Water: A Friend Or Foe To The Environment?

Water pollution is the contamination of water bodies, including lakes, rivers, oceans, aquifers, reservoirs, and groundwater, with substances that render it unsafe for human use and harm aquatic ecosystems. Water pollution can be caused by a range of contaminants, such as toxic waste, petroleum, and disease-causing microorganisms, which can have devastating impacts on the environment and human health. While water pollution is often associated with human activities, it can also be caused by natural processes, such as the release of mercury from the Earth's crust.

Water pollution is a pressing issue that affects the health and well-being of millions worldwide, and it is crucial to address this problem to ensure the availability of clean water for future generations.

Sewage and wastewater

Sewage is defined as the discharge of human waste materials into bodies of water, including rivers, dams, and the ocean. This type of pollution has several harmful impacts on the environment. For example, sewage discharge leads to a significant decline in water quality as pathogens in the waste harm aquatic ecosystems and make the water unsafe for human and animal use. Sewage is also a major source of plant nutrients, mainly nitrates and phosphates, which promote the growth of algae and can cause algal blooms. These blooms can lead to a change in biodiversity and impact the functioning of aquatic ecosystems.

In addition to the environmental impacts, sewage pollution also poses severe health risks to humans. It is linked to several life-threatening diseases, including cholera, typhoid, dysentery, and hepatitis A. Contamination of drinking water sources by sewage can endanger human and animal health and also lead to expensive water treatment processes.

Wastewater is used water that comes from sinks, showers, and toilets (sewage) and from commercial, industrial, and agricultural activities. According to the United Nations, more than 80% of the world's wastewater flows back into the environment without being treated or reused. This untreated wastewater contains a range of pollutants, including pathogens, heavy metals, toxic chemicals, and microplastics. These contaminants can have far-reaching consequences for climate resilience, aquatic biodiversity, and food and water security.

To address the issue of sewage and wastewater pollution, proper sanitation and wastewater control are essential. This includes maintaining septic systems, ensuring proper disposal of waste, and implementing effective wastewater treatment processes. By taking these measures, we can prevent the harmful impacts of sewage and wastewater pollution on both the environment and human health.

Industrial activities

Sources of Industrial Water Pollution

• Burning Fossil Fuels: The burning of coal, oil, petroleum, and natural gas releases pollutants into the atmosphere and can also lead to water contamination.
• Chemical Solvents: Industries use and release various chemical solvents, such as ammonia, which can find their way into water bodies.
• Radioactive Material Leakage: Nuclear power plants and radioactive waste disposal sites pose risks of radioactive leaks, which can contaminate water sources.
• Release of Untreated Waste: Inadequate waste management practices often result in the discharge of untreated industrial waste into water bodies, including sewage, chemicals, and heavy metals.
• Agricultural Runoff: Pesticides, fertilizers, and other agrochemicals used in agriculture can runoff into nearby water sources, leading to pollution.

Types of Industrial Wastewater

• Stormwater Runoff: Rainfall or floodwater that does not soak into the ground can carry pollutants like plastics, pesticides, oils, and heavy metals into nearby waterways.
• Domestic Wastewater: Wastewater from households, including toilet waste, kitchen waste, and bathing water, can contain contaminants such as urine, faecal matter, and cleaning chemicals.
• Agricultural Wastewater: Excess water from irrigation, along with agrochemicals, fertilisers, and animal waste, can run off into nearby water sources, contributing to pollution.
• Industrial Wastewater: Water discharged from various industrial processes, containing contaminants like heavy metals, chemicals, oils, pesticides, pharmaceuticals, and other by-products.

Effects of Industrial Water Pollution

• Eutrophication: Industrial wastewater often contains high levels of nutrients like nitrogen and phosphorus, leading to excessive growth of algae and plants, which can deplete oxygen levels in water, causing aquatic life to suffocate.
• Toxicity: Industrial pollutants such as heavy metals, chemicals, and sewage released into water bodies can have toxic effects on aquatic life, including fish and crustaceans, leading to biodiversity loss.
• Groundwater Contamination: Polluted water from rivers and lakes can infiltrate the ground and contaminate groundwater sources, posing risks to human health.
• Bioaccumulation: Persistent pollutants like chlorobenzene can accumulate in the fatty tissues of animals and humans, leading to health issues, including cancer.
• Waterborne Diseases: Contaminated water sources can lead to the spread of waterborne diseases such as diarrhoea, cholera, hepatitis, and cancer.

Preventing and Mitigating Industrial Water Pollution

• Wastewater Treatment: Implementing proper wastewater treatment processes, such as biological, chemical, and physical methods, to remove or reduce pollutants before discharging water into the environment.
• Closed-Loop Systems: Adopting closed-loop systems where treated wastewater is recycled and reused in production processes, reducing the need for freshwater withdrawal.
• Sustainable Technologies: Investing in new, sustainable technologies that minimise water consumption and pollution, such as membrane systems and vacuum distillation systems.
• Effective Policies and Enforcement: Governments play a crucial role in enacting and enforcing strict environmental policies, such as the Zero Pollution Action Plan in the EU, to regulate industrial waste management and discharge practices.

