Human Activities: A Major Cause Of Water Pollution

Water pollution is a pressing issue that jeopardises human health and safety. It occurs when harmful substances contaminate bodies of water, degrading water quality and rendering it toxic. Human activities are a significant contributor to water pollution, with industrial sites, agricultural practices, sewage systems, and oil spills being key factors.

Industries often produce toxic waste that ends up in freshwater systems, while agricultural runoff allows pesticides and fertilisers to mix with rainwater, leading to contaminated waterways. Sewage and wastewater, even when treated, contain harmful chemicals and bacteria, affecting water quality and marine life. Oil leaks and spills, often from drilling operations or shipping, are another major cause of water pollution.

These human activities have severe consequences for ecosystems, human health, and the economy. It is crucial to address these issues and implement measures to reduce water pollution, protect our limited water resources, and ensure a sustainable future for our planet.

Sewage and wastewater

The treatment of sewage and wastewater is crucial in reducing water pollution. Wastewater treatment facilities work to reduce pollutants such as pathogens, phosphorus, nitrogen, heavy metals, and toxic chemicals before discharging the treated water back into waterways. However, it is important to note that even treated sewage and wastewater may still contain harmful substances. According to the United Nations, more than 80% of the world's wastewater flows back into the environment without proper treatment, and aging sewage treatment systems can release billions of gallons of untreated wastewater each year.

The impact of sewage and wastewater pollution on water quality is significant. It can cause harmful algal blooms, which starve the water of oxygen and lead to the death of aquatic species. It also poses risks to human health, with water users susceptible to contracting illnesses, including viruses and antimicrobial-resistant bacteria.

The inadequate management of sewage and wastewater can be attributed to several factors. In the UK, for example, the sewerage system is antiquated and relies heavily on sewer overflows to discharge raw sewage into rivers and the ocean. Additionally, water companies have been accused of profiting from pollution and failing to invest in protecting coastal and river environments.

To address the issue of sewage and wastewater pollution, it is essential to advocate for improved wastewater treatment infrastructure and hold water companies and governments accountable for their environmental impact. Public awareness and support for initiatives like the Clean Water Act are crucial in driving change and protecting our water resources.

Industrial waste

Hazardous waste may result from manufacturing or other industrial processes, and it can be toxic, ignitable, corrosive, or reactive. Certain commercial products, such as cleaning fluids, paints, or pesticides discarded by commercial establishments or individuals, can also be defined as hazardous waste. If improperly managed, hazardous waste can pose dangerous health and environmental consequences. For example, in the United States, the amount of hazardous waste generated by manufacturing industries increased from an estimated 4.5 million tons annually after World War II to approximately 265 million tons by 1990.

Wastewater from manufacturing or chemical processes in industries contributes to water pollution. Industrial wastewater usually contains specific and readily identifiable chemical compounds. Water pollution is particularly concentrated within a few subsectors, mainly in the form of toxic wastes and organic pollutants. A large portion can be traced back to the processing of industrial chemicals and the food products industry.

Most major industries have treatment facilities for industrial effluents, but small-scale industries often cannot afford the enormous investments in pollution control equipment. As a result, their waste is discharged into rivers, streams, and other bodies of water that lead directly to the sea, causing water pollution and endangering aquatic life.

Oil spills

Sources of Oil Spills

Impact of Oil Spills

Preventing and Responding to Oil Spills

To prevent oil spills, double hulls have been implemented in large tankers to reduce the risk and severity of spills in collisions or groundings. Other innovations, such as GPS, sectioning of vessels, and sea lanes in narrow straits, have also contributed to the reduction of oil tanker spills.

When an oil spill occurs, the U.S. Coast Guard is responsible for cleaning it up, while organizations like the National Oceanic and Atmospheric Administration (NOAA) provide scientific support to make informed decisions during emergency operations. Various methods and tools are used for cleanup, including booms, skimmers, controlled burning, dispersants, bioremediation, and solidification.

Agricultural runoff

Causes of Agricultural Runoff

Fertilizers and Pesticides

Fertilizers and pesticides are commonly used in agriculture to enhance crop growth and protect against pests. However, they can enter runoff due to over-application, improper timing, or failure to incorporate them into the soil. When it rains or irrigation water is used, these chemicals are washed off fields and into nearby rivers, lakes, and oceans. Nitrogen-based fertilizers, in particular, can be carried away in the flow, while pesticides can bind to soil particles and be transported via sediment runoff.

Animal Waste

Animal waste from livestock farming is a significant contributor to agricultural runoff. Manure contains high levels of nutrients, pathogens, and organic matter. During rainfall or irrigation, this waste can be washed into water bodies, increasing the biological oxygen demand (BOD) and further degrading water quality. Large-scale concentrated animal feeding operations (CAFOs) produce substantial amounts of waste that often exceed the land's absorption capacity, leading to spills and leaks that contaminate surface and groundwater.

