Ionic Pollution: Large Bodies Of Water At Risk

Water pollution is a critical problem worldwide, with large sources of water such as rivers, reservoirs, lakes, and seas being contaminated by chemicals, waste, plastic, and other pollutants. One of the main contributors to water pollution is the agricultural sector, which uses about 70% of the earth's surface water supplies and releases toxic substances such as fertilizers, pesticides, and animal waste into waterways. Industrial wastewater is another significant source of water pollution, with factories, farms, and cities contributing to oil pollution in the sea. Heavy metal ions including selenium, lead, copper, mercury, arsenic, and manganese, are also major impurities in water bodies, causing noxious impacts on aquatic life and posing threats to human health. Natural factors, such as volcanic activity and metal corrosion, also play a role in water pollution. With less than 1% of accessible freshwater on Earth, addressing water pollution is crucial to ensure the availability and quality of this vital resource.

Industrial units and factories

The type and quality of wastewater generated depend on the industry. For example, the waste from agricultural sites, mines, and manufacturing plants can contain heavy metals, toxic chemicals, oils, and greases, which are harmful to both human health and the environment. Industrial wastewater can also be contaminated with organic sludge, radioactive sludge, pesticides, plastics, paper, leather, and wool. When such polluted water is discharged into oceans or other water bodies without proper treatment, it becomes unsuitable for any use, including drinking, fishing, and swimming.

Textile manufacturing has been identified as one of the biggest polluters, with textile mills contributing about one-fifth of the world's industrial water pollution. The wastewater from textile production contains a mix of chemicals, including lead, phthalates, and organochlorines, which can cause severe health issues in humans. Similarly, petroleum refining, another large industry, discharges wastewater containing heavy metals like arsenic, mercury, oils, and greases, as well as industrial salts.

To address industrial water pollution, several strategies and technologies are being developed and employed. These include biological, chemical, electrochemical, and physical processes for treating wastewater and releasing potable water. Additionally, membrane technology, ultra filtration, and microfiltration are used as pre-treatments for reverse osmosis. Deionization is another process that removes all ionized minerals and salts from the water. While industrial releases of pollutants in Europe declined between 2010 and 2022, with heavy metals and nitrogen emissions showing significant decreases, more efforts are still needed to improve the ecological and chemical status of water bodies.

Domestic waste

Another critical aspect of domestic waste is the presence of microbes and organic matter. The decomposition of organic matter in sewage by bacteria depletes the dissolved oxygen content in water, endangering aquatic life in lakes and streams that rely on high oxygen levels. Additionally, domestic sewage may contain active pharmaceutical ingredients, which can harm aquatic organisms and contribute to antibiotic resistance.

Furthermore, domestic waste can introduce chemicals, oils, and grease into water bodies. Oil spills and leaks, often accidental, are a significant cause of water pollution. Oil reduces oxygen supply in the water and destroys marine life and ecosystems. Other chemical contaminants can come from poorly designed or maintained subsurface sewage disposal systems, industrial wastes disposed of in landfills, and leaks from underground storage tanks.

The impact of domestic waste on water pollution is evident in various regions. For instance, the Yamuna River in India is highly polluted by domestic sources, and in China, unreated domestic sewage contributes to water contamination. Insufficient sewage treatment, as seen in Bangladesh, further exacerbates the problem, leading to severe health issues for those dependent on polluted water sources.

Natural factors

The most common cations (positively charged ions) found in water include calcium, magnesium, sodium, and potassium. On the other hand, the most prevalent anions (negatively charged ions) are bicarbonate, chloride, and sulfate. The concentration of these ions in groundwater samples helps characterize and describe the chemical quality of the water. For instance, sodium-bicarbonate-type water has more than 50% of its cation milliequivalents as sodium and over 50% of its anion milliequivalents as bicarbonate.

Natural processes, such as volcanic activity, metal corrosion, metal evaporation from soil and water, soil erosion, and geological weathering, contribute to the contamination of heavy metals in water. For example, the Child Loess Plateau exhibits higher concentrations of hexavalent chromium and arsenic than the global average. Poor river water quality is often associated with elevated levels of sodium and salinity hazards.

Additionally, groundwater pollution is a pressing issue, with regulatory bodies detecting high levels of toxic compounds in potable water systems worldwide. Nitrate and fertilizer compounds, for instance, have been found in high concentrations in groundwater systems. The contamination of groundwater by waste sewage or spill areas flowing into surrounding rivers, channels, and lakes is another concern.

Oil pollution

Transportation and transfers of oil also increase the risk of spills. The more transfers that are required between ocean tankers, pipelines, trains, and trucks, the higher the likelihood of accidental releases. Additionally, routine ship operations, such as bilge pumping, contribute to oil pollution in the oceans, and it can be challenging to measure the impact of these small but frequent discharges.

Land-based runoff is another significant source of oil pollution in water. Oil from cars, trucks, and other vehicles can drip onto roads and parking lots and eventually find its way into water sources through stormwater runoff. This includes oil leaks in vehicles, fuel depots, and even lawnmowers. Oil can also enter water sources through domestic operations, such as the improper disposal of oil down storm drains. It is estimated that the runoff from a city of five million people can discharge as much oil as a large oil tanker spill.

The improper disposal of drilling muds, tank washing, depot leakage, and pipeline failures or ruptures are additional sources of oil pollution. Oil exploration and production often generate toxic waste, and the wastewater from this process, known as formation water or produced water, is often discharged untreated into the environment, containing low concentrations of oil and other chemicals.

Agricultural pollution

One of the main ways agriculture pollutes water sources is through the use of pesticides, herbicides, insecticides, rodenticides, and fungicides. These toxic chemicals can have serious side effects on the environment and human health. Pesticide leaching occurs when pesticides dissolve in water and migrate to off-target sites, contaminating groundwater. The use of fertilizers can also lead to nutrient runoff, which can negatively affect groundwater and surface waters, pollute the atmosphere, and degrade soil health.

Another significant source of agricultural pollution is livestock and their manure. Manure emits ammonia, which combines with other air pollutants to create harmful solid particles that can cause heart and lung diseases. Bacteria and pathogens in manure can also contaminate streams and groundwater if grazing, storing manure, and applying manure to fields are not properly managed.

To mitigate the impact of agricultural pollution on water sources, farmers can adopt several practices. These include following fertilizer best practices, improving soil health through planting cover crops, and improving water quality by planting streamside buffer crops. Additionally, contour strip cropping can help reduce erosion and runoff, and drip irrigation can decrease water loss and allow better control of the amounts of pesticides and nutrients added to irrigation water.

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