Water Quality: Pollutants And Their Impact

Water pollution is a severe environmental issue that impacts human health, wildlife, and ecosystems. Water pollution occurs when harmful substances contaminate a body of water, degrading water quality and rendering it toxic. Some examples of pollutants that affect water quality include:

- Chemicals: Industrial sites contribute solvents and metals, while agricultural practices introduce pesticides and fungicides.

- Wastewater: Sewage, industrial waste, and agricultural runoff can contain high levels of nutrients, encouraging weed and algae growth, which depletes oxygen levels and clogs filters.

- Oil spills: While often localized, oil spills can spread for miles, harming marine life and disrupting ecosystems.

- Macroscopic pollutants: Trash, especially plastic waste, is a significant issue, with items being thrown directly into bodies of water or accidentally deposited via streams and rivers.

- Pathogens: Bacteria, protozoa, and viruses can cause diseases such as cholera and typhoid, with human and animal waste being a common source.

- Heavy metals: Arsenic, mercury, copper, and other heavy metals, even in small concentrations, can act as pollutants and cause severe health issues for humans and other organisms.

Sewage and wastewater

The issue of sewage and wastewater pollution is not limited to a single source but can come from various point sources and dispersed sources. Point sources refer to specific pipes or channels, such as those from industrial facilities or city sewerage systems. On the other hand, dispersed sources are more widespread and include agricultural runoff, stormwater runoff, and discharges from factories.

The impact of sewage and wastewater on water quality is significant. When released into water bodies, sewage and wastewater introduce a range of harmful substances. These can include disease-causing microorganisms, such as bacteria and viruses, as well as toxic chemicals and heavy metals. One of the major concerns is the depletion of oxygen in the water, which can lead to anaerobic decay and the death of aquatic life. Sewage often contains organic waste, which, during decomposition, consumes oxygen in the water. This depletion of oxygen can create "dead zones" where aquatic life cannot survive.

Furthermore, sewage and wastewater can introduce plant nutrients, particularly nitrates and phosphates, which promote excessive algae growth, known as algal blooms. While algae may not seem harmful, their rapid growth and subsequent decomposition by microorganisms further deplete the oxygen levels in the water. This process, known as eutrophication, can lead to the premature aging and death of water bodies.

Another concern with sewage and wastewater is the presence of solid waste, including garbage, electronic waste, and construction debris. These can be directly dumped into bodies of water or carried there by wind or rainfall. Solid waste not only damages aquatic ecosystems and harms wildlife but also releases harmful chemicals into the water as they break down.

To address the issue of sewage and wastewater pollution, it is crucial to have proper wastewater treatment facilities. These facilities are designed to reduce the amount of pollutants, such as pathogens, heavy metals, and toxic chemicals, before the treated water is discharged back into waterways. However, it is important to recognise that even in developed countries like the United States, ageing sewage treatment systems can release billions of gallons of untreated wastewater each year.

Industrial waste

The effects of industrial waste water pollution include:

• Contamination of drinking water sources and irrigation water used for farming.
• Degradation or destruction of habitats for animals and plants.
• Contamination of fish and other aquatic life in coastal areas, leading to closures of beaches and recreational areas.
• Accumulation of toxic substances in aquatic sediments, which can enter the groundwater or be stirred up during floods or dredging.
• Illness and death of fish, crustaceans, and other aquatic creatures, disrupting the biodiversity.
• Human health risks, as polluted water can cause various diseases and adverse health issues.

To mitigate the impact of industrial waste on water quality, most countries have enacted legislation and implemented treatment systems. However, enforcement and compliance vary globally, and emerging industrialized nations may lack the necessary resources and technology for effective waste management.

Agricultural waste

One of the significant concerns with agricultural waste is the presence of animal waste, fertilizers, and pesticides. Every time it rains, these substances are washed from farms and livestock operations into nearby waterways. This contributes to nutrient pollution, caused by excess nitrogen and phosphorus in water or air, which is the number-one threat to water quality worldwide. Nutrient pollution can lead to algal blooms, a toxic soup of blue-green algae that can be harmful to both people and wildlife.

The impact of agricultural waste on water quality is not limited to immediate surroundings but can also affect downstream environments, including oceans. As the ocean is downstream from nearly every terrestrial location, it ultimately receives much of the plastic waste and other pollutants generated on land. This has severe consequences for marine life and ecosystems, with unsightly and dangerous waste materials sometimes washed back to shore, littering beaches with hazardous debris.

Oil spills

The clean-up and recovery process following an oil spill is challenging and depends on various factors, including the type of oil spilled, the temperature of the water, and the types of shorelines and beaches involved. Physical clean-up methods are very expensive, while chemical remediation is now the norm, using compounds to herd and thicken oil for physical recovery, or facilitate burning the oil off.

Radioactive substances

Radioactive waste is a primary contributor to water pollution. This waste is generated by various human activities, including uranium mining, nuclear power plants, military weapons production and testing, and the use of radioactive materials in universities and hospitals for research and medical purposes. The challenge with radioactive waste is its persistence in the environment, remaining hazardous for thousands of years. Improper disposal or accidental release of radioactive waste can contaminate groundwater, surface water, and marine resources, rendering them unsafe for human and ecological use.

The presence of radioactive substances in water poses a health risk due to the radiation they emit. This radiation, known as ionizing radiation, includes alpha, beta, gamma rays, and free neutrons. The hazard posed by this radiation depends on factors such as the concentration of contaminants, the energy and type of radiation, and proximity to the human body. Ingesting or inhaling radioactive substances can result in internal irradiation, while external irradiation can occur through radiation from contaminated sources outside the body. Prolonged exposure to elevated levels of radiation increases the risk of developing cancer and other health issues.

To address the issue of radioactive substances in water, regulatory agencies like the U.S. Environmental Protection Agency (EPA) have established standards and regulations. The EPA's Radionuclides Rule sets federal standards for radionuclides in drinking water, aiming to ensure safe levels for human consumption. Additionally, public drinking water systems regularly test and filter water to remove radioactive contaminants. These measures are crucial to mitigate the potential health risks associated with radioactive substances in water.

Frequently asked questions