Properties and behavior of H 2 0 1: The specifics

1. Properties and behavior of H20 1: The specifics • Lecture goal: • To identify and describe the properties of water that are most important to understanding broader patterns of habitat structure and ecology in freshwater systems.

2. Molecular Structure • Density • Temperature • Oxygen • Light Properties and behavior of H20 1: The specifics

3. Molecular Structure • Density • Temperature • Oxygen • Light The Specifics

4. Structure of H2O • Polarity • Solvent properties

6. Surface Tension

7. Surface Tension

8. Molecular Structure • Density • Temperature • Oxygen • Light The Specifics

9. Temperature and Water Density

10. Anchor Ice

11. Density increases with depth. • Influenced by atmospheric pressure and other factors. Depth and Water Density

12. Density (g / ml) • Freezing point of sea water (35 g/L) = -2ºC • Max density of sea water = -2ºC • Salinity of “Freshwater” ranges from 0.01 – 1.0 g/L • Saline lake  60 g/L Salinity and Water Density

13. Molecular Structure • Density • Temperature • Oxygen • Light The Specifics

14. Temperature and Water Density

15. Specific Heat of Water • Specific heat: amount of heat in calories required to raise a unit (i.e., a gram) of the substance by 1C. • Specific heat of water = 1 • Latent heat of fusion = 80 • Latent heat of vaporization = 540

16. Measuring Water Temperature • Standard / immediate temperature • Seasonal max, min, mean • Degree days

17. Molecular Structure • Density • Temperature • Oxygen • Light The Specifics

18. How oxygen gets into water

19. How oxygen gets into water…or not

20. Pressure and O2 Solubility

21. Temperature and O2 Solubility Oxygen Solubility (mg / L)

22. Salinity and O2 Solubility

23. Saturation or Equilibrium Concentration • Amount of DO that can be held by water in equilibrium with the atmosphere at a particular temperature, pressure, and salinity. • Supersaturation • Anoxia • Hypoxia Oxygen Terminology

24. Molecular Structure • Density • Temperature • Oxygen • Light The Specifics

25. Light is energy, capable of work and being transformed from one form to another. • Radiant energy of light transformed to potential energy by biochemical reactions (e.g., photosynthesis). • Light provides the majority of energy input to aquatic systems – but getting light INTO aquatic systems is tough. Why is light important in aquatic systems?

26. Wavelength Frequency More Blue More Red

27. How do plants receive light energy? • Quanta or photons at specific frequencies

28. Controls on light input: season and latitude

29. Controls on light input: direct solar radiation

30. Other controls on direct solar radiation • Time of day • Altitude • Meteorological conditions • Topography

31. Controls on light input: indirect solar radiation

32. Controls on indirect solar radiation • Scattering through atmosphere • Solar height

33. Controls on light input: reflectivity

34. Controls on reflectivity • Angle of incidence • Surrounding topography • Surface conditions of water

35. Albedo • Ratio of reflected to incident irradiance • Increases with reflection at surface and scattering within the lake.

36. Albedo

37. Light scattering within lakes

38. Density (g / ml) Anthropogenic Salinization Effect of Salinity on Density and O2 Solubility