- Water pollution is defined as the “introduction or existence of undesirable substances in water, encompassing organic, inorganic, biological, radiological, or thermal elements, leading to a deterioration in water quality to the extent that it becomes unsuitable for various purposes.”
- Natural causes of water pollution involve soil erosion, mineral leaching from rocks (due to both natural solubility and acidity induced by acid rain), and the decomposition of organic matter.
- Point source pollution arises when contaminants are released from a specific location, such as a drain pipe discharging industrial effluents directly into a water body.
- On the contrary, non-point sources involve the discharge of pollutants from diffuse origins or a larger area, including runoff from agricultural fields, grazing lands, construction sites, and abandoned mines and pits, among others.
- Water pollution extends beyond surface water and has affected groundwater, seas, and oceans as well.
CAUSES OF WATER POLLUTION
Sewage Water
Sewage water incorporates discharges from residential and commercial establishments, containing human and animal excreta, food remnants, cleaning agents, detergents, and various contaminants. Household and hospital sewage can harbor numerous pathogenic microorganisms.
Industrial Wastes
Wastewater released by industries, such as petroleum, paper manufacturing, metal extraction and processing, and chemical manufacturing, often contains toxic substances, notably heavy metals like mercury, cadmium, copper, lead, and arsenic. Additionally, various organic compounds contribute to the pollution from industrial discharges.
Agricultural Factors
Agricultural runoff introduces dissolved salts like nitrates, phosphates, and ammonia, along with other nutrients and toxic metal ions and organic compounds. Fertilizers, rich in plant nutrients such as nitrogen, phosphorus, and potassium, may leach into groundwater or mix with surface water. Pesticides, including chlorinated hydrocarbons and organophosphates, pose a threat, and runoff from poultry farms, piggeries, and slaughterhouses adds to water pollution.
Dissolved Oxygen (DO)
The presence of organic and inorganic wastes diminishes the dissolved oxygen content in water. Water with DO content less than 8.0 mg/L is considered contaminated, and levels below 4.0 mg/L are indicative of high pollution. Adequate DO content is vital for the survival of aquatic organisms, influenced by factors like surface turbulence, photosynthetic activity, organismal oxygen consumption, and organic matter decomposition.
Biological Oxygen Demand (BOD)
Biochemical Oxygen Demand (BOD) measures organic wastewater pollution, representing the amount of dissolved oxygen needed by bacteria to decompose organic waste. It is expressed in milligrams per liter of water, and higher BOD values suggest low DO content. However, BOD has limitations as it focuses on biodegradable materials.
Chemical Oxygen Demand (COD)
COD is a more comprehensive method for measuring pollution load, assessing the oxygen required to oxidize both organic and inorganic compounds in water samples, expressed in parts per million.
Thermal and Radiation Pollution
Thermal pollution arises from the discharge of hot water into water bodies by thermal and nuclear power plants and other industries. This elevates water temperature, decreasing dissolved oxygen and threatening aquatic life. Effective mitigation involves cooling hot water in ponds before release.
Nuclear accidents, especially near water bodies, pose the risk of radiation leakage into the environment. This radiation exposure can lead to DNA mutations in marine organisms, potentially causing cancer. Thyroid cancer risks arise from the absorption of radioactive iodine by the thyroid gland.
Marine Pollution
Oceans receive pollutants from natural and human-made sources, including coastal cities’ sewage, garbage, and pollutants discharged during activities like navigation, offshore oil mining, and oil spills. This contamination affects marine ecosystems, posing threats to aquatic life and biodiversity.
EFFECTS OF WATER POLLUTION
On Human Health
- Domestic and hospital sewage, if untreated, can lead to severe waterborne diseases like typhoid and cholera due to the presence of pathogenic microorganisms. Industrial wastewater, containing harmful metals such as lead, zinc, arsenic, copper, mercury, and cadmium, poses health risks to humans.
- Arsenic accumulation from polluted water can result in skin lesions and, ultimately, skin cancer.
- Bacterial transformation of mercury compounds produces toxic methylmercury, causing neurological issues.
- Mercury pollution, as seen in Minamata disease, adversely affects human health.
- Lead exposure leads to poisoning, causing various organ and tissue damage.
- Cadmium-contaminated water can result in itai itai disease and increase the risk of lung and liver cancer.
Economic Slowdown
- Projected water stress for half the global population by 2030 could hinder economic growth.
- A scarcity of freshwater may limit the production of water-intensive goods like automobiles, food, and clothing, impacting the overall economy.
On the Environment
- Biodegradation of organic matter in sewage waste consumes oxygen, depleting levels in water bodies and causing harm to aquatic life.
- High nutrient levels in water can lead to algal blooms, accelerating the aging of lakes. Some toxic substances, like mercury and DDT, can be magnified in the aquatic food chain, disrupting ecosystems.
