A pollutant is a substance which causes harm to the environment or humans. Pollutants may be natural, but there has been a constant creation of man-made pollutants since the beginning of industrial production and mechanisation or transport. Here is a list of major pollutants and acronyms.
Chlorofluorocarbon: a group of organic compounds containing carbon (C), chlorine (Cl) and fluorine (F). CFCs were used as refrigerants, solvents and aerosol propellants. Cause of the depletion of stratospheric ozone, the so-called 'ozone hole'. Regulated by the Montreal Protocol (1987), which oversees the phase out and replacement of CFCs by alternatives (HFCs, hydrocarbons, CO2).
Polychlorinated biphenyls are a group of compounds used previously in a broad range of industrial applications, including as a dielectric fluids and coolants in electrical devices, such as transformers, motors, and capacitors. Highly toxic and carcinogenic, and will bio-accumulate. Regulated by the Stockholm Convention on POCs (2001).
Persistent Organic Pollutants. A classification of organic compounds, typically pesticides, herbicides, and similar products, which have long biodegradable half-lives. These pollutants typically transport and bioaccumulate and biomagnify well, and are found in dangerous concentrations of animals, fish and birds far from the source. Regulated by the Stockholm Convention on POPs (2001).
Dichlorodiphenyltrichloroethane. Insecticide now banned in most countries, except in regions of Africa where it is considered the non-use would have consequences (malaria control) that would outweigh the consequences of its continued use. First used during the Second World War to combat insect-borne vectors of malaria and typhus, it was the subject of Silent Spring by Rachel Carson, which exposed the long-term impacts on human health and natural ecosystems of excessive and uncontrolled use of the compound in agriculture. Regulated by the Stockholm Convention on POPs (2001).
Volatile Organic Compound. These have high vapour pressure and low boiling points at room temperature, which results in a high evaporation rate at ordinary ambient temperatures. This is a very broad group, and not all are toxic or undesirable (e.g. perfumes are VOCs). VOCs occur naturally as well as the result of deliberate or unintentional human activities. High doses and prolonged exposure in closed environments may lead to health problems.
The means by which pollution can be reduced include:
Infrastructure means the physical structures and systems which exist. Many problems related to water management are a question of good disposal systems ensuring black and grey water are kept separate from white water. White water is water that is clean enough to drink and use domestically. Grey water is water which cannot be used where hygiene may be affected. There are uses, such as in industry, where grey water may be recycled to some degree. Black water is water that must be processed and disposed of. The obvious case is effluent from toilets, but road run-off, industrial and agricultural waste water would also need to be processed by the same or similar means. Processing of black water occurs through a sewerage treatment plant, which has a series of stages (primary, secondary and tertiary) involving physical filtration, chemical treatment, and biological treatment.
Legislation. This is usually national law, following international guidelines contained in agreements, treaties, and non-binding documents such as Agenda 21. The purpose of environmental law is to ensure that pollution is contained to safe levels, safe for humans and for the environment. The tolerance levels depend on the substance involved and its potential for harm. Hazardous goods are more strictly regulated for storage, use, transport and disposal than other substances, which have limits on concentrations released into the air, water and ground.
Recycling. This is often an economic question, since recycling may involve high energy use for transport and processing. There is a distinction between reuse (e.g. a beer bottle) and the recycling of materials (the used material is processed to make it available for the production of items using the same material: e.g. glass melted down to reuse for bottles, and paper.
Technology. As resources become rare, the market price increases. This drives the search for viable alternatives and technology which reduces waste and recyclability of the resource. Governments often provide funding for innovative research.
Economic incentives: when free market forces do not provide the security of return on investment (ROI), it may be necessary for the public purse to fund research and development of new, cleaner technologies.
As is the case for asbestos, chlorinated paraffins were once used widely in building materials, and need now to be removed under controlled conditions, since if released they can be hazardous to human health and the environment.
CPs are a family of organic compounds which contain chloride, and are polychlorinated n-alkanes. The number of carbon atoms in the chain can vary greatly, so the compounds are sub-divided by chain length: SCCPs = short-chain CPs (10-13 carbon); MCCPs = medium-chain CPs (14-17 carbon); LCCPs = long-chain CPs (>17 carbon). The chain length determines the colour (colourless or light yellow) and state (liquid or solid).
Since their discovery in the 1930s, over 200 CP types have been used as flame retardant, plasticizers, sealants, paints, surface coatings, as additives to metal working fluids, and as a germicide solvent. As a persistent organic pollutant (POP), CPs will bioaccumulate, and are toxic and carcinogenic to rats and mice, and currently are rated by the IARC (International Agency for Research on Cancer) as class 2B (possibly carcinogenic to humans).
SCCPs are under consideration for a global ban under the Stockholm Convention on Persistent Organic Pollutants.
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Leonardo da Vinci's name is synonymous with genius and polymath. The range of his interests and talents seems endless. Despite his many lines of scientific investigation, his work in anatomy and botany was largely lost till rediscovered centuries later.
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