Water contamination, whether it occurs in groundwater or surface water, is the tainting or alteration of the water’s physical, chemical, or biological properties that endangers the public’s health, safety, or welfare, the aquatic life dependent on the water, or any designated beneficial uses of the water.
Types of Water Pollution
The many forms of water contamination may be categorized as follows.
- Surface water pollution
- Groundwater pollution
- Microbial pollution
- Oxygen depletion pollution
- Nutrient pollution
- Suspended matter pollution
- Chemical pollution
1) Surface Water Pollution: The most noticeable type of pollution is surface water, which is visible floating on the water’s surface in lakes, streams, and seas. The majority of human garbage is often visible on water surfaces, including plastics, water bottles, and other waste materials. It also comes from oil spills and gasoline waste that floats on the water’s surface and has an impact on aquatic life.
2) Groundwater Pollution: As a result of its impact on the aquifers that supply us with our drinking water, groundwater contamination is gaining more and more importance. Highly toxic chemicals and pesticides that escape through the earth and poison the wells and aquifers underground are the typical culprits behind groundwater contamination.
3) Microbial Pollution: The natural type of water contamination brought on by microorganisms in untreated water is known as microbiological pollution. The majority of these species are benign, but certain bacteria, viruses, and protozoa can spread harmful illnesses like cholera and typhoid. In third-world or developing nations, where many people lack access to safe drinking water and/or water filtration systems, this is a major issue.
4) Oxygen Depletion Pollution: Biodegradable materials are a source of food for aquatic microorganisms. These microbes multiply and use the available oxygen when there is an influx of biodegradable material from sources like garbage or agricultural erosion. Beneficial aerobic microbes perish when oxygen levels drop, whereas anaerobic germs flourish. These organisms can create poisonous byproducts like sulphide and ammonia.
5) Nutrient Pollution: Usually, fertilizers and wastewater include nutrients. Increased algae and weed growth in water bodies due to an excessive concentration of nutrients can deplete the water’s oxygen supply, harming nearby marine life and other aquatic species.
6) Suspended Matter Pollution: When contaminants enter the water and do not combine with the water molecules, it happens. By removing nutrients, limiting oxygen penetration into the water body, and disrupting their habitat, these suspended particles, which form fine silt on the waterbed, cause harm to marine life.
7) Chemical Pollution: Chemical runoff from industrial facilities and agriculture into surrounding rivers and water sources. Metals and solvents leak from industries into the water, contaminating it and harming aquatic life. Aquatic life is likewise endangered by pesticides used on farms. These toxic pesticides and chemicals can spread through diseased fish and have an impact on human health. Petroleum is another kind of chemical pollution that has a significant negative impact on aquatic life.
Effects of Specific Pollutants Present in Water
|Zinc (Zn)||It is an important cell component in several metalloenzymes. Heavy doses of Zinc salt (165 mg/l) for consecutive 26 days cause vomiting, renal damage, cramps, etc.|
|Copper (Cu)||Excess of Cu in human body (more than 470 mg) is toxic, may cause hypertension, sporadic fever, uremia and coma. Copper also produces pathological changes in brain tissue.|
|Barium (Ba)||Excess of Ba (more than 100 mg) in human body may cause excessive salivation, colic, vomiting, diarrhea, tremors, paralysis of muscles or nervous system, damage to heart and blood vessels.|
|Iron (Fe)||It is a component of blood cells and liveral metalloenzymes. However, more than 10 mg per kg of body weight causes rapid respiration and pulse rates, congestion of blood vessels, hypertension and drowsiness. It increases hazard of pathogenic organisms, as many of them require Fe for their growth.|
|Cadmium (Cd)||50 mg may cause vomiting, diarrhea, abdominal pains, loss of consciousness. It takes 5–10 years for chronic Cd intoxication. During first phase, discolouration of teeth, loss of sense of smell and mouth dryness occurs. Afterwards it may cause decrease of red blood cells, impairment of bone marrow, lumber pains, disturbance in calcium metabolism, softening of bones, fractures, skeletal deformations, damage of kidney, hypertension, tumor formation, heart disease, impaired reproductive function, genetic mutation, etc.|
|Mercury (Hg)||Excess mercury in human body (more than 100 mg) may cause headache, abdominal pain, diarrhea, destruction of hemoglobin, tremors, very bad effects on cerebral functions and central nervous system, paralysis, damage of renal tissues, hyper coagulability of blood, mimamata disease, inactivates functional proteins and even causes death. It may cause impairment of vision and muscles and even coma. It disturbs reproductive and endocrine system. It also causes insomnia, memory loss, gum inflammation, loosening of teeth, loss of appetite, etc.|
