Water Pollution: Human Actions, Damaging Reactions

Water pollution is a pressing issue that jeopardizes human health and the environment. It occurs when harmful substances contaminate water bodies, degrading water quality and rendering it toxic or unsafe for human use. This contamination can result from various human activities, such as industrial waste, sewage treatment, agricultural practices, and oil spills. For instance, more than 80% of the world's sewage flows untreated into seas and rivers, according to the United Nations. Additionally, oil leaks and spills from drilling operations or ships transporting oil can have devastating impacts on aquatic ecosystems. Other sources of water pollution include improper disposal of chemicals, pesticides, and antibiotics, as well as runoff from farming and fossil fuel power plants. With less than 1% of Earth's freshwater accessible, addressing water pollution is crucial to ensure the availability of this vital resource for future generations.

Industrial waste and chemical dumping

Manufacturing, mining, and waste disposal companies are among the worst water polluters. They contaminate drinking water with arsenic, lead, mercury, chromium, and other toxic chemicals. For example, the now-defunct Diamond Alkali Co. in Newark, New Jersey, polluted the Passaic River, a drinking water source for millions, with chemicals used to make Agent Orange. Similarly, the Conklin Dumps in New York leaked volatile organic chemicals into groundwater.

Industrial sites, construction sites, and factories produce or use toxic chemicals in manufacturing, which are then exposed to rainwater, washing them into the soil or directly into rivers, streams, or lakes. This is a major factor in the increase in industrial water pollution. When industrial waste is not treated properly, or worse, not treated at all, it can easily pollute the freshwater systems it comes into contact with.

In addition to industrial waste, chemical dumping from sectors such as agriculture is a significant contributor to water pollution. Farmers use chemicals and pesticides to protect their crops from bacteria and insects, but these substances can seep into groundwater, harming animals, plants, and humans. When it rains, these chemicals mix with rainwater, which then flows into rivers and streams that filter into the ocean, causing further water pollution.

The improper disposal of chemical waste can also lead to water pollution. Human error and negligence can cause chemical spills and leaks, which, if not contained and cleared, can quickly make their way into water streams. This is often due to the high cost of implementing modern systems, outdated technology, and a lack of investment in pollution control equipment and management.

Sewage and wastewater treatment

Sewage treatment plants, while identified as a ""point source"" of pollution, are not the original source of the pollution. They treat the wastewater that comes from human activities, such as what goes down our toilets and sinks. However, aging and overwhelmed sewage treatment systems can also release billions of gallons of untreated wastewater into water bodies, contributing to water pollution.

Wastewater from industrial plants and chemical process facilities often contains toxic chemicals such as lead, mercury, and chromium. When this wastewater is not properly treated or disposed of, it becomes a significant source of water pollution. These toxic chemicals can contaminate groundwater, making it unsafe for human consumption and harmful to the environment.

Additionally, sewage and wastewater from agricultural activities can contain high levels of pesticides and fertilizers. When these substances find their way into water bodies, they can cause eutrophication, leading to ""dead zones"" where aquatic life cannot survive due to a lack of oxygen. Agricultural runoff is considered a ""dispersed source"" of pollution, which is more challenging to control compared to point sources.

To reduce water pollution from sewage and wastewater treatment, proper waste management systems are essential. This includes ensuring that wastewater treatment facilities are well-maintained and equipped to handle the volume of wastewater they receive. Additionally, individuals can play a role by being mindful of what they flush down their toilets and dispose of chemicals, oils, and non-biodegradable items properly to prevent them from entering the water supply.

Oil spills and leaks

Oil drilling operations and transportation are major sources of oil spills. Oil companies drill and pump out crude oil from reservoirs below the ocean floor, transporting it through pipes, ships, trucks, or trains to refineries. This process can result in leaks and spills, with oil released into the ocean or coastal waters. Oil spills from tankers and offshore platforms can be particularly damaging, as they can involve large amounts of oil and affect vast areas.

