Surface Water Pollution: Understanding The Contaminants

Surface water pollution is a pressing issue that affects our oceans, lakes, rivers, and other bodies of water. It is primarily caused by human activities, including industrial waste discharges, agricultural runoff, and urban stormwater runoff. This runoff carries pollutants such as pesticides, oils, chemicals, and debris into our waterways, contaminating them and rendering them unsafe for human use and harmful to aquatic ecosystems. Other sources of surface water pollution include sewage discharges, pharmaceutical waste, and accidental spills of harmful substances, such as oil leaks and spills. With the increasing population and human activities, the quest for food and industrial production has intensified, contributing to the pollution of freshwater sources. The consequences of surface water pollution are far-reaching, impacting human health, the environment, and the economy.

Industrial waste

One of the primary ways industrial waste reaches surface water is through wastewater discharges. Industrial activities generate large volumes of wastewater, which can contain various pollutants, such as heavy metals (lead, mercury, cadmium, chromium), arsenic, selenium, nitrogen compounds, and radioactive materials. If this wastewater is not properly treated before being discharged into water bodies, it can contaminate them.

For example, shale gas extraction produces wastewater from hydraulic fracturing (fracking) that contains high levels of dissolved solids (salts), radionuclides, metals, and other drilling chemicals. Similarly, fossil fuel power stations, particularly coal-fired plants, discharge wastewater with significant levels of pollutants, as seen in the case of the Northern Indiana Public Service Corp. coal-fired power plant, which polluted groundwater in Indiana.

Another way industrial waste pollutes surface water is through improper waste disposal. Industries often dispose of their waste in landfills, which can leach toxic chemicals into the surrounding soil and water. This has been observed in cases like Love Canal, where chemical companies dumped waste in landfills, contaminating groundwater in the Buffalo area. Additionally, accidents or leaks can occur, such as the Ford Motor Co. incident in New Jersey, where 35,000 tons of toxic paint sludge were dumped on indigenous land, poisoning their groundwater.

Furthermore, surface runoff from industrial areas can carry pollutants into nearby water bodies. This runoff can include chemicals, oils, grease, and other contaminants used or produced by industries. Urban stormwater runoff, a significant contributor to surface water pollution, can pick up these industrial pollutants and carry them into rivers, lakes, and oceans.

The impact of industrial waste on surface water quality is significant, and it has led to the contamination of drinking water sources for millions of people in the United States alone. The EPA monitors and regulates many of these industrial sites, but there are still gaps in oversight, particularly regarding private wells, that allow contaminants to go unnoticed.

Agricultural activities

Agriculture is the single largest user of freshwater resources, accounting for 70% of all surface water supplies. It is both a cause and victim of water pollution. Agricultural activities discharge pollutants and sediments into surface and/or groundwater through poor agricultural practices, such as the net loss of soil, and the salinization and waterlogging of irrigated land.

Agricultural water pollution is caused by the use of wastewater and polluted surface and groundwater, which contaminates crops and transmits diseases to consumers and farmworkers. Farms discharge large quantities of agrochemicals, organic matter, drug residues, sediments, and saline drainage into water bodies. This includes pesticides, antibiotics, fungicides, anti-fouling agents, and other substances that can contaminate water.

The use of fertilizers and pesticides in crop production is a major contributor to water pollution. While these chemicals are important for crop growth, they can also be harmful to the environment if not used properly. When it rains, the water carries these chemicals into nearby water bodies, contaminating them. This is known as agricultural runoff, which is a significant source of water pollution.

In addition to chemical pollutants, agriculture also contributes to water pollution through organic matter such as livestock manure. Manure contains high levels of nutrients and bacteria that can be harmful to water ecosystems if not properly managed. Storing livestock manure in protected areas can help minimize runoff risks. Efficient irrigation schemes can also reduce water return flows, thereby decreasing the migration of fertilizers and pesticides into water bodies.

