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Hey, we saw recently on the Made-Up Facts Channel that the human body is:
- 81% water;
- 18% carbon, calcium and nitrogen compounds; and
- 1% odor molecules.
After collecting so many causes of water pollution for this article, we think that last 1% might be from water too!
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In this article—part 2 of a series—we list the top water pollution causes. Some will surprise you!
There are many specific causes of water pollution, but before we list the toppers, it's important to understand two broad categories of water pollution:
“Point source” — occurs when harmful substances are emitted directly into a body of water.
“Nonpoint source” — delivers pollutants indirectly through transport or environmental change.
An example of a point source of water pollution is a pipe from an industrial facility discharging effluent directly into a river. An example of a nonpoint-source of water pollution is when fertilizer from a farm field is carried into a stream by rain (i.e. run-off).
Point-source pollution is usually monitored and regulated, at least in Western countries, though political factors may complicate how successful efforts are at true pollution control. Nonpoint sources are much more difficult to monitor and control, and today they account for the majority of contaminants in streams and lakes.
Now, on to the more specific categories of water pollution causes.
Pesticides that get applied to farm fields and roadsides—and homeowners' lawns—run off into local streams and rivers or drain down into groundwater, contaminating the fresh water that fish swim in and the water we humans drink. It's tempting to think this is mostly a farming problem, but on a square-foot basis, homeowners apply even more chemicals to their lawns than farmers do to their fields! Still, farming is a big contributor to this problem. In the midwestern United States, a region that is highly dependent on groundwater, water utilities spend $400 million each year to treat water for just one chemical—the pesticide Atrazine.
Many causes of pollution, including sewage, manure, and chemical fertilizers, contain "nutrients" such as nitrates and phosphates. Deposition of atmospheric nitrogen (from nitrogen oxides) also causes nutrient-type water pollution.
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In excess levels, nutrients over-stimulate the growth of aquatic plants and algae. Excessive growth of these types of organisms clogs our waterways and blocks light to deeper waters while the organisms are alive; when the organisms die, they use up dissolved oxygen as they decompose, causing oxygen-poor waters that support only diminished amounts of marine life. Such areas are commonly called dead zones.
Nutrient pollution is a particular problem in estuaries and deltas, where the runoff that was aggregated by watersheds is finally dumped at the mouths of major rivers.
Oil spills like the Exxon Valdez spill off the coast of Alaska or the more recent Prestige spill off the coast of Spain get lots of news coverage, and indeed they do cause major water pollution and problems for local wildlife, fishermen, and coastal businesses. But the problem of oil polluting water goes far beyond catastrophic oil spills. Land-based petroleum pollution is carried into waterways by rainwater runoff. This includes drips of oil, fuel, and fluid from cars and trucks; dribbles of gasoline spilled onto the ground at the filling station; and drips from industrial machinery. These sources and more combine to provide a continual feed of petroleum pollution to all of the world's waters, imparting an amount of oil to the oceans every year that is more than 5 times greater than the Valdez spill.
Shipping is one of these non-spill sources of oil pollution in water: Discharge of oily wastes and oil-contaminated ballast water and wash water are all significant sources of marine pollution, and drips from ship and boat motors add their share. Drilling and extraction operations for oil and gas can also contaminate coastal waters and groundwater.
As for gasoline and gas additives, leaking storage tanks are a big problem. The US Environmental Protection Agency (EPA) estimates that about 100,000 gasoline storage tanks are leaking chemicals into groundwater. In Santa Monica, California, wells supplying half the city's water have been closed because of dangerously high levels of the gasoline additive MTBE.
Mining causes water pollution in a number of ways:
- The mining process exposes heavy metals and sulfur compounds that were previously locked away in the earth. Rainwater leaches these compounds out of the exposed earth, resulting in "acid mine drainage" and heavy metal pollution that can continue long after the mining operations have ceased.
