After reading this article you will learn about:- 1. Effects of Chemicals 2. Types of Chemicals 3. Life Cycle.
Effects of Chemicals:
1. Chemicals Pollutants to the Soil:
Contamination of soil by various metallic and non-metallic chemicals is very common. Soil contamination by fluoride and manganese, however, becomes serious with persistent chemicals especially when they are used for a number of years.
Residues of chemicals may have adverse effects on soil micro-organisms and could perhaps affect the soil fertility as well moreover crops which are grown in contaminated soil also contain residue chemicals and thus become unfit for human and animal consumption.
Chemical pollution in soil can be caused by overuse of fertilizers, pesticides and herbicides construction & demolition sites all are sources of soil pollution, as are mines landfills and foundries.
2. Pollution of Water due to Chemicals:
Fluoride, Manganese, Barium, Cadmium, antimony & many other substances are carried into water bodies in various ways. They contaminate both surface and ground water, Contamination of water occurs as a result of aerial spraying of chemicals on cultivated areas by move from soil to water, movement in drainage, surface run off, blowing of surface dust by effluents of chemicals manufacturing plants.
Pesticides and fertilizers that contain nitrates and phosphate are source of chemicals that cause water pollution. These chemicals go into the groundwater by various methods and mix with runoff moving to lakes and rivers.
Nitrates in drinking water are chemical hazards. Certain bacteria’s in intestinal canal can convert them into nitrites which after reaching the blood destroy the oxygen carrying capacity of hemoglobin in red blood corpuscles. Infants whose food happen to be made up with such water have been found to suffer vary badly and even die of asphyxia.
Industrial emissions can also cause water pollution. An example is mercury in waste water from paper industry. The mercury reacts on bacteria in the water and changes to methyl mercury which enters into fish such as swordfish, and can pose danger to people who eat it.
Fluoride in water causes fluorosis in men. It also creates stomach ailments and mental disorders while manganese salts generate eye blindness in human beings. Fluoride and manganese salts also affect in growth and development of plants and make them more susceptible to chemical attack.
A major source of chemical pollution in air is fossil fuels burnt in like utilities, industries and motor vehicles. Sulphur dioxide is produced when coal is burnt. It is an ingredient to acid rain and can cause lung damage to people who breathe large amount of it. Motor vehicles such as cars, trucks and airplanes- produce nitrogen oxides (NOx) as byproduct which also causes acid rain and lung damage to people. Other chemicals that cause air pollution include ozone, carbon monoxide and lead.
3. Growing Soil Erosion:
The presence of chemicals in soil and other factors have affected soil erosion problems in 90 million hectares of land. The amount of soil displaced by water erosion is of the order of 60,000 million tonnes per year. The genesis of erosion lies in the destruction of natural vegetation cover of soil by chemicals beside over felling and over-grazing.
It is the time when we should think, plan and act ecologically. If it is done, we will also anticipate most of the ramification and consequence following the land resource use technologically. We should also create awareness among people about hazardous chemicals. We must start environmental studies in our schools and colleges and they only can check the pollution of Indian rivers and soils.
4. Effects on Man and Plants:
Every human being is subjected to contact with dangerous chemicals every moment. These offensive chemicals have been found to cause headache, vomiting, blindness along with skin, lever, heart and kidney troubles. They affect necrosis in interventional areas and skeletonize the leaves.
Types of Chemicals:
1. Toxic Chemicals:
Chemicals having the following values of actual toxicity and which owing to their physical and chemical properties are capable of producing major accident hazards:
2. Flammable Chemicals:
(i) Flammable gases:
Gases which at 20°C and at standard pressure of 101.3 Kpa are ignitable when in a mixture of 13 percent or less by volume with air.
(ii) Extremely flammable liquids:
Chemicals which have flash point lower than or equal to 23°C and boiling point less than 35°C.
(iii) Very highly flammable liquids:
Chemicals which have a flash point lower than or equal to 23°C and initial boiling point higher than 35°C.
(iv) Highly flammable liquids:
Chemicals which have a flash point lower than or equal to 60°C but higher than 23°C.
(v) Flammable liquids:
Chemicals which have a flash point higher than 60°C but lower than 90°C.
Explosives means a solid or liquid or pyrotechnic substances (or a mixture of substances) or an article which is in itself capable by chemical reaction of producing gas at such a temperature and pressure and at such a speed as to cause damage to the surroundings.
Life Cycle of Chemicals:
Chemicals that enter the environment usually do so as wastes or as byproducts, and as such are mixed with other chemicals. They may interact when they are mixed in an additive, synergistic or antagonistic way. They may produce breakdown products, by-products or react to form new substances in the waste stream or in the environment.
Pollution does not recognize national borders. Priority pollutants which tend to persist in the environment for long periods and can therefore be transported long distances, have led to growing international action on priority pollutant control.
Government, regulatory agencies and industrial initiatives have recognized a hierarchy of approaches to priority pollutant control:
Use another, more environmentally friendly chemicals
Use as little of the priority pollutants as possible
Use in a carefully managed way to minimize accidental or adventitious loss and waste
Preventing pollution of the environment by chemicals is very complex as chemicals are released and can enter into the environment at any stage from development and testing, through manufacture, storage and distribution through to use and finally disposal.
Release of chemicals into the environment can broadly be categorized into:
(a) Point source release and
(b) Diffuse or non-point source release.
Controls have been made in the past, to concentrate on tackling the largest point source and introducing strict requirements on discharge to water and sewer.
It is widely recognized that control of pollution is not a single environmental medium or single industry issue. The implementation of Integrated Pollution Control (IPC) has played an important role in introducing a more holistic control philosophy to environmental management. IPC applies to releases from the most polluting industrial process.
The system tightened pollution control requirements by introducing the concept of Best Available Techniques Not Entailing Excessive Costs (BATNEEC). Release of the most polluting substances must be prevented or, where this is not possible, it must be minimized and rendered harmless.
For process resulting in release to more than one environmental medium the Best Practicable Environmental Option (BPEO) has to be identified in order to minimize the impact of the process on the environment as a whole. This approach will be further advanced under the IPPC Regulations which apply to a wider range of processes and require a more wide ranging criteria in the consideration of best available techniques.
The HCFCs (hydro-chlorofluorohydrocarbons) are expected to break down in the atmosphere fairly rapidly.
This is the reason that they are preferred over the CFCs (chlorofluorohydrocarbons) to use:
However, trifluoroacetic acid, some HCFCs are expected to produce, is very stable and will wash out from the atmosphere in rain. In areas like seasonal wetlands which have high evapotranspiration rates the triluoracetic acid may concentrate to levels which may damage plants.
Direct Toxicity Assessment considered as a control tool for chemical mixtures for both process and emissions control. In addition, in order to provide a more integrated view of the state of the environment, ecological monitoring is essential.
The ultimate aim of chemical control is protection of the environment by measuring improvement in ecological quality that the ultimate effectiveness of chemical control measures and other control measures can be determined.