Water Pollution: Understanding The Causes Of Aquatic Contamination

Water pollution is a pressing issue that occurs when toxic substances contaminate bodies of water such as lakes, rivers, and oceans, degrading water quality and rendering it toxic or unsafe for human use. This is largely due to water's quality as a universal solvent, allowing it to easily dissolve and mix with a wide range of substances. Sources of these toxic substances include industrial waste, agricultural practices, oil spills, and improper disposal of chemicals, plastics, and other waste. With less than 1% of Earth's freshwater accessible, the increasing global demand for freshwater by 2050 underscores the urgency to address water pollution and its detrimental effects on health, the environment, and the economy.

Industrial waste and sewage

Water pollution occurs when harmful substances contaminate a body of water, degrading water quality and rendering it toxic to humans or the environment. Industrial waste and sewage are two major contributors to this issue.

Industrial Waste

Industries and industrial sites are a major source of water pollution worldwide. Many industrial processes produce toxic waste, and some facilities lack proper waste management systems. As a result, untreated industrial wastewater is often discharged into nearby freshwater systems, contaminating rivers, streams, and other bodies of water that lead directly to the sea. This wastewater contains toxic chemicals, heavy metals, hazardous wastes, and non-degradable toxins that accumulate in aquatic sediments and slowly enter groundwater. The production of industrial goods generates wastewater contaminated with toxic substances, which, if not properly treated, can pollute public waters. While some regions, like Europe, have strict limits on wastewater discharge, other areas, such as emerging countries with growing industrial sectors, may have less stringent environmental policies or face challenges in implementing and monitoring legislation.

Sewage

Sewage pollution, including both human waste and stormwater, has severe effects on natural ecosystems and human health. When released into rivers, streams, and oceans, sewage can cause algal blooms, which block light needed for photosynthesis, leading to plant and algae death. This, in turn, reduces oxygen levels in the water, killing fish and other organisms, particularly freshwater insects like stoneflies and mayflies. Sewage also contains harmful bacteria and viruses, contributing to the spread of diseases such as gastroenteritis, ear infections, typhoid, cholera, and giardia.

Addressing the Problem

To address water pollution caused by industrial waste and sewage, proper waste management and treatment systems are essential. This includes investing in modernizing and upgrading sewage treatment infrastructure, as aging systems can struggle to handle increasing volumes of wastewater, especially in expanding urban areas. Additionally, individuals can take responsibility by reducing plastic consumption, properly disposing of chemicals, oils, and non-biodegradable items, and maintaining vehicles to prevent leaks.

Oil spills and leaks

Oil spills in water bodies are a form of leakage of petroleum onto the surface of a large body of water. Oil spills in water bodies became a significant environmental problem in the 1960s due to intensified petroleum exploration and production on continental shelves and the use of supertankers for transporting oil. While stringent shipping and environmental regulations have made large oil spills from supertankers rare, thousands of minor and several major oil spills related to well discharges and tanker operations are still reported each year.

Oil spills in water bodies can have severe environmental, economic, and social consequences. Oil spills can harm plant and animal life, with oil coating birds' wings and leaving them unable to fly, and stripping away the insulating properties of sea otters' fur, putting them at risk of hypothermia. Oil spills in water bodies can also contaminate drinking water supplies, impacting human health and causing respiratory and reproductive problems, as well as liver and immune system damage.

Oil spills in water bodies can have long-lasting effects on ecosystems and economies. The consequences of oil spills can be felt for decades, with major oil spills frequently followed by the immediate suspension of commercial fishing to prevent damage to vessels and equipment and ensure food safety. Oil spills in water bodies can also affect tourism and commerce, as well as power plants and other utilities that rely on or discharge seawater.

To address oil spills in water bodies, experts from organizations like NOAA's Office of Response and Restoration provide scientific support and expertise to help oversee the response and inform decision-making during emergency operations. Additionally, the development of specialized tools, such as an oil spill trajectory model, helps estimate how spilled oil will move and change, aiding in cleanup and recovery efforts.

Agricultural chemicals and pesticides

Water pollution occurs when harmful substances contaminate a body of water, degrading water quality and rendering it toxic to humans and the environment. Water is a universal solvent, meaning it can dissolve more substances than any other liquid on Earth, making it easily polluted.

