Seawater Chemistry 10/5/2010. Unique Properties of Fresh Water CHAPTER 5

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1 Seawater Chemistry Chapter 5: Unique properties of fresh water Origin of Seawater??? Chapter 6: The 6 major constituents, trace elements Salinity, normal, hypersaline, brackish Changes in surface salinity Sources of salts.. Compare to river water How salts removed? The Principle of Constant Proportions Conservative and Nonconservative Constituents Residence Time Determining Salinity Desalination Unique Properties of Fresh Water CHAPTER 5 H2O IMPORTANCE / PERCENTAGES (Hydro Cycle)/ AVAILABILITY UNIQUE PROPERTIES: See Table on Page 126 Only substance that occurs naturally in all 3 states within temp range at earth s surface. Polar compound, hydrogen bonds Ability to change its state (solid, liquid gas) Maximum Density is at 4 degrees Celsius, thermal expansion and contraction, lakes freeze from top down, not bottom up Water has High Heat Capacity, changes temp slowly, latent heat of vaporization and fusion, moderates earth s climate, excellent coolant Water is less dense in the solid state Adhesion, Cohesion & Surface Tension Surface Tension (droplets, bubbles, capillary waves) and Viscosity Dissolving ability (universal solvent) Incompressibility 1

2 Figure 4.1 Molecule: the smallest particle of a substance that retains the chemical and physical properties of the substance and is composed of two or more atoms held together by chemical bonds. Unique Properties of Fresh Water CHAPTER 5 H2O IMPORTANCE / PERCENTAGES (Hydro Cycle)/ AVAILABILITY Table 5.4 UNIQUE PROPERTIES: See Table on Page 126 Only substance that occurs naturally in all 3 states within temp range at earth s surface. Polar compound, hydrogen bonds Ability to change its state (solid, liquid gas) Maximum Density is at 4 degrees Celsius, thermal expansion and contraction, lakes freeze from top down, not bottom up Water has High Heat Capacity, changes temp slowly, latent heat of vaporization and fusion, moderates earth s climate, excellent coolant Water is less dense in the solid state Adhesion, Cohesion & Surface Tension Surface Tension (droplets, bubbles, capillary waves) and Viscosity Dissolving ability (universal solvent) Incompressibility Specific Heat: the quantity of heat required to produce a unit change of temperature in a unit mass of that material, typically 1 gram of that material. Heat Capacity: depends on the specific heat and the mass, ie HC of 1Kg of water is 1,000 calories/c and HC of 1 Kg of shale is 390 calories/c 2

3 Figure 6.24 Wood has high heat capacity Latent heat of Vaporization: the amount of heat required to change the state of 1 gram of water from liquid to gas without changing temperature. The latent heat of evaporation is 585 cal/gram at 20 degree C. Latent heat of Fusion (melting): the amount of heat required to change the state of 1 gram of water from ice to liquid without changing temperature. Latent means hidden or stored. Unique Properties of Fresh Water CHAPTER 5 H2O IMPORTANCE / PERCENTAGES (Hydro Cycle)/ AVAILABILITY Fig. 5.8 UNIQUE PROPERTIES: See Table on Page 126 Only substance that occurs naturally in all 3 states within temp range at earth s surface. Polar compound, hydrogen bonds Ability to change its state (solid, liquid gas) Maximum Density is at 4 degrees Celsius, thermal expansion and contraction, lakes freeze from top down, not bottom up Water has High Heat Capacity, changes temp slowly, latent heat of vaporization and fusion, moderates earth s climate, excellent coolant Water is less dense in the solid state Adhesion, Cohesion & Surface Tension (droplets, bubbles, capillary waves) and Viscosity Dissolving ability (universal solvent) Incompressibility 3

4 Attenuation: the decrease in the intensity of light over distance. Rate of light attenuation also depends on the wavelength Table 05_01 Table 05_01 Seawater Chemistry Chapter 5: Unique properties of fresh water Origin of Seawater??? Chapter 6: The 6 major constituents, trace elements Salinity, normal, hypersaline, brackish Changes in surface salinity Sources of salts.. Compare to river water How salts removed? The Principle of Constant Proportions Conservative and Nonconservative Constituents Residence Time Determining Salinity Desalination 4

5 O C E A N 10 Fall 2010 Agenda QUIZ #3: is next week in lab (Nautical Charts only) We ll also start Lab #4, SFS etc QUIZ #4: WEEK OF 10/19 (Cont Drift, SFS, P. Tectonics and Marine Sediments! Wow. Tectonic Map with Earthquake Plots due week of 10/19. MIDTERM (Tuesday 10/26) Bring a scantron form 882, pencil, simple calculator. Other electronic devices NOT permitted including ALL cell phones / ipods / GPS wrist watches etc.. The Origin of Seawater??? Juvenile Water? Comets? Old Water, Young Containers Decreasing Rate Theory Kuiper Belt, shown in green, Units are AU s (Astronomical Units) 5

6 Seawater Chemistry Chapter 5: Unique properties of fresh water Origin of Seawater??? Chapter 6: The 6 major constituents, trace elements Salinity, normal, hypersaline, brackish Changes in surface salinity Sources of salts.. Compare to river water How salts removed? The Principle of Constant Proportions Conservative and Nonconservative Constituents Residence Time Determining Salinity Desalination Major Constituents of Seawater & Salinity Trace Elements Hypersaline Bodies of water Salton Sea ~ 40 ppt (once 44 ppt) Mono Lake Salinity ~ 80 ppt Great Salt Lake Salinity ~ ppt Dead Sea ~ ppt 6

7 The Dead Sea Seawater Chemistry Chapter 5: Unique properties of fresh water Origin of Seawater??? Chapter 6: The 6 major constituents, trace elements Salinity, normal, hypersaline, brackish Changes in surface salinity Sources of salts.. Compare to river water How salts removed? The Principle of Constant Proportions Conservative and Nonconservative Constituents Residence Time Determining Salinity Desalination Surface Salinity Distribution Surface Salinity Distribution Sources of Salts? Sources of Salts? 7

8 Major Constituents of Seawater & Salinity Major Constituents of Seawater How Salts Added / Removed? How Salts Removed? Seawater Chemistry Chapter 5: Unique properties of fresh water Origin of Seawater??? Chapter 6: The 6 major constituents, trace elements Salinity, normal, hypersaline, brackish Changes in surface salinity Sources of salts.. Compare to river water How salts removed? The Principle of Constant Proportions Conservative and Nonconservative Constituents Residence Time Determining Salinity Desalination 8

9 Major Constituents of Seawater Figure 5.7 Determining Salinity Refractometer Hydrometer 9

10 Figure 5.5 Salinometer Desalination: converting salt water to freshwater Techniques: Reverse Osmosis (shown below) There are ~11,100 desalination plants in 120 countries. This meets less than 0.15% of world s water needs. This would have to increase ~33 fold just to supply 5% of current water use. Where used: Middle East, Israel, Kuwait, Saudi Arabia Florida, California North Africa; Algeria Major Limitations: Expensive; it takes large amounts of Energy. Produces lots of waste water with high level of salt and other minerals. There are over 13,000 desalination plants Worldwide that produce more than 12 billion gallons of water/day. Largest in US is in Tampa Bay Florida, 25 million gal/day Water shortage in Algeria was eased in February 2008 as the $250 million Hamma Seawater Desalination Plant (SWDP) was officially opened. The Hamma SWDP purifies up to 200,000 cubic meters (53 million gallons) of seawater per day enough for 25 percent of the city s daily needs. Figure 5.10 Figure