Water Bodies: Sources Of Pollution And Their Impact

Water pollution is the contamination of water bodies, which can have a negative impact on their use. Water pollution is usually a result of human activities, with toxic substances entering water bodies such as lakes, rivers, oceans, and so on. These toxic substances can get dissolved in the water, lie suspended in the water, or deposit on the bed, degrading the quality of the water. The main water pollutants include bacteria, viruses, parasites, fertilisers, pesticides, pharmaceutical products, nitrates, phosphates, plastics, faecal waste, and even radioactive substances.

Sewage and wastewater treatment

Wastewater treatment facilities play a crucial role in treating and reducing these pollutants before discharging the water back into waterways. In the United States, these facilities process approximately 34 billion gallons of wastewater daily. However, it is important to note that more than 80% of the world's wastewater is released into the environment without proper treatment, according to the United Nations.

Domestic sewage, also known as sanitary sewage, is wastewater from houses and apartments. It is primarily composed of water, with less than 0.1% consisting of dissolved and suspended impurities. These impurities, however, pose a significant challenge due to their nature and the large volumes of sewage they are carried in. Domestic sewage often contains disease-causing microbes, putrescible organic materials, and plant nutrients. The presence of active pharmaceutical ingredients in domestic sewage can also harm aquatic organisms and contribute to antibiotic resistance.

Industrial sewage, on the other hand, is wastewater from manufacturing or chemical processes. It typically contains specific chemical compounds depending on the nature of the industrial activity. Improperly disposed of industrial wastewater is a significant source of toxic chemicals, including lead, mercury, and chromium, which can have detrimental effects on the environment and human health.

To address sewage and wastewater treatment effectively, it is essential to understand the sources of pollution. Point source pollution originates from a single source, such as a pipe or channel used for discharge by an industrial facility or a city sewerage system. Nonpoint source pollution, also known as dispersed source pollution, comes from broad, unconfined areas where various pollutants enter the water body, such as agricultural runoff or urban stormwater drainage.

Optimizing wastewater treatment plants to reduce nitrogen and phosphorus loads is crucial. This can be achieved through various strategies, such as upgrading technology and implementing nutrient removal techniques. Additionally, properly maintaining septic systems is essential to preventing nutrient pollution, as improperly managed systems can release elevated levels of nitrogen and phosphorus into local water bodies or groundwater.

Industrial activities

Industrial waste from various sectors, including agriculture, mining, and manufacturing, can contain harmful chemicals, heavy metals, toxic sludge, and even radioactive sludge. This waste can contaminate water sources, making them unsafe for human consumption and dangerous for aquatic life. For example, the increase in mineral content and change in pH levels caused by mining waste can be detrimental to aquatic ecosystems. Similarly, the release of radioactive sludge can have serious health implications for nearby communities, as it can remain highly radioactive for decades.

Thermal pollution, which refers to the increase in water temperature, is another issue stemming from industrial activities. Nuclear reactors and power plants are significant contributors to thermal pollution, which can be harmful to aquatic and marine life, particularly organisms sensitive to temperature changes. Additionally, the discharge of nutrients like nitrogen and phosphorus can lead to eutrophication, causing algal blooms that deplete oxygen levels in the water, resulting in the death of aquatic organisms.

The improper disposal of industrial waste is a pressing issue. While wastewater treatment facilities aim to manage this waste, more than 80% of the world's wastewater is released back into the environment without adequate treatment, according to the United Nations. This untreated wastewater can contain harmful substances such as metals, solvents, and toxic sludge, which then contaminate water bodies.

Furthermore, some industries rely on outdated technologies that generate more pollutants than modern alternatives. To avoid the high costs of upgrading to newer, cleaner technologies, some companies continue using outdated methods, contributing to water pollution. This issue is exacerbated by the lack of strict policies and effective enforcement in some countries, allowing industries to bypass existing regulations.

Agricultural activities

Agriculture is a major cause of water pollution, particularly as a contributor of chemical pollutants to water bodies. As the largest user of freshwater globally, accounting for 70% of water withdrawals, agriculture has a huge impact on water quality. Farms discharge large quantities of agrochemicals, organic matter, drug residues, sediments, and saline drainage into water bodies.

Pesticides are widely used in agriculture and are a significant pollutant, with atrazine being one of the most commonly detected pesticides in surface water. Older chlorinated agricultural pesticides have been linked to various human health issues and are now generally banned in developed countries. There is an international effort to ban these pesticides worldwide, as they have caused significant and widespread ecosystem dysfunction through their toxic effects on organisms.

Soil erosion, nutrient loss, and bacteria from livestock manure are other primary stressors on water quality. Poor agricultural practices can lead to the net loss of soil, salinization, and waterlogging of irrigated land, further contributing to water pollution.

Urban runoff

One of the most pronounced effects of urban runoff is on watercourses that historically contained little or no water during dry weather periods, often called ephemeral streams. Urban runoff creates an unnatural year-round streamflow that hurts the vegetation, wildlife, and stream bed of the waterway. It causes severe erosion, increasing sediment loads downstream while severely carving the stream bed upstream. Urban runoff can also carry trash, pollutants, excessive silt, and other wastes, posing moderate to severe health hazards.

Oil spills

The economic impact of oil spills can be significant, affecting tourism, commerce, and utilities that rely on seawater. The cleanup of oil spills is also challenging, as complete removal of the spilled oil is often impossible, and some cleanup methods can cause additional harm. For example, after the Exxon Valdez oil spill in 1989, it was found that high-pressure, hot-water hoses used to clean up beaches caused more damage than the oil alone.

To address the problem of oil spills, the Oil Pollution Act of 1990 was established, holding those responsible for oil spills accountable for paying for cleanup and restoration. This process, known as Natural Resource Damage Assessment (NRDA), involves federal, state, and tribal agencies working together with the responsible party to select restoration projects with input from the public.

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