The contamination refers to the presence of unwanted species or substances in environment, air, water, soil, any material or human body. The unwanted substances are considered as contaminants. All the chemical substances have some degree of contamination.
The contaminants show the level of pollutants in atmosphere, the presence of harmful toxins, and microorganism in food, medicines or drugs etc. contamination causes the damage of products, reduction in manufacturing yields, and harmful effect on environment. The process of contamination is a major risk factor for research and development methods, production activities, technical process, and also for human beings. There are different kinds of contamination like water, soil, chemical, food etc.
The contamination of water refers to the presence of harmful materials and vectors in water. These hazardous chemical causes the pollution of water. The pollutants are both chemical and biological in nature. The water sources are ponds, rivers, lakes, seas, reservoirs etc which are used for various purposes like drinking, industrial, and various human activities.
Sources of water contamination
There are several sources of water contamination. The sources of water contamination are mainly the disposal of chemical from homes, industries, and human or animal excreta materials. The sources of water contamination are also the water purification process, dumping of chemicals in the water resources, accidents of oil leakage etc.
Some of them are described below.
- Bacterial water contamination
- Surface water contamination
- Water turbidity contamination
- Waste water contamination
- Non-biodegradable water contamination
1. Water pollution
- Water pollution refers to the any change in the quality of water which causes the harmful effect in water.
- The changes can be chemical, biological or physical.
- There are mainly two sources of water contamination.
- One is point source water contamination and other is non-point water contamination sources.
- The point sources water contamination involves the direct sources of water contamination.
- Like the textile factories, sewage plants, mines, oil plants and tankers, leakage of fuel, direct disposal of waste in water sources, and agriculture while the non-point sources include the indirect contamination sources of pollution.
- The indirect sources are the pesticides and fertilizers through the crop production which carry with the soil into the water sources and the water becomes polluted and contaminated with harmful chemicals.
2. Water pollutants
There are various types of water pollutants.
- Disease causing agents like yeast, mould, bacteria, fungi, virus, protozoa or toxins which come form the sewage systems and untreated waste.
- The oxygen-demanding wastes reduce the oxygen level in the water that causes the death of water living organism and thus the water gets contaminated.
- The acids, salts and toxic metals come in the category of water soluble inorganic materials that affect the aquatic life and quality of drinking water.
- The nutrients are also considered as water pollutants. The water-soluble nitrates and phosphates are the common example of nutrients which grows the algae and other harmful water plants and reduce the oxygen supply in water.
- The organic compounds like oil, pesticides, and plastics are also produced harmful effects in the water.
The suspended sediment is the main cause of depletion of the water light absorption quality and it spreads the dangerous compounds like pesticides through the water.1. Bacterial water contamination
The bacterial water contamination is removed from water disinfection. 0This is the technique to remove the pathogenic microorganism form the water. The process reduces the growth of microorganism. The physical or chemical disinfectants are used for water disinfection. The chemical disinfectants are chlorine, halogens, metals like copper and silver, soap and detergent, many acids and bases etc while the physical includes the light, heat, and rays like gamma, ultra violet etc.2. Surface water contamination
The surface and ground water gets contaminated through high suspended solids which contain bacteria, algae, organic compounds, and give bad taste and odor to water.
Some conventional surface water treatments are used to remove the impurities which involve coagulation and flocculation, and sedimentation, and advanced ultra filtration technology etc. The ground water contains fewer amounts of microbes than surface water. Thus the ground water is less contaminated and safer than surface water. 3. Water turbidity and mineral water impurity
The mineral water contains the salts of cation and anion. These are removed with the ion exchanger plants. The ion exchanger includes the use of softener to remove the calcium and magnesium, heavy metals. The turbidity of water is due the presence of suspended particulates.
The turbidity is increased due to phytoplankton, sediments, disposal of waste, algae etc. The turbidity also depletes the level and concentration of water oxygen by decreasing the photosynthesis process of plants. This is measured by measuring the total suspended solids. Thus both the turbidity and mineral water impurities contaminate the water and affect the quality of water.4. Waste water contamination
The waste water contains many contaminants like the organic and inorganic particles of arsenic, antimony, asbestos, cadmium, nitrates etc. So the water gets treated through the waste water treatment process. The treatment includes the various physical and chemical treatments.5. Non-biodegradable water contamination
The non-biodegradable contaminants includes the organic and oxidizable inorganic components like cyanides and ammonia. The catalytic wet air oxidation process is used for removal of non-biodegradable contaminants in which the organic contaminants get converted into carbon dioxide and water at the higher temperature. The hetroatom of nitrogen and sulfur are converted into their molecules.