- Similarly, the action of rainwater on piles of mining waste (tailings) transfers pollution to freshwater supplies.
- In the case of gold mining, cyanide is intentionally poured on piles of mined rock (a leach heap) to chemically extract the gold from the ore. Some of the cyanide ultimately finds its way into nearby water.
- Huge pools of mining waste "slurry" are often stored behind containment dams. If a dam leaks or bursts, water pollution is guaranteed.
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Perhaps the worst offense in the category of mining vs. water pollution causes: Mining companies in developing countries sometimes dump mining waste directly into rivers or other bodies of water as a method of disposal. Developed countries are not immune from such insanity: The US government in 2003 reclassified mining waste from mountaintop removal (a type of coal mining) so it could be dumped directly into valleys, burying streams altogether.
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MINING –
A TOP CAUSE OF WATER POLLUTION |
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The Iron Mountain mine in California, USA has been closed since 1963 but continues to drain sulfuric acid and heavy metals (such as cadmium and zinc) into the Sacramento River. The river's bright orange water is completely devoid of life and has a pH of -3, which is 10,000 times more acidic than battery acid. Experts say the pollution may continue for another 3,000 years.
Source:
Worldwatch Institute /
Earthworks
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When forests are "clear cut," the root systems that previously held soil in place die and sediment is free to run off into nearby streams, rivers, and lakes. Thus, not only does clearcutting have serious effects on plant and animal biodiversity in the forest, the increased amount of sediment running off the land into nearby bodies of water seriously affects fish and other aquatic life. Poor farming practices that leave soil exposed to the elements also contribute to sediment pollution in water.
Almost all bodies of water in the world have some level of pollution from chemicals and industrial waste.
In the United States, 34 billion liters per year (60%) of the most hazardous liquid waste—solvents, heavy metals, and radioactive materials—is injected directly into deep groundwater via thousands of "injection wells." Although the EPA requires that these effluents be injected below the deepest source of drinking water, some pollutants have already entered underground water supplies in Florida, Texas, Ohio, and Oklahoma.
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The US is not alone in careless treatment of its groundwater. In the late 1990s, India's Central Pollution Control Board found that groundwater was unfit for drinking in all 22 major industrial zones it surveyed.
Plastics and other plastic-like substances (such as nylon from fishing nets and lines) can entangle fish, sea turtles, and marine mammals, causing pain, injury, and even death. Plastic that has broken down into micro-particles is now being ingested by tiny marine organisms and is moving up the marine food chain.
Sea creatures that are killed by plastic readily decompose. The plastic does not—it remains in the ecosystem to kill again and again.
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GLOWING REVIEWS — NOT! |
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Even nuclear energy is among the causes of water pollution. Radioactive water pollution has a number sources, including
- the normal operation of nuclear power stations (i.e. from the nuclear waste);
- the mining and refining of uranium and thorium; and
- the use of radioactive materials in industrial, medical, and scientific processes.
In the oceans, the biggest sources of man-made radioactive elements are the nuclear fuel reprocessing plants at La Hague in France and at Sellafield in the UK. Discharges from these facilities have resulted in the widespread contamination of large marine areas. Radioactive elements traceable to reprocessing can be found in seaweed as far away as the western coast of Greenland.
Source: Greenpeace, et al
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Whenever we use personal-care products and household cleaning products—whether they be laundry detergent, bleach, or fabric softener; window cleaner, dusting spray, or stain remover; hair dye, shampoo, conditioner, or Rogaine; cologne or perfume; toothpaste or mouthwash; antibacterial soap or hand lotion—we should realize that almost all of it goes down the drain when we do laundry, wash our hands, brush our teeth, bathe, or do any of the other myriad things that incidentally use household water. Similarly, when we take medications, we eventually excrete the drugs in altered or unaltered form, sending the compounds into the waterways. Studies have shown that up to 90% of your original prescription passes out of you unaltered. Animal farming operations that use growth hormones and antibiotics also send large quantities of these chemicals into our waters.