In addition to drilling and transportation, natural seepage from the ocean floor and well discharges contribute to oil spills. While major oil spills from supertankers have become rare due to stringent regulations, thousands of minor and several major oil spills related to well discharges and tanker operations are still reported each year. The total quantity of oil released annually into the world's oceans exceeds one million metric tons.

Oil spills have severe environmental, economic, and social consequences. Oil on the ocean's surface harms aquatic life by reducing sunlight penetration and dissolved oxygen levels. It also damages the insulating and waterproofing properties of feathers and fur, making birds and marine mammals more vulnerable to temperature fluctuations and hypothermia. Ingesting oil can be toxic to animals, and the spill can slow the long-term recovery of animal populations by damaging their habitats and reproductive rates.

To address oil spills, cleanup and recovery efforts are essential, but they can be challenging and time-consuming. The Oil Pollution Act of 1990 established that those responsible for oil spills can be held accountable for paying for cleanup and restoration. However, cleanup activities can never remove 100% of the spilled oil, and scientists must ensure their actions do not cause further harm.

Agricultural activities and pesticides

Agriculture is a leading cause of water pollution, particularly in the United States, where nearly 1.2 billion acres, or about half of the country's land area, is used for farming. The US-EPA has declared that "agriculture is the leading source of impairment in the nation's rivers and lakes".

Agricultural activities, such as the use of pesticides and fertilisers, contaminate water bodies. Pesticides are used to protect crops from bacteria and insects, but they can seep into the groundwater, harming animals, plants, and humans. When it rains, pesticides also mix with rainwater, which then flows into rivers and streams, ultimately reaching the ocean and causing further pollution.

The excessive use of synthetic pesticides can result in high concentrations of heavy metals in the soil, which negatively impacts plants and the soil's biochemistry and microbial activities. Heavy metals, which are considered emerging pollutants, have been detected in European aquatic environments. Pesticides can also remain in the soil for extended periods, especially insoluble chlorinated hydrocarbon pesticides, which have been linked to various human health issues and ecosystem dysfunction.

Fertilisers, which contain high levels of nitrogen and phosphorus, can also pollute water resources. When excess fertilisers are used, the remaining nutrients are washed off the soil during irrigation or rainfall, eventually reaching water resources. This can lead to increased levels of nitrogen and phosphorus in lakes and rivers, causing algal blooms and hypoxic conditions that are harmful to aquatic life.

To address these issues, farmers can adopt soil and water conservation practices, such as nutrient management and improved irrigation techniques, to reduce the runoff of pesticides, fertilisers, and other pollutants into nearby water bodies.

Domestic sewage and toxic waste

One of the primary concerns with sewage is the presence of toxic chemicals and pollutants. These can include heavy metals, radionuclides, pharmaceuticals, biocides, and thermal pollution. When industrial wastewater is combined with domestic sewage, the volume of sewage dilutes the concentration of pollutants unique to industrial wastewater. However, this does not reduce the overall mass of pollutants and can still lead to contaminated water bodies.

Untreated domestic wastewater is a significant source of marine environment contamination, especially in sensitive ecosystems like the Caribbean. The high costs of building and maintaining traditional sewage treatment plants are often cited as reasons for the lack of sewage treatment before disposal. This results in the discharge of untreated or partially treated sewage into water bodies, leading to pollution.

In addition to sewage, toxic waste from various sources also contributes to water pollution. Industrial sites are major contributors, producing waste in the form of toxic chemicals and pollutants. While regulations exist, some industrial sites lack proper waste management systems, leading to contaminated water. Chemical dumping from industries is a leading cause of eutrophication, where excessive nutrients, often nitrogen and phosphorus, stimulate algae growth and deplete oxygen levels, creating dead zones in water bodies.

Agricultural activities also play a role in water pollution. Farmers use chemicals and pesticides to protect crops from bacteria and insects, but these substances can seep into groundwater and harm humans, animals, and plants. When it rains, these chemicals mix with rainwater, eventually flowing into rivers and streams that feed into oceans, causing further pollution. Additionally, fertilizers can increase the salinity of water, negatively impacting agricultural yields and contributing to cases of stunted growth in children.

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