POLLUTION - WATER QUALITY REVIEW SHEET A] INTRODUCTION

• How pollutants enter the water supply
  • point source pollution - pollution that can be traced back to a particular source (e.g. a factory releasing chemicals into a stream)
    • relatively easy to control legislatively
  • non-point source pollution - pollution that is released in small amounts from many sources
    • spread through runoff
    • biggest threat to United States water supplies
    • control usually means that many people have to change their behavior

B] WATERSHED

• Watershed - all the land area that drains into a given body of water (e.g. stream, lake, creek)
  • usually named after the body of water that it drains into
• 4 major groups of pollutants:
  • Microbial (biological) pollutants - microorganisms that live in untreated water and can cause disease in people who drink them
    • examples: typhoid fever, dysentery, cholera, giardia, etc.
    • usual source - untreated human sewage (feces)
    • usual test involves looking for coliform bacteria as an indicator of fecal contamination
  • Organic chemical pollutants -
    • pesticides and herbicides are examples of man-made organic compounds
    • oil and petroleum would also fall into this category
  • Inorganic pollutants
    • usually salts and metal ions
    • examples include chlorine, copper, fluoride, lead
    • common non-point source pollutants like nitrate nitrogen and phosphorus would be classified here
  • Radioactive pollutants
    • may leach into the water from rocks or soils containing radioactive materials
    • may be the result of runoff from mining activities

C] ORGANIC POLLUTANT EXERCISE

• Oil and water do not mix (oil is hydrophobic)
• Oil floats on the surface of water - creates a barrier between the water and the air
  • stops the movement of oxygen from the atmosphere into the water
  • allows heat to pass into the water but does not let the heat escape, thereby causing the water to heat up faster than normal

D] PESTICIDES

• Insecticides - chemical pesticides used to kill insects and their relatives
• Herbicides - chemical pesticides used to kill weeds
• Commonly used by farmers and golf courses, but also by individual homeowners
• It is very important to carefully read the label of any pesticide and only use that pesticide as directed.  These chemicals are dangerous poisons if used incorrectly!

E] FERTILIZERS

• Chemical fertilizers typically contain 3 major ingredients: Nitrate Nitrogen, Phosphorus, and Potassium
• The 3 numbers on the label refer to these 3 major ingredients
• Too much fertilizer will kill the plants (be sure to follow instructions on the label!)

F] BIOLOGICAL CONTAMINANTS: ALGAE BLOOMS

• Algae bloom - an expolsive growth of algae on surface water
• usually caused by fertilizers (chemical fertilizers or animal feces) entering the water
• usually the result of nonpoint pollution
• can kill organisms in the water by lowering the supply of oxygen in the water - eutrophication
• Most algae do not cause illness in humans
  • one common exception is Microcystis which produces a toxin that can cause rashes or nausea in sensitive individuals
  • algaecides - chemicals used to kill algae (usually for aesthetic reasons)
  • disinfectants - chemicals added to drinking water to kill algae and other microorganisms that may be detrimental to human health (e.g. chlorine in tap water)
• Certain species of algae are typical of "healthy" water and others are typical of polluted water - these characteristic species are called indicator species
• Phytoplankton - microscopic algae and plants in water
• Zooplankton - microscopic animals and animal-like protists in water

G] BIOLOGICAL CONTAMINANTS: WATERBORNE PATHOGENS

• Pathogenic - disease causing
• Coliform bacteria - bacteria associated with feces (normally found in digestive system)

H] pH

• pH - the relative acidity of water
• pH scale goes from 0-14, with 7 in the middle representing a neutral pH (the pH of pure, distilled water)
• pHs below 7 are considered to be acidic (the lower the pH, the more acidic the solution is)
• pHs above 7 are considered to be basic (the higher the pH, the more basic, or alkaline, the solution is)
• the pH of ground and surface water is kept near neutral, to slightly basic, in this area due to reactions with carbonate in local rock and soil
• the pH of rain water (and snow) is slightly acidic due to a reaction with carbon dioxide in the air (causing the formation of carbonic acid)
• even lower pHs are caused as sulfur dioxide from coal burining factories and power plants mixes with water vapor to form sulfuric acid
• in other cases, lower pHs are caused when nitrous oxides from automobile exhaust mixes with water vapor to form nitric acid
• rain with low pH caused by either of these two situations is called acid rain

I] CHLORINE

• Chlorine - a chemical that is often added to drinking water to kill microorganisms in the water
• Carcinogenic - cancer causing
•  Chlorine containing compounds are known to be of risk (generally low risk) of causing cancer.  They are added to the water supply because the benefit of killing microorganisms is thought to outweigh the risk of causing cancer in a limited number of individuals who drink the water
• Cisterns - a common local water supply that relies on collection and purification of rain water (it relies on living things to purify the water, a biological purification process)

J] COPPER

• Sources of copper
  • copper salts are used to control the growth of algae
  • corrosion of copper pipes brings copper through the plumbing system
• High concentrations of copper can result in nausea and vomiting and, long term, can damage the liver and kidneys

K] NITRATE AND PHOSPHORUS

• Nitrate concentration in surface water is affected by contamination from fertilizers, sewage, or manure
  • High levels can lead to algae blooms and eutrophication
  • drinking nitrate contaminated water can lead to a reduction in the oxygen carrying ability of red blood cells
  • Most contamination results from non-point sources
• Phosphorus occurs as a group of chemicals known as phosphates
  • Found in laundry and dishwashing soaps and as a major ingredient in chemical fertilizers
  • Can cause eutrophication
  • Is usually found in association with nitrate pollution