What is water pollution？
Water pollution is the release of substances into bodies of water that makes water unsafe for human use and disrupts aquatic ecosystems. Water pollution can be caused by a plethora of different contaminants, including toxic waste, petroleum, and disease-causing microorganisms.
What causes water pollution?
1. Sewage and Wastewater
According to the UN, more than 80% of the world’s wastewater flows back into the environment without being treated or reused; in some least-developed countries, this figure tops 95%. Harmful chemicals and bacteria can be found in sewage and wastewater even after it’s been treated. Households release sewage and wastewater, which makes its way to the ocean, mixing with freshwater and affecting the water quality and marine life. Also, the bacteria and pathogens found in wastewater breed disease, and cause health-related issues in humans and animals.
2. Oil Spills
Large oil spills and leaks are some of most significant causes of water pollution. These are often caused by oil drilling operations in the ocean, but nearly half of the estimated 1 million tons of oil that makes its way into marine environments each year come not from oil tankers, but from land-based sources like factories, farms and cities. In England and Wales, there are about 3,000 pollution incidents involving oil and fuel each year. Oil makes drinking water unsafe and a substantial amount of oil released into oceans or become river water pollution, will destroy marine life and the ecosystems that support them. What’s more, oil reduces the oxygen supply within the water environment. Oil is also naturally released from under the ocean floor through fractures known as seeps.
3. Industrial Waste
Industrial waste is one of the biggest sources of water contamination. Many industrial sites produce waste in the form of toxic chemicals and pollutants, and some don’t have proper waste management systems in place. Sometimes, industrial waste is dumped into nearby freshwater systems. The toxic chemicals leached from this waste can make the water unsafe for human consumption, and they can also cause the temperature in freshwater systems to change, making them dangerous for marine life. Finally, industrial waste can cause “dead zones,” which are areas of water that contain so little oxygen that marine life cannot survive in them.
4. Agricultural Runoff
To protect crops from pests, farmers use pesticides, however when these substances seep into the groundwater, they can harm animals, plants and humans. Additionally, when it rains, the chemicals mix with rainwater, which flows into waterways and creates further pollution. Other agricultural processes such as uncontrolled spreading of slurries and manures, tillage and ploughing the land can also cause water pollution.
5. Marine Dumping and Plastic Pollution in the Sea
Most items collected and dumped into oceans by many countries can take anywhere from two to 200 years to decompose completely! Other sources of waste at sea include plastic and other materials blown or washed from land. Currently, about 11 million metric tons of plastic make their way into the oceans each year. Research has found that should this rate of pollution continues, the amount of ocean plastics will grow to 29 million metric tons per year by 2040. The damage to wildlife habitats and to life on land is incalculable.
6. Radioactive Waste
Radioactive waste can persist in the environment for thousands of years, making disposal a major challenge and one of the most harmful water contaminants. Radioactive waste released from facilities that create nuclear energy can be extremely harmful to the environment and must be disposed of properly; uranium, the element used in the creation of nuclear energy, is a highly toxic chemical. Accidents occur at these facilities from time to time, and toxic waste is released into the environment.
In April 2021, Japan discharged contaminated water containing radioactive materials from the damaged Fukushima nuclear plant into the sea. Though the Japanese government claims potential health risks and damage to marine life to be minimal as the waste water have been treated, close monitoring is required to ensue there are no environment effects from the water pollution.
What are the effects of water pollution?
On aquatic wildlife
Sewage can promote algae growth, which can eventually result in eutrophic “dead zones” where aquatic life cannot survive because of a lack of oxygen. Microplastics are often found in marine wildlife and can become concentrated in humans who consume seafood because of biomagnification. Oil spills, such as the Deepwater Horizon oil spill in 2010, strand and kill many different marine species.
On groundwater and oceans
Groundwater—water contained in underground geologic formations called aquifers—is a source of drinking water for many people. For example, about half the people in the United States depend on groundwater for their domestic water supply. Although groundwater may appear crystal clear (due to the natural filtration that occurs as it flows slowly through layers of soil), it may still be polluted by dissolved chemicals and by bacteria and viruses. Sources of chemical contaminants include poorly designed or poorly maintained subsurface sewage-disposal systems (e.g., septic tanks), industrial wastes disposed of in improperly lined or unlined landfills or lagoons, leachates from unlined municipal refuse landfills, mining and petroleum production, and leaking underground storage tanks below gasoline service stations. In coastal areas, increasing withdrawal of groundwater (due to urbanization and industrialization) can cause saltwater intrusion: as the water table drops, seawater is drawn into wells.
Although estuaries and oceans contain vast volumes of water, their natural capacity to absorb pollutants is limited. Contamination from sewage outfall pipes, from dumping of sludge or other wastes, and from oil spills can harm marine life, especially microscopic phytoplankton that serve as food for larger aquatic organisms. Sometimes, unsightly and dangerous waste materials can be washed back to shore, littering beaches with hazardous debris. By 2010, an estimated 4.8 million and 12.7 million tonnes (between 5.3 million and 14 million tons) of plastic debris had been dumped into the oceans annually, and floating plastic waste had accumulated in Earth’s five subtropical gyres that cover 40 percent of the world’s oceans (see also plastic pollution).
