Understanding Aquatic Pollution: Causes And Human Impact

Water pollution is a pressing global issue that poses a threat to human health, the environment, and the economy. It occurs when harmful substances contaminate bodies of water, making them unsafe for human use and disrupting aquatic ecosystems. The main sources of water pollution are diverse and include sewage discharges, industrial activities, agricultural activities, and urban runoff. These sources introduce a range of contaminants, from toxic chemicals and heavy metals to plastic waste and disease-causing microorganisms, into our water systems, leading to far-reaching consequences.

Industrial waste

The production of industrial goods generates wastewater that is often contaminated with toxic substances. This wastewater can contain chemicals, heavy metals, and other pollutants. For example, the metal processing industry's wastewater may contain lubricants and mineral oils, while electroplating can result in high levels of heavy metals such as zinc, nickel, copper, or cadmium in the water. Burning coal and fossil fuels, as well as construction, demolition, manufacturing, and waste treatment processes, also contribute to water pollution.

Untreated wastewater is often released back into bodies of water due to a lack of infrastructure, regulations, or proper enforcement of existing laws. This can have devastating consequences for the environment. When untreated wastewater is discharged into lakes, rivers, and coastal waters, it can lead to eutrophication, a process where the water becomes enriched with nutrients and minerals, promoting excessive growth of algae and plants. This algal bloom reduces oxygen levels in the water, creating "dead zones" where aquatic life cannot survive. The toxins produced during eutrophication can also be harmful to wildlife and humans, leading to health issues such as cancer, hormone disruption, and altered brain function.

In addition to hazardous waste, industrial waste also includes non-hazardous waste such as rubbish and debris. This waste can accumulate in aquatic sediments for years, slowly releasing toxins into the water and affecting water quality. The impact of industrial waste on water pollution is significant, and it is essential to address this issue through proper wastewater treatment, stricter environmental policies, and innovative solutions to break the cycle of pollution and protect our precious water resources.

Sewage and wastewater treatment

Sewage treatment plants, while designed to address this issue, have been identified as a "point source" of pollution. These plants treat the waste that enters our sewage systems, but the treatment process itself can result in the discharge of contaminated water, contributing to aquatic pollution. This is known as "point source pollution".

Untreated sewage is a significant concern, as it allows human and animal waste, which carries harmful bacteria and viruses, to enter water bodies. This waste can come from various sources, including combined sewer overflows, urban runoff, and solid waste discarded into the environment. Stormwater, untreated sewage, and wind are the primary means through which microplastics, a persistent form of pollution, reach the oceans.

Wastewater treatment, another major source of pollution, encompasses industrial and municipal activities that release chemicals and heavy metals into waterways. These contaminants are toxic to aquatic life, reducing lifespan and reproductive abilities, and they can accumulate in the food chain, leading to higher concentrations in larger fish and marine predators.

The impact of sewage and wastewater treatment on aquatic ecosystems is far-reaching. It disrupts the delicate balance of species interactions and can lead to the degradation of these ecosystems. Additionally, the economic consequences are significant, affecting sectors such as commercial fishing, recreational businesses, and tourism, all of which rely on clean water.

Agricultural activities

Agriculture is a major contributor to aquatic pollution, with farms discharging large quantities of agrochemicals, organic matter, drug residues, sediments, and saline drainage into water bodies. This is known as agricultural runoff, a nonpoint source category of pollution. Farms and ranches can affect water quality both locally and across multi-state watersheds.

The expansion of irrigation practices has also contributed to aquatic pollution. The area equipped for irrigation has more than doubled in recent decades, from 139 million hectares in 1961 to 320 million in 2012, transferring agricultural pollution to water bodies. Increased production has been accompanied by greater use of antibiotics, fungicides, and anti-fouling agents, which may pollute downstream ecosystems.

Livestock production, which now accounts for 70% of all agricultural land and 30% of the planet's land surface, is another significant source of pollution. Fish excreta and uneaten feeds from aquaculture diminish water quality, and bacteria and nutrients from livestock and poultry manure can contaminate drinking water supplies and affect shellfish beds.

To mitigate these issues, protection zones along surface watercourses and buffer zones around farms have been shown to effectively reduce pollution migration into water bodies. Additionally, efficient irrigation schemes can significantly reduce the migration of fertilizers and pesticides into water bodies.

Oil spills

The effects of oil spills on aquatic ecosystems are devastating. Oil on the water surface blocks sunlight from penetrating, reducing the dissolved oxygen levels. This lack of oxygen, known as eutrophication, suffocates aquatic plants and animals, creating "dead zones" devoid of life. Oil also damages the insulating and waterproofing abilities of feathers and fur, causing birds and marine mammals to succumb to hypothermia. Ingesting oil is toxic to animals and can slow the recovery of animal populations, impacting their habitats and reproductive rates.

Additionally, oil spills harm marine wildlife, including sea turtles, birds, and fish. The Deepwater Horizon oil spill in 2010, for example, affected various marine species, including juvenile Kemp's ridley sea turtles. Oil spills also contaminate seafood, making it unsafe for human consumption, and can have significant negative impacts on tourism, commerce, and industries that rely on seawater, such as power plants.

The fishing industry is one of the most affected by oil spills, often resulting in the immediate suspension of commercial fishing to prevent damage to equipment and ensure food safety. Oil spills also have long-term effects on the ecological system, which are challenging to assess and may require compensation for affected individuals and communities.

To address oil spills, satellite technology, such as that pioneered during the Deepwater Horizon incident, is used to monitor and patrol oceans for pollution. While there is no thoroughly satisfactory method for cleaning up major oil spills, advancements in oil spill science continue, and innovative solutions, such as renewable wood sponges, are being explored.

Microplastics

The presence of microplastics in the aquatic environment has adverse effects. They can act as carriers of contaminants to wildlife, potentially delivering toxic substances to aquatic organisms and microorganisms. Studies have shown that microplastics may work their way up the marine food chain, from zooplankton and small fish to large marine predators.

The abundance of microplastics in aquatic ecosystems is a growing concern. Despite efforts to reduce plastic waste, delays in action can significantly increase plastic pollution in oceans. Microplastics are now recognised as emerging pollutants, receiving increased attention due to their negative impact on the environment.

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