Water Pollution: Global Crisis, Local Impact

Water pollution is the contamination of water bodies, including lakes, rivers, oceans, and reservoirs, with harmful substances that degrade water quality and render it toxic or unfit for human use. This can happen through various means, such as oil spills, sewage discharge, industrial waste, agricultural runoff, and urban stormwater. These sources of pollution introduce toxic chemicals, plastics, pathogens, and other contaminants into water systems, leading to negative impacts on human health, the environment, and the economy.

Oil spills and leaks

Oil spills have severe environmental and economic consequences. Oil on the ocean's surface is harmful to many forms of aquatic life as it prevents sufficient sunlight from penetrating and reduces the level of dissolved oxygen. Oil ruins the insulating and waterproofing properties of feathers and fur, causing birds and marine mammals to be more vulnerable to temperature fluctuations and much less buoyant in the water. Ingesting oil can be toxic to affected animals, and the damage to their habitat and reproductive rate may slow the long-term recovery of animal populations. Plant life can also be significantly impacted; saltwater marshes and mangroves are two notable shore ecosystems that frequently suffer from oil spills.

Oil spills can also have negative impacts on human health, including respiratory and reproductive problems, as well as liver and immune system damage. They can also lead to the closure of beaches, parks, and fisheries, and create fire hazards. The cleanup and recovery from an oil spill are challenging and depend on various factors, including the type of oil spilled, the temperature of the water, and the types of shorelines involved. It can take weeks, months, or even years to clean up an oil spill, and even then, cleanup activities can never remove 100% of the spilled oil.

Oil pollution can also occur through pipeline oil spills, which can be caused by trawling of fishing boats, natural disasters, pipe corrosion, construction defects, sabotage, or attacks. Oil can also reach oceans and waterways through runoff from roads, asphalt, and other impermeable surfaces, as well as from storm drains and sewers. Oil leaks in vehicles, fuel depots, and even domestic operations can contribute to oil pollution in water sources.

Industrial waste

The production of all kinds of industrial goods generates wastewater that can be contaminated with toxic substances. This wastewater is often released into nearby public waters, such as rivers and lakes. In some cases, it is properly cleaned by industrial wastewater recycling systems and is sometimes reused or disposed of in an environmentally friendly way. However, in many areas of the world, it is discharged untreated, leading to water pollution.

The impact of industrial waste on water bodies is particularly significant in emerging countries such as China, India, Africa, and South America, where the number of industrial plants has recently increased. In these countries, environmental policies and regulations are often lacking or not consistently enforced, leading to the illegal discharge of wastewater from industries. Even in developed countries like the United States, industrial waste still contributes significantly to water pollution. For example, a News21 analysis of EPA data showed that the drinking water of more than 244 million people in the US contains contaminants linked to industrial practices.

To address the issue of industrial water pollution, stricter enforcement of environmental regulations and the development of new technologies for separation and recycling of industrial waste are necessary. Additionally, communities affected by industrial pollution, especially low-income communities and communities of color, should not be forced to bear the burden of additional treatment costs to ensure safe drinking water.

Agricultural activities

Agriculture accounts for 70% of water withdrawals worldwide and is a major contributor to water pollution. Farms discharge large quantities of agrochemicals, organic matter, drug residues, sediments, and saline drainage into water bodies. This includes pesticides and fertilizers, which contaminate both groundwater and surface water. The use of pesticides also poses risks to aquatic life, fish-eating wildlife, drinking water supplies, and human health.

The expansion of agricultural land and the intensification of farming practices have also contributed to water pollution. The area equipped for irrigation has more than doubled in recent decades, from 139 million hectares in 1961 to 320 million in 2012. This has transferred agricultural pollution to water bodies. Additionally, the total number of livestock has increased significantly, from 7.3 billion units in 1970 to 24.2 billion in 2011. Livestock production now accounts for 70% of all agricultural land and 30% of the planet's land surface.

The use of veterinary medicines, such as antibiotics, vaccines, and growth promoters, has emerged as a new class of agricultural pollutants. These medicines move from farms through water to ecosystems and drinking water sources. Fish excreta and uneaten feeds from fed aquaculture also diminish water quality. The increased use of antibiotics, fungicides, and anti-fouling agents may contribute to polluting downstream ecosystems.

