Chemistry Reference
In-Depth Information
Connections
Organisms that live in the water, such as fish and aquatic invertebrates,
depend on oxygen gas dissolved in water. Animals and many other
organisms require oxygen for
cellular respiration
, a biochemical process
that converts the energy in glucose to adenosine triphosphate (ATP).
Oxygen enters waterways through
photosynthesis
or
aeration
. Generally,
plants and algae within aquatic ecosystems produce enough oxygen
through photosynthesis to maintain high concentrations of the gas. Fast-
moving waterways also incorporate oxygen when the water flows over
rocks and other rough surfaces, mixing atmospheric oxygen with the water.
Pollution is one of the primary causes of low oxygen in waterways. When
pollutants run into rivers, streams, and lakes, the amount of dissolved
oxygen is decreased in a process known as
eutrophication
. The worst
pollutants are those that carry high levels of nutrients, such as agricultural
runoff, sewage, animal waste, and industrial wastes. The excess nutrients
support the growth of algae. When the algae die, they are consumed by
fast-growing populations of bacteria that use up the oxygen in the water.
Loss of oxygen due to eutrophication can lead to massive death of fish
and other aquatic animals that need the dissolved oxygen to survive.
Want to Know More?
See appendix for Our Findings.
Further Reading
Aus-e-tute. “Percent Composition.” Available online. URL: http://www.
ausetute.com.au/percentc.html. Accessed July 17, 2010. This Web
site explains how to find percent compositions and provides sample
calculations.
Bellis, Mary. “Introduction to Pop: The History of Soft Drinks,” 2010.
About.com. Available online. URL: http://inventors.about.com/od/
foodrelatedinventions/a/soft_drinks.htm. Accessed July 17, 2010. Bellis
explains the formulas and marketing of early carbonated beverages in this
article.
The Human Touch of Chemistry: Famous Scientists. “Joseph Priestley.”
Available online. URL: http://www.humantouchofchemistry.com/node/39.
Accessed July 17, 2010. This brief biography describes Priestley's
scientific work including research into oxygen gas and the mechanism of
photosynthesis.
