Water Pollution: Understanding The Causes And Impact

Water pollution is a pressing issue that affects one in three people worldwide, according to the United Nations. It is caused by a variety of factors, including industrial waste, agricultural runoff, oil spills, and sewage. These sources release toxic chemicals, pollutants, fertilisers, pesticides, and disease-causing microorganisms into our water systems, contaminating rivers, lakes, and oceans. The agricultural sector is the biggest consumer of freshwater resources and a significant contributor to water pollution, with farming and livestock operations washing nutrients, fertilisers, pesticides, and pathogens into waterways. Water pollution poses a severe threat to human health, the environment, and the economy, underscoring the urgent need to address this global challenge.

Industrial waste

Hazardous industrial waste includes commercial products such as cleaning fluids, paints, or pesticides discarded by commercial establishments or individuals. Dry cleaning fluids and embalming fluids are two types of industrial waste of particular concern. Dry cleaning fluids have contaminated groundwater supplies across the United States, with PCE (perchloroethylene or tetrachloroethylene) being a suspected carcinogen that must be removed from water supplies. Cemeteries can also be a source of groundwater contamination due to embalming fluids and decaying organic matter.

Non-hazardous industrial waste does not meet the EPA's definition of hazardous waste and is not municipal waste. Examples of non-hazardous industrial waste include cafeteria garbage, dirt and gravel, masonry and concrete, scrap metals, trash, oil, solvents, and similar wastes.

The effects of water pollution from industrial waste are devastating to people, animals, fish, and birds. Polluted water is unsuitable for drinking, recreation, agriculture, and industry. It also diminishes the aesthetic quality of lakes and rivers and destroys aquatic life and reduces its reproductive ability.

Technologies have been developed to address solid waste and other environmental and recycling problems, and the EPA has regulations in place to control non-domestic discharges from industrial and commercial sources into municipal sewer systems. However, small-scale industries may struggle to afford investments in pollution control equipment, and EPA regulations have been criticised as ineffective in keeping people safe from industrial pollution in drinking water.

Agricultural pollution

Agriculture is the leading cause of water degradation worldwide. The agricultural sector is the biggest consumer of global freshwater resources, with farming and livestock production using about 70% of the earth's surface water supplies.

Every time it rains, fertilizers, pesticides, and animal waste from farms and livestock operations wash nutrients and pathogens—such as bacteria and viruses—into our waterways. Nutrient pollution, caused by excess nitrogen and phosphorus in water or air, is the number-one threat to water quality worldwide and can cause algal blooms, a toxic soup of blue-green algae that can be harmful to people and wildlife.

Pesticides, fertilizers, and livestock manure contain nutrients, bacteria, and other substances that do not always remain in the soil. Instead, they are transported into local streams, rivers, and groundwater through runoff, infiltration, and irrigation return flows. Rainfall and snowmelt transport the majority of these pollutants into surface waters, but other factors, such as cattle loafing in stream corridors, can also contribute to agricultural pollution.

Pollutants from agricultural operations can also enter groundwater and degrade sources of drinking water. For example, bacteria and nutrients from livestock and poultry manure can contaminate drinking water supplies and cause beach and shellfish bed closures.

Agricultural conservation practices can help mitigate these issues. For instance, drip irrigation instead of furrow irrigation decreases water loss and allows better control of the amounts of pesticides and nutrients added to irrigation water. Storing livestock manure in covered stockpiles or protected upland areas minimizes runoff risks. Implementing a systems approach to agricultural conservation allows for the control of multiple pollutants through carefully tailored systems of conservation practices.

Sewage and wastewater treatment

Sewage and wastewater are among the leading causes of water pollution globally. Wastewater is water that has been used in activities such as washing or manufacturing and is contaminated with a range of harmful substances. These include human waste, household chemicals, personal hygiene products, pharmaceuticals, fertilisers, pesticides, and plastics.

Untreated sewage and wastewater can contaminate water with disease-causing microorganisms and poisonous substances, posing a significant risk to human health and aquatic ecosystems. According to the World Health Organization (WHO), polluted water is water that has been altered to the extent that it is unusable, and it can cause diseases like diarrhoea, cholera, dysentery, typhoid, and poliomyelitis, killing hundreds of thousands of people worldwide annually.