To mitigate the harmful impacts of agricultural activities on water resources, proper diagnosis, prediction, and monitoring are key requirements. Nutrient management practices, such as targeted fertilizer and manure application, can help minimize runoff. Storing livestock manure in lagoons, covered stockpiles, or protected upland areas can also reduce runoff risks. Implementing a systems approach to agricultural conservation can effectively control multiple pollutants by tailoring specific systems of conservation practices to target critical source areas.

Sewage and wastewater

One of the primary concerns with sewage is the presence of disease-causing microbes. Domestic sewage is known to harbour millions of microorganisms per gallon, with coliform bacteria from the human intestinal tract being the most prevalent. These bacteria are indicators of sewage pollution and can lead to various health issues. In the United States alone, it is estimated that 3.5 million Americans fall ill each year after coming into contact with sewage-laden waters, suffering from ailments such as skin rashes, pink eye, respiratory infections, and hepatitis.

In addition to the health risks, sewage pollution also poses a severe threat to the environment, particularly aquatic ecosystems. Sewage discharge introduces excessive nutrients, specifically nitrogen and phosphorus, into water bodies, leading to a phenomenon known as eutrophication. This process stimulates the growth of algae, resulting in algal blooms that can be harmful to both people and wildlife. As the algae proliferate, they block light necessary for photosynthesis, leading to a decline in oxygen levels as they are consumed by bacteria during decomposition. This oxygen depletion, or eutrophication, can suffocate plants and animals, creating "dead zones" devoid of life in lakes and marine environments.

The impact of sewage pollution extends beyond just rivers and lakes. Global mapping exercises have identified sewage contamination hotspots in terrestrial, aquatic, and marine systems, including coral reefs, salt marshes, and fish-rich river systems. The presence of untreated or poorly treated sewage elevates concentrations of nutrients, pathogens, endocrine disruptors, heavy metals, and pharmaceuticals, which can have far-reaching consequences for biodiversity and ecosystem health.

To address the issue of sewage and wastewater pollution, it is imperative to prioritize mitigation measures. This includes investing in upgrading and maintaining wastewater infrastructure, as well as exploring innovative solutions such as waste-free toilets and resource recovery to generate fuel and drinking water. Additionally, natural areas that help prevent stormwater from rushing into sewers should be protected and expanded, as they offer a cost-effective way to enhance the capacity of sewer systems. Strong notification programs are also essential to alert the public about potential dangers from raw sewage releases, giving people the information they need to stay safe and healthy.

Microplastics and chemicals

Microplastics are tiny plastic particles that are less than five millimetres in diameter. They can be formed from the breakdown of larger plastic items, such as water bottles, or be intentionally designed as microplastics for commercial use, such as cosmetics. Microplastics have been detected in marine organisms, from plankton to whales, and even in our drinking water.

A 2022 study found that microplastics accumulate within freshwater systems, especially at the source of a river or stream, where the flow of water is relatively low. This means that the microplastics can stay in one place for up to seven years, increasing the likelihood of ingestion by marine animals. In turn, this means that the plastic debris enters the food web and human diets, potentially threatening the entire food chain.

Microplastics can also bind with other harmful chemicals before being ingested by marine organisms. Although it is not yet known what impact this has on human health, the entanglement effect caused by microplastics is known to be harmful, if not fatal, to aquatic species. 55% of marine organisms are associated with entanglement, with sea turtles, seabirds and crustaceans among the most threatened.

Primary microplastics are intentionally produced small plastic particles like microbeads in cosmetics, exfoliating creams, and toothpaste. They are also used in health and beauty products as microbeads, which are very tiny pieces of manufactured polyethylene plastic that act as exfoliants. These particles easily pass through water filtration systems and end up in the ocean, posing a potential threat to aquatic life.

Secondary microplastics are created from the breakdown of larger plastic products, such as car tires and asphalt on road surfaces. When a car drives, the abrasion of the tires against the road causes tiny plastic particles to wear off, which eventually make their way into the water table. Another source of secondary microplastics is plastic fibres that shed from fleece or other synthetic clothing in washing machines.

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