Soil pollution project, Essays (high school) of Environmental science

Download Soil pollution project and more Essays (high school) Environmental science in PDF only on Docsity! SOIL POLLUTION Definition: Soil pollution is defined as the build-up in soils of persistent toxic compounds, chemicals, salts, radioactive materials, or disease causing agents, which have adverse effects on plant growth and animal health. Soil is the thin layer of organic and inorganic materials that covers the Earth's rocky surface. The organic portion, which is derived from the decayed remains of plants and animals, is concentrated in the dark uppermost topsoil. The inorganic portion made up of rock fragments, was formed over thousands of years by physical and chemical weathering of bedrock. Productive soils are necessary for agriculture to supply the world with sufficient food. There are many different ways that soil can become polluted, such as: • Seepage from a landfill • Discharge of industrial waste into the soil • Percolation of contaminated water into the soil • Rupture of underground storage tanks • Excess application of pesticides, herbicides or fertilizer • Solid waste seepage The most common chemicals involved in causing soil pollution are: • Petroleum hydrocarbons • Heavy metals • Pesticides • Solvents Types of Soil Pollution • Agricultural Soil Pollution i) pollution of surface soil ii) pollution of underground soil • Soil pollution by industrial effluents and solid wastes i) pollution of surface soil ii) disturbances in soil profile • Pollution due to urban activities i) pollution of surface soil ii) pollution of underground soil Causes of Soil Pollution Soil pollution is caused by the presence of man-made chemicals or other alteration in the natural soil environment. This type of contamination typically arises from the rupture of underground storage links, application of pesticides, percolation of contaminated surface water to subsurface strata, oil and fuel dumping, leaching of wastes from landfills or direct discharge of industrial wastes to the soil. The most common chemicals involved are petroleum hydrocarbons, solvents, pesticides, lead and other heavy metals. This occurrence of this phenomenon is correlated with the degree of industrialization and intensities of chemical usage. A soil pollutant is any factor which deteriorates the quality, texture and mineral content of the soil or which disturbs the biological balance of the organisms in the soil. Pollution in soil has adverse effect on plant growth. Pollution in soil is associated with • Indiscriminate use of fertilizers • Indiscriminate use of pesticides, insecticides and herbicides • Dumping of large quantities of solid waste • Deforestation and soil erosion Indiscriminate use of fertilizers Soil Erosion occurs when the weathered soil particles are dislodged and carried away by wind or water. Deforestation, agricultural development, temperature extremes, precipitation including acid rain, and human activities contribute to this erosion. Humans speed up this process by construction, mining, cutting of timber, over cropping and overgrazing. It results in floods and cause soil erosion. Forests and grasslands are an excellent binding material that keeps the soil intact and healthy. They support many habitats and ecosystems, which provide innumerable feeding pathways or food chains to all species. Their loss would threaten food chains and the survival of many species. During the past few years quite a lot of vast green land has been converted into deserts. The precious rain forest habitats of South America, tropical Asia and Africa are coming under pressure of population growth and development (especially timber, construction and agriculture). Many scientists believe that a wealth of medicinal substances including a cure for cancer and aids, lie in these forests. Deforestation is slowly destroying the most productive flora and fauna areas in the world, which also form vast tracts of a very valuable sink for CO2. Pollution Due to Urbanisation Pollution of surface soils Urban activities generate large quantities of city wastes including several Biodegradable materials (like vegetables, animal wastes, papers, wooden pieces, carcasses, plant twigs, leaves, cloth wastes as well as sweepings) and many non-biodegradable materials (such as plastic bags, plastic bottles, plastic wastes, glass bottles, glass pieces, stone / cement pieces). On a rough estimate Indian cities are producing solid city wastes to the tune of 50,000 - 80,000 metric tons every day. If left uncollected and decomposed, they are a cause of several problems such as • Clogging of drains: Causing serious drainage problems including the burst / leakage of drainage lines leading to health problems. • Barrier to