Water Contaminants: Understanding Potential Pollutants And Their Sources

Water pollution is a serious issue that poses a threat to both human health and the environment. It occurs when harmful substances contaminate bodies of water, degrading water quality and rendering it unsafe for human use and damaging to aquatic ecosystems. These harmful substances, or water pollutants, can come from a variety of sources and take many forms, including chemicals, waste, plastic, microorganisms, and other toxins. With water being a universal solvent, it is particularly vulnerable to pollution, and the identification and management of potential water pollutants are crucial to safeguard this finite resource.

Oil spills

The use of supertankers for transporting oil has been a significant contributor to oceanic oil spills since the 1960s. While stringent shipping and environmental regulations have reduced the occurrence of spectacular oil spills from wrecked or damaged supertankers, thousands of minor and several major oil spills are still reported each year. These spills can have detrimental effects on aquatic life, including birds and marine mammals. Oil spills can ruin the insulating and waterproofing properties of feathers and fur, leading to hypothermia. Ingesting oil can be toxic to animals, and it can also slow the long-term recovery of animal populations by damaging their habitats and reducing reproductive rates.

The cleanup process after an oil spill is challenging and requires careful consideration to avoid causing further harm. While cleanup activities can remove a significant portion of the spilled oil, it is challenging to remove 100% of it. In the case of the Exxon Valdez oil spill in 1989, it was found that the use of high-pressure, hot-water hoses for cleanup caused more damage than the oil alone. As a result, sensitive habitats require extra caution during the cleanup process. The Oil Pollution Act of 1990 established that those responsible for oil spills can be held accountable for the costs of cleanup and restoration.

It is important to note that not all oil pollution comes from major oil spills. The United States National Research Council (NRC) reported in 2002 that approximately 1.3 million tonnes of oil are released into the sea each year through various sources. This includes natural seepage from the ocean floor, industrial and domestic runoff, and oil discharges from ships' operations, such as bilge pumping. Combined with natural seepage, these sources contribute an estimated 3.5 million to 6 million metric tons of oil to the world's waterways annually.

Industrial operations

One of the major sources of industrial water pollution is the improper treatment and direct release of hazardous effluents into sewerage systems, which eventually contaminate groundwater and other water bodies. This can include organic waste from animal slaughter and processing, as well as heavy metals, pesticides, and plastic. Industrial wastewater often contains toxic substances such as benzene, toluene, ethylbenzene, and xylene, which may be released during drilling or other industrial processes. Fossil fuel power stations, particularly coal-fired plants, are a significant source of wastewater containing metals such as lead, mercury, cadmium, and chromium, as well as arsenic, selenium, and nitrogen compounds.

The release of pollutants from petroleum refineries and petrochemical plants is also a concern. These facilities emit conventional pollutants like oil and grease, suspended solids, ammonia, chromium, phenols, and sulfides. Mine tailings, a mixture of water and finely ground rock left over from mining operations, pose environmental and cost challenges for mining companies.

Additionally, the manufacturing of plastics and synthetic fibers releases millions of pounds of pollutants, including nitrogen, benzene, lead, phthalates, PFAS, and microplastics. The textile industry also contributes to water pollution by generating heavy metals, surfactants, bleaching agents, and perfluorooctane sulfonate (PFOS).

The improper management of industrial wastewater can have severe environmental and health consequences. It can lead to the proliferation of waterborne pathogens, affect the ecosystem, and cause waterborne diseases such as diarrhoea, giardiasis, typhoid, cholera, hepatitis, and cancer.

Agricultural activities

Pesticides and herbicides: The excessive use of pesticides and herbicides in agriculture is a major concern. These chemicals are often applied to crops to control pests and weeds, but they can also find their way into nearby water sources through runoff or leaching. This can result in the contamination of drinking water supplies and harm aquatic ecosystems. To reduce the potential for water pollution, it is important for farmers to use integrated pest management (IPM) strategies, which emphasize the use of natural predators and cultural practices to control pests, rather than solely relying on chemical pesticides.

Fertilizer use: Fertilizers are essential for maintaining soil fertility and crop production, but they can also contribute to water pollution when mismanaged. Excessive use of nitrogen-based fertilizers, for example, can lead to high levels of nitrogen and phosphorus in water bodies, causing algae blooms and subsequent oxygen depletion, which can result in the death of fish and other aquatic organisms. Implementing best management practices (BMPs), such as precision farming techniques, can help farmers optimize fertilizer application rates and reduce the potential for runoff into water bodies.

