Need Clean Water? Stop Dumping Garbage Into the Waters.
Water pollution is the contamination of water sources including ponds, lakes, rivers, ground water and the ocean. Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without removing harmful compounds. Water pollution affects plants and organisms living in these bodies of water as well as human communities that use the polluted water.
Here are some UN statistics and facts on water pollution:
The major sources of water pollution are from human settlement and industrial and agricultural activities.
Every day, 2 million tonnes of human waste are disposed of in water bodies.
At least 1.8 billion people worldwide are estimated to drink water that is faecally contaminated. An even greater number drink water, which is delivered through a system without adequate protection against sanitary hazards.
In developing countries, 70% of industrial wastes are dumped untreated into waters where they pollute the usable water supply
Nitrate from agriculture is the most common chemical contaminant in the world’s groundwater aquifers.
Half of the world’s wetlands, which act as natural filters, have been lost since 1900.
What are the Pollutants of fresh Water and what are the effects?
Most of the freshwater sources in the world like rivers, lakes, and ground water are already polluted. This is true even of remote places like the polar regions. Most of the pollution that ultimately reaches the ocean contaminates freshwater sources on the way.
The main categories of water pollutants and their effects are:
Sediments: Excessive amounts of soil particles carried by flowing water, when there is severe soil erosion. Sediments cloud the water and reduce photosynthesis, clog reservoirs and channels, smother coral reefs, destroy the feeding grounds of fish, and disrupt aquatic food webs.
Oxygen-demanding wastes: Organic waste such as animal manure and plant debris decomposed by bacteria, from sewage, animal feedlots, paper mills, and food processing facilities. Bacteria that decompose these wastes deplete the oxygen and cause the death of fish and other aquatic organisms.
Infectious Microorganisms: Parasitic worms, viruses, and bacteria from infected organisms and human and animal wastes. They are responsible for water-borne diseases that kill thousands of adults and children, primarily in developing countries.
Organic compounds: Synthetic chemicals containing carbon from industrial effluents, surface runoff, and cleaning agents. These chemicals cause many health problems for humans and harm fish and wildlife.
Inorganic nutrients: include nitrogen and phosphorus from animal waste, plant residues, and fertilizer runoff. The nutrients can cause eutrophication and can affect infants and unborn babies.
Inorganic chemicals: Acids, salts, and heavy metals like lead and mercury from industrial effluents, surface runoff, and household cleaning agents. They make water unfit for drinking or irrigation, harm fish and other aquatic organisms, cause many health problems for humans, and lower crop yields.
Radioactive substances: Wastes from nuclear power plants, nuclear weapons production, and mining and refining uranium and other ores. Such substances cause cancers, birth defects, miscarriages, etc.
Thermal Pollution: Hot water from industrial processes. That heat lower oxygen levels and makes aquatic organisms more vulnerable to disease, parasites, and toxic chemicals. When the hot water is let in, the sudden increase in temperature produces thermal shock in aquatic organisms.
Major sources of water pollution are as below:
Domestic Sewage: Human beings use water for drinking, cooking, washing clothes, gardening, recreation, etc. The discharged water has soluble and insoluble, organic and inorganic matter. It includes detergents, toxic heavy metals and even pathogens. In the municipal drains the domestic sewage is mixed up with garbage from urban and rural settlements. This highly polluted water is discharged into rivers, lakes and ponds. Thus the domestic waste and garbage are the main source of water pollution.
Industrial Waste: The industrial wastes are most harmful of all water pollutants as they contain toxic metals (lead, mercury, zinc, copper, chromium and cadmium) and toxic non-metals (arsenic, acids, alkalis, cellulose fibers, coloring and bleaching materials, petrochemicals, etc.). These pollutants are continuously discharged in the water bodies either directly or from waste dumps.
Agricultural Waste: Water pollution caused by agriculture is mainly an outcome of fertilizers and agricultural chemicals such as insecticides and herbicides that runoff into streams and lakes. They are rich in many nutrients and lead to phenomenon like eutrophication.
Off-shore Oil Drilling: This pollution is mainly due to the loss of oil during off-shore exploration, oil drilling and extraction of mineral oil, leakage of oil and natural gas from under-water pipelines and oil spills from oil tankers. The waste oil also reaches the oceans and seas due to leakage during loading and unloading of oil tankers, runoff from the roads at seaports and washing of oil tankers.
5. Thermal Pollution: Most of the large-scale industrial units, thermal power plants, nuclear power plants, oil refineries, etc., are located along the banks of rivers. These industries use large quantities of fresh water for cooling purposes. The hot water is generally discharged into the rivers. This increases the temperature of river water by about 10 Degrees Celcius, and this leads to thermal pollution of water. This has a harmful effect on aquatic organisms, such as fish and algae. The increase in temperature of river water also decreases the level of dissolved oxygen, which results in the release of foul and toxic gases.
