Water Pollution: Ecological Imbalance And Its Impact

Water pollution is a critical issue that has far-reaching consequences for the environment and human health. It occurs when harmful substances contaminate a body of water, degrading water quality and rendering it toxic to humans and the environment. The main sources of water pollution are industrial waste, sewage discharge, and agricultural runoff, which release toxic chemicals, waste, plastic, and other pollutants into our rivers, reservoirs, lakes, and seas. These pollutants contaminate the water, leading to serious damage to the delicate balance of aquatic ecosystems, harming aquatic life and impacting the quality of water that we rely on for drinking, agriculture, and recreation. This can result in a domino effect, where the entire food chain is disrupted, leading to a decline in biodiversity that can be challenging to fix.

Industrial and agricultural waste

Industrial and agricultural activities are major contributors to water pollution, which in turn disturbs the ecological balance.

Agricultural Waste

Agriculture is the leading cause of water degradation. The overuse of pesticides and fertilizers, as well as animal waste from farms and livestock operations, contaminates water bodies. When it rains, these pollutants are washed into nearby rivers, lakes, and other water bodies. This is known as agricultural runoff, and it is the leading cause of water quality impacts on rivers and streams. It is also the third leading source of lake pollution and the second-largest source of wetland impairments.

Agricultural non-point source pollutants, such as sediment, pesticides, nutrients, and pathogens, are transported through rainwater and melting snow, eventually reaching groundwater, wetlands, rivers, and lakes, and finally, the oceans. The ecological impact of these pollutants can range from simple nuisance substances to severe ecological impacts involving fish, birds, and mammals, as well as human health.

Nutrient pollution, caused by excess nitrogen and phosphorus in water or air, is the number one threat to water quality worldwide. It can cause algal blooms, which are harmful to people and wildlife. Bacteria from livestock manure can contaminate drinking water supplies and cause beach and shellfish bed closures. Pesticide runoff can also pose risks to aquatic life, wildlife, and drinking water supplies.

Poor agricultural practices can lead to soil erosion, nutrient loss, and waterlogging of irrigated land, further contributing to water pollution.

Industrial Waste

Industrial activities also contribute significantly to water pollution. The production of industrial goods generates wastewater contaminated with toxic substances. In many cases, this wastewater is discharged untreated into nearby public waters, causing extensive ecological degradation. According to a 2009 American study, about 44% of assessed streams, 64% of lakes, and 30% of bays and estuaries are still classified as polluted.

Industrial wastewater can contain a mix of toxic substances, including heavy metals such as mercury, chromium, lead, cadmium, copper, zinc, and nickel. These metals accumulate in water reservoirs and enter the food chain, leading to further contamination. Other contaminants include antibiotics, hormones, cytostatic drugs, and complex chemical ingredients.

The release of untreated wastewater from industries harms aquatic ecosystems by reducing oxygen levels and increasing pollutant levels. It can also introduce dangerous pathogens into the food supply chain, leading to serious illnesses.

Sewage and wastewater

Sewage is also a major source of plant nutrients, particularly nitrates and phosphates. Excessive amounts of these nutrients in water bodies can cause abnormal growths of algae known as algal blooms. These blooms can lead to the deaths of many species, including fish, as they block light required for photosynthesis and deplete oxygen levels in the water, creating "dead zones" devoid of life. Furthermore, the presence of sewage in rivers and other water bodies can induce the growth of biofilms, which are mats of algae and bacteria that accumulate on surfaces.

In addition to the ecological consequences, sewage pollution also poses risks to human health. Domestic sewage often contains active pharmaceutical ingredients, which can harm aquatic organisms and contribute to the development of antibiotic resistance. Moreover, studies have shown that treated wastewater can cause physiological changes in fish, including the development of ovarian cavities in male brown roaches and alterations in kidney and immune system functions.

Wastewater, a broader term, includes sewage as well as stormwater runoff, and industrial, commercial, and agricultural waste. It is estimated that over 80% of the world's wastewater is discharged into the environment without adequate treatment, jeopardising nature and public health. This untreated wastewater introduces a range of toxic contaminants, including pathogens, pharmaceuticals, microplastics, heavy metals, and endocrine disruptors. These pollutants have far-reaching consequences for aquatic ecosystems, biodiversity, food and water security, and climate resilience.

The impact of sewage and wastewater pollution is evident in the degradation of aquatic ecosystems, including coral reefs, salt marshes, and fish-rich river systems. The high levels of contamination observed globally highlight the urgent need for improved sewage management and cross-sector collaboration between conservation and public health sectors.

Oil spills and leaks

The impact of oil spills on marine and coastal wildlife is extensive. Larger species, such as marine mammals and seabirds, are often the most visibly affected. Oil can physically harm animals, causing skin irritation, altering their immune systems, and leading to reproductive or developmental issues, and liver disease. It can also destroy the insulating ability of the fur of mammals like sea otters and the water-repelling properties of birds' feathers, leaving them vulnerable to harsh weather conditions and at risk of hypothermia.