Manure management: Livestock operations generate large amounts of manure, which, if not properly managed, can contaminate water sources with excess nutrients and harmful bacteria. Proper storage and treatment of manure, such as through composting or anaerobic digestion, can help reduce the risk of water pollution.

Soil erosion: Agricultural activities, such as improper land tillage practices and the removal of natural vegetation, can lead to soil erosion, particularly in areas with sloping landscapes. Eroded soil can end up in nearby rivers, lakes, and streams, causing sedimentation and negatively impacting water quality. Conservation techniques, such as no-till or reduced tillage, can help mitigate soil erosion by keeping soil in place and reducing the exposure of bare soil to wind and water erosion.

Irrigation and water management: Inefficient irrigation practices can contribute to water pollution in several ways. For example, when too much irrigation water is applied or is improperly managed, it can cause runoff that carries sediment, nutrients, and pesticides into water bodies. Additionally, using contaminated water sources for irrigation can introduce pollutants into the soil and impact the quality of runoff water. Improving irrigation efficiency, such as through drip irrigation or precision water application, can minimize these issues.

By adopting sustainable agricultural practices and implementing appropriate management strategies, farmers can reduce their operations' impact on water quality and contribute to the health of aquatic ecosystems.

Human waste

Additionally, human waste often contains elevated levels of nitrogen and phosphorus, which can lead to nutrient pollution in water. This excess nutrient input can cause excessive growth of algae, known as algal blooms. When these algal blooms decompose, they deplete the oxygen levels in the water, creating "dead zones" where aquatic life cannot survive. Nitrate and nitrite, which are also present in human waste, pose a severe risk, particularly to infants, as they can cause methemoglobinemia or "blue baby syndrome," a potentially fatal condition.

Furthermore, human waste can contain organic chemicals and toxic substances that can contaminate groundwater and surface water. These chemicals, often found in household products, agriculture, and industry, include pesticides, pharmaceuticals, and solvents. Ingestion of water contaminated with these chemicals can lead to health issues in multiple organ systems, including the kidneys, liver, circulatory system, nervous system, and reproductive system.

Improperly managed septic systems and wastewater treatment plants can also contribute to water pollution from human waste. Septic system failures due to aging infrastructure, poor design, or inadequate maintenance can result in the release of untreated or partially treated sewage into local water bodies or groundwater. Similarly, wastewater treatment plants may struggle to remove all contaminants, particularly if they lack advanced equipment or proper treatment processes.

To address the issue of water pollution from human waste, it is crucial to prioritize proper wastewater management and invest in effective treatment technologies. This includes regularly maintaining septic systems, upgrading infrastructure, and ensuring that treatment plants have the necessary resources and protocols to thoroughly treat human waste before discharging it into the environment. By taking these steps, we can help protect water sources, preserve aquatic ecosystems, and safeguard public health.

Microplastics

Another source of microplastics is microbeads, which are very small manufactured plastic beads used in health, beauty, and personal care products. These microbeads are added as exfoliants in products like cleansers and toothpaste. While their use has been banned in some countries, such as the US, they continue to be found in waterways and oceans, as they easily pass through water filtration systems.

The presence of microplastics in water has detrimental effects on aquatic life. Aquatic organisms, such as sea turtles, seabirds, and crustaceans, can easily mistake microplastics for food, leading to ingestion. The ingestion of microplastics can have fatal consequences for these organisms, contributing to a significant number of incidences. Additionally, microplastics can cause entanglement, leading to drowning, suffocation, or strangulation of aquatic wildlife.

Furthermore, microplastics can act as a magnet for heavy metals and organic pollutants in the water, such as polychlorinated biphenyls (PCBs). They have the ability to concentrate these pollutants up to 100,000 to 1,000,000 times the levels found in seawater. This contamination poses a severe threat to the marine food chain, impacting key foraging species and the organisms that rely on them for food.

To address the issue of microplastics in water, it is essential to reduce plastic usage and properly manage plastic waste. Individuals can play a crucial role by opting for reusable and sustainable alternatives, recycling, and supporting companies that use biodegradable and sustainable packaging. Additionally, participation in clean-up programs and advocacy for better waste management practices can help mitigate the impact of microplastics on our water sources and the environment.

Frequently asked questions