|Lead (Pb)||More than 400 mg of lead in human body can cause brain damage, vomiting, loss of appetite, convulsions, uncoordinated body movements, helplessly amazed state, and coma. It is retained in liver, kidney, brain, muscle, soft tissues, and bones. It leads to high rate of miscarriages, affects skin, and respiratory system, damages kidney, liver and brain cells. It also disturbs endocrine system, causes anaemia, and long term exposure may cause even death.|
|Arsenic (As)||It is poisonous to fishes, animals and humans. More than 25 mg of arsenic in human body causes vomiting, diarrhea, nausea, irritation of nose and throat, abdominal pain, skin eruptions inflammations and even death. It binds globulin of blood haemoglobin in erythrocytes. It may cause cancer of skin, lungs and liver, chromosomal aberration and damage, gangrene, loss of hearing, injury to nerve tissue, liver and kidney damage. Minor symptoms of As poisoning, are weight loss, hair loss, nausea, depression, fatigue, white lines across toe nails and finger nails.|
|Vanadium (V)||It is very toxic, may cause paralysis.|
|Silver (Ag)||It causes pathological change in kidney, liver and may even damage kidney. and may cause Argyria (discolouration of skin). It affects mucous membranes and eyes. In high doses, it may be fatal to humans.|
|These generally cause ‘Gene’ mutation, ionization of body fluids, chromosomnal mutations and cancers. It destroys body cell tissue, and adversely affects reproductive system. If the mother is exposed to radiation during pregnancy, it causes severe mental retardation and leukaemia in infants. Radioactive metals like heavy metals are nephrotoxic and damage kidneys.|
|Fluoride||Excess fluoride intake in body results in progressive crippling scourge (sponging)/fluorosis of bones, and teeth. It may cause metabolic alternations in soft tissues and their functional mechanism.|
|Selenium (Se)||Signs of Se poisoning (more than 4 mg) are fever, nervousness, vomiting and low blood pressure. It causes damage to liver, kidney and spleen, loss of nails and hair and blindness to animals. It affects enzyme systems and interferes with sulphur metabolism. It can cause growth inhibition, skin discolouration, bad teeth, psychological problem, and gastro intestinal problems, but trace amount of Se is protective against poisoning by Hg, Cd, and Ag.|
|Chromium (Cr)||Any chromium compound is toxic but hexavalent Cr greater than 70 mg is very toxic. It causes cancer, anuria, nephritis, gastrointestinal ulceration, and perforation in partition of nose. It penetrates cell membrane and badly affects the central nervous system. It causes respiratory trouble and lung tumors when inhaled. It may cause complications during pregnancy. and has an adverse effect on aquatic life. Trace amount of CrIII is essential for normal glucose, protein and fat metabolism and hence it is an essential trace element in diet.|
|Manganese (Mn)||Mn is essential for mammals but in concentration greater than 100 ppm, is toxic and causes growth retardation, fever, sexual impotence, muscles fatigue, and eye blindness.|
|Cobalt (Co)||High dose (27 mg or above) can cause paralysis, diarrhea, low blood pressure, lung irritation and bone defects.|
|Nickel (Ni)||More than 30 mg may cause changes in muscle, brain, lungs, liver and kidneys and can also cause cancer, tremor, paralysis and even death.|
|Boron (B)||Boron in traces is essential for plant growth. In higher concentration it is harmful to crops and affects metabolic activities of plants. It also affects central nervous system.|
|Alkalinity and Acidity||Permissible range of pH value if violated may cause health problems to human and animals and loss of productivity in agriculture.|
|Phosphate and nitrates||Phosphates and nitrates are soil nutrients and not toxic in low concentration. They deplete oxygen by promoting excess algae production in water and -giving bad odour and taste of water which are detrimental to aquatic life. They are toxic for human and animal life if concentration is beyond the permissible limits. Nitrates also cause cyanosis or blue body disease.|
|Chlorine (Cl)||It destroys plant and aquatic life and is a biocide.|
|Sulphide||It gives bad odour, toxic to many aquatic organisms and animals.|
|Salinity||Salinity is very harmful for soils as it destroys agricultural land.|
|Petroleum products in general are very harmful for soils, aquatic life, animal, human and plant life. They are very toxic. Agricultural land may suffer accumulation of oily waste affecting aeration and fertility. Many constituents of oily sludge are even carcinogenic and potent immunotoxicants.|
|Surfactants and detergents||They are toxic and harmful for aquatic life, animals and humans. They inhibit self-purification of water.|
|Phenols||They are toxic and impart objectionable odour. They generally subdue plant growth. Some phenols (nitrophenyl etc) are carcinogens.|
|Cyanides||Cyanide poses a serious health hazard. Apart from acute toxicity and chronic toxicity, it leads to development of iodine deficiency disorders.|
|They are highly poisonous for humans and animals. Also they lower seed germination, play a role in the development of Parkinson’s disease, destruction of nerve cells in certain regions of brain resulting in loss of dopamine which is used by nerve cells to communicate with brain. Some of these are physical poisons, some are protoplasmic poisons causing liver damage, some are respiratory poisons and some are nerve poisons.|
|Aluminium (Al)||It is especially toxic for brain and sometimes may lead to Alzheimer’s disease in humans.|
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