About 2 billion people, approximately one-third of the world’s population, depend on ground water for their daily needs. About 600 cubic km of ground water is withdrawn every year, mostly from shallow aquifers.
It was believed for long that water that slowly seeps or infiltrates into the ground would be thoroughly filtered by the soil and hence ground water would be free of pollutants. We know now that this is not necessarily true. The filtering capacity of soil varies greatly from place to place. Further there is also a limit to the amount of pollutants the soil can filter.
Excessive extraction leads to the natural pollution of ground water. Example- fluoride concentration. In coastal areas, when water tables drop due to excessive extraction, there is intrusion of salt water and this is often an irreversible process.
Ground water receives pollutants from septic tanks, landfills, hazardous waste dumps, and underground tanks containing petrol, oil, chemicals, eyc. Substances like paint thinners and motor oil that we pour on the ground ultimately reaches the ground water.
Groundwater pollution is long-lasting because it does not get flushed or decomposed away. The flow of groundwater is very slow, decomposing bacteria are few in number, and the cold temperatures slow down the decomposing process. As a result, even degradable waste stays in the water for hundreds to thousands of years. In any case, non-degradable waste like lead, arsenic, and fluoride remains in groundwater permanently.
Thermal Pollution is defined as sudden increase or decrease in temperature of any natural body of water, which is caused by human activity. This normally occurs when a plant or facility takes in water from a natural resource and puts it back with an altered temperature. Most often, water is used as a coolant and hence the discharged water is at a higher temperature.
Thermal population also occurs due to other causes. Here are some examples:
Deforestation, which exposes water bodies to direct sunlight.
Run-off from hot surfaces such as roads falling into water bodies.
Volcanoes and geothermal activity under the ocean that trigger warm lava to raise the temperature of water.
What is the impact of thermal pollution?
Thermal pollution has negative effects such as the following:
Decrease in the levels of dissolved oxygen in water, which can suffocate species. An example is the mass of fish kills seen in some water bodies.
Loss of biodiversity because some species cannot tolerate the higher water temperatures - their reproductive systems are affected and they migrate to other areas.
Alien species could migrate into the area.
pH of water bodies depends on both natural and human factors. When rain water falls through air, gases such as carbon dioxide dissolve in rain water and form carbonic acid. Therefore, rain water is slightly acidic in nature. It has pH value of 5-6
Water organisms can live in pH values of about 5.0 to 9.0. Fishes prefer waters between 6.0 and 8.2. The suitable pH for most of the aquatic organisms is 6.0
What are the effects of decrease in pH value of water?
Sulphur dioxide and nitrogen oxide form sulphuric acid and nitric acid. These mix with rainwater to form acid rain. pH of water falls to 4 or lower due to acid rain. It kills fish and many aquatic animals. It decreases crop production. Historical buildings are blackened due to acid rain.
Mining operations also add acids to water. Metals such as iron, cadmium, lead, chromium etc dissolve more easily in acidic water. Many heavy metals become toxic when dissolved in water. This causes water pollution.
Bacteria and fungi decrease in acidified water. This decreases the rate of decomposition of organic matter. As a result, the nutrient cycling is disturbed.
Water pollution due to the toxic elements and their effects :
Lead processing plants working with lead ores
Production of lead acid batteries.
Lead pipes: Lead is found in drinking water from plumbing.
Lead contaminated soil: Plants take up high levels of lead up to 500 ppm from contaminated soil. Thus, lead enters the food chain. It affects each member of the chain.
Organic lead is used in petroleum industries and inorganic lead compounds for battery and paint production.
Lead smelters, household dust etc also add lead to water.
Harmful effects on lead as water pollutant
Lead poisoning causes headache, depression, nausea, muscle pain, loss of appetite etc. High doses of lead cause colics, abdominal pain, memory loss, kidney failure, slin pigmentation and even paralysis.
Lead pollution can damage internal organs especially the brain, nervous and reproductive systems. Organic lead products may be cancer causing also.
Women and children are more affected by lead poisoning than men. Lead causes menstrual disorder and infertility. It increase risk of stillbirth. In children, it can cause learning problems, and mental retardation.
Lead poisoning decreases wild bird populations.
Sources of mercury in water
Use of mercury in products and manufacturing, production of zinc, steel and other metals.
Coal fired power plants where burning of coal releases mercury.
Use of mercury in industries to prepare thermometers, pressure gauges, electric switches, fluorescent lamps, and dental fillings.
Use Of Inorganic mercury compounds in batteries, paper manufacturing and the chemical industries.
Release of mercury naturally present in limestone, coal, crude oil, metal ores, volcanic eruptions etc.
