Point-Source Pollution: Examples Of Water Contamination

Water pollution is a widespread problem that jeopardizes human health. Unsafe water kills more people annually than war and other forms of violence combined. Water pollution occurs when harmful substances contaminate a body of water, degrading water quality and rendering it toxic. Point-source pollution is pollution that comes from a single, identifiable place, such as a pipe, ditch, ship, or factory smokestack. In the United States, the Clean Water Act has helped limit point-source pollution. This article will explore examples of point-source water pollution and its impacts.

Characteristics and Values of Point Source Water Pollution

Industrial and manufacturing plants

Industrial waste is the largest contributor to water pollution. It includes waste generated from industrial processes, such as garbage, oils, chemicals, dirt, concrete, scrap metals, and more. While some manufacturers may directly pollute water sources, others may do so indirectly by leaving waste and pollutants on land, which can be absorbed into the soil and eventually make their way into groundwater.

Chemical companies are the worst offenders, releasing the most contaminants of all industries, according to EPA documents. In 2019, the EPA estimated that 59 chemical fertilizer plants dumped nearly 90 million pounds of pollution into waterways. These plants make nitrogen-based fertilizers and dump millions of pounds of nitrogen, cyanide, chromium, nickel, lead, and other harmful substances into our waterways. Inorganic chemical plants are some of the biggest industrial dischargers of toxic pollution in the US, manufacturing products like PVC and vinyl chloride.

Plastics and rubber manufacturers are the second-worst offenders, followed by utilities, mining companies, and petroleum and coal producers. For example, in North Carolina, residents living near coal-fired power plants were informed that their water contained elevated levels of chromium-6 and other chemicals. In Louisiana, Gulf States Utilities discharged toxins, including benzene and other chemicals, into marshlands, polluting the waters.

The impact of industrial water pollution is far-reaching, making rivers and lakes unsafe for swimming and threatening human health. It also adds significant costs to water treatment and harms wildlife. For instance, US oil refineries discharge nearly half a billion gallons of wastewater into waterways every day, including heavy metals like arsenic and mercury, contributing to mutations in freshwater wildlife.

To reduce water pollution, it is crucial for governments to establish and enforce stringent clean water standards. Manufacturers can play a significant role in reducing waste by treating their wastewater before either recycling it back into the plant or releasing it into a waterway.

Agricultural and farming practices

Agricultural pollution is both a direct and indirect cause of human health impacts. The World Health Organization (WHO) reports that nitrogen levels in groundwater have increased globally due to the "intensification of farming practices." This has resulted in higher nitrate levels in drinking water, exceeding the recommended guidelines. WHO also states that 4 million children die annually from diarrhoea caused by water-borne infections, with bacteria commonly found in polluted water being coliforms excreted by humans.

Farming practices that contribute to water pollution include the use of pesticides, fertilizers, and animal manure. These pollutants can enter groundwater, depending on local land use and geologic conditions. Soil erosion, nutrient loss, and the runoff of pesticides and other contaminants from agricultural land are leading causes of water quality impairment. Increased levels of nitrogen and phosphorus from fertilizer and manure can cause algal blooms in lakes and rivers, leading to hypoxic conditions harmful to aquatic life and recreational uses. Excessive sedimentation from erosion can smother breeding areas and degrade coastal and marine ecosystems.

To address these issues, farmers can adopt soil and water conservation practices. Nutrient management practices, such as targeted fertilizer and manure application through soil testing and timing applications, can help minimize runoff. Storing livestock manure in protected areas and using drip irrigation can also reduce the risk of pollutants entering water sources. Additionally, agricultural conservation through a systems approach allows for the control of multiple pollutants by implementing tailored conservation systems.

Power plants and refineries

Steam-electric power plants, for instance, use vast amounts of water for various industrial processes. In 2015, these facilities withdrew approximately 133 billion gallons of water per day, primarily from rivers, lakes, and estuaries. The cooling processes, air pollution scrubbing, and coal ash transportation in coal-fired power plants all contribute to water pollution. The EPA has proposed stricter wastewater discharge standards for these plants, aiming to reduce pollutants discharged through wastewater by approximately 584 million pounds per year.

