Oxygen5

** Oxygen What is the Winkler Method?**
The Winkler Method is a technique used to measure dissolved oxygen in freshwater systems. Dissolved oxygen is used as an indicator of the health of a water body, where higher dissolved oxygen concentrations are correlated with high productivity and little pollution. This test is performed on-site, as delays between sample collection and testing may result in an alteration in oxygen content.



In some rivers the oxygen levels are so low that it can not sustain life.



Water temperature and the volume of water moving down a river (discharge) affect dissolved oxygen levels. Gases, like oxygen, dissolve more easily in cooler water than in warmer water. River discharge is related to the climate of an area. During dry periods, flow may be severely reduced and air and water temperatures are often higher. Both of these factors tend to reduce dissolved oxygen levels. Wet weather, melting snows, and downstream of a dam spillway can increase flow, resulting in higher saturation levels of oxygen.

Depletions in dissolved oxygen can cause major shifts in the diversity of aquatic organisms found in water bodies. Species that cannot tolerate low levels of dissolved oxygen - mayfly nymphs, stonefly nymphs, caddisfly larvae and beetle larvae - will be replaced by a few kinds of pollution-tolerant organisms, such as worms, blood midges and fly larvae.



[] [|http://serc.carleton.edu/micro belife/research_methods/environ_sampling/oxygen.html]

** Carbon Dioxide Carbon Dioxide comes from either the earths atmosphere (the air that comes in contact with water) or the organism that live in the water. Photosynthesis helps regulate the amount of carbon dioxide in streams, because organisms absorb carbonate minerals from water. Humans have affected the amount of carbon dioxide in water by burning fossil fuels which adds more carbon dioxide to the air so there is more in the water.

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