movement of water: Solid wastes have seriously damaged the normal movement of water thus creating problem of inundation, damage to foundation of buildings as well as public health hazards. • Foul smell: Generated by dumping the wastes at a place. • Increased microbial activities: Microbial decomposition of organic wastes generate large quantities of methane besides many chemicals to pollute the soil and water flowing on its surface • When such solid wastes are hospital wastes they create many health problems: As they may have dangerous pathogen within them besides dangerous medicines, injections. Pollution of Underground Soil Underground soil in cities is likely to be polluted by • Chemicals released by industrial wastes and industrial wastes • Decomposed and partially decomposed materials of sanitary wastes Many dangerous chemicals like cadmium, chromium, lead, arsenic, selenium products are likely to be deposited in underground soil. Similarly underground soil polluted by sanitary wastes generate many harmful chemicals.These can damage the normal activities and ecological balance in the underground soil Causes in brief: • Polluted water discharged from factories • Runoff from pollutants (paint, chemicals, rotting organic material) leaching out of landfill • Oil and petroleum leaks from vehicles washed off the road by the rain into the surrounding habitat • Chemical fertilizer runoff from farms and crops • Acid rain (fumes from factories mixing with rain) • Sewage discharged into rivers instead of being treated properly • Over application of pesticides and fertilizers • Purposeful injection into groundwater as a disposal method • Interconnections between aquifers during drilling (poor technique) • Septic tank seepage • Lagoon seepage • Sanitary/hazardous landfill seepage • Cemeteries • Scrap yards (waste oil and chemical drainage) • Leaks from sanitary sewers Effects of Soil Pollution Agricultural Applying bio-fertilizers and manures can reduce chemical fertilizer and pesticide use. Biological methods of pest control can also reduce the use of pesticides and thereby minimize soil pollution. Reusing of materials Materials such as glass containers, plastic bags, paper, cloth etc. can be reused at domestic levels rather than being disposed, reducing solid waste pollution. Recycling and recovery of materials This is a reasonable solution for reducing soil pollution. Materials such as paper, some kinds of plastics and glass can and are being recycled. This decreases the volume of refuse and helps in the conservation of natural resources. For example, recovery of one tonne of paper can save 17 trees. Reforesting Control of land loss and soil erosion can be attempted through restoring forest and grass cover to check wastelands, soil erosion and floods. Crop rotation or mixed cropping can improve the fertility of the land. Solid waste treatment Proper methods should be adopted for management of solid waste disposal. Industrial wastes can be treated physically, chemically and biologically until they are less hazardous. Acidic and alkaline wastes should be first neutralized; the insoluble material if biodegradable should be allowed to degrade under controlled conditions before being disposed. As a last resort, new areas for storage of hazardous waste should be investigated such as deep well injection and more secure landfills. Burying the waste in locations situated away from residential areas is the simplest and most widely used technique of solid waste management. Environmental and aesthetic considerations must be taken into consideration before selecting the dumping sites. Incineration of other wastes is expensive and leaves a huge residue and adds to air pollution. Pyrolysis is a process of combustion in absence of oxygen or the material burnt under controlled atmosphere of oxygen. It is an alternative to incineration. The gas and liquid thus obtained can be used as fuels. Pyrolysis of carbonaceous wastes like firewood, coconut, palm waste, corn combs, cashew shell, rice husk paddy straw and saw dust, yields charcoal along with products like tar, methyl alcohol, acetic acid, acetone and a fuel gas. Anaerobic/aerobic decomposition of biodegradable municipal and domestic waste is also being done and gives organic manure. Cow dung which releases methane into the atmosphere, should be processed further in 'gobar gas plants' to produce 'gobar gas' and good manure. Natural land pollution: Land pollution occurs massively during earth quakes, land slides, hurricanes and floods. All cause hard to clean mess, which is expensive to clean , and may sometimes take years to restore the affected area. These kinds of natural disasters are not only a problem in that they cause pollution but also because they leave many victims homeless.