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group members :
~ Lim Zheng Yuan
~ Louis Peh
~ Melissa Lok
~ Rosanne Too


Pure chemistry of course!

Websites About Water Pollution

Effects of Water Pollution
Causes of Water Pollution

Past Posts

June 2007

Wednesday, 20 June 2007

Ways to Reduce Water Pollution

DON'T dump hazardous household products. Keep paints, used oil, cleaning solvents, polishes, pool chemicals, insecticides, and other hazardous household chemicals out of drains, sinks, and toilets. Many of these products contain harmful substances, such as sodium hypochlorite, petroleum distillates, phenol and cresol, ammonia and formaldehyde that can end up in Toronto's waterfront. The City of Toronto has a household hazardous waste (HHW) program that helps prevent toxic materials from entering our landfill sites and sewers.

DO use non-toxic household products. Discarding toxic products correctly is important, but not buying them in the first place is better. Ask local stores to carry non-toxic products if they don't already.

DO recycle and dispose of all trash properly. Never flush non-degradable products, such as disposable diapers, down the toilet. They can damage the sewage system and end up littering beaches and waters.

DO conserve water. Low-flow toilets and showerheads save you both water and money. Repair dripping faucets promptly because they can waste up to 20 gallons of water a day and a leaking toilet up to 200 gallons a day. You can also conserve water by sweeping your driveway and sidewalk instead of hosing them down.

DON'T over-water lawns and gardens. Use slow-watering techniques on lawns and gardens. Over-watering your lawn can increase the leaching of fertilizers into groundwater. Trickle or "drip" irrigation systems and soaker hoses are 20 per cent more efficient than sprinklers. It is also better to water your lawn in the early morning or late evening to prevent water evaporation due to the midday heat.

DO plant native plants in your gardens. Some ornamental plant species are not adapted to our local climate and may require extra water to maintain. Check with your local garden centre for native plant species that can act as ornamentals for gardens. They will not require any special care because they have already adapted to our climate.

DO use natural fertilizers. Apply natural fertilizers, such as compost, manure, bone meal or peat, whenever possible. Ask your local hardware and garden supply stores to stock these natural fertilizers. You can also buy a composter at a garden supply or hardware store, or by mail. Composting decreases the need for fertilizer and helps the soil retain moisture.

DO disconnect your downspouts. Disconnecting downspouts can redirect rain gutters and downspouts to soil, grass, or gravel areas instead of into the city's sewer system.

DO your landscaping with vegetation, gravel, or other porous materials instead of cement. Also, planting vegetation at lower elevations than nearby hard surfaces allows runoff to seep into soil.

DO use the garbage cans and recycling containers provided. Keeping Toronto's beaches free from garbage will go a long way to help keep our water clean. Garbage is the most visible sign of environmental pollution - it feeds pests such as rats and mice and spreads germs and diseases.

3:15 pm
I Love Chemistry

Tuesday, 19 June 2007

Causes of Water Pollution [Part 2]

Personal Care Products, Household Cleaning Products, and Pharmaceuticals

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.

Air Pollution

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.

Carbon Dioxide

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.


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.

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.

2:41 pm
I Love Chemistry

Monday, 18 June 2007

Causes of Water Pollution [Part 1]


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.

Fertilizers / Nutrient Pollution

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.

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, Gasoline and Additives

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.

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.


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.

Chemical and Industrial Processes

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.

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.

2:30 pm
I Love Chemistry

Friday, 15 June 2007

Effects of Water Pollution [Part 2]

Marine Debris

Marine debris is basically trash in the ocean. Trash fouls inland waterways too, for sure, but trash seems to be a particular problem in our seas.

The debris includes escaped inland trash and garbage thrown overboard by ships and boaters—plastic bottles and bags, six-pack rings, cigarette butts, Styrofoam, etc. Marine animals can swallow the trash items, which often look similar to prey they would normally eat, or the trash item may have barnacles or other delectables attached and is inadvertently ingested with the food. For instance, sea turtles will eat a plastic bag believing it to be a jellyfish. The bag can cause an intestinal blockage and sometimes death.

A new and potentially devastating effect of marine debris is emerging. After years of degradation at sea, plastic breaks up. The plastic has not biodegraded but rather has disintegrated into very small pieces. Marine animals near the bottom of the food chain are now ingesting these teeny-tiny little pieces of plastic pollution. How far up the food chain the stuff will go is unknown.

Discarded or lost fishing gear—line, rope, nets—and certain trash items can get wrapped around marine animals fins or flippers, causing drowning or amputation. Marine debris can also degrade coral reefs, sea grass beds, and other aquatic habitats.

Thermal Pollution

It's easy enough to see how discharging the heated-up water from a power plant into a river could cause problems for aquatic organisms used to having their water home stay at a fairly specific temperature. Indeed, industrial thermal pollution is a problem for our waterways—fish and other organisms adapted to a particular temperature range can be killed from thermal shock, and the extra heat may disrupt spawning or kill young fish.

Additionally, warmer water temperatures lower the dissolved oxygen content of the water. That's a double-whammy to aquatic organisms, since the warmer water also causes them to increase their respiration rates and consume oxygen faster. All this increases aquatic organisms' susceptibility to disease, parasites, and the effects of toxic chemicals.

Global warming is imparting extra heat to our oceans, which have absorbed about 20 times as much heat as the atmosphere over the past half-century. The ocean is a complex system, and scientists don't know yet what all of the effects of this type of "water pollution" will be, but here are some likely ones:
  • Sea levels will rise (because of thermal expansion and melting ice), increasing coastal flooding and inundation.
  • There will be more intense hurricanes as they gather additional strength from warmer surface waters.
  • Temperature-sensitive species like corals will see tougher times. The Pew Oceans Commission notes that an increase in the mean sea-surface temperature of only 2 degrees F could cause the global destruction of coral reef ecosystems.
  • Increasing sea-surface temperatures are associated with the northward spread of a oyster pathogen in the eastern US. Similar cases are highly likely.

