Environmental History

APES Ch 19 Outline: Water Pollution
A. Water is polluted by infectious bacteria, inorganic & organic chemicals, & excess heat.
1. Water pollution is any chem., boil., or phys. change in water quality that has a harmful effect on living organisms.
3. The WHO estimates that 3.4 million people die prematurely each year from waterborne diseases.
4. In the U.S., an estimated 1.5 million people a year become ill from infectious agents.
B. Scientists monitor water quality by using bacterial counts, chemical analysis, & indicator organisms.
1. One method of measuring water quality involves measuring the number of colonies of fecal coliform bacteria
present in a water sample.
2. Drinking water should not contain any colonies/100 milliliters, & safe swimming water should not have more
than 200 colonies/100 milliliters.
3. A new field of science called bacterial source tracking (BST) uses molecular biology techniques to determine
subtle differences in strains of E. coli based on their animal host.
4. Scientists measure biological oxygen demand (BOD), the amount of dissolved oxygen consumed by aquatic
decomposers.
5. Chem. analysis includes checking inorganic & organic chemicals present, sediment content, & turbidity of water.
6. Indictor species are living organisms that are monitored to determine levels of pollution.
7. Genetic techniques are being used to develop organisms that will glow in the presence of specific pollutants such
as toxic heavy metals in the ocean & carcinogens in food.
C. Water pollution can come from a single source or from a variety of dispersed sources.
1. Point sources discharge pollutants at specific locations through drainpipes, ditches, or sewer lines into bodies of
surface water.
2. These sources are easy to identify, monitor, & regulate.
3. Non-point sources are scattered & diffuse & can’t be traced to any single site of discharge. Such things as runoff
from croplands, livestock...