The Impact Of Pollution On Our Freshwater Sources

Water pollution is a pressing global issue that affects both human and wildlife health. It occurs when harmful substances contaminate bodies of water, including lakes, rivers, oceans, and groundwater, degrading water quality and rendering it toxic. This contamination can come from a variety of sources, such as industrial waste, agricultural runoff, sewage discharges, and urban stormwater runoff. These pollutants have severe impacts on aquatic ecosystems, including physical harm to fish and other organisms, the destruction of habitats, and the spread of water-borne diseases. With only a small percentage of freshwater easily accessible on the planet, safeguarding water supplies and addressing water pollution are crucial for the health and well-being of both humans and the environment.

Industrial waste

The effects of industrial waste on freshwater include:

• Toxicity: Industrial wastewater often contains toxic substances such as heavy metals, solvents, and chemicals. These toxins can accumulate in water sediments and be ingested by fish, crustaceans, and other aquatic creatures, causing illness or death.
• Groundwater contamination: Polluted water from rivers and lakes can infiltrate the groundwater through cracks in the ground, contaminating drinking water sources.
• Biodiversity loss: Industrial waste can reduce biodiversity by killing or impairing the reproductive ability of aquatic life.
• Human health risks: Contaminated water can cause various health issues in humans, including cancer, hormone disruption, and altered brain function. Certain toxins, such as chlorobenzene, can accumulate in the body and be passed on through breast milk.
• Eutrophication: Industrial wastewater containing high levels of nutrients, such as nitrates and phosphates, can cause eutrophication, leading to the death of aquatic life and the creation of "dead zones".
• Thermal pollution: Water used for cooling industrial equipment is often discharged back into water sources at elevated temperatures, reducing oxygen levels and altering the food chain composition.
• Soil pollution: Industrial waste can also contaminate the soil near water bodies, further impacting the surrounding ecosystem.

To address the issue of industrial waste in freshwater, proper waste treatment and disposal methods are crucial. While most countries have enacted legislation to manage industrial waste, enforcement and compliance vary. Treatment methods can include biological, chemical, and physical processes to remove or reduce the concentration of contaminants. Additionally, waste minimization techniques, such as reducing hazardous materials in the production process and recycling, can help prevent pollution.

Agricultural waste

Agriculture is the biggest consumer of global freshwater resources, with farming and livestock production using about 70% of the Earth's surface water supplies. It is also a serious water polluter.

Farms discharge large quantities of agrochemicals, organic matter, drug residues, sediments, and saline drainage into water bodies. The use of pesticides and chemical fertilisers in crop production has exploded in recent years, with the global market in pesticides now worth more than USD 35 billion per year.

The use of pesticides and fertilisers has severe consequences for water quality. Every time it rains, fertilisers, pesticides, and animal waste from farms and livestock operations wash nutrients and pathogens (such as bacteria and viruses) into waterways. Nutrient pollution, caused by excess nitrogen and phosphorus in water or air, is the number-one threat to water quality worldwide. It can cause algal blooms, a toxic soup of blue-green algae that can be harmful to people and wildlife. High levels of nitrates in water from nutrient pollution can interfere with infants' ability to deliver oxygen to tissues and potentially cause "blue baby syndrome", a potentially fatal illness.

Agricultural pollution is the top source of contamination in rivers and streams in the US, the second-biggest source in wetlands, and the third main source in lakes. It is also a major contributor to contamination in estuaries and groundwater. In China, agriculture is responsible for a large share of surface-water pollution and is almost exclusively responsible for groundwater pollution by nitrogen. In the European Union, 38% of water bodies are under pressure from agricultural pollution.

The expansion of irrigation has also contributed to agricultural pollution. In recent decades, the area equipped for irrigation has more than doubled from 139 million hectares in 1961 to 320 million in 2012, transferring agricultural pollution to water bodies.

The growth in livestock production has also had an impact. Livestock production now accounts for 70% of all agricultural land and 30% of the planet's land surface. Fish excreta and uneaten feeds from fed aquaculture diminish water quality. Increased production has combined with greater use of antibiotics, fungicides, and anti-fouling agents, which may contribute to polluting downstream ecosystems.

Aquaculture has grown more than 20-fold since the 1980s, particularly in Asia. Total global aquatic animal production reached 167 million tonnes in 2014.

Agricultural pollution poses demonstrated risks to aquatic ecosystems, human health, and productive activities.