Precautions for controlling water contamination
The water contamination can be controlled through some precautions. Some are described as below.
- The management of proper crop production methods like crop rotation, cover crop, appropriate selection of crop and seeds, proper drainage systems and equipments etc can be the good methods for controlling the water contamination.
- The use of proper conservation buffer is also a good source for trap the chemicals like pesticides, sediments, bacteria, fertilizers etc to prevent the surface water contamination.
- The conservation practices like the best management practices is a useful tool to measures and control the loss of soil and water quality due to nutrients, waste, toxics etc.
- The water contamination can be controlled by the selection of appropriate chemicals, pesticides and other organic and inorganic substances, their disposal sites of wastes of industries, and the mixing procedures.
The chemical contamination shows the presence of unwanted substances which makes the environmental tools and food unfit for the consumption of living organism.
Different kind of chemicals contaminates in the water, soil, air and involve in the pollution process. Some of the harmful chemicals are described below.
- The iron is a essential element for the human body but it must be up to a appropriate level. Iron is not so much harmful for the human body when it is present in a limited concentration.
- The iron is found in the form of soluble ferrous iron when it is exposed to air or to a disinfectant in the water treatment then it becomes oxidized to insoluble iron.
- The insoluble iron is in the form of suspended colloidal and particulate iron which discolors water.
- The sources of iron are pipes, installation process of well, pumps, and storage tanks, galvanized steel etc. two types of effects are shown by iron contamination.
- One is aesthetic effects and other is physical effects.
- The aesthetic effects include the distinct taste and odors.
- When the concentration of iron is above 0.3 mg/litre then it discolors the laundry and gives a different taste to water.
- It gives the rusty color and metallic taste to the water.
- Some treatments like water softening or reverse osmosis treatment are used to remove the iron contamination.
- The Physical effects involve the damage of the water system and reduction in the effectiveness of the treatment plants.
- Like corrosion for which the conventional treatments and metal solubility treatments are used.
- The manganese is found in soil ad rocks and also a part of human diet.
It is also found in water as ground water mineral or due to the underground pollution sources.
- The common sources of manganese are reciprocating, centrifugal and rotary compressor as detergent, additives, alloy etc, hydraulics, gear system etc.
- The presence of manganese in drinking water grater than 0.05 mg/l causes the coloration, distinct taste and odor of water.
- The ground water becomes polluted with manganese when its concentration is 10 times higher than the appropriate value.
Heavy metal contamination
- The heavy metals are also worked as a major pollutant for water and soil.
It includes the metals like chromium, lead and cadmium, mercury etc.
- The sources of heavy metal exposure are both the natural and the anthropogenic sources which include disposal of untreated industrial waste water, automobile exhausts, agricultural and mining operations.
- Mercury is exposed through disinfectants like mercurochrome, organo metal, toiletries anti fungal agents etc while cadmium is through nickel/cadmium batteries, paints, and cigarette.
- The higher concentration of heavy metals is produced a chronic health effect. Their contamination removal is a difficult process so the good precautions steps should be taken.
- The agriculture and fertilizers is the major reason of the contamination of nitrates or nitrogen containing compounds because 20% of the unused nitrogen compounds are remained in the environment and enter in the surface and groundwater sources.
- Some other sources are human activities, combustion engines, effluents (domestic and municipal) etc.
- Animal manure is another big cause for the contamination of nitrogen in the environment.
- The drinking water must contain only 50 mg/litre concentration of nitrate.
- Above this limit, it shows the adverse effects for human body like the blue-baby syndrome, convert the hemoglobin (Hb) to meta-hemoglobin which reduces the transformation of oxygen in body.
- The pollution of fluoride is mainly spread due to natural sources.
- The use of phosphate fertilizer, domestic sewage, waste water by treatment with lime, industrial sources etc.
- The presence of excess fluoride causes the fluorosis which affects tissues, organs and systems and clinical manifestations.
