Soil Pollution

1. Soil Pollution Soil is a thin covering over the land consisting of a mixture of minerals, organic material, living organisms, air and water that together support the growth of plant life. • Sources of soil pollution: • Dumping of domestic and industrial waste on soil surface results into soil pollution. Domestic waste include garbage, rubbish material like glass, plastic, metallic can, paper, fibers etc. • Industrial wastes are effluent discharged from industries and type of contaminant are dependent upon the type of Industry present. For example: paper and pulp industry mostly generate organic waste, Thermal power plant generate fly ash, or precipitate forms during treatment of pollutant gas produced due to combustion processes. • Application of fertilizers and Insecticides into agricultural land are other important category of soil pollution. Persistent pesticides once applied are effective for a long time. However as they do not break down easily they tend to accumulate in the soil and in the bodies of animals in the food chain.

2. Soil also receive excreta from animals and humans. The sewage sludge contain many pathogenic organism, bacteria, viruses and intestinal worm which cause pollution in the soil. • The source of radioactive substances in soil are explosion of radioactive devices, radioactive waste discharged from industries and laboratories, aerial fall out etc. The main isotopes are radium, uranium, thorium, strontium etc. Effects of soil pollution: • Sewage and industrial effluents which pollute the soil ultimately affect human health. One example is Itai-Itai disease which occurs due to consumption of Cd containing rice. The chemical discharge on soil such as acid and alkali also affects the soil fertility. • Some of the persistent toxic chemicals target the non-target organisms, soil flora and fauna and reduced soil fertility. These chemical accumulates in food chain and ultimately affect human health. • Radioactive fallout on soil are source of radio-isotopes which enter the food chain. Some of these replace essential elements in the body and cause abnormalities. Example: strontium-90 instead of calcium gets deposited in the bones and tissue.

3. Nitrogen and phosphorous from fertilizers in soil reach nearby water bodies with agricultural run-off and cause eutrophication. • Control of Soil Pollution: • Effluent should be properly treated before discharging them on the soil. • Solid waste should be properly collected and disposed off by appropriate method. • Biodegradable organic waste( cattle waste, human faeces) should be used for generation of biogas. • Microbial degradation of biodegradable substances is also employed for reducing soil pollution.

4. Nuclear Hazards Radioactive substances undergo natural radioactive decay in which unstable isotopes spontaneously give out fast moving particles, high energy radiation or both, at fixed rate until a new stable isotope is formed. The isotopes release energy either in the form of gamma rays high energy electromagnetic radiation), or ionization particles i.e. alpha particles and beta particles.

6. Penetrating power of alpha, beta and gamma particle

7. Sources of Radioactivity: It can be both natural or man made sources: 1) Natural sources: It includes cosmic rays from outer space, radioactive radon-222, soil, rocks, air, water and food , which contain one or more radioactive substances. 2) Anthropogenic sources: It includes nuclear power plants, nuclear accidents, nuclear weapon testing, X-rays, diagnostic kits, research laboratories etc. • Effect of Radiations: Ionization radiations can affect living organisms by causing harmful changes in body cells and also damage at genetic level. • Genetic damage: It includes mutation in the DNA, thereby affecting genes and chromosome. The damage can be transmitted up to several generation. • Somatic damage: it includes burns, miscarriage, eye cataract and cancer of bone, thyroid, lungs and skin. Example: Radioactive iodine (I131) accumulates in thyroid gland and causes cancer. Strontium-90 accumulates in the bones and causes leukemia or cancer of bone marrow.

8. The damage cause by different type of radiation depends on the penetration power. The Alpha particles cannot penetrate the skin to reach internal organs whereas beta particles can damage the internal organs. • Greater threat is posed by radioisotopes with intermediate half-lives as they have long time to find entry inside the human body. • The radioactive material present in the earth crust or fall down as dry deposition from atmosphere enters the crop grown there and ultimately in Human beings. Radionuclide enters the water bodies such as ground water by coming in contact with the radionuclide bearing rocks. • Control of Nuclear Pollution: • Siting of nuclear power plants should be carefully done after studying long term and short term effects. • Proper disposal of wastes from research laboratory and hospital involving in the use of radioisotopes should be done. • Complete ban on Nuclear weapon testing should be imposed.

9. Solid waste management • Change in the standard of living of ever increasing population has resulted in an increase in the quantity and variety of waste generated. Management of solid waste has, therefore become very important in order to minimize the adverse effect of solid wastes. Solid waste( waste other than liquid and gaseous) can be classified as municipal (MSW), industrial, agricultural, mining waste and sewage sludge. • Sources of solid waste: • Waste from homes( Domestic waste) : It can contain food waste such as vegetable and meat material, left over food, egg shells, etc which is classified as wet garbage as well as paper, plastic, tetrapacks, plastic cans, newspaper, glass bottles, cardboard boxes, aluminum foil, metal items, wood pieces, etc. which is classified as dry garbage. • Biomedical waste: It includes anatomical wastes, pathological wastes, infectious waste etc.

