so the problems are growing. The demand for food means that crops need to be perfect so the use of fertilisers and herbicides is increasing too.

One of the problems in the countryside affecting the environment is the disposal of effluent and other pollutants. The main type of waste that we have to dispose of is organic effluent particularly from farms and sewage works. This is disposed of in several ways, the main one being pumping it into the sea and rivers around the country. In more recent years sewage recycling plants have been developed to reuse the water in the waste. Water treatment works are used to treat the waste before it is pumped into the river or sea.

The disposal of the waste is accomplished in several ways. Direct removal into a stream or lake is the most commonly used means of disposal. In parts of the world that are faced with worsening shortages of water for both domestic and industrial use, authorities are reusing appropriately treated wastewater for, irrigation of non-edible crops, industrial processing, recreation, and other uses. In one such project, the Potable Reuse Demonstration Plant in Denver, Colorado, the treatment process uses normal primary and secondary treatment followed by lime clarification to remove suspended organic compounds. During this process, an alkaline state is created to improve the process. In the next step, re-carbonation is used to bring the pH level to neutral. Then the water is filtered through several layers of sand and charcoal, and ammonia is removed by ionisation. Pesticides and any other dissolved organic materials still present are absorbed by a granular, activated-carbon filter. Viruses and bacteria are then killed by ozonisation. At this stage the water should be cleansed of all contaminants, but, for added reliability, second-stage carbon absorption and reverse osmosis are used, and chlorine dioxide is added to obtain the highest possible water standard.

The other main place that effluent is disposed of from is industry. Industrial plants put their waste into the main drains, because they pump it into the main drains it has to be a particular pH i.e. neutral (between pH6 and pH10). If the pH fluctuates out of this range, there are valves along the main pipe line from the industrial works that close to prevent the effluent leaking into the main sewage system. The pH can then be regulated by either adding caustic soda (an alkaline) or hydrochloric acid to neutralise it again. If the valves did not close and the effluent were allowed to travel into the sewage works then it would kill all the nitrifying and denitrifying bacteria that break down the waste. The bacteria are very sensitive to the chemicals that are used and if these levels fluctuate too much, it will kill the bacteria and the whole decomposition process will be affected. The bacteria remove the ammonia in the effluent. There are filters in the water treatment works that sieve out a lot of the suspended solids and there are chemicals which are added to make the rest of the solids bind together with the help of bacteria so that they come to the surface and can then be filtered off. The water that eventually comes out is pumped from an outlet into the river unless it is to be recycled then it goes on for further cleansing. The effluent that is pumped into the streams gives the decomposers in the water a huge food supply, therefore they use up much of the oxygen and eutrophication - death of the waterway - results. The decomposers deprive the other organisms such as fish and crustaceans of oxygen causing them to die. This in turn affects the whole food chain.

Phosphates are products formed by the replacement of some or all of the hydrogen of a phosphoric acid by metals. Depending on the number of hydrogen atoms that are replaced, the resulting compound is described as a primary, secondary, or tertiary phosphate. Also known as trisodium phosphate, tertiary sodium phosphate is used as a detergent and water softener. Primary and secondary phosphates contain hydrogen and are acid salts. Phosphates are important to metabolism in both plants and animals. Primary calcium phosphate, Ca(H2PO4)2, is an ingredient of plant fertilisers. When it is used as a fertiliser it can be washed into the waterways by the rain and pollute the rivers and streams. Increasing attention has been focused on the environmentally harmful effects of phosphates in household detergents. Detergents containing phosphates are known to be water pollutants because phosphates are a primary nutrient of algae. When algae grows in excess, it can choke a lake or river and draw off needed oxygen from aquatic life. This is called eutrophication

Nitrates are also harmful to the environment. Calcium, sodium, potassium, and ammonium nitrates are used in fertilisers to provide a source of nitrogen for plant growth. If these nitrates get into the water flow then they can, like phosphates, have damaging effects on the life that live there.

Factory chimneys emit Sulphur Dioxide, which has to be monitored. Inside the chimneys are several filters that sift out the solids in the emissions. Sulphur dioxide emitted into the atmosphere by industrial processes is ultimately converted into dilute sulphuric acid, returning to Earth as acid rain. For this reason, sulphur dioxide is a major cause of air pollution. Acid rain is rain with a greatly lowered pH. Oxides of nitrogen are also emitted from car exhausts that also add to the formation of acid rain. The acid rain in turn comes down and erodes buildings and other things. In heavily industrialised areas of America, ladies have reported holes appearing in their tights when rain falls on them. In areas with plenty of limestone rocks, the effects are reduced because the acid reacts with the rocks and neutralises the rain. In areas without limestone, lakes become acidic, leading to the death of the wildlife. Trees are also killed as a direct result of acid rain. Many governments are ignoring the warnings and not controlling the emissions from their industry before it is too late.

Crude oil, known as petrol, is used in the manufacture of fertilisers, medicines, plastic, building materials, paints and to generate electricity. It is also used for the fuelling of transport such as cars and planes. Petrol contains hydrocarbons and sulphur. When the hydrocarbons and sulphur are burned for use they give off sulphur dioxide and carbon dioxide. These gases are harmful to the environment. Sulphur dioxide forms sulphuric acid and causes acid rain, carbon dioxide adds to the greenhouse effect. The greenhouse effect means that the levels of carbon dioxide and other greenhouse gases that usually prevent heat loss from the earth are increasing. This results in raised temperatures on earth leading to partial melting of the polar ice caps. If the ice caps melted too much some countries would be flooded, if they were all to melt then the whole world would be underwater.