Mercury present in atmosphere enters lakes and other water bodies through rain and snow.
Harmful effects of mercury as water pollutant
When mercury is deposited in lakes or waterways, bacteria convert it to methyl mercury. Methyl Mercury deposits in algae and is eaten by smaller fish, which in turn are eaten by larger fish. Mercury present in fishes is eaten by human or other wildlife. Methyl mercury is able to enter our bloo and organs. It can damage brain and nervous system.
Acute mercury poisoning can lead to depression, Suicidal tendencies, Paralysis, Kidney failure, Allergies
Minamata disease in japan was caused due to mercury poisoning.
Children and Pregnant women are more affected by mercury. Inorganic mercury is easily absorbed into the bodies of children.
Some people show allergic response for very small amounts of mercury.
Sources of cadmium in water
Corrosion of galvanized pipes when soft water with low pH passes through these pipes.
Erosion of natural deposits,
Discharge from metal refineries
Runoff from waste batteries and paints.
Metal processing (Zinc, aluminium, iron and steel) industries
Battery re-cycling plants
Coal and oil combustion in power plants
Use of cadmium for metal plating, coating, for making transportation equipment, machinery and baking enamels, photography, nickel-cadmium solar batteries and pigments.
Use of cadmium sulphide as pigments in plastics.
Harmful effects of cadmium as water pollutant
Cadmium deposits in fishes. When human beings eat fishes, cadmim is absorbed. It binds to a low molecular weight protein metallothinein in liver, kidney, intestine and pancreas. Kidneys are most affected by cadmium poisoning. Kidney stones are formed.
Cadmium poisoning causes following; Nausea, Vomiting, Diarrhoea, Muscle cramps and loss of calcium from bones, Yellow colouration of teeth,Decrease of red blood cells, Damage of bone marrow, Hypertension, Kidney failure, Lung irritation.
The disease Itai Itai is caused by cadmium contamination associated with a diet low in calcium and vitamin D. It is osteomalacia and severe urinary system disease.
Cadmium compounds can also cause various types of cancer.
Sources of Arsenic in water
Arsenic occurs in more than 200 minerals mainly as arsenopyrite (FeAsS) and other sulfide minerals. Arsenic is found as local bedrock mainly in Bangladesh, West Bengal (India) and some regions of China. In all these areas, arsenic occurs in deltaic alluvial sediments in the shallow aquifers. These are the main sources of ground water arsenic pollution.
Erosion of natural deposits,
Runoffs from glass and electronics production wastes
Agricultural, mining and smelting activities.
Weathering of rocks and minerals followed by leaching and runoff. Igneous rocks formed from volcanoes have high arsenic content.
Igneous rocks formed from volcanoes have high arsenic content.
Harmful effects of arsenic in water
Arsenic in drinking water causes bladder, lung and skin cancer. It may also cause kidney and liver cancer.
Arsenic causes serious skin problems.
Arsenic harms the central and peripheral nervous systems.
It affects the heart and blood vessels.
It also may lead to birth defects and reproductive problems.
Keratosis on the palms of the hands and sores of the feet
Cardiovascular disease, Bone marrow depression
Arsenic is harmful to the liver and causes cirrhosis of the liver sometimes.
Water Pollution Control and Abatement
There are three major ways of slowing and managing water pollution.
Source Reduction of waste - It means producing less waste from input sources of pollution like industries and households. It is least costly and environmentally most benign method of slowing water pollution.
Wastewater Treatment - In this, wastewater from industries, cities and households is treated before discharge into natural streams. There can be multiple techniques of water treatment-
Chlorination - It kills micro-organisms such as harmful bacteria and disinfects water.
Septic-Tank Sewage Disposal System - This is deployed in areas with no central sewage treatment facilities. The sewer lines carry waste water from households to a septic-tank. The tank is designed to separate solids from liquids. The wastewater is then biochemically treated before disposal into natural water streams.
Wastewater Treatment Plants - These are specially designed plants to treat municipal sewage from homes, businesses and industrial sites. The raw sewage is delivered to the plant through network of sewer pipes. The wastewater treatment is a three step process - primary treatment, secondary treatment and advanced treatment. Following treatment, the wastewater may be discharged into natural water streams or used for crop irrigation.
Nanotechnology - In this, use of nano- particles (extremely small particles) is done. These can capture heavy metals such as lead, mercury and arsenic from water.
3. Remediation - This means cleaning up natural water streams like rivers, lakes, groundwater etc. after they have been polluted. Although it is much more expensive than reducing pollutant input or wastewater treatment before discharge, it is sometimes the only option. For example - Groundwater can be treated with microbes to decompose organic pollutants.
Lake acidity caused by acid rain can be treated with chemical bases such as lime. Lime is disseminated in the lake to neutralise acidity.
