120209-Th-Water-Seawater.R

120209-Th-Water-Seawater.R - 2/12/12 WATER MOLECULE! VERY...

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Unformatted text preview: 2/12/12 WATER MOLECULE! VERY STABLE MOLECULE Text covalent bonds What happens when "HEAT" (calories) is added to water water warms water molecules move faster (vibrate, cohesion: water molecules stick to other water molecules by hydrogen bonding What happens when "HEAT" (calories) is added to water water warms water molecules move faster (vibrate, What happens when "HEAT" (calories) is added to water water warms water molecules move faster (vibrate, rotate, 1 2/12/12 What happens when "HEAT" (calories) is added to water water warms water molecules move faster (vibrate, rotate, What happens when "HEAT" (calories) is added to water water warms water molecules move faster (vibrate, rotate, translate ) What happens when "HEAT" (calories) is added to water water warms water molecules move faster (vibrate, rotate, translate ) What happens when "HEAT" (calories) is added to water T EA E H sed L vibration, rotation, translation is IB sebonding of resisted by the hydrogen n S water. N E S n be It takes a lot of added heat to raise the ca temperature of water 1 cal / 1 deg for each gram Heat Capacity is a measure of the heat required to raise the temperature of 1g of a substance by 1C. 2 2/12/12 Water molecules with greater energy are more likely to "escape" the H bonds Evaporation removes energetic molecules. Evaporation is a cooling process. http://ed101.bu.edu/StudentDoc/current/ED101fa10/vebado/Content_1.html http://ed101.bu.edu/StudentDoc/current/ED101fa10/vebado/Content_1.html For water to evaporate, heat must be added to water in the liquid state. After water reaches 100C, an input of 540 cal/gram is required to break the hydrogen bonds and allow evaporation. The amount of energy required to break the bonds is termed the latent heat of vaporization. Water has the highest latent heat of vaporization of any known substance. 3 2/12/12 End Tuesday 2012-February 7 Temperature of water affects how water molecules stick to each other The relationship of density to temperature for pure water. Why is seawater salty? Water and Dissolved Salt Water evaporates - no dissolved salt - salts accumulate 4 2/12/12 Why is seawater salty? 1. Rivers carry minute amounts of dissolved "salts" to the ocean. 2. Evaporation removes water (but not salts) from the ocean. 3. Salt content increases in ocean. 2 -4 4 ) If river salt accumulates in ocean - we expect the ocean salts to have this relative composition -4 4 ) -4 4 ) 2 2 Big decreases in some ions -4 4 ) -4 4 ) s ot N 2 im e pl ac m cu u lat ion Big INCREASES in some ions 2 5 2/12/12 -4 4 ) calcite formation skeletons of forams and coccolithss 2 COCCOLITH (calcite - CaCO3) COCCOLITH (calcite - CaCO3) Coccolith plates in sediment FORAMS Calcite (CaCO3 ) planktonic CaCO3 extracted from seawater skeletons to sediment 6 2/12/12 -4 4 ) "opal" formation skeletons of diatoms and radiolarians 2 diatoms have shells made of SiO2 radiolarians have shells made of SiO2 skeletons to sediment -4 4 ) 2 7 2/12/12 Other processes affecting the chemistry of oceans Hydro-thermal "percolation" Water-Rock chemical interactions Garrison, 2008 Fig. 4-19, p. 91 Trujillo and Thurman, 2010 Garrison, 2008 Fig. 4-19, p. 91 -4 4 ) Major elements in seawater Is the ocean getting more and more salty?! 2 8 2/12/12 Is the ocean getting more and more salty?! NO Trujillo and Thurman, 2010 Subduction removes deep-sea sediment (recycles the chemical ingredients of sediments) Evaporation in isolated basins removes some "salt" STEADY STATE" input # output! Residence Time of Salts (elements) in the Ocean! 9 2/12/12 amount rate e.g. grams grams/year = years Residence Time millions of years Residence Time millions of years Residence Time millions of years 10 2/12/12 How do we know about the salt content of the oceans? What else do we know? Weigh Evaporate all the water Weigh 1. weigh 1 kg of seawater 2. evaporate water completely 3. weigh residual salt = grams salt per kg seawater = grams salt per 1000 grams seawater = Salinity Salinity salt remaining after evaporation of 1 kg (1000 grams) ! 35 grams Trujillo and Thurman,2010 salt remaining after evaporation of 1 kg (1000 grams) ! 35 grams "salinity" = 35 (parts per thousand) Salinity 96.5% Salinity salt remaining after evaporation of 1 kg (1000 grams) ! 35 grams "salinity" = 35 (parts per thousand) "salt content" 3.5 % Water 96.5 % 11 2/12/12 mostly around 35 Amazon River freshwater input http://www.esa.int/images/ Amazon2010_07_1415161718.jpg VARIABILITY nearshore different oceans Challenger Expedition http://marineodyssey.co.uk/abioticoceans.html http://oceanworld.tamu.edu/resources/ocng_textbook/chapter02/Images/Fig2-1.html! Atlantic Ocean is saltier than the Pacific Ocean What else do we know? Trujillo and Thurman,2010 Weigh Evaporate Weigh 1. weigh 1 kg of seawater 2. evaporate water completely 3. weigh residual salt = grams salt per kg seawater = grams salt per 1000 grams seawater = observation # 2 by researcher B observation # 1 by researcher A Then analyze salts 12 2/12/12 observation # 2 by researcher B observation # 1 by researcher A observation # 2 by researcher B observation # 1 by researcher A Is there a relationship between Cl- and salinity?! Divide the total grams of salt (salinity) by the grams of Cl. ! observation # 2 by researcher B observation # 1 by researcher A observation # 2 by researcher B observation # 1 by researcher A 9.03 / 5 = 1.8060! 9.03 / 5 = 1.8060! 18.07 / 10 = 1.8070! observation # 2 by researcher B observation # 1 by researcher A observation # 2 by researcher B observation # 1 by researcher A 9.03 / 5 = 1.8060! 18.07 / 10 = 1.8070! 27.10 / 15 = 1.8067! 9.03 / 5 = 1.8060! 18.07 / 10 = 1.8070! 27.10 / 15 = 1.8067! 36.13 / 20 = 1.8065! 13 2/12/12 observation # 2 by researcher B observation # 1 by researcher A observation # 2 by researcher B observation # 1 by researcher A 9.03 / 5 = 1.8060! 18.07 / 10 = 1.8070! 27.10 / 15 = 1.8067! 36.13 / 20 = 1.8065! 45.16 / 25 = 1.8064! 9.03 / 5 = 1.8060! 18.07 / 10 = 1.8070! 27.10 / 15 = 1.8067! 36.13 / 20 = 1.8065! 45.16 / 25 = 1.8064! observation # 2 by researcher B observation # 1 by researcher A Constancy of Composition x x x x x 1.8 1.8 1.8 1.8 1.8 =! =! =! =! =! "Relative" Concentrations Cl -! 1.8065 = salinity! x 14 ...
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