Water Pollution: Understanding The Causes Of Contamination

Water pollution is a pressing issue that affects the health of millions of people and endangers ecosystems worldwide. While water covers 70% of the Earth's surface, only 3% is freshwater, and two-thirds of that is tucked away in frozen glaciers or otherwise inaccessible. This limited freshwater supply is vulnerable to contamination from various sources, including human activities such as industrial waste, agricultural runoff, sewage, and climate change. Natural processes like mercury filtration from the Earth's crust and red tide can also contribute to water pollution. The leading type of contamination in freshwater sources is nutrient pollution, which includes nitrates and phosphates from farm waste and fertilizer runoff. Water pollution has severe consequences, including the spread of diseases, economic losses, and harm to aquatic life and human health.

Industrial waste and chemicals

The production of industrial goods generates wastewater contaminated with toxic substances. This wastewater can be discharged untreated into nearby public waters, leading to water pollution. In some areas, there are strict limits that industries must follow when discharging wastewater. However, in emerging countries with a growing number of industrial plants, environmental policies may not be adequately implemented or monitored, leading to the illegal discharge of wastewater.

Industrial wastewater can contain hazardous substances that are difficult to biodegrade. These substances accumulate in water sediments, and through cracks in the ground, they can contaminate groundwater and drinking water. The toxic chemicals in industrial waste can make water unsafe for human consumption and cause changes in temperature and oxygen levels in freshwater systems, making them dangerous for marine life.

Petroleum products, heavy metals, hazardous wastes, and per- and polyfluorinated alkyl compounds (PFAS) are some specific types of industrial waste that contribute to water pollution. Petroleum products are used as fuel or lubricating oil and are produced during plastic manufacturing. Heavy metals, such as copper, lead, and selenium, come from various industrial processes like car manufacturing and mining. Hazardous wastes are highly flammable and corrosive and are often associated with construction, demolition, manufacturing, and waste treatment. PFAS are commonly found in the textile industry, hard chrome plating, and extinguishing agents.

Sewage and wastewater

Sewage is a primary source of pathogens, which are disease-causing microorganisms like bacteria and viruses. These pathogens are present in human faeces, and their release into water bodies can lead to the spread of waterborne diseases such as cholera, typhoid, hepatitis A, and dysentery. The Ganges River in India, for example, has faecal bacteria levels as high as 31 million per 100 millilitres, making it one of the most polluted rivers globally.

Wastewater from homes, cities, and towns can also contain putrescible organic substances. As these organics decompose, they deplete the dissolved oxygen content in the water, creating "dead zones" where aquatic life cannot survive due to a lack of oxygen. This process promotes algae growth, which further contributes to oxygen depletion and harms aquatic ecosystems.

Additionally, untreated human wastewater often contains harmful bacteria that can contaminate water sources, making them unfit for drinking, swimming, or other activities. This is a particular concern in areas with inadequate sanitation infrastructure or improper waste disposal practices, as bacteria from human waste can easily contaminate nearby water bodies.

Furthermore, sewage and wastewater can introduce toxins into the food chain, posing risks to human health. For instance, fishing in polluted waters or using wastewater for livestock farming and agriculture can result in the accumulation of harmful substances in seafood, which then gets passed on to humans through consumption.

To address these issues, proper wastewater treatment facilities and effective sanitation infrastructure are crucial. While modern sewage treatment plants have been developed, dispersed sources of pollution, such as sewage from individual homes, continue to contribute significantly to water contamination. Therefore, it is essential to raise awareness about proper waste disposal practices, such as not flushing non-degradable products and ensuring that pet waste is properly disposed of to prevent it from reaching water supplies.

Oil spills

The impact of oil spills on the environment, economy, and society can be disastrous. Oil spills can harm sea creatures, including birds, sea mammals, fish, algae, and coral. Oil-coated birds and marine mammals can suffer from hypothermia as oil ruins the insulating and waterproofing properties of their feathers and fur. Ingesting oil can be toxic to these animals and can also make seafood unsafe for human consumption. Oil spills can also damage fishing equipment and boats, and the resulting cleanup operations can interrupt fishing routes and lead to fishing bans, causing massive economic damage to the fishing industry.

Overall, oil spills are a significant contributor to water pollution, causing severe ecological, economic, and societal impacts that can persist for years.

Agricultural runoff

Excess nitrogen and phosphorus from fertilizer and manure can stimulate algal blooms in lakes and rivers. These blooms can block sunlight, disrupting the ecosystem below the water surface that relies on sunlight for energy. Additionally, as algae decompose, they consume oxygen, leading to hypoxic conditions that are harmful to aquatic life. Algal blooms have been responsible for the decline of fish and shellfish populations in affected areas, such as the Chesapeake Bay.

Soil erosion from pasturelands and croplands is another consequence of agricultural runoff, leading to excessive sedimentation in aquatic ecosystems. This sedimentation can smother breeding areas and degrade coastal and marine ecosystems, including coral reefs. Additionally, the use of pesticides in agriculture can result in pesticide runoff, contaminating streams and posing risks to aquatic life, wildlife, and drinking water supplies.

To address these issues, farmers can adopt best management practices and regenerative agriculture strategies. This includes following fertilizer best practices to reduce nutrient runoff, improving soil health through cover crops, and planting streamside buffer crops to protect water quality. By implementing these measures, farmers can play a crucial role in ensuring clean and safe water for drinking, recreation, and supporting diverse ecosystems.

Solid waste

Improper disposal of solid waste is a major source of water pollution. This can occur when solid waste is intentionally dumped into bodies of water or when trash and debris are carried by animals, wind, or rainfall into these water sources. Developing countries often lack the necessary infrastructure and resources to manage solid waste effectively, exacerbating the problem.

Uncollected solid waste can obstruct stormwater runoff, leading to stagnant water bodies that become breeding grounds for diseases such as malaria, cholera, and diarrhoea. Rotting food and other decaying organic waste within solid waste release methane and carbon dioxide, contributing to air pollution and, indirectly, water pollution.

Additionally, solid waste landfills and dumping sites pose risks to nearby water sources. Contamination can occur through waste dumping or leakage, exposing people who rely on groundwater for drinking and other purposes to harmful substances. High levels of organic and inorganic pollutants and heavy metals have been detected in water sources near solid waste landfills.

Plastics, a significant component of solid waste, are a particular concern. They can break down into microplastics, which are often consumed by marine wildlife and can accumulate in the bodies of humans who eat seafood. Plastics can also release toxic chemicals into the water, further damaging aquatic ecosystems and harming wildlife.

Frequently asked questions