Unfortunately, most wastewater treatment facilities are not equipped to filter out personal care products, household products, and pharmaceuticals, and a large portion of the chemicals passes right into the local waterway that accepts the treatment plant's supposedly clean effluent.
Study of the effects of these chemicals getting into the water is just beginning, but examples of problems are now popping up regularly:
- Scientists are finding fragrance molecules inside fish tissues.
- Ingredients from birth control pills are thought to be causing gender-bending hormonal effects in frogs and fish.
- The chemical nonylphenol, a remnant of detergent, is known to disrupt fish reproduction and growth.
In developing countries, an estimated 90% of wastewater is discharged directly into rivers and streams without treatment. Even in modern countries, untreated sewage, poorly treated sewage, or overflow from under-capacity sewage treatment facilities can send disease-bearing water into rivers and oceans. In the US, 850 billion gallons of raw sewage are sent into US rivers, lakes, and bays every year by leaking sewer systems and inadequate combined sewer/storm systems that overflow during heavy rains. Leaking septic tanks and other sources of sewage can cause groundwater and stream contamination.
Beaches also suffer the effects of water pollution from sewage. The chart below shows the typical reasons that about 25% of the beaches in the US are put under water pollution advisories or are closed each year. It's clear that sewage is part of the problem, even in what is supposedly the most advanced country in the world.
Figure 1.
Sources of pollution that resulted in beach advisories and closings
[Source: US EPA]
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Hey, I thought we were doing WATER pollution causes! Well, surprisingly enough, air pollution contributes substantially to water pollution. Pollutants like mercury, sulfur dioxide, nitric oxides, and ammonia deposit out of the air and then cause problems like mercury contamination in fish, acidification of lakes, and eutrophication (nutrient pollution). Most of the air pollution that affects water comes from coal-fired power plants and the tailpipes of our vehicles, though some also comes from industrial emissions.
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CRABBING ABOUT WATER POLLUTION |
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One-third of the excess nitrogen in the Chesapeake Bay comes from deposition and transport of pollutants from the air.
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According to the United Nations Environment Programme, a 15-year-long study of the role of man-made CO2 in the earth's oceans found that the oceans had absorbed enough CO2 to already have caused a slight increase in ocean acidification. The fear is that further CO2 uptake will increase acidification even more and cause the carbonate structures of corals, algae, and marine plankton to dissolve. This could have significant impacts on the biological systems of our oceans.
Heat is a water pollutant—increased water temperatures result in the deaths of many aquatic organisms. These increases in temperature are most often caused by discharges of cooling water by factories and power plants.
Global warming is also imparting additional heat to the oceans. The impact on marine life is unknown at this point, but it's likely to be significant.
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Many marine organisms, including marine mammals, sea turtles and fish, use sound to communicate, navigate, and hunt. The ever-increasing din of noise from ship engines and sonars has a negative effect. Because of this noise pollution, some species may have a harder time hunting; others may have a harder time detecting predators; still others may just not be able to navigate properly.
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WATER POLLUTION
BY DEATH |
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Even the dead are a cause of water pollution. In India, if a deceased person's family cannot afford a funeral they may immerse the ashes of their loved one in the sacred Ganges River—or they may put the corpse itself in the river.
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In a well publicized case in 2000, at least 17 whales were stranded on beaches in the northern Bahama Islands, with the likely cause being US Navy vessels operating mid-frequency sonar systems nearby.
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There are as many causes of water pollution as man has had ingenious ideas. We've provided info on the main ones above, but lest you think that's all there is, here are a few others that we just don't have time to get into:
- Poorly designed landfills
- Road deicing salts
- Hazardous waste sites
- Pet feces and wild animal droppings
- Cruise ships
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Well, that's all for this segment, but we hope you'll row on to Part 3—Water Pollution Effects on wildlife and humans.
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