Sewage and wastewater

Untreated or partially treated sewage can cause loss of biodiversity, physiological and behavioral changes in species, community shifts, and fish mortality. Sewage contains nutrients such as nitrogen and phosphorus, which cause eutrophication of water bodies. Eutrophication refers to the abundant growth of phytoplankton, causing imbalanced primary and secondary productivity and a high rate of succession from the existing seral stage to a higher seral stage. This process can lead to harmful algal blooms, which can be toxic to humans and wildlife.

The presence of heavy metals in sewage and wastewater is also a concern. These metals can accumulate in the bodies of fish and other aquatic organisms, impacting their growth and reproduction. Heavy metals can also be passed up the food chain to humans, causing potential health risks.

Oil leaks and spills

The density of oil, which varies depending on its type, plays a crucial role in its behaviour during a spill. Some oils are denser than river water, causing them to sink and making cleanup particularly challenging. In such cases, vacuum devices may be employed, but they often capture a significant amount of water and sand along with the oil, reducing their effectiveness. On the other hand, very heavy oils with a density of 1.01 grams per cubic centimetre would float in the ocean but sink in a river.

The movement of oil in rivers is typically downstream, influenced by the river's currents. Dams and locks can further slow down or divert the flow of oil, causing it to collect in certain areas. Additionally, vegetation along riverbanks can hinder cleanup efforts, as oil removal from plants is more difficult than from hard-packed sand beaches.

Oil spills in freshwater lakes present their own set of challenges. A study conducted by researchers from the University of Ottawa, Queen's University, and the University of Manitoba, called the "Boreal Oil Release Experiment by Additions to Limnocorrals" (BOREAL), investigated the impact of oil spills in freshwater lakes. They found that volatile hydrocarbons in diluted bitumen (dilbit) quickly evaporated, causing the oil to become denser and thicker, with a consistency similar to molasses. This denser oil eventually sank to the bottom of the lake after heavy rainfall.

The presence of oil in freshwater sources can have significant ecological consequences. Oil spills can block sunlight, hindering photosynthesis in plants, and reduce the level of dissolved oxygen in the water, affecting aquatic life. Oil-coated birds and marine mammals lose their insulating and waterproofing abilities, making them susceptible to hypothermia. Ingesting oil can also be toxic to these animals, and the damage to their habitats and reproductive rates may impede the long-term recovery of their populations.

Furthermore, oil spills can have economic repercussions, particularly in industries such as fishing and tourism. Commercial fishing is often suspended following major oil spills to prevent damage to vessels, equipment, and the contamination of catch. Tourism and commerce may also suffer if beaches and populated shorelines are affected.

While there is no thoroughly satisfactory method for cleaning up major oil spills, several techniques are employed to contain and remove the oil. Floating booms are used to contain the spill and prevent its spread. Skimming, which is most effective in calm waters, physically separates the oil from the water and collects it in tanks. Sorbents, such as straw, volcanic ash, and polyester-derived plastic shavings, are used to absorb oil from the water. Chemical surfactants and solvents may also be applied to accelerate the natural dispersion of the oil into the water.

Radioactive waste

Radioactive contamination in water is a pressing issue for human health and the environment. Radioactive elements can contaminate water through natural and human-induced sources. Natural sources include the percolation of naturally occurring radioactive materials (NORM) from soil sediments into aquifers, resulting in groundwater contamination. Human-induced sources include nuclear weapon testing, nuclear disasters, nuclear power plants, and the dumping of radioactive waste into surface water bodies.

Nuclear power plants, particularly those located in coastal regions, contribute to radioactive contamination in marine water. The water used for cooling the reactors becomes contaminated and is subsequently released into the ocean or nearby bodies of water. While the ocean has a significant capacity to dilute radiation, radioactive isotopes can enter the local food chain. For example, small fish off the coast of Fukushima, Japan, were found to have elevated levels of radioactive cesium and iodine following the 2011 nuclear disaster.

The effects of radioactive contamination on marine life and humans are complex and not yet fully understood. Studies have shown that radioactive material can be absorbed by phytoplankton, zooplankton, kelp, and other marine life, subsequently moving up the food chain to fish, marine mammals, and humans. The potential health risks associated with exposure to radioactive contamination include acute radiation syndrome, cutaneous radiation injury, cancer, leukaemia, genetic mutations, and various other disorders.

To address the challenges posed by radioactive waste, it is crucial to ensure transparency in nuclear technology and establish internationally accepted regulations for radiation exposure levels. Additionally, the development of new nuclear plants must be accompanied by effective waste management strategies, such as improved waste minimisation techniques and the utilisation of emerging technologies like nuclear fusion.

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