Ecology 3.docx

Human Impact on an Ecosystem Some of the issues that result from human activity include global warming, reduction in biodiversity, pollution, and the resistance of microorganisms to antibiotics. Biodiversity refers to a large variety of organisms in an ecosystem. When humans interfere, usually to fa...

Human Impact on an Ecosystem Some of the issues that result from human activity include global warming, reduction in biodiversity, pollution, and the resistance of microorganisms to antibiotics. Biodiversity refers to a large variety of organisms in an ecosystem. When humans interfere, usually to farmland, biodiversity is lost. For example, when land is cleared only a small number of crops are grown. These few crops can only support a small number of organisms, which now have a superabundance of food. This can result in the populations of these species swelling to enormous numbers. There are no natural predators so humans will apply insecticides to control the organism. These insecticides kill not only the pest but also many other useful organisms. The effects of the insecticides often spread to adjoining areas, which continues to upset the balance of nature. Pollution is any harmful addition to the environment. Pollutants are the substances that cause the undesirable change. Most pollution arises from human activities such as dumping, sewage disposal, litter, radioactivity, and noise. Natural pollutants include volcanic emissions and smoke from forest fires. Pollution can affect air, freshwater, sea and soil or land. Types of pollution - Domestic pollutions – household wastes - Agricultural pollution – use of sprays to control pests and weeds, overuse of fertilisers, and disposal of farm wastes such as slurry and silage effluent. - Industrial pollution - includes that may cause acid rain and wastes that may damage rivers. Ozone depletion – an example of air pollution **Know in detail** Ozone is a gas (O3) that forms a protective layer above the surface of the earth. It absorbs and shields the earth from incoming UV radiation. Ozone depletion is caused by CFCs e.g., in spray cans, refrigerators, insulating foam and industrial detergents. Some fire extinguishers (halons) and agricultural sprays (fumigants) also destroy ozone, as do emissions from high-flying jets. - Effects of ozone depletion Ozone absorbs harmful UV radiation from sun. Increased UV radiation can: a. damage DNA and cause skin cancer, eye cataracts (lens in the eye lose transparency) and weakened immunity. b. cause serious damage to crops and plant life, c. Plankton may be depleted thus affecting aquatic food chains and less oxygen to breathe. Control of ozone depletion - A reduction in use of CFCs will eventually allow the ozone to be replenished. Ozone is formed by the reaction of UV light with oxygen. - CFCs are now being replaced by HFCs which break down much faster and do not reach the upper atmosphere. - Do not use sprays or foam products that contain CFCs. - Fridges should not be dumped in landfill sites. They should be returned to organisations that will dispose of their CFCs in an environmentally friendly way. Conservation Conservation is the wise management of existing resources to maintain existing populations. Conservation practices in Fisheries **Know in detail** Problems are pollution, overfishing and use of small-mesh nets. -Pollution reduces number of fish in waters. It may take years to replenish. Solution - Reduce pollution which kills fish and prevents migratory fish e.g., salmon from reaching breeding grounds. -Overfishing Solution - Fish quotas are set to ensure that enough fish are left to replenish the stocks Net size Solution - Use large-mesh nets so that young fish can escape and breed. -Monitor the fisheries by: a. Taking and analysing water samples b. Checking fish catches and fishing equipment c. Sampling fish stocks to calculate their numbers. Waste Management Waste Management involves preventing pollution and conserving the environment. Waste Management Practices in Agri Industry **Know in Detail** Slurry – a liquefied waste material produced by animals- contains high levels of nitrogen and phosphorus which cause algal bloom. When these algae die, they are decomposed by bacteria which use up the oxygen in the water depleting it for other plants and animals. This addition of nutrients to fresh water is called eutrophication. By controlling the release of nutrients into rivers and lakes the water quality can be improved. Slurry can also be stored in leakproof pits. This slurry can then be spread out on dry land in the summer as nutrients for plants. Problems associated with Waste Disposal - Vermin: Waste attracts vermin such as rats and gulls. Rate carry disease and destroy food and property. Gull’s droppings carry disease and are a particular problem near airports, where bird strikes can cause damage to planes. - Odours: Dumps have passive odours which are unpleasant for those that live nearby. - Contamination: Waste can contaminate groundwater when unsuitable items are left at dumps. This can make groundwater unsafe to consume. Roles of Microorganisms in Waste Management - Sewage: Sewage is all biological waste produced by humans. It is treated on a local level using domestic septic tanks and on a larger scale by pumping the sewage to treatment plants. It is made safe by biological oxidation using microorganisms to break down organic waste and destroy pathogens. The remnants of these processes are then heat-treated to complete the process before being spread on the land as a fertiliser. - Bioremediation: Uses microorganisms to remove pollution and allow the area to revert to its unpolluted state. For example, breaking down oil spills. Importance of Waste Minimisation It is important to reduce waste to conserve resources. Reduce waste at source i.e., reduce packaging of goods (now a charge on plastic bags in Ireland). Buy loose vegetables and fruit Re-use – reuse carrier bags when shopping, reuse glass bottles, unwanted clothing charities. Recycle – sort household waste and use Bring Banks/Collection Scheme . Using a compost bin for vegetable peelings and garden waste. The compost can be added to soil to improve the growth of plants.