Agricultural activities

Agriculture is the single largest user of freshwater resources, using a global average of 70% of all surface water supplies. It is both a cause and a victim of water pollution.

Agricultural water pollution is caused by:

• The use of fertilizers and pesticides, which can lead to eutrophication and the growth of harmful algal blooms.
• Animal waste from intensive livestock breeding, which can contaminate water with pathogens and metals.
• Irrigation, which can carry salts, nutrients, and pesticides into water bodies.
• Land cultivation, which can result in soil erosion and the silting of rivers and streams.
• The use of unlined irrigation canals, which can lead to the rising of groundwater levels.
• The use of persistent pesticides, which can contaminate water sources and harm aquatic life.
• The improper disposal of solid waste, such as plastic and electronic waste, which can break down and leach harmful chemicals into the water.

Agricultural water pollution has various impacts on both the environment and human health:

• It can lead to eutrophication, or the rapid biological "aging" of lakes, streams, and estuaries, causing them to become oxygen-depleted "dead zones" where aquatic life cannot survive.
• It can contaminate drinking water sources, leading to an increased risk of waterborne diseases such as cholera, typhoid, and giardiasis.
• It can disrupt the reproductive and developmental processes of humans and animals, damage DNA, and cause cancer.
• It can affect the growth and development of fish, reduce their ability to reproduce, and even cause death.
• It can lead to a decline in frog biodiversity and tadpole mass.
• It can increase the susceptibility of marine organisms to disease and affect their reproductive processes.
• It can disrupt photosynthesis in aquatic plants and harm ecosystems that depend on them.
• It can contaminate crops and transmit diseases to consumers and farm workers.

To address agricultural water pollution, the following actions can be taken:

• Establish and operate cost-effective water quality monitoring systems for agricultural water uses.
• Prevent the adverse effects of agricultural activities on water quality through the optimal use of on-farm inputs and the minimization of external inputs.
• Establish water quality criteria for agricultural water users and for marine and riverine ecosystems.
• Prevent soil runoff and sedimentation through the use of conservation practices such as contour strip cropping.
• Properly dispose of sewage from human settlements and manure produced by intensive livestock breeding.
• Minimize the adverse effects of agricultural chemicals by using integrated pest management and adopting soil and water conservation practices.
• Educate communities about the pollution impacts of using fertilizers and chemicals on water quality and food safety.

Urban runoff

This has several negative consequences. Firstly, it lowers the water table by reducing groundwater recharge. Secondly, it can cause flooding as more water remains on the surface. Thirdly, it contributes to water pollution as the stormwater picks up pollutants such as gasoline, motor oil, heavy metals, trash, fertilizers, and pesticides, which are then deposited into streams, lakes, and groundwater.

Roads and parking lots are significant sources of polycyclic aromatic hydrocarbons (PAHs) and heavy metals like nickel, copper, zinc, cadmium, and lead. Roof runoff also contributes high levels of synthetic organic compounds and zinc from galvanized gutters. Improperly applied fertilizers or over-fertilized lawns can be a measurable source of nitrates and phosphorus in urban runoff.

Eroding soils or poorly maintained construction sites can lead to increased sedimentation in runoff, which can directly affect water quality. Excessive sediment and suspended solids can damage existing infrastructure and reduce reservoir capacities, leading to increased expenses for public land agencies and impacting water quality in recreational areas.

Additionally, urban runoff can induce bioaccumulation and biomagnification of toxins in ocean life. Small amounts of heavy metals carried by runoff into the oceans can accumulate within aquatic animals, leading to metal poisoning, which can also affect humans who ingest these poisoned animals.

The increased water flow and velocity caused by urban runoff can also have detrimental effects on natural watercourses, including increased erosion and the destruction of natural features such as meanders and sandbars. Eutrophication often occurs in waterways affected by this type of runoff due to the presence of fertilizer and organic waste, leading to deadly consequences for fish and other aquatic organisms.

To mitigate the impacts of urban runoff, local governments employ various stormwater management techniques, known as best management practices for water pollution (BMPs). These techniques may focus on water quantity control or improving water quality, or both. Prevention practices include low-impact development (LID) or green infrastructure techniques, such as green roofs and improved chemical handling. Runoff mitigation systems, such as infiltration basins and constructed wetlands, are also utilized to manage the volume and quality of stormwater.

Oil spills

Causes of Oil Spills

Impact of Oil Spills

Response and Cleanup

The response to and cleanup of oil spills can be challenging and depends on various factors, including the type of oil spilled, water temperature, and the types of shorelines and beaches involved. Physical cleanups are expensive, and complete removal of oil from the environment is often impossible. Various methods are used to contain and remove oil, including booms, skimmers, controlled burning, and the use of chemical dispersants. However, cleanup activities must be carefully executed to avoid causing additional harm to the environment.

Prevention and Mitigation

To prevent and mitigate the impacts of oil spills, several measures can be implemented. These include double-hulling in vessels, which reduces the risk and severity of spills, and the use of spill response procedures and Oil Spill Prevention Control and Countermeasures (SPCC) programs. Additionally, the Oil Pollution Act of 1990 holds those responsible for oil spills accountable for the cleanup and restoration costs.

Frequently asked questions