Water Pollution: Human Actions, Environmental Reactions

Water pollution is a pressing issue that poses a significant risk to both human health and the environment. It occurs when toxic substances contaminate water bodies, degrading water quality and causing potential harm to aquatic ecosystems and human health. The sources of water pollution are diverse and far-reaching, including industrial waste, sewage, agricultural runoff, plastic pollution, and the improper disposal of toxic chemicals. With only a small fraction of Earth's freshwater accessible to us, addressing water pollution is crucial to safeguard our health and ensure the sustainability of aquatic life.

Industrial waste and toxic chemicals

Industries and industrial sites are a major source of water pollution, as they produce waste in the form of toxic chemicals and pollutants. While regulations are in place, some industrial sites still lack proper waste management systems. Industrial wastewater, which is water contaminated by manufacturing, cleaning, or other commercial activities, contains chemicals, heavy metals, oils, pesticides, pharmaceuticals, and other industrial by-products. These contaminants are often difficult to treat, as they require industry-specific treatment methods.

The food products industry, mining industry, steel/iron production plants, industrial laundries, power plants, oil and gas fracking plants, and metal finishers are among the industries that produce industrial wastewater. For example, in the United States, industries have dumped about 600 million pounds of toxic substances, including ammonia and nitrates, into the Ohio River, which provides drinking water to nearly 3 million people. Similarly, in North Carolina, coal-fired power plants have contaminated the water with elevated levels of chromium-6 and other chemicals, affecting nearly 1,000 households.

The improper treatment or disposal of hazardous industrial waste can have toxic effects on all life forms. Heavy metals, such as chromium-6, are persistent and non-biodegradable, and can cause various health issues in aquatic life, other animals, and humans through the food chain. Phenolic compounds, another prevalent pollutant released by industries, can inhibit normal microbial function and affect biological treatment processes, leading to health issues in humans and other organisms.

Sewage and wastewater treatment

Effective wastewater treatment aims to remove as many suspended solids and contaminants as possible before discharging the treated water, called effluent, back into the environment. This process is crucial as it reduces the impact of water pollution on aquatic life and ensures that water can be safely reused. Nature can handle small amounts of water waste and pollution, but billions of gallons of wastewater and sewage are produced daily, overwhelming natural processes if not adequately treated.

Primary treatment, the first stage of sewage treatment, involves removing solid materials and aerating the wastewater to restore oxygen levels. This step eliminates about 60% of suspended solids. The secondary treatment stage removes over 90% of the remaining solids, with advanced treatment systems incorporating a tertiary stage for further polishing and nutrient removal.

In many cities, sewage and stormwater are carried through combined sewer systems to treatment plants. However, during high precipitation, these systems can experience overflows, resulting in untreated sewage and stormwater being released directly into water bodies. This untreated effluent can contain human waste, industrial waste, toxic materials, and debris, posing a severe threat to public health and the environment.

To address this challenge, some cities are investing in separate storm and waste systems to reduce the risk of overflows. Additionally, decentralized systems, such as on-site sewage facilities and septic tanks, can treat sewage closer to the source, reducing the burden on central treatment plants. By implementing a combination of centralized and decentralized treatment methods, cities can better manage wastewater and minimize water pollution.

Farming and pesticides

The pressure to produce enough food has led to the expansion of irrigation and the increasing use of fertilizers and pesticides. These pesticides and fertilizers, along with livestock manure, contaminate water supplies, causing agricultural water pollution. This is especially true in the case of farms that use irrigation, as the return flows can move these contaminants into local streams, rivers, and groundwater.

In the last twenty years, a new class of agricultural pollutants has emerged in the form of veterinary medicines (antibiotics, vaccines, and growth promoters). These move from farms to ecosystems and drinking water sources. The use of pesticides and fertilizers is also influenced by the type of crop and land use management techniques.

Farmers routinely use pesticides like herbicides, insecticides, rodenticides, and fungicides to keep away any unwanted weeds, insects, rodents, and fungi. However, these toxic chemicals have serious side effects. For example, pesticides like neonics are bad for pollinators, and populations of insects like the monarch butterfly and native bees have plummeted in recent decades due to these toxins. More than 90% of Americans have pesticides in their bodies, which can cause adverse health effects. Farmworkers are particularly susceptible to exposure, and rural residents may be exposed to contaminated water, air, and food.

To reduce water pollution, farmers can adopt soil and water conservation practices. These include planting cover crops and streamside buffer crops to improve soil and water quality, respectively. Using drip irrigation instead of furrow irrigation also allows for better control of the amounts of pesticides and nutrients added to irrigation water. Storing livestock manure in lagoons, covered stockpiles, or protected upland areas minimizes runoff risks.

Radioactive waste

Anthropogenic sources of radioactive pollution include nuclear weapons, nuclear power plants, nuclear calamities, and the dumping of radioactive waste. Industries that produce nuclear waste include nuclear power stations, reprocessing plants, and the military. As the nuclear energy industry grows, more and more radioactive waste is disposed of every year. For example, in 2006, nuclear waste disposal in the UK amounted to 12,900 cubic metres, enough to fill over five Olympic swimming pools. Radioactive waste can persist in the environment for thousands of years, making disposal a major challenge.

Radioactive contamination has been reported in many parts of the globe, including the Irish Sea, the English Channel, and the Arctic Ocean. The Fukushima Daiichi nuclear disaster in 2011 caused thousands of tons of radioactive water to be released into the Pacific Ocean. Radioactive caesium and plutonium have been found in seals and porpoises in the Irish Sea, and nuclear isotopes are moving up the local food chain. Radioactive iodine-131, for example, can be taken up by seaweed or plankton and transferred to fish, which are in turn eaten by larger fish.

Standard home or water treatment plant filters may not remove all radioactive contaminants, and there is a need for greater monitoring and stronger regulations to address this issue. Drinking water suppliers can help prevent water sources from becoming contaminated by identifying the path that water travels to reach the drinking water system and determining areas where drinking water could become contaminated. They can also prepare for emergencies, such as floods or spills, and participate in voluntary programs that help keep contaminants out of drinking water.

Oil spills

Water pollution is caused by a variety of factors, including industrial waste, agricultural runoff, and improper waste management. Oil spills, in particular, are a significant contributor to water pollution and have devastating impacts on the environment, wildlife, and human health.

The cleanup and recovery process after an oil spill is complex and time-consuming. It depends on factors such as the type of oil spilled, the temperature of the water, and the types of shorelines and beaches involved. Physical cleanups are expensive, and in the past, the best method was to use straw to soak up the oil manually. Oil spills have initiated intense media attention and political debates, with a focus on government responses and prevention measures.

To prevent and mitigate the impacts of oil spills, it is essential to prioritize safe disposal and proper waste management practices. By understanding the sources and consequences of oil spills, we can work towards reducing their occurrence and protecting our aquatic environments.

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