The ingestion of oil is another critical pathway of impact. Birds and animals may swallow oil or consume prey that has been exposed to it, leading to poisoning. Fish, shellfish, and corals can come into contact with oil if it mixes into the water column, potentially causing changes in reproduction and growth rates or even death. Oil spills can also reduce the population of important species such as oysters, shrimp, swordfish, and tuna, either through direct harm or by making them unsafe for consumption by predators, including humans.

The magnitude of an oil spill's impact depends on the extent of the spill and the duration of exposure. Larger spills increase the difficulty for animals to avoid oil particles, while longer exposure periods heighten the likelihood of exposure for species that forage at or near the water surface. Additionally, wave action and winds can accelerate the mixing of oil into the water column, increasing the exposure of benthic organisms (animals living at the ocean floor) to smaller oil particles.

Oil spills can have both acute and long-term effects on populations, communities, and ecosystems. While some acute effects may be short-lived and localized, others can have persistent impacts on specific species and their habitats. For example, in the Exxon Valdez spill, oil persisted in mussel beds for years, leading to continued exposure for fish, seabird, and sea otter species even over a decade later.

The ecological balance is further disrupted as oil spills force species to alter their foraging activities and congregate in smaller areas, leading to increased competition for food sources. This congregation can make rare species more vulnerable to predation and future environmental disasters. Overall, oil spills and leaks have far-reaching consequences, impacting multiple levels of the ecological hierarchy, from individual organisms to entire ecosystems.

Heavy metals and toxic chemicals

There are various natural and anthropogenic sources of heavy metals in water. Natural sources include leaching, weathering, and volcanic eruptions. Anthropogenic sources include industrial production, mining, agriculture, transportation, fossil fuel burning, smelting, municipal waste, fertilizers, pesticides, sewage, and domestic waste. Industrial wastewater, in particular, has been identified as a major contributor, with hazardous chemicals, including heavy metal ions, being directly or indirectly released into the environment.

Heavy metals can enter the water system through different pathways. In the context of mining, for example, exposed mined-out areas can lead to acid mine drainage (AMD), which, due to its low pH, mobilizes heavy metals in the water. Additionally, the disposal of mined ores on the ground surface further contributes to soil and water pollution.

The presence of heavy metals in water has detrimental effects on ecological health. Heavy metals can cause acute toxicity and chronic exposure issues. They can impact the development of aquatic organisms, disturb oxygen levels, and interfere with reproductive processes. In fish, for instance, heavy metals can enter through the gills, body, or digestive tract, accumulating in the liver, kidneys, and gills, and leading to lesions and operational disturbances.

Heavy metal toxicity can also have severe consequences for human health, including liver and renal dysfunction, dermatological issues, neurotoxicity, and an increased risk of cancer. The accumulation of heavy metals in the food chain further exacerbates the problem, posing risks to both wildlife and human health.

To address this issue, various remediation methods have been developed, including physical, chemical, and biological processes. However, these methods often have limitations, such as high costs and the generation of secondary pollutants. As a result, integrating different remediation approaches and employing eco-friendly techniques have been suggested to enhance the efficiency of heavy metal removal and reduce their impact on ecological balance.

Climate change and rising temperatures

Increased Flooding and Sea Level Rise: Climate change is causing more frequent and intense heavy downpours, leading to increased flooding. As a result, more pollution flows into waterways, contaminating water resources with pollutants, sediment, and other contaminants. This not only disrupts aquatic ecosystems but also complicates the treatment of drinking water, leading to increased costs. Rising sea levels, driven by melting glaciers, also contribute to the intrusion of saltwater into freshwater sources, further threatening water security in coastal areas.

Drought and Water Scarcity: Climate change intensifies droughts, reducing water sources such as reservoirs, lakes, and snowpack. This, in turn, affects long-term water storage and availability. Drought conditions can also increase drinking water treatment costs by concentrating contaminants in source waters, further diminishing water quality. By 2050, an estimated 2.7 to 3.2 billion people will live in potential severely water-scarce areas, facing challenges in accessing sufficient clean water.

Warmer Air and Increased Evaporation: Warmer air sucks up more water from oceans, lakes, soil, and plants. This leads to drier conditions, negatively impacting drinking water supplies and agriculture. The increased evaporation also contributes to higher humidity, making higher temperatures even more unbearable in some places as it blocks the cooling effects of sweating.

Snowpack Decline: As the air warms, many regions receive more precipitation as rain instead of snow. This results in less water being stored as snowpack, leading to drier conditions later in the year. This can have significant impacts on regions that rely on snowmelt for drinking water and irrigation, such as California, which has experienced long-term droughts and water shortages due to declining snowpack.

Water Temperature and Ecosystem Disruption: Higher water temperatures can have significant ecological consequences. For example, wetlands, such as mangroves and marshes, are effective carbon sinks and provide natural protection against storms and excess precipitation. Increased water temperatures can disrupt these ecosystems, reducing their ability to absorb carbon dioxide and provide natural buffers against extreme weather events.

Groundwater Pollution and Overuse: Groundwater, which is a vital source of freshwater, is often overexploited and polluted. Climate change intensifies these issues, and sustainable groundwater management becomes crucial in adapting to changing water availability and quality.

Frequently asked questions