Natural Water Pollution: Causes And Effects

Water pollution is a pressing issue that jeopardizes the health of millions worldwide, with unsafe water causing more deaths annually than war and all other forms of violence combined. While human activities, such as improper waste disposal and industrialization, are major contributors, water pollution can also occur without direct human influence. Natural factors, such as algal blooms, can cause water pollution. For example, when algae die, microorganisms use oxygen for decomposition, reducing the oxygen available for aquatic life, leading to eutrophication and the creation of dead zones where aquatic life cannot survive. Climate change, caused by both human and natural factors, also plays a role in water pollution by increasing water temperatures, which can be detrimental to aquatic ecosystems.

Natural factors like algal blooms

Harmful algal blooms (HABs) occur naturally in the environment and are caused by an abundance of nutrients like nitrogen and phosphorus, which are essential for plant growth. These nutrients act as fertilisers, promoting the growth of algae and bacteria. When there is an excess of these nutrients in water, it is called nutrient pollution, and it can lead to the formation of algal blooms.

Algal blooms are more likely to form in warm, slow-moving, or stagnant water with low water levels. This is because higher temperatures give cyanobacteria a competitive advantage, allowing them to grow faster than other types of algae. Additionally, when water levels are low and water moves slowly, such as during a drought, the water becomes thermally stratified, with a layer of warm water floating on top of cooler water, creating ideal conditions for algal blooms.

The growth of algal blooms can also be influenced by changes in water conditions like pH or turbidity (the amount of suspended matter in the water). For example, when turbidity is low, light can easily penetrate the water, promoting the growth of algal blooms. Similarly, changes in the local ecology, such as the introduction of new species or the loss of existing ones, can impact the growth of harmful algal blooms.

The impact of algal blooms on the environment can be detrimental. As the blooms grow thicker, the dark surfaces of the algae mats absorb more sunlight, leading to warmer water temperatures and further algal growth. This process creates a feedback loop that intensifies the problem. Additionally, when the algae eventually die, their decomposition consumes oxygen, leading to the creation of "dead zones" where oxygen levels are too low for aquatic life to survive.

Climate change

Water and climate change are inextricably linked. Climate change affects the world's water in complex ways, from unpredictable rainfall patterns to shrinking ice sheets, rising sea levels, floods, and droughts.

Firstly, climate change is exacerbating water scarcity. Over the past 20 years, terrestrial water storage, including soil moisture, snow, and ice, has dropped at a rate of 1 cm per year, with major ramifications for water security. By 2050, the number of people at risk of floods will increase from 1.2 billion to 1.6 billion. In 2015, 1.9 billion people, or 27% of the global population, lived in potential severely water-scarce areas. This number will increase to 2.7 to 3.2 billion people by 2050.

Secondly, climate change is causing more frequent and intense flooding, which can endanger human lives, damage homes, kill crops, and hurt the economy. Heavier rainstorms increase surface runoff, which can pick up pollutants, dirt, and other contaminants, flushing them into nearby bodies of water. This can muck up water supplies and make it more expensive to clean the water to drinking standards.

Thirdly, rising temperatures can cause water to lose oxygen content, endangering aquatic life. Warmer air can hold more moisture than cool air. As a result, in a warmer world, the air will suck up more water from oceans, lakes, soil, and plants, leaving drier conditions that negatively affect drinking water supplies and agriculture.

To address these issues, several strategies can be implemented:

• Climate-smart agriculture: Using techniques such as drip irrigation, reducing food waste, and reusing wastewater can help reduce the demand on freshwater supplies.
• Protecting and restoring wetlands: Wetlands act as effective carbon sinks, absorbing and storing CO2, and providing natural protection against storm surges and excess water.
• Implementing early warning systems: Early warnings for floods, droughts, and other water-related hazards can significantly reduce disaster risk and save lives.
• Reducing CO2 emissions: Limiting global warming can help prevent the further acidification of oceans and the loss of glaciers and ice sheets.

Radioactive substances

Radioactive contamination of water has emerged as a pressing concern for global human health and the environment. Radioactivity refers to the spontaneous emission of particles or waves from the unstable nuclei of certain elements. There are three types of radioactive emissions: Alpha particles, which are positively charged helium atoms; Beta particles, which are negatively charged electrons; and Gamma rays, which are neutral electromagnetic radiations.

While natural sources contribute to radioactive water pollution, human activities also play a significant role. Nuclear reactors, nuclear weapon testing, and nuclear power plants are key sources of human-induced radionuclide discharge. These activities produce a range of radioisotopes, some of which are utilized in medical and industrial applications, while others are considered unnecessary waste. For example, Cobalt-60 and Iridium-192 are radioisotopes used in gamma radiation for radiotherapy, whereas Strontium-90 and Caesium-137 are classified as unwanted radioactive waste.

The improper disposal of radioactive waste from nuclear facilities and the dumping of radioactive substances into surface water bodies are significant contributors to water pollution. Additionally, mining activities involving radioactive elements like uranium and thorium can contaminate both surface water and groundwater. Furthermore, radioactive gases released from magma and the atmospheric deposition of cosmogenic radionuclides also lead to radioactive contamination in water bodies.

To address the issue of radioactive water pollution, drinking water suppliers implement various strategies. These include identifying potential contamination sources, preparing for emergencies, and participating in voluntary programs aimed at maintaining the purity of drinking water sources.

Oil spills

When an oil spill occurs, experts from organisations like the National Oceanic and Atmospheric Administration (NOAA) evaluate what happened, assess the impacts, and design restoration projects to help the environment recover. Restoration is different from cleanup as it involves projects like building marshland or protecting bird nesting habitats to actively bolster the environment. While there are various equipment and tactics that trained experts can use to contain or remove oil from the environment, cleanup activities can never remove 100% of the spilled oil, and scientists must be careful not to cause additional harm.

Sedimentation

Sediment carried by water can have a variety of effects. It can impact the transport and fate of pollutants, making it a concern for water quality management. For example, toxic chemicals can attach themselves to sediment particles and be transported and deposited in other areas. These pollutants may later be released into the environment, endangering the health of water users, particularly aquatic organisms.

In addition, dredging activities, which involve the direct removal of aquatic life, can release silt or sediments that cover and destroy fish feeding and breeding habitats. Spoils deposited directly into a water system can smother and destroy organisms, and contaminants can accumulate over time in the sediments, which can re-enter the water system when dredged.

Sediment pollution is particularly relevant in coastal zones, as the recycling of contaminants from sediments is more likely to occur in shallow environments compared to deeper waters. The ecological and economic impacts of pollution can be especially harmful in these productive coastal ecosystems.

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