In the wake of the current situation worldwide where water scarcity is increasingly becoming a major issue, pollution of the available water only makes it worse.
According to the data provided by the United Nations (UN) in 2015, since 1990, 2.6 billion people have gained easy availability to potable drinking water, whereas 663 million people still lack access to safe drinking water.
What is Water Pollution?
Water pollution is an undesirable change in the state of water, contaminated with harmful substances. Any change in the physical, chemical, and biological properties of water that has a harmful effect on living things is called water pollution. It affects all the major water bodies of the world, such as lakes, rivers, oceans, and groundwater.
Water pollution has been increasing at a worrying rate. If consumed in a contaminated state, it may prove fatal to both — human beings and the environment.
Sources of Water Pollution
Point Sources – A definite source of pollution is called a point source. The examples include sewage water discharges from industries.
Non-point Sources – Pollution generated by more than one source is called non-point source pollution, and the sources are called non-point sources. Pesticides, fertilizers, domestic waste, and other day-to-day activities carried out by humans form the category of non-point sources.
Causes of Water Pollution
Excess fertilizers, pesticides, and insecticides used for agricultural procedures often get discharged in water bodies right from streams to lakes and seas. Ungoverned control of manure and slurries also leads to polluting the water.
During mining, the rock strata is crushed with the help of heavy equipment on a large scale. These rocks are often composed of sulfides and heavy metals, which when combined with water form sulfuric acid and other harmful pollutants.
The leftover or excess water that is left after carrying out domestic and industrial activities is called sewage water. This water consists of a lot of chemicals, and if left untreated, it can cause diarrhea. People flushing medicines and other chemical substances down the toilet has been a cause of concern for the developed countries today.
Burning of Fossil Fuels
It is a well-known fact that combustion of fossil fuels, such as coal, oil, and natural gas, emits large amount of greenhouse gases. The offshore drilling of these fossil fuels poses a serious threat to water quality and the aquatic life that depends on it.
When a water body is filled with excessive nutrients, often due to surface runoff, it results in dense growth of algae which in turn depletes the oxygen level in the water. This process is called eutrophication. Coupled with anthropogenic activity, it causes premature aging and waste-filled water content of the water body.
The amount of organic waste that can be degraded by the water bodies is measured in terms of Biological Oxygen Demand (BOD). BOD is nothing but the amount of oxygen needed by microorganisms to decompose the organic waste present in the sewage. The higher the amount of BOD, the more water is polluted with organic waste. Soaps and detergents enrich water with phosphates which lead to harmful algal bloom (HAB). It leads to the suffocation of fish and other organisms in a water body.
The areas where a city’s garbage is buried are called landfills. An ideal landfill should be well-protected at the base to prevent seepage. However, if there exists even a slight crack in the bottom layer, the pollutants seep through it and mix with the groundwater present below. This makes the water unfit for consumption in any form.
The causes of oil spills can be both, natural and anthropogenic. More often than not, they result from human activities, be it accidentally, or deliberately. Oil products stored in special containers often leak over a long period; the same can happen during handling of the containers or improper transport. Sometimes, oil and its products are intentionally discharged down the drain after their use, proving harmful in the long run.
Effects of Water Pollution
Due to surface runoff, the harmful anthropogenic matter gets dissolved in water. If this water is consumed, it can lead to diarrhea, vomiting, and intestinal problems.
The dense cover of algae that grows over water as a result of eutrophication reduces the oxygen-carrying capacity of water, thus affecting the aquatic plants and animals. Species, such as trout are unable to survive in dissolved oxygen-deficit waters, thereby leading to their death.
Aquifers (underground geological formation) form a major source of drinking water in most parts of the world. However, with the increase in the amount of different types of pollution, pollutants often seep in through the soil, and the groundwater gets polluted with metals, such as fluoride and arsenic. This leads to instances of dental fluorosis and weakening of bones in humans.
Oil spills infiltrate into the fur, feathers, and skin of animals and birds, affecting their buoyancy in water. It also hampers their ability to adapt to temperature fluctuations. Excessive exposure to oil can also affect the visibility in animals and birds. Often, it enters the lungs, leading to their death.
When excess fertilizers are used on crops and the same crops are consumed by humans, the cadmium present in the fertilizers has adverse effects on the health. It affects the functioning of the liver and kidney, causing abdominal and intestinal complications.
Case Study – The Minamata Disease
- Minamata disease is a neurological condition or a syndrome caused by excessive intake of mercury. The disease was named after it was first reported in the Minamata city of Japan in the year 1956.
- The Chisso Corporation was a chemical factory started in 1908 in Minamata producing a wide range of chemicals, such as acetaldehyde, acetic acid, vinyl chloride, acetylene, etc.
- The waste matter resulting from the manufacturing of chemicals was discharged into the Minamata Bay off the city coast.
- In 1932, the corporation started the production of acetaldehyde where the catalyst used was mercury sulfate. The by-product of the reaction after introducing the catalyst was a small amount of methylmercury (organic mercury compound).
- From 210 tons in 1932, the production increased to 6,000 tons annually in 1951. However, the company continued to discharge the waste, which now contained methylmercury, into the Minamata bay.
- In April 1956, people residing around the Minamata bay started showing bizarre symptoms of difficulty in walking, talking, and overall crippling of limbs. Sudden fits or convulsions were also reported in the factory hospital of Chisso Corporation.
- The same symptoms were shown by cats, pigs, dogs, crows, and other animals. Cats reportedly started experiencing attacks, followed by which they would lose their sanity and die. This became a frequent sight, and locals named it as “cats dancing disease”. Crows and dogs were found dead on the streets, as were fish, which were found floating dead on seawater.
- The disease struck without any premonition. The patients would complain of having trouble while walking, or develop a change in their voice, experience deteriorating vision and weak motor skills. These symptoms would last a day or two, and the patients would slip into coma, and in worst cases, it would lead to death.
- By October 1956, out of the 46 patients, who complained of similar complications, 14 had died.
- This alarming mortality rate drew a lot of attention, and after conducting a lot of research, the study group from Kumamoto University stated that all the symptoms were linked to food poisoning, probably caused due to fish and shellfish, which was the city’s staple diet.
- In 1959, after the Minamata Bay was investigated, the scientists found strikingly high levels of mercury in the samples of fish and shellfish. Further studies pointed out Chisso Corporation to be the source of contamination, who by then had started discharging the waste into the Minamata River (Shiranui Sea). Thereon, the reports of victims from the areas near Shiranui Sea started increasing, along with the mortality of fish at the mouth of Shiranui Sea. Chisso Corporation then reached an agreement with the government and patients and installed a wastewater treatment plant.
- In the year 1965, the disease broke out yet again at an alarming rate. This time, the source was the wastewater of a different factory, which used a similar catalyst to that of Chisso Corporation.
- It was later found out that the plant installed by Chisso Corporation was futile, and the company continued to pollute the water between 1959 and 1969. The government thus ordered the Chisso Corporation to pay compensation to the families of the patients, who had died and the medical costs of those who were undergoing treatment.
- By March 2001, Chisso Corporation had paid financial compensation to the 2,265 officially identified victims, out of which 1,784 had died along with other 10,000 patients
- The amount of compensation was about $86 million by 2004, and the corporation was also ordered to clean up the rivers and the bay till the contamination came down to nil.
To prevent water pollution, use eco-friendly products, such as low-phosphate detergents and other toiletries, turning off the water tap when not in use, disposing the household waste in proper sites far away from the water sources, etc. Last but not the least, planting more trees can also prevent water pollution by reducing soil erosion and water runoff. Educating people about this problem is an important approach to reduce water contamination.