Noise Pollution

"Noise pollution" from ship engines and sonar systems make it difficult for marine mammals like whales, dolphins, and porpoises to communicate, find food, and avoid hazards. Powerful sonar systems operating at certain frequencies have been implicated in whale beachings and may cause damage to marine mammals' sound-sensitive internal structures, causing internal bleeding and even death.

Frequent or chronic exposure to both high- and low-intensity sounds may cause stress on all higher forms of marine life, potentially affecting growth, reproduction, and ability to resist disease.

2:20 pm
I Love Chemistry

Thursday, 14 June 2007

What are the effects of water pollution?[Part 1]

Waterborne Infectious Diseases

Human infectious diseases are among the most serious effects of water pollution, especially in developing countries, where sanitation may be inadequate or non-existent. Waterborne diseases occur when parasites or other disease-causing microorganisms are transmitted via contaminated water, particularly water contaminated by pathogens originating from excreta. These include typhoid, intestinal parasites, and most of the enteric and diarrheal diseases caused by bacteria, parasites, and viruses. Among the most serious parasitic diseases are amoebiasis, giardiasis, ascariasis, and hookworm.

Developed countries are not immune to the problem of infectious waterborne diseases. In 1993, high cryptosporidium levels in Milwaukee's drinking water supply sickened more than 400,000 residents. That was an unusually extreme case, but transmission of disease agents such as bacteria and cysts via contaminated but poorly treated municipal water is more common than it should be. Every year, seven million Americans are sickened by contaminated water. This is only partly due to drinking water—contamination of recreational water (such as beach water) is also a problem.

Every year there are thousands of beach closings and outdated monitoring methods may in some cases leave beachgoers vulnerable to a range of illnesses. Polluted beach water can cause rashes, ear aches, pink eye, respiratory infections, hepatitis, encephalitis, gastroenteritis, diarrhea, vomiting, and stomach aches.

Nutrient Pollution

Nutrient pollution the most widespread, chronic environmental problem in the coastal ocean. The discharges of nitrogen, phosphorus, and other nutrients come from agriculture, waste disposal, coastal development, and fossil fuel use. Once nutrient pollution reaches the coastal zone, it stimulates harmful overgrowths of algae, which can have direct toxic effects and ultimately result in low-oxygen conditions.

Certain types of algae are toxic. Overgrowths of these algae result in "harmful algal blooms," which are more colloquially referred to as "red tides" or "brown tides." Zooplankton eat the toxic algae and begin passing the toxins up the food chain, affecting edibles like clams, and ultimately working their way up to seabirds, marine mammals, and humans. The result can be illness and sometimes death.

Developed countries have started monitoring for toxic algal blooms, closing fisheries as necessary. This has reduced the incidence of related human illness but has had the obvious economic cost of lost income for fishers and related businesses—and it does nothing the solve the problem for the marine life stuck in the middle of the brown tide.

Nutrient-pollution-driven blooms of non-toxic algae and seaweed can also cause problems by reducing water clarity, making it hard for marine animals to find food and blocking the sunlight needed by sea grasses, which serve as nurseries for many important fish species.

Finally, nutrient pollution can trigger unusual outbreaks of fish diseases. For instance, scientists have found that Pfiesteria, a tiny marine pathogen, can thrive in nutrient-polluted waters. In 1991, one million menhaden fish in North Carolina's Neuse River were killed in a Pfiesteria outbreak. In 1997, several tidal creeks in the Chesapeake Bay watershed experienced Pfiesteria outbreaks, and serious fish kills occurred. Nutrient pollution played a role in both cases.

Chemical Contamination

Over the years, many types of chemicals have gotten into our waterways—and they continue to do so today. Chemical water pollution typically occurs because :

  1. the chemicals were dumped into the water intentionally
  2. the chemicals seeped into groundwater, streams, or rivers because of failing pipes or storage tanks
  3. the chemicals catastrophically contaminated waterways because of industrial accidents
  4. the pollution settled out of polluted air (or was precipitated out of polluted air)
  5. chemicals were leached out of contaminated soil

1:55 pm
I Love Chemistry

Wednesday, 13 June 2007

What is domestic sewage?
Domestic sewage is water-carried wastes, in either solution or suspension, that flows away from a community. It is also known as wastewater flows, sewage is the used water supply of the community. It is more than 99.9% pure water and is characterized by its volume or rate of flow, its physical condition, its chemical constituents, and the bacteriological organisms that it contains. Depending on their origin, wastewaters can be classed as sanitary commercial, industrial, or surface runoff.

The spent water from residences and institutions, carrying body wastes, ablution water, food preparation wastes, laundry wastes, and other waste products of normal living, are classed as domestic or sanitary sewage. Liquid-carried wastes from stores and service establishments serving the immediate community, termed commercial wastes, are included in the sanitary or domestic sewage category if their characteristics are similar to household flows.

Wastewaters from this source may carry pathogenic organisms that can transmit disease to humans and other animals; contain organic matter that can cause odor and nuisance problems; hold nutrients that may cause eutrophication of receiving water bodies; and may contain hazardous or toxic materials. Proper collection and safe, nuisance-free disposal of the liquid wastes of a community are legally recognized as a necessity in an urbanized, industrialized society.

1:29 pm
I Love Chemistry