Irrigation Practices

Inefficient irrigation methods, such as flood irrigation or poorly managed sprinkler systems, can contribute to excessive runoff. When more water is applied than the soil can absorb, the excess flows over the surface, carrying soil, nutrients, and pesticides into nearby water bodies. Flood irrigation, for example, involves inundating the entire field with water, but it is highly inefficient, especially on soils with low infiltration rates.

Land Management Practices

Tilling and other poor land management practices disrupt the soil structure, making it more susceptible to erosion. When the soil is bare and exposed, rainfall can easily dislodge soil particles, leading to sedimentation in rivers and streams, a significant source of non-point source pollution. Deforestation and the removal of natural vegetation for agricultural expansion further exacerbate soil erosion, as they remove the protective cover that helps hold soil particles in place.

Environmental Impact of Agricultural Runoff

Impact on Aquatic Life

Pesticides, herbicides, and fertilizers can be toxic to fish, amphibians, and invertebrates, causing mortality and sub-lethal effects such as reproductive failure and developmental abnormalities. These chemicals can also bioaccumulate in the tissues of aquatic organisms, leading to higher concentrations as they move up the food chain through biomagnification. This poses significant risks to predators, including birds and humans, who consume contaminated fish.

Impact on Inland and Coastal Waters

Impact on Soil

The loss of topsoil and the introduction of chemical contaminants from agricultural runoff can cause soil degradation. The use of chemical fertilizers and pesticides alters soil pH, kills beneficial microorganisms, and reduces organic matter, leading to diminished soil fertility and structure. As soil health declines, farmers often increase their use of fertilizers and pesticides, further degrading soil quality and compromising long-term agricultural sustainability.

Impact on Human Health

Additionally, agricultural runoff can carry pesticides and herbicides, such as glyphosate and atrazine, which can persist in water sources and contaminate drinking water. Chronic exposure to these chemicals has been linked to various health issues, including cancer, reproductive disorders, endocrine disruption, and neurological impairments. Pathogens, such as E. coli, Salmonella, and Cryptosporidium, can also enter water supplies through runoff contaminated with animal waste or improperly treated sewage, leading to acute health risks for communities.

Marine dumping

Types of Marine Dumping

• Dredged Material: This includes silt and sand removed from rivers, canals, and harbors, often to create new waterways. While most dredged material is dumped onto land or used for development, around 20-22% ends up in the ocean. This waste can be contaminated with heavy metals, hydrocarbons, nutrients, and pesticides, posing a significant threat to marine life and ecosystems.
• Industrial Waste: Until the early 1970s, it was legal to dump industrial waste into the ocean. Even though it is now regulated, illegal dumping still occurs worldwide. Industrial waste contains hazardous substances such as acids, alkaline waste, scrap metals, and toxic chemicals. When dumped into the ocean, it can have adverse effects on marine life, such as disrupting spawning in herring and lobster populations.
• Sewage Sludge: Sludge from sewage treatment can be recycled as fertilizer if it is not contaminated with oils, organic chemicals, and metals. However, it is often cheaper for treatment centers to dump this sludge into the ocean, particularly if it is chemically contaminated. While the UN considers properly treated sludge relatively safe, sewage dumping can still pose risks to human health and the marine environment.
• Radioactive Waste: Nuclear waste is typically dumped into the ocean as a result of nuclear power processes, medical and industrial uses, and research. This waste can remain radioactive for decades, and its long-term effects are not well understood. Some estimates predict up to 1,000 deaths in the next 10,000 years due to evaporated nuclear waste.

Impacts of Marine Dumping

• Habitat Destruction: Marine dumping can destroy or degrade important habitats for aquatic species. For example, seagrass, which is crucial for the survival of sea turtles, manatees, fish, shrimps, and crabs, is sensitive to pollution and development and is being lost at an alarming rate.
• Coastal Erosion: The accumulation of waste and excess sediment from dumping can lead to coastal erosion, further degrading coastal habitats and ecosystems.
• Entanglement and Ingestion: Marine debris, such as plastic bags, fishing lines, and litter items, can entangle or be ingested by marine animals. This can lead to injury, starvation, or death. For example, sea turtles often mistake plastic bags for jellyfish, their favorite food, which can clog their intestines and lead to death.
• Toxicity and Eutrophication: Industrial waste and sewage sludge often contain toxic substances that can contaminate seawater and harm marine organisms. Additionally, the release of nutrients from fertilizers and sewage can cause excessive growth of algae, leading to eutrophication and the creation of "dead zones" where oxygen levels are too low to support life.
• Economic and Health Impacts: Marine dumping can have serious economic consequences, especially for coastal communities dependent on fishing and tourism. It can also impact human health, as contaminants can accumulate in seafood, leading to the consumption of harmful chemicals and increased health risks.

Frequently asked questions