Pesticides are chemicals used to kill or control pests. In agriculture, this includes herbicides (for weeds), insecticides (for insects), fungicides (for fungi), nematocides (for nematodes), and rodenticides (vertebrate poisons). These pesticides contain toxic materials that pose significant environmental and human health risks. When pesticides seep into groundwater, they can harm animals, plants, and humans. Additionally, when it rains, pesticides can mix with rainwater, which then flows into rivers and streams, eventually filtering into the ocean and causing further water pollution.

The use of pesticides in agriculture is increasing due to the growing population's need for more food, requiring the use of many pesticides in agriculture. This has led to a high concentration of pesticides being detected worldwide, and the need for effective treatment processes is urgent. The complex nature of pesticides, which are often made up of complex molecules, makes it challenging to apply existing mitigation processes.

Agricultural runoff is a significant source of water contamination, as herbicides and pesticides find their way into water through leaching in soil or the direct discharge of contaminated wastewater. Pesticides interact with water in different ways due to their physical and chemical properties, and their presence in water may be due to the active ingredients, fillers, and impurities or intermediates during the degradation process.

Removing pesticides from water requires knowledge of their physical and chemical properties and their interactions with water. Due to the large volume of wastewater in agriculture, physical processes are generally preferred to avoid using large volumes of chemicals, which could generate new sources of pollution. Adsorption is the preferred option for separating pesticides from water, with different adsorbents available depending on the pesticide's properties.

Plastic pollution

Water is a universal solvent, meaning it can dissolve more substances than any other liquid on Earth. This quality makes it extremely susceptible to pollution. Water pollution occurs when harmful substances, often chemicals or microorganisms, contaminate a body of water, degrading water quality and rendering it toxic.

Plastic water pollution is a significant contributor to this issue, affecting every continent on Earth. Plastics are the most prevalent type of marine debris found in waterways today. These microplastics and macroplastics can originate from larger pieces of plastic trash that have broken down or from manufactured microplastics called nurdles, used to make plastic products. Most marine debris comes from land sources through runoff, wind, human intervention, and other sources. This debris includes litter, trash, plastic bottles, plastic bags, fishing lures, nets, and fishing lines.

Storm drains make it easy for stormwater runoff to carry debris and trash into large bodies of water and rivers that eventually flow into the ocean. The plastic pollution then passes through storm drains and empties into other bodies of water, such as marinas and harbors. While some solutions like debris booms and trash mesh booms can help contain and capture plastic pollution, the most effective approach requires large-scale, systemic change, with governments and businesses taking responsibility and implementing solutions.

The plastic industry often attributes the responsibility for marine debris to individual behavior and littering. However, this fails to address the unsustainable consumption of resources involved in producing packaging and single-use disposable goods. As the quantity of disposable packaging and products continues to increase, controlling litter and cleaning up waterways require significant and sustained funding.

Climate change

Water and climate change are inextricably linked. Climate change is a significant contributor to water pollution, and water pollution, in turn, accelerates climate change.

Water Scarcity and Extreme Weather Events

Rising Sea Levels and Saline Water Intrusion

The rising sea levels caused by climate change further contribute to water pollution. As sea levels rise, saline water intrudes into groundwater aquifers, reducing the availability of freshwater resources. This intrusion affects both human populations and ecosystems in coastal areas, with nearly 50% of the world's population relying on groundwater for various activities.

Water Warming and Algal Blooms

Methane Emissions and Gas Releases

Water pollution and climate change have a bidirectional relationship. As organic material, such as trees and woody debris, enters water bodies through erosion and human activities, it combines with bacteria and nutrients, generating methane. This methane, 25 times more potent as a greenhouse gas than carbon dioxide, is released into the atmosphere, contributing to global warming and further exacerbating climate change.

Mitigation Measures

To address these challenges, various climate change mitigation measures can be implemented, including carbon dioxide capture and storage, planting bio-energy crops, proper solid waste disposition, afforestation, and cropland management. Additionally, adopting climate-smart agriculture, improving water use efficiency, and exploring unconventional water sources, such as treated wastewater, can help mitigate the impacts of climate change on water systems.

Frequently asked questions