Water Pollution: Sources And Causes Of Contamination

Water pollution is a pressing issue that poses a threat to human health, the environment, and the economy. Water pollution occurs when harmful substances contaminate water bodies, degrading water quality and rendering it toxic or unusable. There are various ways in which water supplies can become polluted, ranging from industrial waste and agricultural runoff to sewage and wastewater issues, as well as oil spills and leaks. These sources of pollution have detrimental effects on both human health and the environment, causing diseases, disrupting ecosystems, and impacting sectors such as commercial fishing and tourism.

Industrial waste

Industry accounts for about 20% of the freshwater withdrawn worldwide. This water is used in production and becomes polluted. In some cases, it is cleaned by industrial wastewater recycling systems and is sometimes reused or disposed of in an environmentally friendly way. However, in some areas, it is discharged untreated into nearby public waters, polluting the drinking water of residents in the surrounding area. This is particularly common in emerging countries such as China, India, Africa, and South America, where environmental policies are not as stringent or well-enforced as in other parts of the world.

The production of industrial goods generates wastewater that can be contaminated with toxic substances, including PFAS (per- and polyfluorinated alkyl compounds). These toxic substances can have far-reaching consequences for the environment and human and animal health. For example, hazardous substances from industries can accumulate in water sediments, leading to illnesses and deaths among fish, crustaceans, and other creatures, reducing biodiversity. These contaminants can also enter the groundwater, contaminating drinking water supplies.

In the United States, industrial waste has been a significant issue since the Industrial Revolution. The amount of hazardous waste generated by manufacturing industries has increased drastically over the years, from an estimated 4.5 million tons annually after World War II to approximately 265 million tons by 1990. This waste is generated at every stage of the production, use, and disposal of manufactured products, and it includes toxic chemicals that can have adverse effects on the environment and human health.

The biggest culprits of industrial water pollution include oil refineries, chemical and plastics manufacturers, and fertilizer plants. For example, U.S. oil refineries discharge nearly half a billion gallons of wastewater into waterways every day, including heavy metals, oils, greases, and industrial salts. Chemical and plastics plants release millions of pounds of pollutants such as nitrogen, benzene, lead, hormone-disrupting phthalates, PFAS, and microplastics. Fertilizer plants dump millions of pounds of nitrogen, cyanide, chromium, nickel, lead, and other pollutants into waterways.

The effects of industrial water pollution are devastating. It makes rivers and lakes unsafe for swimming and other recreational activities, and it poses serious risks to human health. Polluted water is also unsuitable for agriculture and industry, and it diminishes the aesthetic quality of lakes and rivers. Additionally, contaminated water destroys aquatic life and reduces its reproductive ability.

To combat industrial water pollution, it is essential to have proper waste management systems in place and ensure that wastewater is treated before being discharged into public waters. Updated regulations and stricter enforcement of environmental policies are also necessary to hold industries accountable and protect our waterways.

Sewage and wastewater

The improper disposal of sewage and wastewater can have detrimental effects on both human health and the environment. According to the United Nations, water pollution causes more deaths annually than all forms of violence combined, including war. The bacteria and viruses present in wastewater from human and animal waste spread diseases such as typhoid, cholera, and giardia. Additionally, the pathogens and bacteria in wastewater breed diseases, causing health issues in humans and animals.

Moreover, sewage and wastewater pollute aquatic ecosystems. When sewage and wastewater enter water bodies, they promote algae growth, leading to eutrophic "dead zones" where aquatic life cannot survive due to oxygen depletion. This disruption in the ecosystem can have far-reaching consequences, affecting biodiversity and food security.

Furthermore, sewage and wastewater contribute to the introduction of toxic substances into water sources. Wastewater contains a cocktail of contaminants, including pathogens, pharmaceuticals, microplastics, heavy metals, and endocrine disruptors. These contaminants threaten marine species and our food and water security. The improper disposal of sewage and wastewater can also lead to habitat loss and extinction, as well as closed beaches and collapsed fisheries.

To address the issue of sewage and wastewater pollution, it is crucial to have adequate treatment processes in place. Currently, a significant amount of the world's wastewater is released into the environment without proper treatment. This untreated wastewater flows back into rivers, reservoirs, lakes, and seas, causing widespread pollution. Upgrading and maintaining sewage treatment systems are essential to reducing the amount of pollutants released into water bodies.

Oil leaks and spills

Oil spills and leaks are a major cause of water pollution. Oil does not dissolve in water, instead, it forms a thick sludge that can suffocate fish, impair the flight of birds, and block light from photosynthetic aquatic plants.

Oil spills can be caused by human error, natural disasters, technical failures, or deliberate releases. Human error accounts for 30-50% of all oil spills, while equipment failure or malfunction accounts for 20-40%. Oil spills from tankers are particularly severe due to the large quantity of oil being released in a single place. Oil spills can also occur during the transport of oil by ships, or through leaks and spills from drilling operations in the ocean.