- DDT, in particular, affects bird populations through eggshell thinning.
On Aquatic Ecosystem
- Polluted water diminishes dissolved oxygen, leading to the death of sensitive organisms.
- Tolerant species may survive in highly polluted water, serving as indicators of water pollution. Biocides, PCBs, and heavy metals directly harm aquatic organisms.
- Eutrophication, accelerated by human activities, alters nutrient levels in lakes, impacting their classification.
- Algal blooms contribute to oxygen depletion, harming primary consumers like small fish. Algal blooms, often red or brown, can lead to coral reef destruction.
Marine Pollution
- Chemicals discharged into the ocean cause marine pollution, impacting plankton and benthos animals.
- Toxins concentrated in food chains can affect livestock and animal husbandry. International efforts, such as the Convention on the Dumping of Wastes at Sea and the United Nations Convention on Law of the Sea (UNCLOS), aim to regulate and reduce marine pollution globally.
CONTROL MEASURES OF WATER POLLUTION
Pollution Prevention and Water Conservation Measures
- Sewage and Industrial Effluent Treatment:
- All sewage water and industrial effluents should undergo proper treatment before being released into water bodies.
- Cooling of Hot Water:
- Hot water discharged from power plants should be cooled before release to prevent thermal pollution in receiving water bodies.
- Prohibition of Domestic Cleaning in Water Sources:
- Domestic cleaning activities should be prohibited in water sources like tanks, streams, and rivers that supply drinking water.
- Reduced Fertilizer and Pesticide Use:
- Excessive use of fertilizers and pesticides should be avoided to prevent nutrient runoff and chemical contamination of water bodies.
- Promotion of Organic Farming:
- Encourage organic farming practices and the effective use of animal waste as fertilizer to minimize chemical inputs.
- Utilization of Water Hyacinth:
- Water hyacinth, an aquatic weed, can be employed to purify water by extracting toxic materials and heavy metals.
- Oil Spill Cleanup Techniques:
- Employ various methods like bregoli (a byproduct of the paper industry resembling sawdust), oil zappers, and microorganisms for effective cleanup of oil spills in water.
- Chemical Treatment Methods:
- Utilize chemical methods such as precipitation, ion exchange, reverse osmosis, and coagulation to control and treat water pollution.
- Individual Conservation Efforts:
- Promote individual actions such as reusing, reducing, and recycling to contribute towards mitigating the impacts of water pollution.
- National Conservation Initiatives:
- Implement national conservation programs like the National Lake Conservation Plan (NLCP) and the National Wetland Conservation Programme (NWCP) for the conservation and management of identified lakes and wetlands.
- Integrated Approach – NPCA:
- Support the integrated scheme of the National Plan for Conservation of Aquatic Ecosystems (NPCA), which combines various conservation activities, including wastewater interception, diversion, treatment, pollution abatement, lake beautification, and biodiversity management.
FAQs – Water Pollution
1. What is water pollution?
Answer: Water pollution is defined as the introduction or existence of undesirable substances in water, encompassing organic, inorganic, biological, radiological, or thermal elements, leading to a deterioration in water quality to the extent that it becomes unsuitable for various purposes.
2. What are the natural causes of water pollution?
Answer: Natural causes include soil erosion, mineral leaching from rocks (due to natural solubility and acidity induced by acid rain), and the decomposition of organic matter.
3. What is the difference between point source and non-point source pollution?
Answer: Point source pollution occurs when contaminants are released from a specific location (e.g., industrial drain pipes), while non-point sources involve the discharge of pollutants from diffuse origins or a larger area (e.g., agricultural runoff).
4. How does water pollution extend beyond surface water?
Answer: Water pollution affects not only surface water but also groundwater, seas, and oceans, impacting a wide range of ecosystems.
5. What are some common causes of water pollution?
Answer:
- Sewage Water: Discharges from homes and businesses containing various contaminants.
- Industrial Wastes: Release of toxic substances from industries.
- Agricultural Factors: Runoff containing dissolved salts, nutrients, and pesticides.
6. How is Dissolved Oxygen (DO) content crucial in assessing water pollution?
Answer: The presence of organic and inorganic wastes reduces DO content. Adequate DO is vital for aquatic organisms, and levels below certain thresholds (e.g., 4.0 mg/L) indicate high pollution.
7. What is Biological Oxygen Demand (BOD)?
Answer: BOD measures organic wastewater pollution, representing the amount of dissolved oxygen needed by bacteria to decompose organic waste.
In case you still have your doubts, contact us on 9811333901.
For UPSC Prelims Resources, Click here
For Daily Updates and Study Material:
Join our Telegram Channel – Edukemy for IAS
- 1. Learn through Videos – here
- 2. Be Exam Ready by Practicing Daily MCQs – here
- 3. Daily Newsletter – Get all your Current Affairs Covered – here
- 4. Mains Answer Writing Practice – here
