1. Introduction to Water

2. Created by Dr. Michael Pidwirny, Department of Geography, Okanagan University College, BC, CA evaporation Soil and Water

3. What is Soil? The interface between the atmosphere, hydrosphere, biosphere and lithosphere naturally occurring layers of mineral and organic constituents that differ from the underlying parent material in their physical, chemical, and mineralogical properties Rock

4. What is Water? A binary compound that occurs at room temperature as a clear colorless, odorless, tasteless liquid Freezes into ice below 0  C and boils above 100  C Necessary for life on earth (human, animals and plants) Constitutes 60-70 % of the human body www.atpm.com

5. 105 0 Oxygen Hydrogen Electro positive Negative Polarity Symmetrical (e.g., CO2) H-O : 0.97 A H-H : 1.54 A angstroms

6. H+H+ H+H+ O -- = + - H2OH2O Hydrogen bond Gives structural strength Bond depends on temperature: Bonds are weaker at higher temperature Positive end attraction with neg. end of other water molecules

7. http://www.chem1.com/acad/sci/aboutwater.html Dipolar nature of water due to unevenly distributed charges

8. O= H+H+ H+H+ Polymer type of grouping Cations: Na +, K +, Ca 2+ become hydrated through their attraction to the negative end of water (Oxygen side) Anions or negatively charged clay surfaces attract water through positive hydrogen side

9. J. L. Fulton, Y. Chen, S. M. Heald, and M. Balasubramanian, Rev. Sci. Instruments., 75(12), 5228-5231 (2004). http://www.pnl.gov/cmsd/highlights/images/20050727water.jpg

10. http://courses.cm.utexas.edu/jrobertus/ch339k/overheads-1/water-structure.jpg

11. Does water swell and shrink with Temperature? 1 0.998 0.996 0.994 0.992 0.990 -100 10 20 304050 Density (g cm -3 ) Temperature ( 0 C) 40C40C

12. www-ssrl.slac.stanford.edu/.../structure_ice.jpg http://www.columbia.edu/cu/biology/courses/c2005/ purves6/figure02-15a.jpg

13. Representation of Ice Melting www.cscs.ch/.../representations/index.html

14. periods groups Dimitri Mendeleev

15. Temperature range in liquid phase for H 2 x compounds 100 50 0 -50 -100 050 Molecular Weight Temperature ( 0 C) 100 H2OH2O H2SH2S H 2 Se H 2 Te Boiling point Freezing point Hydrogen sulfide Hydrogen selenide Hydrogen telluride (2+16=18) (2+32=34) (80) (130) The sum of the atomic weights of all atoms in a molecule

16. If water were an ordinary compound whose molecules are subject to weak forces, its boiling and freezing points would fall below hydrogen sulfide Strong hydrogen bonding between water molecules prevents this so that liquid water acts more like a gel, cluster, or polymer Water occurs in all three states (solid, liquid, and gaseous) at prevailing temperatures on the earth’s surface Example: Ice cubes in a glass at room temperature

18. Soil Solution aqueous liquid phase of the soil and its solutes

19. Hydrogen Bonding

20. Water is a powerful solvent How salt dissolves in water nutrition.jbpub.com/.../chemistryreview6.cfm

22. How do plants obtain the nutrients in the soil? http://www2.mcdaniel.edu/Biology/botf99/nutrition/catex.jpg

23. www2.mcdaniel.edu/.../botf99/nutrition/soils.htm

24. Clay minerals as sources of ions http://www.ca.uky.edu/agc/pubs/agr/agr11/fff00003.gif

25. Typical ion concentrations (can be much higher in arid regions due to high evapotranspiration (ET) and concentrating effects) K + 1-10 (mg/L) Na + 1-5 Ca +2 20-200 Mg +2 2-50 Si +4 10-50 SO 4 -2 60-300 Cl - 50-500

26. Solutes exist in solution as: Free hydrated ions Complexes with ligands organic or inorganic (H 2 O, NH 3 +, F -, OH -, Cl -, CN - or EDTA, citric acid, DTPA, NTA,…)

27. “Free” hydrated ions

28. http://www.freepatentsonline.com/7115549-0-large.jpg Metal-ligand complexes http://journals.iucr.org/e/issues/2006/11/00/ng2089/ng2089scheme1.gif

29. Ligand Exchange Mechanisms [ ML 6 + Y -  ML 5 Y + L - ] www.meta-synthesis.com/.../mechanism.html