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Introduction to Water. Soil and Water. evaporation. Created by Dr. Michael Pidwirny, Department of Geography, Okanagan University College, BC, CA. What is Soil?. The interface between the atmosphere, hydrosphere, biosphere and lithosphere - PowerPoint PPT Presentation
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Introduction to Water
Created by Dr. Michael Pidwirny, Department of Geography, Okanagan University College, BC, CA
evaporation
Soil and Water
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
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
1050
Oxygen
Hydrogen Hydrogen Electro positive
Negative
Polarity
Symmetrical (e.g., CO2)
H-O : 0.97 A
H-H : 1.54 A
angstroms
H+
H+
O--= + -H2O
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
http://www.chem1.com/acad/sci/aboutwater.html
Dipolar nature of water due to unevenly distributed charges
O=
H+H+
Polymer type of grouping
Cations: Na+, K+, Ca2+ 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
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
http://courses.cm.utexas.edu/jrobertus/ch339k/overheads-1/water-structure.jpg
Does water swell and shrink with Temperature?
1
0.998
0.996
0.994
0.992
0.990
-10 0 10 20 30 40 50
De
nsi
ty (
g c
m-3)
Temperature (0C)
40C
www-ssrl.slac.stanford.edu/.../structure_ice.jpg
http://www.columbia.edu/cu/biology/courses/c2005/purves6/figure02-15a.jpg
Representation of Ice Melting
www.cscs.ch/.../representations/index.html
periodsgroups
Dimitri Mendeleev
Temperature range in liquid phase for H2x compounds
100
50
0
-50
-100
0 50Molecular Weight
Te
mp
era
ture
(0C
)
100
H2O
H2S
H2Se
H2Te
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
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
Soil Solution
aqueous liquid phase of the soil and its solutes
Hydrogen Bonding
Water is a powerful solvent
How salt dissolves in water
nutrition.jbpub.com/.../chemistryreview6.cfm
How do plants obtain the nutrients in the soil?
http://www2.mcdaniel.edu/Biology/botf99/nutrition/catex.jpg
www2.mcdaniel.edu/.../botf99/nutrition/soils.htm
Clay minerals as sources of ions
http://www.ca.uky.edu/agc/pubs/agr/agr11/fff00003.gif
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
SO4-2 60-300
Cl- 50-500
Solutes exist in solution as:
• Free hydrated ions
• Complexes with ligandsorganic or inorganic
(H2O, NH3+, F-, OH-, Cl-, CN- or
EDTA, citric acid, DTPA, NTA,…)
“Free” hydrated ions
http://www.freepatentsonline.com/7115549-0-large.jpg
Metal-ligand complexes
http://journals.iucr.org/e/issues/2006/11/00/ng2089/ng2089scheme1.gif
Ligand Exchange Mechanisms[ ML6 + Y- ML5Y + L- ]
www.meta-synthesis.com/.../mechanism.html