Understanding Surface Water Pollution: Causes And Origins

Water is a universal solvent), meaning it can easily dissolve more substances than any other liquid on Earth. This makes all water, but especially surface water, vulnerable to pollution. Surface water is any body of water found on Earth's surface, including oceans, lakes, and rivers. Surface water pollution is detrimental to the health and well-being of not only humans but all living creatures. It can be caused by a variety of different contaminants, including toxic waste, petroleum, and disease-causing microorganisms. Leading causes of surface water pollution include contaminated rainwater runoff from farms, homes, and infrastructure such as roads, as well as sewage leaks and waste products from farms and factories that leach into the environment.

Industrial sources and human waste

Water is a "'universal solvent'", meaning it can dissolve more substances than any other liquid on Earth. This makes it extremely susceptible to pollution from a range of sources, including industrial processes and human waste.

Industrial Sources

Industries that discharge wastewater (also called effluent) can be a major source of water pollution. This can be done legally or illegally and can include contamination from oil refineries, chemical and oil spills, and illegal dumping. Oil pollution can occur through surface runoff from roads and parking lots, or accidental oil spills, which have devastating impacts on surrounding ecosystems.

Another form of pollution caused by industrial sources is thermal pollution, which is the degradation of water quality by any process that changes the ambient water temperature. This can be caused by the practice of discharging cooling water from power plants into rivers, which may be much warmer than the naturally occurring water.

Human Waste

Human waste, also called domestic sewage, can cause water pollution by contaminating water with disease-causing microorganisms and poisonous substances. Human waste can enter water sources through the practice of open defecation, where human feces are moved from the ground into surface waters during rain or flood events. Simple pit latrines may also get flooded during rain, causing further contamination.

Lack of access to sanitation is a major concern, with around 4.5 billion people globally not having safely managed sanitation as of 2017. This can lead to the spread of waterborne diseases when people use polluted water for drinking or irrigation.

Agricultural activities

Farms discharge large quantities of agrochemicals, organic matter, drug residues, sediments, and saline drainage into water bodies. When it rains, fertilisers, pesticides, and animal waste wash into waterways, contributing to surface water pollution. This is known as nonpoint source pollution, which is derived from diffuse sources.

Fertilisers and sewage waste carry many pathogens and waterborne diseases, which can be harmful to humans and wildlife. Nutrient pollution, caused by excess nitrogen and phosphorus in water or air, can cause algal blooms, which can be toxic and are harmful to people and wildlife.

Agricultural pollution also affects estuaries and groundwater. Fish excreta and uneaten feeds from aquaculture diminish water quality, and increased production has combined with greater use of antibiotics, fungicides, and anti-fouling agents, which may contribute to polluting downstream ecosystems.

To prevent agricultural water pollution, it is important to implement management measures such as limiting and optimising the type, amount, and timing of applications of fertilisers and pesticides to crops. Establishing protection zones along surface watercourses and efficient irrigation schemes can also help reduce the migration of pollutants to water bodies.

Sewage and wastewater

Sewage leaks are a significant source of wastewater pollution, introducing harmful pathogens and microorganisms into water bodies. These include bacteria, viruses, protozoans, and parasitic worms, which can cause waterborne diseases in both humans and animals. In addition to the health risks, sewage can also promote algae growth, leading to eutrophic "dead zones" where aquatic life cannot survive due to a lack of oxygen. This disruption in the ecological balance can have far-reaching consequences for the environment and human well-being.

Wastewater from industrial activities also contributes to surface water pollution. This includes the discharge of toxic chemicals, heavy metals, and other harmful substances into water bodies. These contaminants can have severe ecological and human health impacts, as they interfere with the natural functioning of ecosystems and render water unsafe for human use. The release of heat from industrial processes, such as power plants, can also cause thermal pollution, which reduces the capacity of water to hold dissolved oxygen, endangering aquatic life.