The presence of sewage in water bodies can also promote the growth of algae, leading to the formation of eutrophic "dead zones" where aquatic life cannot survive due to a lack of oxygen. This process occurs when excess nitrogen and phosphorus in water or air cause algal blooms, which can be harmful to both people and wildlife. These algal blooms can block the light that plants need for photosynthesis, and when the plants and algae die, they are consumed by bacteria, further reducing oxygen levels and killing fish and other organisms.

The inadequate treatment of wastewater is a significant issue, with 80% of the world's wastewater entering the environment untreated. This has far-reaching consequences for climate resilience, aquatic biodiversity, and food and water security. In the United States, for example, between 1985 and 2000, the Centers for Disease Control (CDC) documented nearly half a million cases of waterborne illness from polluted drinking water. Similarly, a 1998 study published in the International Journal of Epidemiology attributed one-third of all reported gastroenteritis cases and two-thirds of ear infection cases to water pollution.

Addressing wastewater pollution requires implementing improved treatment options and investing in innovative practices that divert waste into valuable resources. It is also essential to prevent stormwater from entering sewer systems by expanding natural areas, planting trees, restoring wetlands, and creating green roofs. These measures help to reduce sewer overflows and improve the capacity of sewer systems, ultimately contributing to the protection of aquatic ecosystems and public health.

Oil spills and leaks

Sources of Oil Spills

Offshore and Maritime Spills

Oil spills at sea often occur due to accidents involving supertankers, offshore drilling rigs, and pipelines. While stricter shipping and environmental regulations have made major spills from wrecked or damaged supertankers rare, thousands of minor and several major spills related to tanker operations and well discharges are still reported each year. Oil spills from pipelines can be caused by various factors, including trawling of fishing boats, natural disasters, pipe corrosion, construction defects, sabotage, or attacks.

Land-Based Spills

Oil spills on land can occur due to operational or human errors, unpreparedness, or the release of used solvents and lubricants by industries and individuals. Land-based spills are different from maritime spills as the oil does not spread as quickly, and the effects remain local. However, oil from roads and land vehicles can be washed into oceans and other water bodies during rainstorms, contributing to water pollution.

Impacts of Oil Spills

Environmental and Ecological Impact

Oil spills have devastating impacts on aquatic ecosystems. Oil floating on the water's surface blocks sunlight from penetrating and reduces the level of dissolved oxygen, harming aquatic life. Oil penetrates the plumage of birds and the fur of mammals, reducing its insulating and waterproofing abilities, making them more vulnerable to temperature changes and less buoyant in the water. Ingesting oil can be toxic to animals, and oil spills can also damage their habitats and reproductive rates, slowing the long-term recovery of affected populations. Oil spills also damage plant life, including saltwater marshes and mangroves.

Economic and Social Impact

Oil spills can severely impact tourism and commerce, especially if they occur in popular beach sites, marinas, or natural reserves. They can also affect industries that rely on clean water, such as power plants and other utilities. The cleanup and recovery process after an oil spill is challenging and can take weeks, months, or even years. It requires careful consideration to avoid causing additional harm to sensitive habitats.

Preventing and Mitigating Oil Spills

To address the issue of oil spills and leaks, it is essential to implement stricter regulations and improve safety measures in the oil industry. This includes enhancing the safety of transportation and storage methods, as well as developing and deploying effective oil spill response and cleanup technologies. Additionally, transitioning to alternative energy sources and reducing our dependence on oil can help mitigate the risks associated with oil spills.

Microplastics

Microfibres are another form of microplastics, consisting of tiny pieces of threads and fibres that break off from clothing. Clothing made from plastic (nylon, polyester, rayon, acrylic, and spandex) sheds microfibres with every wash, which go down the drain into sewer systems. Wastewater treatment plants are not designed to remove all particles, so microfibres can remain in the sewage sludge that is applied as fertiliser on agricultural fields. They can also enter waterways through dust fallout and surface runoff.

The concentration of microplastics differs depending on the region, with surface water in China and Saudi Arabia found to be much more contaminated compared to water bodies in other countries. Microplastics have also been discovered in freshly fallen snow in Antarctica, with potentially detrimental effects on the marine food chain.

To reduce the impact of microplastics, individuals can use reusable products, refuse single-use plastics, recycle, and support products made with biodegradable materials and sustainable packaging.

Frequently asked questions