- It enters through the use of drinking water, food, drugs, dental products and industrial emissions.
- The optimum concentration level of fluoride is 1.5 mg/litre in drinking water.
- The arsenic is most commonly used for wood preservatives, fertilizers, pesticides, and weed-killers.
- It is a toxic element and mostly contaminated in shallow ground water.
- The arsenic-contaminated drinking water causes the chronic problem, arsenicosis, skin problem like hyper-pigmentation, de-pigmentation, keratosis etc, cancer etc.
- The set limit of arsenic content is 0.01 mg/litre.
Precautions to avoid the Chemical Contaminants
Some precautions can be control the chemical contamination which is given as below.
- There should be banned on the smoking as cigarette contains chemical contaminants.
- Try to avoid the burning of candles, fuels or waste because combustion process includes aromatic hydrocarbon, carbon monoxide, VOCs, and soot. So the proper treatment must be taken for their disposal.
- The use of pesticides, disinfectants, fungicide or biocide should be in control. The use of fertilizer in agriculture must be in limit. Try to use of unscented products like bathing soaps, shampoos, body deodorants and body lotions.
- There should be control on the use of unwanted fuel-based appliances.
- The building materials should be with low-emission or odor materials and water-based adhesives.
- The disposal of waste water treatment is done carefully or away forms the surface water or ground water sources.
Soils are formed by the decomposition of rock and organic matter. The property of soil differs from place to place but due to excess level of some chemical substances, the soil becomes polluted or contaminated with the chemicals. Thus the contaminated soil is harmful for the human health and plants and for the production of crops. This is because of the use of fertilizers, plasticizers, leakage of chemicals near the industries, accidental spills etc.
The chemical contaminants affects the various quality of soil as they get degrades in to the various other organic compounds and affects the characteristic of soil. Some of them are the water level of soil, soil texture, pH level of soil, level of organic matter in soil, temperature, moisture level etc. Some common sources of soil contamination are given as below. 1. Lead Paint
The paint is used for buildings and home. This is removed from the various activities like stripping, scraping or sandblasting. This increases the concentration of lead in soil. 2. Land fills or Garbage Dumps
The dumping of garbage includes the burning fuel like petroleum products, pesticides, lead and heavy metals. All these chemicals contaminates in the soil of near waste disposal location. 3. Fires
The accidental fires or burning of synthetic material, garbage emits PAHs, dioxins or other chemicals that contaminates in soil.
4. Automobile or Machine Repair
The machine and automobile repair works release the many chemicals like petroleum products, tires and rubber products, trichloroethylene (TCE), chromium, lead, molybdenum, or nickel etc. The dumping of these substances increases the soil contamination.
5. Furniture Refinishing
The process of refinishing the furniture includes the methylene chloride and solvents like toluene and methanol which contaminates the soil and water.
The pesticides include insecticides, herbicides, fungicides, rodent poisons etc. The use of pesticides is the main cause of soil contamination.7. Industrial or commercial Site
The soil present near the industries and highly traffic area are contaminated at high level.
8. Petroleum Spills
The leakage of petroleum, heating of oil tank, fuel tanks sites which contaminants benzene, toluene, and xylene in the soil. The effect of contamination depends upon the contact of living organism with the contaminants. The soil contamination shows the negative effect on the human health, plant vigor, animal health, microbial processes, metabolic process of plants etc.
Precautions to avoid soil contamination
The soil contamination can be controlled through some precautions. Some important factors are given as below.
- The production of crop should be away from industrial and traffic area. The waste must be disposed off carefully.
- The use of pesticides should be according to the standard limits. The vegetables and other food products should be washed before taking in use.
- The rotation in the crop production according to the weather decreases the soil contamination.
- The pH of soil is up to 6.5 or more as it lowers the mobility of metals in the soil.
- The legume plants like beans, lentils, peas, and peanuts etc are used to replenish the level of nitrogen in the contaminated soil as the nitrogen is the key element for the growth of plants.
- The fruit crops have fewer tendencies to absorb the contaminants rather than root crops. The root crops, leafy vegetables, or herbs absorb more contaminants from the soil. The use of cover crop and appropriate selection of crop and seeds is a good tool for reduce the level of soil contamination.
- Organic matter is used to reduce the mobility of metals and modifies the pH of the soil.