The expansion of aquaculture, or fish farming, has also had a significant impact on water pollution. Fish excreta and uneaten feed from aquaculture diminish water quality. The close quarters of fish in aquaculture can also lead to the increased use of antibiotics and other chemicals, which can further pollute downstream ecosystems.

Urban runoff

Urban stormwater runoff is a major contributor to surface water pollution. When rain falls on urban areas, it can become polluted as it flows over roads, parking lots, and other impervious surfaces. This polluted stormwater then rushes into nearby gutters and storm drains, eventually making its way into rivers, lakes, and other bodies of surface water.

There are several sources of pollutants that contribute to urban runoff. Vehicular transportation-related activities are a significant source, as oil, grease, and road salts can be picked up by stormwater and washed into waterways. Atmospheric deposition, including pollutants from the air, can also contribute to urban runoff. In addition, metallic building envelopes have been identified as a major source of pollution, as well as the use of chemicals and pesticides in urban areas.

The impact of urban runoff on surface water quality can be significant. Polluted stormwater can contaminate drinking water supplies, harm or kill fish and other wildlife, and damage recreational areas. It can also lead to the closure of swimming beaches and shellfish growing areas due to contamination. In some cases, urban runoff can even contribute to flooding, as stormwater is unable to soak into the ground and instead flows quickly downstream, overwhelming streams and wetlands.

The distribution and concentration of pollutants in urban runoff can vary depending on various factors and can have different environmental impacts. For example, the presence of antibiotics in the water can lead to antibiotic resistance, while excessive nutrients can result in harmful algal blooms. Chemical pollutants can have toxic effects, and sediment from soil erosion or construction activity can interfere with the penetration of sunlight and disrupt the ecological balance of water bodies.

To reduce the impact of urban runoff on surface water, it is important to implement source controls and other mitigation measures. Individuals can play a role by properly maintaining their vehicles, recycling used oils and fluids, and disposing of waste properly. Communities can also work to prevent stormwater runoff as development takes place, such as by reducing impervious surfaces and increasing vegetated land cover.

Sewage discharge

Sewage can contain a range of contaminants, including disease-causing microorganisms, poisonous substances, and nutrients like nitrogen and phosphorus, which can cause harmful algal blooms. These contaminants can pose risks to both human health and aquatic ecosystems. For example, sewage can lead to oxygen depletion in water, affecting the survival of fish and other aquatic life.

In urban areas, hospitals, drug stores, and pharmaceutical industries contribute to sewage discharge by releasing pharmaceutical products and residues into wastewater. These products are not fully metabolized by humans or animals, leading to pharmaceutical pollution in aquatic environments.

To address sewage discharge, regulations such as MARPOL Annex IV have been implemented to control the discharge of sewage from ships and land-based sources. Treatment plants are required to treat sewage to specified standards, and permits are needed for discharging sewage into surface waters. Additionally, technologies like sewage comminuting and disinfecting systems aim to prevent the spread of pollution.

It is important to note that improper sewage treatment and disposal can have significant environmental and health impacts. Therefore, it is crucial to prioritize effective sewage treatment and adhere to regulations to protect surface water quality and mitigate the negative effects of sewage discharge on the environment and human well-being.

Microplastics

The presence of microplastics in drinking water has been detected, and studies have been conducted to assess their potential impact on human health. While the health effects are still unknown, animal studies suggest that microplastics may accumulate and induce an immune response, leading to potential chemical toxicity. The ubiquity of microplastics in surface water, groundwater, and wastewater has raised concerns about the pollution of drinking water sources.

To address the issue of microplastics in surface water, standardized field methods for collecting sediment, sand, and surface-water microplastic samples have been developed. These methods are still being refined to allow for global comparisons of microplastic release into the environment. In 2015, the United States banned the use of microbeads in cosmetics and personal care products through the Microbead-Free Waters Act.

Overall, microplastics are a significant contributor to surface water pollution, and ongoing research and regulatory efforts are crucial to understanding and mitigating their impact on aquatic ecosystems and human health.

Frequently asked questions