10. 3) Construction/ demolition waste: includes debris and rubbles, wood, concrete etc. 4) Horticulture waste and waste from slaughter houses: include vegetable part, residual and remains of slaughtered animals, respectively. The MSW can be divided into biodegradable wastes( that can be degraded by micro-organism) and non-biodegradable wastes( can not degrade). 5) Industrial waste: The type of waste generated varies depending upon the type of industry for example: Mining industry solid waste will contain loose earth material, Thermal power plant will produce solid waste in form of fly ash and slurry produce during the treatment of flue gas. In Europe and North America the environmental laws are very strict regarding solid waste disposal, thereby these countries started exporting their solid waste to less developed countries like Asian and African countries for dumping.

11. Effects of Solid waste: Municipal solid wastes heap up on the road due to improper disposal system. These type of dumping allows biodegradable materials to decompose under uncontrolled and unhygienic conditions. This produces foul smell and breeds various types of insects and infectious organisms besides spoiling the aesthetics of the site. Industrial solid wastes are sources of toxic metals and hazardous wastes, which may spread on land and can cause changes in physico-chemical and biological characteristics thereby affecting productivity of soils. Toxic metals can also leach or percolate to contaminate the ground water. If MSW get mixed with industrial waste , this make segregation and disposal of waste very difficult. Burning of some of the solid material produce dioxins, furans and polychlorinated biphenyls, which have the potential to cause various type of ailments including cancer.

12. Management of solid waste: An integrated waste management strategy includes three main components. For waste management stress is on three R’S’- Reduce, reuse and recycle before destruction and safe disposal of solid waste. 1) Source reduction: is one of the fundamental ways to reduce waste. This can be done by using less material when making a product, reuse of products on site, designing products or packaging to reduce their quantity. On an individual level we can reduce the use of unnecessary items while shopping, buy items with minimal packaging, avoid buying disposable items and also avoid asking for plastic carry bags. 2) Recycling of materials: is reusing some components of the waste that may have some economic value. Metal, paper, glass and plastics are recyclable. Mining of new aluminum is expensive and hence recycled aluminum has a strong market and plays a significant role in the aluminum industry. Paper recycling can also help preserve forests as it takes about 17 trees to make one ton of paper. Crushed glass (cullet) reduces the energy required to manufacture new glass by 50 percent. The problems associated with recycling are either technical or economical.

13. Collection, sorting and transport account for about 90 percent of the cost of paper recycling. The processes of pulping, deinking and screening wastepaper are generally more expensive than making paper from virgin wood or cellulose fibers. • 3) Disposal: It is done most commonly through a sanitary landfill or through incineration. • Sanitary landfill: is a depression in an impermeable soil layer that is lined with an impermeable membrane. The three key characteristics of a municipal sanitary landfill that distinguish it from an open dump are: • Solid waste is placed in a suitably selected and prepared landfill site in a carefully prescribed manner. • The waste material is spread out and compacted with appropriate heavy machinery. • The waste is covered each day with a layer of compacted soil.

14. The problem with older landfills are associated with groundwater pollution. Pollutants seeping out from the bottom of a sanitary landfill (leachates) very often percolate down to the groundwater aquifer. Advanced sanitary landfill sites are equipped with suitable bottom liners and leachate collection systems along with the installation of monitoring systems to detect groundwater pollution. it has become increasingly difficult to find suitable land filling sites that are within economic hauling distance and very often citizens do not want landfills in their vicinity.

15. Incineration: is the process of burning municipal solid waste in a properly designed furnace under suitable temperature and operating conditions. For complete oxidation the waste must be mixed with appropriate volumes of air at a temperature of about 815o C for about one hour. Incineration can reduce the municipal solid waste by about 90 percent in volume and 75 percent in weight. The risks of incineration however involve air quality problems and toxicity and disposal of the fly and bottom ash produced during the incineration process. Vermicomposting: Vermicomposting is a simple biotechnological process of composting, in which certain species of earthworms are used to enhance the process of waste conversion and produce a better end product. It is a mesophilic process, utilizing microorganisms and earthworms that are active at 10–32°C. The process is faster than composting; because the material passes through the earthworm gut, a significant transformation takes place, whereby the resulting earthworm castings (worm manure) are rich in microbial activity and plant growth regulators, and fortified with pest repellence attributes as well!