Air Pollution And Its Control
* An undesirable change in the physical, chemical or biological characteristics of air, water, land or soil that may have detrimental effect on living organisms is called pollution.
* Substances that bring about such undesirable changes are called pollutants.
* Common air pollutants are automobiles exhausts, chemicals and toxic gases from industries and natural particulate matter such as dist, pollen and ash.
* The Usage of CNG, unleaded and low-sulphur petrol and diesel, catalytic converters and the implementation of stringent pollution level norms can reduce air pollution.
* Noise is also considered as an air pollutant.
Domestic Sewage And Industrial Effluents
* Pollutants entering water bodies are broadly classified as domestic sewage and industrial effluents.
* Domestic sewage is the waste water that drains from houses in a town or city.
* Domestic sewage contains about 99.9 per cent water and 0.1 per cent impurities such as suspended soils, colloidal and dissolved materials.
* Algal blooms, pathogens, thermal waste water and excessive nutrient, pollute water.
* Industrial effluents such as toxic metals, detergents, alcohol and acid pollute water bodies.
* Toxic, non-biodegradable substances get incorporated into the food chain, causing biomagnifications of the toxicant.
* Bio magnification is an increase in the concentration of a toxicant at successive trophic levels.
Integrated Wastewater Treatment
* Water bodies have become receptors of large quantities of domestic sewage and industrial wastes, which contain a variety of pollutants.
* Wastewater is treated in sewage treatment plants in three stages: primary, secondary and tertiary.
* Most cities in the world use a combination of natural and artificial processes for wastewater treatment.
* In Arcata, an integrated wastewater treatment process included the construction of marshlands.
* Ecosan toilets eliminate wastewater generation and are practical hygienic, efficient and cost-effective.
Solid Wastes
* A sanitary landfills is a place where municipal solid wastes are compacted and dumped in a depression or trench.
* Solid wastes include items such as paper, food wastes, plastics, glasses, metals, rubber, leather and textiles.
* Solid wastes must be segregated into three categories: recyclable, biodegradable and non-biodegradable.
* Large-scale use of plastic bags has significantly contributed to environmental pollution as it has choked drain pipes and caused severe land pollution.
* Medical wastes consist of disposable syringes, surgical instruments, tubes, bottles, disinfectants and blood-soaked cotton.
* Electronic waste, commonly known as e-waste, includes irreparable computers and other electronic goods.
* The best way to treat e-waste is to recycle it. However, the process must safeguard human and environmental health.
Degradation of Natural Resources
* Improper resource utilisation has caused soil erosion, desertification , water-logging and soil salinity.
* Desertification is caused by over-cultivation, poor irrigation and unrestricted grazing.
* Agricultural malpractices have caused water-logging and soil salinity.
* Increasing population has caused the conversion of large forest area into agricultural land, thereby causing deforestation.
* In India, in the early twentieth century, forest cover was about 30 per cent, which decreased to 19.4 per cent by the end of the century.
* In the north-eastern states, Jhum cultivation has significantly contributed to deforestation.
* People’s participation plays a vital role in conservation of forests.
Greenhouse Effect And Global Warming
* The greenhouse effect is the heating of the earth’s surface due to greenhouse gases such as carbon dioxide, methane, nitrous oxide and ozone.
* Continuous heating of the earth due to the greenhouse effect has resulted in global warming.
* The rise in the earth’s temperature is resulting in odd climatic changes such as El Nino effect and melting of polar and mountain ice caps.
* The melting of glaciers and snow caps will result in a rise in sea level, which could submerge many coastal areas.
* A reduction in the use of fossil fuels and deforestation can help reduce global warming.
* Optimal utilisation of energy and planting trees can reduce greenhouse gases.
Ozone Depletion
* Ozone is found in low concentrations throughout the earth’s atmosphere but its highest concentration is found in the lower portion of the stratosphere, where it forms the ozone layer.
* The thickness of the ozone in a column of air the ground to the top of the atmosphere is measured in Dobson units.
* In the troposphere, ozone acts as an air pollutant while in the stratosphere, ozone serves as a protective layer.
* The ozone layer is depleting due to CFCs, which are mainly used as refrigerants i air-conditioners, refrigerators and aerosol products.
* A thin layer of ozone, known as an ozone hole, exists over the Antarctic and Arctic regions.
* There are 196 nations who have signed the Montreal Protocol to limit their production of CFCs.
Effects of Agro-chemical and Radioactive Wastes
* Agro-chemical include substances such as fertilisers, pesticides and fungicides, which have harmed our environment.
* Agricultural runoff carries toxic agro-chemicals into water bodies, thereby polluting them.
* Most agro-chemicals are non-biodegradable and are easily incorporated into the food chain, thereby causing bio magnifications of the toxicant.
* Organic farming is a cyclic, zero waste procedures, where waste products from one process are cycled in as nutrients for other processes.
* Radioactive wastes are highly hazardous to living organism and our environment and so their proper disposal is essential.