Oil refineries have also been identified as significant contributors to water pollution, releasing billions of pounds of pollutants into waterways annually. These pollutants include heavy metals, nitrogen, and other compounds that are harmful to aquatic life and human health. Regulatory data has revealed that this pollution disproportionately affects people of color, with a concentration of impacted communities along the Gulf Coast, in California, and near Chicago. ExxonMobil, a major operator of refineries, has referred to their adherence to federal guidelines and waste management programs to address pollution concerns.

Additionally, power plants contribute to non-point source pollution, such as acid rain. This type of pollution results from the long-range movement of airborne pollutants like sulfur dioxide and nitrogen oxides, which combine with water vapour in the atmosphere. The Clean Air Act and the Clean Water Act in the United States have played a crucial role in limiting both point-source and non-point-source pollution from power plants and refineries.

Wastewater treatment plants

One of the primary concerns with WWTPs is their inability to effectively remove all contaminants from the water. For instance, hormones from animal farming, residues from human hormonal contraception, synthetic compounds that mimic hormones, and pharmaceuticals have been detected in treated wastewater. These compounds are present in very low concentrations, but they can still negatively affect aquatic life and ecosystems. The presence of these contaminants highlights the challenges in ensuring that treated wastewater is safe for release back into the environment.

In addition to hormonal and pharmaceutical contaminants, WWTPs can also release heavy metals into water bodies. Metals from sources such as construction materials, batteries, vehicles, and personal care products can end up in wastewater. These metals are challenging to control and remove, and they can accumulate in the environment, leading to ecological and human health risks.

Furthermore, wastewater treatment plants may not always operate optimally, leading to the discharge of untreated or partially treated sewage. This can occur due to overloaded or malfunctioning treatment systems, resulting in the release of harmful pollutants into water bodies. In some cases, combined sewer overflows during heavy rainfall can also contribute to the discharge of untreated sewage.

The impact of WWTPs as a source of point-source pollution is significant. It underscores the need for improved wastewater treatment technologies and stricter regulations to ensure that treated wastewater meets the required standards before being released into the environment. It is crucial to address this issue to protect water quality, safeguard aquatic ecosystems, and preserve finite drinkable water sources for future generations.

Shipping and transport

Oil spills from ships: Oil tankers and other vessels can accidentally release large quantities of oil into marine environments, leading to catastrophic ecological consequences. Oil spills can occur due to collisions, grounding, or operational failures, and the released oil forms a slick on the water surface, harming marine life and contaminating coastal areas.

Chemical discharges from cargo ships: Cargo ships often carry a variety of chemicals, including toxic substances, which need to be properly managed and disposed of. Unfortunately, there are instances where ships illegally discharge these chemicals into the sea, causing severe pollution incidents. These chemicals can contaminate water bodies, harm aquatic ecosystems, and accumulate in the food chain, eventually impacting human health.

Ballast water release: Ships take on ballast water to maintain stability during voyages. However, this ballast water can become a vector for the introduction of invasive species and pathogens into new ecosystems. When ships release ballast water, they may inadvertently introduce non-native organisms that can outcompete native species and disrupt the ecological balance of the receiving water body.

Runoff from roads and highways: Roads and highways are susceptible to rainwater runoff, which can pick up various pollutants such as oil, grease, heavy metals, and road salts. This polluted runoff often ends up in nearby water bodies, degrading water quality and harming aquatic life. The accumulation of road salts, for example, can increase water salinity beyond tolerable levels for many freshwater organisms.

Port and marina operations: Ports and marinas are hubs for shipping activities, and they can be sources of point source pollution. Debris and contaminants may be released into the water during cargo loading and unloading operations. Additionally, marinas with high boat traffic increase the risk of fuel and oil leaks. Regular maintenance and cleaning activities at ports and marinas may also contribute pollutants if not properly managed.

To mitigate the impact of shipping and transport on water pollution, strict regulations, and proper waste management practices must be enforced. This includes improving ballast water management, implementing better spill response plans, and ensuring the proper treatment and disposal of ship-generated wastes. Additionally, promoting sustainable practices in the shipping industry, such as adopting cleaner fuels and technologies, can help reduce the environmental footprint of this sector.

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