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8 Most Common Causes of Water Pollution


Of all humanity’s needs, water is the most basic, urgent, and immediate. Without water most won’t last three days. Without consistent access to clean water countless health problems can arise. Lack of access to clean drinking water is one of the largest problems facing impoverished and developing nations today. Water pollution can severely restrict this access.
The countries with water shortages are also among the most likely to have significant amounts of water pollution. Water pollution is a serious problem that requires serious action. Here are some of the common causes of water pollution:

1. Sewage

Sewage is one of the leading causes of water pollution. Any concentrated populous requires significant sewage handling infrastructure. Even in the best of cases there are leaks and issues with these systems. Most cases are not the best of cases and can have substantial run off to water sources.

In many cases, this is by design as many developing nations have more immediate problems and can’t afford to plan effectively for the future. The presence of non-organic waste, like plastics, in municipal sewage makes it much harder to treat. The wide variety of chemicals people send down the drain further complicates the process.

2. Urban Development

More people live in cities as opposed to the countryside than ever before. Urban sprawl can have profound and lasting effects on local water sources. The production associated with cities is sure to have waste products that, if not properly handled, will infect the water supply with a variety of toxic and hazardous compounds.

Waste products find their way into rivers and oceans. Major production isn’t the only factor, the everyday citizen also contributes. Various chemicals and detergents find their way through municipal waste water treatment and into the water supply.

3. Chemical Waste

Many chemical plants still engage in the practice of directly dumping chemical waste into rivers or oceans. While there have been marked improvements in this area in recent decades, there are many holdouts that are still causing problems. Some of the most significant problems are heavy metals like cadmium and lead.

Without proper disposal methods and procedures, these compounds are very dangerous and typically stick around for years. Mercury is a major concern as it ends up in the fish that people eat all over the world. This causes a variety of health problems and is directly connected to water pollution.

4. Radiation

Radiation is a major concern in many different fields of environmental preservation. Radioactive waste is long lasting. When this waste is discharged into the ocean it can end up almost anywhere in the world. It can drift far and wide, all the while discharging hazardous radiation.

This was a particular issue during the era of open water nuclear weapon testing, as these transferred significant radioactive waste to the ocean. There has also been a significant discharge of radiation from the recent Fukushima disaster. The long-term effects of this disaster are unknown.

5. Fertilizer

Fertilizer is used all over the world to increase crop yields. Given the global food requirements there is no obvious alternative. Fertilizers contain phosphorus, potassium, and nitrogen. These are all essential for plant growth. Fertilizer is often directly applied to the surface of a field. When it rains many of the nutrients are washed away with the rainwater.

This leads to the nutrients ending up in rivers and lakes. The nutrients stimulate the growth of algae to an extreme extent. These algal blooms can kill off other river plants and animals, damaging the delicate ecosystem.

6. Oil Spills

Oil spills are perhaps the most obvious of the major ways that humanity pollutes the ocean. Oil spills typically occur when an oil tanker ruptures and discharges its oil into the ocean. This creates a very densely concentrated patch of oil. Oil floats on top of water, reducing its ability to dissipate. Oil is also immiscible, or un-mixing, with water.

This means that oil spills take an extremely long time to thin out to concentrations that aren’t immediately harmful. These spills are a massive threat to wildlife, both seabirds and fish. The spills often wash onto shore as well, threatening sea turtles.

7. Thermal Pollution

Pollution is typically associated with chemical pollutants. The image of a large pipe discharging a green liquid is what most would imagine. Thermal pollution is another type of pollution. Many facilities, particularly power plants, continuously draw water from a source to be used as cooling water. The water accepts heat from a cooling loop and is then returned to the source.

This leads to heating of the source, be it a river or a local section of ocean. Warm water holds less oxygen, this can cause a disruption of the ecosystem of that water source.

8. Plastics

Plastics are one of the largest sources of ocean pollution. Plastic poses a large threat to nearly every type of marine life. Many animals ingest plastic and are killed when they cannot digest it. Plastic is a particular problem because it is long lasting. Nearly all plastics are not biodegradable. They could potentially persist for hundreds or thousands of years before fully disintegrating.

Plastics also typically float, leading to large patches forming on the surface. These present a particular threat to seabirds who often scoop up plastic from the surface and die from ingesting it.


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