Explain the roles that pressure p : The force exerted per unit area. Explain the physical basis for oxygen supersaturation and how it is related to photosynthesis. Keywords gas solubility: The ability of a gas to dissolve into another substance.
Curriculum Connections Biology - abiotic: Not alive; non-biological; for example, temperature and mixing are abiotic factors that influence the O 2 content of lake water whereas photosynthesis and respiration are biotic factors that affect O 2 solubility. WOW Curriculum Links Thermal stratification; oxygen; aquatic respiration: Refers to the use of oxygen in an aquatic system including the decomposition of organic matter and the use of oxygen by fish, algae, zooplankton, aquatic macrophytes, and microorganisms for metabolism.
Procedure Work through the following discussions with the students. This could be offered as a demonstration and lecture using computerized projections, or with students in a computer lab while stopping periodically for discussions. Discuss how oxygen dissolves and review the animation , Shockwave plug-in required.
Notes : Water, as a polar molecule: A molecule in which one structural end an atom or atoms possesses a slight negative charge and another structural end possesses a slight positive charge but the charges do not cancel one another out but rather create two separate poles.
In animation, observe a polar water molecule approaching a nonpolar O 2 molecule. The electron cloud of O 2 is normally distributed symmetrically between the bonded O 2 atoms. As the negative end of the H 2 O molecule approaches the oxygen molecule, the electron cloud of the O 2 moves away to reduce the negative-to-negative repulsion. As a result, a dipole a molecule with positive and negative charges separated by a distance has been induced in the nonpolar O 2 molecule, causing O 2 and H 2 O to become weakly attracted to each other.
This intermolecular attraction between the oppositely charged poles of nearby molecules is termed a dipole- induced dipole forces: Very weak forces between a dipole and non-polar molecule that acts like a dipole in the presence of a dipole molecule.
The creation of these forces then explains the mechanism by which gases dissolve in water. Notes : Because dipole-induced dipole forces are very weak, the quantity of nonpolar gases such as O 2 that will dissolve in a given volume of water is strongly affected by temperature and pressure. Henry's Law describes the effect of pressure on the solubility of a gas in a liquid.
When gas under pressure contacts a liquid, the pressure tends to force gas molecules into solution. At a given pressure the number of gas molecules that will enter into solution rises until equilibrium is reached. Gills work better when there is more oxygen in the surrounding water. As dissolved oxygen levels decrease, it becomes harder for animals to get the oxygen they need to survive. However, the amount of oxygen an animal needs varies depending on how large or complex the animal is and where it lives.
Anoxic, or no-oxygen, areas are regions with less than 0. Areas in the Bay that have low dissolved oxygen levels are the result of a complex interaction of several natural and man-made factors, including temperature, nutrient pollution , water flows and the shape of the Bay's bottom.
Temperature limits the amount of oxygen that can dissolve in water: water can hold more oxygen during winter than during the hot summer months.
Water Properties Information by Topic Learn more. Water Quality Information by Topic Learn more. Science Center Objects Overview Related Science Publications Multimedia Dissolved oxygen DO is a measure of how much oxygen is dissolved in the water - the amount of oxygen available to living aquatic organisms.
Multi-parameter monitor used to record water-quality measurements. Learn more about dissolved oxygen and related water topics. Date published: October 22, Filter Total Items: 8. Year Select Year Apply Filter. Date published: June 28, Note: This section of the Water Science Date published: June 6, Attribution: Water Resources.
Date published: November 15, Contacts: Jon Hortness. Date published: July 13, Date published: March 10, Contacts: Jeffrey Frey. Below are publications associated with dissolved oxygen and water. Year Published: Chapter A6. Section 6.
Dissolved oxygen Accurate data for the concentration of dissolved oxygen in surface and ground waters are essential for documenting changes in environmental water resources that result from natural phenomena and human activities. Rounds, Stewart A. View Citation. Rounds, S. Filter Total Items: 1.
Year Published: Gulf of Mexico dead zone - the last years 'Gulf of Mexico Dead Zone-The Last Years' discusses the dead zone that forms seasonally in the northern Gulf of Mexico when subsurface waters become depleted in dissolved oxygen and cannot support most life.
Osterman, Lisa; Swarzenski, P. Virgin Islands , Region 4: Mississippi Basin. Below are multimedia items associated with dissolved oxygen and related water topics. Filter Total Items: 5. List Grid. This can lead to decreased levels of biologically available oxygen, in some cases leading to fish kills and death to other aquatic organisms. Florida's surface water quality standards include minimum values for dissolved oxygen saturation. The standards for freshwater vary in different bioregions of the state:.
Dissolved oxygen standards for marine water bodies are expressed as minimums for daily, weekly, and monthly averages. Detailed water quality standards for dissolved oxygen can be found in Chapter DO can be expressed as a concentration per unit volume, or as a percentage. In aquatic environments, oxygen saturation is a ratio of the concentration of dissolved oxygen O 2 , to the maximum amount of oxygen that will dissolve in that water body, at the temperature and pressure which constitute stable equilibrium conditions.
Oxygen enters water through several methods, including diffusion from the atmosphere, rapid movement of water waves, e. Dissolved oxygen is routinely recorded as part of basic water quality sampling in most surface waters and near-shore coastal systems.
There are three common methods for measuring DO. The most practical and consistently accurate method for field measurements employs the polarographic DO sensor. If calibrated correctly, this method provides accurate measurements that can be performed in-situ i.
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