Another ocean pollution problem is the seasonal formation of “dead zones” (i.e., hypoxic areas, where dissolved oxygen levels drop so low that most higher forms of aquatic life vanish) in certain coastal areas. The cause is nutrient enrichment from dispersed agricultural runoff and concomitant algal blooms. Dead zones occur worldwide; one of the largest of these (sometimes as large as 22,730 square km [8,776 square miles]) forms annually in the Gulf of Mexico, beginning at the Mississippi River delta.
On human
Water-borne diseases account for the deaths of 3,575,000 people a year! That’s equivalent to a jumbo jet crashing every hour, and the majority of these are children.
Infectious diseases can be spread through contaminated water. Some of these water-borne diseases are Typhoid, Cholera, Paratyphoid Fever, Dysentery, Jaundice, Amoebiasis and Malaria.
Chemicals in the water also have negative effects on our health.
Pesticides – can damage the nervous system and cause cancer because of the carbonates and organophosphates that they contain. Chlorides can cause reproductive and endocrinal damage.
Nitrates – are especially dangerous to babies that drink formula milk. It restricts the amount of oxygen in the brain and cause the “blue baby” syndrome.
Lead – can accumulate in the body and damage the central nervous system.
Arsenic – causes liver damage, skin cancer and vascular diseases
Flourides - in excessive amounts can make your teeth yellow and cause damage to the spinal cord.
Petrochemicals – even with very low exposure, can cause cancer.
These are just to name a few.
How can we prevent water pollution?
1. Pick up litter and dispose of it properly
One of the best ways to reduce water pollution is to prevent it at the source: by disposing of waste properly. In fact, 60% of water pollution today can be attributed to litter.
Waste that litters our roads, fields, and sidewalks often flows into nearby drains and streams when it rains. When the litter degrades, chemicals and microparticles are released.
Chemicals and other pollutants from this litter can negatively impact the environment and wildlife in waterways. Cigarette butts are a common example of litter that can seriously damage the natural environment. They can contain chemicals like arsenic and formaldehyde that will seep into soil, and in turn, freshwater sources.
2. Dispose of chemicals and fuel properly
It’s important to know that you should never pour used motor oil or antifreeze down a storm drain, onto the soil, into a waterway, or into the sanitary sewer. All of these drains flow into rivers, meaning this harmful substance will certainly make its way to wreak havoc on the natural life of your waterway.
So how can we dispose of it?
Put used oil or antifreeze in a sturdy container and take it to a local service station or other approved center.
Your community may have a recycling center that will accept the used motor oil and recycle it. Community collection centers and drop-off sites also exist in some areas.
It’s even a good idea to label the container, so others will know that allowing liquids other than storm water to get into the drain leads to the pollution of lakes and streams.
3. Mulch or compost grass or yard waste
In many places around the world, leaves and grass are important parts of the natural environment. Left on land, leaves decompose, feeding your plants and enriching your soil. However, these same leaves and yard waste can lead to problematic water pollution. When large amounts of leaves are washed off our lawns, down our driveways, and into storm drains, they make their way into our water bodies; they release phosphorus and nitrogen into our water, contributing to water pollution.
There are a few potential solutions to this issue, however:
- Your city may be able to dispose of your leaves and yard waste – you can bag your leaves for curbside pick-up.
- You can also mix your leaves into your compost pile, creating a nutrient-rich fertilizer for your plants.
- Using a mulching mower, you can create mulch from your leaves to use in flower beds.
- Leave leaves and yard waste in your front yard if you can’t compost them – avoid blowing leaves into the street and clogging and damaging storm drains.
4. Don’t pour fat and grease down the drain
Most of the dishes we cook leave some sort of fat, oil, or grease residue behind. These substances should never be disposed of down the drain in your kitchen.
When poured down the drain, fat and grease can build up over time and clog your pipes. This will lead to sewer pipes clogging and even backing up into your yard and basement. It can also lead to water pollution by carrying contaminants to local bodies of water.
Instead, grease, fat, and used cooking oil should be disposed of in the trash or kept in a glass jar for disposal with other solid waste.
5. Minimize your use of pesticides, herbicides, and fertilizers
In the continental U.S., about half a million tons of pesticides, 12 million tons of nitrogen, and 4 million tons of phosphorus fertilizer are applied annually to crops. These chemicals can cause critical damage to our waters through the soil, runoff, and air.The Environmental Protection Agency (EPA) recommends several techniques for large-scale farm operations to mitigate these effects, such as Integrated Pest Management (IPM) which encourages natural barriers and limits pesticide use.At home, however, you can do your part by minimizing your use of fertilizers and pesticides on your lawn and gardens. You can also select plants that are native to the area and can thrive in your landscape’s natural conditions. In turn, you will have to fertilize them less and use less water in the long run.If you must use fertilizers, make sure to blow or sweep it back onto your grass if it gets onto paved areas, and avoid applying fertilizer on the grass right before it rains, so it doesn’t wash into storm drains and waterways.
7. Dispose of medical waste properly
Never flush pills, powders, or liquid medicines down the toilet or dump them outside, whether on land or water. These drugs can accumulate in the water and be consumed by fish and other wildlife.Hormones and other compounds end up causing a variety of health problems in fish and birds and contaminate drinking water that people and livestock use.Studies have found that medicines flushed down the drain can contaminate our lakes and streams and eventually end up in our drinking water. This can lead to adverse reactions for some people and even cases of accidental poisoning. University of Minnesota researchers have also detected antibiotics used for human and animal treatment at low levels in lakes, rivers, and streams throughout Minnesota. The U.S. Geological Survey has also found antibiotics in groundwater in both non-agricultural and urban areas.