Another concern is the presence of microplastics in wastewater, which are particularly prevalent in aquatic and marine ecosystems. Synthetic fabrics, tyres, and city dust are major sources of microplastics, which find their way into water bodies through stormwater, untreated sewage, and wind. These tiny plastic particles can accumulate in marine wildlife and eventually concentrate in humans who consume seafood, posing potential health risks that are not yet fully understood.

The impact of sewage and wastewater pollution on surface water is a global issue. According to the United Nations, more than 80% of the world's wastewater flows back into the environment without proper treatment. This statistic rises to over 95% in some least-developed countries, highlighting the urgent need for improved wastewater management and treatment infrastructure to protect our precious water resources and safeguard human health.

Oil pollution

Oil spills occur due to the leakage of petroleum onto the surface of large water bodies. The frequency and severity of oil spills increased in the 1960s due to intensified petroleum exploration and production on continental shelves, as well as the use of supertankers for oil transportation. Oil spills can have catastrophic consequences for aquatic life, including birds and marine mammals, by impairing their movement, reducing available sunlight, and decreasing oxygen levels in the water.

The impact of oil spills on aquatic ecosystems is long-lasting and complex. Oil can coat the feathers of birds or the fur of marine mammals, impairing their movement, reducing their insulation capabilities, and increasing the risk of hypothermia. Oil spills can also create a layer on the water surface, blocking sunlight from penetrating and disrupting the growth of aquatic plants and algae, which form the base of the aquatic food chain.

Additionally, oil spills can contaminate fish and seafood, making them unsafe for human consumption. Oil pollution introduces toxins and pathogens into the water, which can accumulate in the tissues of fish and other aquatic organisms, potentially leading to health issues for humans who consume them.

To address oil spills, various methods such as booms, skimming, in situ burning, and the use of chemical dispersants are employed. However, cleanup efforts can be challenging, and it is nearly impossible to remove 100% of the spilled oil. The Oil Pollution Act of 1990 holds those responsible for oil spills accountable for the costs of cleanup and restoration, recognizing the significant environmental and economic impact of such incidents.

Radioactive substances

Radioactive pollution in water can have natural and anthropogenic sources. Naturally occurring radioactive materials (NORM) are found in rock and soil and can dissolve in water. Examples include uranium, thorium, actinium, and radium. Radium, in particular, can penetrate groundwater through aquifer rock dissolution, the decay of uranium and thorium, or desorption processes. The percolation of NORM from soil sediments into aquifers causes groundwater contamination. Additionally, radon, a radioactive gas created through radium decay, can occur naturally in groundwater.

Anthropogenic sources of radioactive water pollution include nuclear weapon testing and development, nuclear power plants, and the dumping of radioactive waste. Radioactive elements used in nuclear weapons, X-rays, and medical equipment like MRI machines and iodine treatments for thyroid disorders can expose humans to radiation. The disposal of radioactive waste in surface water bodies is a significant contributor to water pollution. Furthermore, industrial activities, such as uranium mining and oil and gas drilling, can unearth radioactive elements present in the bedrock. Nuclear reactors and nuclear warhead experiments produce radioisotopes and unnecessary radioisotopic wastes, which can contaminate water.

The presence of radioactive substances in water has serious implications for human health. Radioactivity is the spontaneous emission of particles or waves from the unstable nuclei of certain elements. There are three types of radioactive emissions: alpha particles, which are positively charged helium atoms; beta particles, which are negatively charged electrons; and gamma rays, which are neutral electromagnetic radiations. When contaminated water is consumed, it can lead to the ingestion of these harmful radioactive particles, causing adverse health effects.

To address the issue of radioactive water pollution, public drinking water systems employ various methods. Drinking water suppliers identify the path of water to determine potential contamination points and prepare for emergencies that could threaten water safety. They also participate in voluntary programs to maintain water quality. Additionally, public water systems follow regulations, such as the Safe Drinking Water Act in the United States, which sets maximum contaminant levels (MCLs) for radionuclides. Water treatment facilities use filters and other methods to remove chemicals and radionuclides from water sources. However, standard filters may not always be effective against all radioactive contaminants, highlighting the need for improved monitoring and regulations.

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