There is a need to produce more food for the population and a need to preserve the wildlife and the environment. It is essential to satisfy the needs of the expanding population but it is also essential to preserve the environment. Living organisms are dependent on each other, if a tiny little fungus or algae plants were destroyed then the rest of the food chain would be affected. The algae or fungi are the producers so the primary consumers have nothing to eat so they die and the secondary consumers then have nothing to eat so they die. Plants and can be used for many purposes which is why they are becoming extinct. Drugs have been derived from plants. Genetic variation also decreases with the loss of species and new genes can never be discovered e.g. for crop breeding. The reduction of trees is leading to more carbon dioxide in the air and therefore increasing global warming.

The government is trying to reverse some of the effects man has had on the environment by, for example, paying farmers to replace hedgerows in their fields which had previously been removed to make room for more crops. Factories have to monitor the amount of emissions that come from their chimneys very closely and if they emit too much sulphur dioxide or other harmful chemicals then the factory can be closed down. Factories also have to monitor the amount of chemicals that they pump into the drains, they have to neutralise the effluent before it is pumped into the main drainage system to prevent any chemicals getting into the main sewers and into the rivers and affecting the ecosystem of the rivers. Some waste can be recycled, at the water treatment works they can make the water clean enough, may be not to drink, but to water non-edible crops and for industrial processes and recreation.

Crop rotation is another way in which the land is being preserved a little more. Different crops are being grown in different places so that the same nutrients aren't being used from the same piece of soil every time and therefore the nutrients are being used in equal quantities. The nutrients in the soil then have time to replenish themselves over the years. In addition, natural fertilisers are being used like farmyard manure instead of phosphates and nitrates. This means that the nutrients are released slowly as they decay and therefore improve the structure of the soil.

The human population is expanding rapidly and the demand for food is increasing too. There are limited resources with which to produce this food so therefore the demand is greater then the production. Farmers are under pressure to produce more and more food. The crops they produce all have to be perfect, there can be no waste so herbicides and fertilisers have to be used to maintain the high production rate. The farmland has to be maintained, this is done with regular grazing of cattle to keep eating the grass and with ploughing to prepare the soil for re-use next time. Ploughing removes the plants that would compete with the crop and gives the seedlings the chance to establish themselves quickly and easily. Ploughing also helps to aerate the soil. Harrows are used to break up the lumps of soil and make the surface smooth. This allows the seedling to be planted at a consistent depth. The farmer uses herbicides to control the weeds among the crops, to do this he uses a crop sprayer. To harvest the crops a combine harvester would be used. This cuts down the crop and chops it and then it is pout into a tractor and trailer. Other crops such as potatoes and peas are harvested differently, peas with a pea viner which picks the peas from the rest of the plant. Potatoes are picked using a potato drill. The farmer will then use fertiliser or farmyard manure to replace the nutrients removed by the plants, they would use a muck spreader to do this. Cattle remove nutrients from the soil so it has to be fertilised regularly to maintain the productivity and allow the animals to eat.

The demand on agriculture to increase food production conflicts greatly with the need to protect the environment. Organic crops are becoming more popular as they don't have any fertilisers on them, which affect the environment. Many farmers are turning to organic crops and the government is introducing incentives to try to encourage farmers to grow organic food as it can be expensive. Interest free loans are being introduced for farmers who will convert their dairy farms to organic ones. Oilseed rape crushers have been introduced to produce organic oilseed rape. The oil is destined for human consumption and the by-products are for animal feed. This is to try to encourage organic oilseed rape to be grown in the UK as it is not currently and has to be bought outside the UK. Farmers are being offered money by the EU to meet agri-environmental measures. The scheme has been set up for the next seven years and is designed to improve the environment. Farmers are being paid to convert farmland into woodland. There are increasing fuel prices to try to discourage people from using their cars as much and protect the environment. But these prices are hitting farmers badly, as they can't afford to run their machinery to maintain and harvest their crops. These crops are ultimately our food therefore, the increasing fuel prices to protect the environment are preventing as much food being produced.

Organic food production seems to be a very good idea. It protects the environment as it doesn't involve the use of herbicides and fertilisers and it allows the farmers to carry on producing food in large enough quantities. The government incentives are helping farmers to become established in the organic farming trades. With organic food becoming more popular with the consumer, the demand for organic produce is increasing. Organic food tends to be more expensive as the entire crop isn't perfect but it is environmentally friendly.

Man's effects on the environment are many but the effects are being slowed down and where possible reversed. The consequences of many years of abuse to the earth are being realised and people are trying to do something about it. Tillage operations that prepare the soil for planting and control weeds expose bare soil to possible erosion by wind and water. An example is the Dust Bowl area of the United States. The planting of crops and raising of cattle here left the soil exposed, which led to extensive wind erosion during the 1930s. Erosion removes fertile soil and contributes to problems of air and water pollution. Several techniques are used to combat erosion. Crop rotation is also being increasingly used to hold soil in place between plantings. Still, many small-seeded crops require a finely worked seedbed, and soil erosion cannot be eliminated. The dust bowl cannot be used for crops or cattle now. If crop rotation and other land maintenance did not take place, this would happen to the land in the UK. Global warming is being reduced as much as possible by the reduction of toxic emissions and wastewater is being recycled instead of pumped into rivers and seas. Man is trying to reverse and slow down the effects on the environment although some things cannot be reversed.

References:

Biology Core - Mike Bailey and Keith Hirst

Encarta 98 Deluxe encyclopedia

Comptons Interactive Encyclopedia

Heinemann Advanced Biology - Ann Fullick

Farmers Weekly Aug 2000

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