Causes of Water Pollution
Water pollution occurs when harmful substances enter natural water sources like rivers and lakes. These substances include faecal waste, fertilisers, pesticides, sewage and chemicals that cannot be broken down naturally.
Water pollution also includes toxic algae, bacteria (such as Escherichia coli and Vibrio cholera), parasites and fungi. It also includes thermal pollution, which is when water is warmer than it should be.
Industrial Waste
Industrial waste is one of the main causes of water pollution. Many factories produce a lot of toxic chemicals and pollutants that are then dumped into freshwater systems like rivers and oceans. These pollutants can make the water unsafe for human consumption and they can also cause the temperature of the water to change which makes it dangerous for many water dwelling organisms. Oil spills are another common source of water pollution. When large amounts of oil are spilled into the ocean it can destroy marine life and cause the oxygen levels in the water to decrease.
Other sources of pollution include sewage, pesticides, heavy metals and environmental persistent organic pollutants. Sewage is a major source of pollution because it contains pathogens from human waste, which can make the water unfit for consumption. In addition, when sewers overflow during storm events it can pollute the water with sewage. Pesticides and herbicides are often used in agriculture to protect crops from disease, but these chemicals can also get into the water supply and harm animals.
Agricultural Runoff
When harmful chemicals and microorganisms contaminate water, it can have a disastrous effect on the environment. The pollutants can harm people, animals and plants and cause waterborne diseases like cholera and typhoid. They can also damage crops and make soil infertile. Water pollution also affects the economy by causing treatment costs to rise, and it can hurt recreational businesses and tourism.
Agricultural runoff is a major source of water pollution. When rain, melting snow or irrigation flows over farm fields, it picks up chemicals, pesticides, sediment and nutrients and washes them away. This is called nonpoint source pollution, and it can carry these pollutants to nearby rivers, lakes, wetlands and coastal areas.
Farmers often use chemicals to protect their crops from bacteria and insects. These chemicals seep into the groundwater, where they can contaminate drinking water sources. Then, when it rains, they wash into lakes, rivers and oceans. These waters can then contaminate drinking water sources again.
Oil Spills
Oil spills are one of the largest contributors to water pollution. They are caused by accidents involving tankers, drilling rigs, and pipelines. They can be very dangerous to marine life and even cause toxic algae blooms.
They can also cause the water temperature to change and can lead to dead zones. These oil spills can be extremely difficult to clean up and can take a long time to recover.
This is because the type of oil, weather conditions, and local environmental conditions can all impact how the spill spreads. The resulting toxins can travel up the food chain and eventually affect human health.
The contaminants that can pollute water include industrial waste (toxic chemicals, metals, plastics), oil, and agricultural runoff. These contaminants can make water unsafe for drinking, and they can disrupt the natural balance of the ecosystem.
Human Activity
Water pollution is the introduction of substances that disrupt the ecological balance of rivers, lakes, oceans and other water bodies. This can happen in many ways, from the addition of toxic chemicals to sewage discharges and thermal pollution, which changes water temperature or decreases oxygen levels.
Pathogens are another major cause of water pollution. Disease-causing microorganisms like bacteria and viruses can contaminate water supplies, causing illnesses like cholera and typhoid fever. Unsafe water sickens about a billion people each year and especially affects low-income communities.
Water pollution is often caused by industrial and agricultural activities. Fertilizers and pesticides run off into lakes and rivers, contaminating groundwater and destroying natural ecosystems. The process of fracking, which uses large amounts of water and chemicals to crack rock for oil, can pollute underground water sources. The dumping of waste products, such as radioactive waste or oil residues, into rivers and oceans can also be considered water pollution. Another example of water pollution is the use of river or seawater as cooling water for power plants, which can increase temperatures and harm fish.