The effects of oil spills can be disastrous for the environment, society, and the economy. They can cause immediate negative health effects on humans, including respiratory and reproductive problems, as well as liver and immune system damage. Oil spills can also contaminate drinking water supplies, as seen in 2013 when two separate oil spills contaminated water supplies for 300,000 people in Miri, Malaysia, and 80,000 people in Coca, Ecuador.

Oil spills can have severe consequences for marine wildlife such as fish, birds, and sea otters. Oil penetrates the structure of the plumage of birds and the fur of mammals, reducing its insulating ability and making them more vulnerable to temperature fluctuations and less buoyant in the water. Oil can impair a bird's ability to fly, preventing it from foraging or escaping predators. The majority of birds affected by oil spills die from complications without human intervention.

Oil spills can also impact the economy, particularly in sectors such as tourism and marine resource extraction industries. For example, the Deepwater Horizon oil spill in 2010 impacted beach tourism and fishing along the Gulf Coast, and the responsible parties were required to compensate economic victims.

Agricultural chemicals

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 victim of water pollution.

Agricultural activities discharge pollutants and sediment into surface and groundwater supplies. Poor agricultural practices can lead to the net loss of soil through erosion and waterlogging of irrigated land. The use of wastewater and polluted surface and groundwater can contaminate crops and transmit diseases to consumers and farmworkers.

Agricultural water pollution can be caused by:

• Irrigation: Irrigation return flows carry salts, nutrients, and pesticides.
• Animal feedlots: Contamination of surface water with pathogens, metals, phosphorus, and nitrogen.
• Fertilizers: Excess nutrients from fertilizers draining into streams can stimulate algal blooms, affecting stream health, recreational uses, and increasing treatment costs for drinking water.
• Pesticides: Pesticides transported into streams can pose risks to aquatic life, fish-eating wildlife, and drinking water supplies.
• Sedimentation: Erosion and sedimentation can overwhelm aquatic ecosystems, smother breeding areas, and degrade coastal and marine ecosystems, including coral reefs.
• Livestock manure: Bacteria and nutrients from livestock and poultry manure can cause beach and shellfish bed closures and affect drinking water supplies.

Agricultural practices can have significant effects on water quality due to the extent of farm activities, the soil-disturbing nature of those activities, and the associated impacts from sediment, nutrients, pesticides, and herbicides.

To mitigate these harmful impacts, farmers can adopt soil and water conservation practices, such as:

• Nutrient management: Targeting fertilizer and manure application through soil testing, crop-specific calibration, and timing applications to minimize runoff.
• Tillage and drainage methods: Using conservation practices such as no-till or conservation tillage to reduce runoff, and implementing cover crops to uptake residual nutrients.
• Vegetated buffer strips: Establishing buffer zones around farms and along rivers to intercept runoff and reduce pollutant concentrations entering waterways.
• Efficient irrigation: Using drip irrigation to decrease water loss and allow better control of pesticide and nutrient amounts.
• Manure storage: Storing livestock manure in lagoons, covered stockpiles, or protected upland areas to minimize runoff risks.

By implementing these practices, farmers can play a crucial role in reducing water pollution and protecting aquatic ecosystems and human health.

Radioactive waste

Radioactive contamination can occur through human-induced and natural processes. Nuclear calamities, nuclear power plants, and the dumping of radioactive waste are significant sources of human-induced contamination. Radioactive waste is often stored in tanks or dumped in shallow trenches and pits, packaged in cardboard, wooden boxes, or drums. These storage methods can fail, leading to leaks and the migration of radioactive materials into nearby water sources. Nuclear submarines and accidents have also been responsible for radioactive contamination in the marine environment.

Natural sources of radioactive contamination include the percolation of naturally occurring radioactive materials (NORM) from soil sediments into aquifers, causing groundwater contamination. Uranium, thorium, and actinium are three NORM series that contaminate water resources. Radium, a descendant of the NORM series, can penetrate groundwater through aquifer rock dissolution, the decay of uranium and thorium, or desorption processes.

The deposition of radioactive gases released from magma into water bodies also contributes to radioactive contamination. Atmospheric deposition, both dry and wet, of cosmogenic radionuclides adds radioactive nuclei to surface water.

Radioactive contamination of water supplies has severe health consequences. Ingesting contaminated water is a major risk pathway for human exposure to radioactivity. High doses of radiation can cause acute radiation syndrome, cutaneous radiation injury, cancer, leukaemia, genetic mutations, osteonecrosis, cataracts, and chromosomal disruption. Exposure to radiation during early life means a long period for damage to develop, and pregnant women and young children are especially vulnerable.

To address radioactive contamination in water supplies, proper analysis, monitoring, and prevention measures are necessary. Treatment methods such as aeration, reverse osmosis, ion exchange, and granular carbon adsorption are effective in treating radioactive contaminated water.

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