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Phase Diagram for Water. Hydrogen Bonding in Water.

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Presentation on theme: "Phase Diagram for Water. Hydrogen Bonding in Water."— Presentation transcript:

1 Phase Diagram for Water

2 Hydrogen Bonding in Water

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4 Transfer Processes and Storage (Reservoirs)

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6 Residence Time Time to replace a substance in a reservoir, or average length of time a substance exists in a reservoir Time to replace a substance in a reservoir, or average length of time a substance exists in a reservoir Total Amount Rate of Addition or Removal Water in atm. = 11 days Water on land = 1 year Water in oceans = 3500 years

7 Importance of Water Cycle to the Earth System Transfers heat Transfers heat Sea level change Sea level change Greenhouse gas Greenhouse gas Global warming will affect it Global warming will affect it Renewable resource; energy source Renewable resource; energy source Weathering and erosion agent Weathering and erosion agent Interacts with the Carbon Cycle Interacts with the Carbon Cycle

8 Energy Absorbed and Released During Phase Changes of Water

9 Difference in Heating of Land and Ocean

10 SummerWinter

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13 A True Color Picture of Earth

14 amount size

15 Sea level also changes due to temperature.

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18 Top Climate-Water Issues Sea-level rise Sea-level rise Snow-pack loss Snow-pack loss Redistribution of water resources Redistribution of water resources Water vapor feedback Water vapor feedback

19 Ice Sheet Melting & Sea Level Rise

20 Rate of Sea Level Rise (Data from IPCC WGI Summary for Policymakers)

21 Sea-Level Rise and Water Supplies Saltwater contamination of coastal ground-water wells Saltwater contamination of coastal ground-water wells Salinity encroachment on municipal water intakes from rivers Salinity encroachment on municipal water intakes from rivers Loss of glacial meltwater Loss of glacial meltwater Coastal States

22 Composition of Natural Waters

23 Carbonate Equilibria: CO 2 + H 2 O CH 3 COOH H + + CH 3 COO - CH 3 COOH H + + CH 3 COO - CH 2 O + O 2 => CO 2 + H 2 O CH 2 O + O 2 => CO 2 + H 2 O CO 2 + H 2 O H 2 CO 3 CO 2 + H 2 O H 2 CO 3 H 2 CO 3 H+ + HCO 3 - H 2 CO 3 H+ + HCO 3 -

24 Chemical Weathering Limestones H 2 CO 3 + CaCO 3 Ca +2 + 2HCO 3 - Silicates 2H 2 CO 3 + NaAlSi 3 O 8 ==> Na + + 2HCO 3 - + clay minerals 2H 2 CO 3 + CaAl 2 Si 2 O 8 ==> Ca +2 + 2HCO 3 - + clay minerals What happens to CO 2 during chemical weathering? Role of water? pH of river water? Seawater?

25 Chemical Weathering

26 Chemical Composition of Seawater Six major constituents Six major constituents Two anions - Cl -, SO 4 = Two anions - Cl -, SO 4 = Four cations - Na +, Mg +, Ca +2, K + Four cations - Na +, Mg +, Ca +2, K + pH is buffered by CO 2 - CaCO 3 system pH is buffered by CO 2 - CaCO 3 system

27 Residence Time Time to replace a substance in a reservoir, or average length of time a substance exists in a reservoir Total Amount Rate of Addition or Removal

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29 Sources of Sea Salt Weathering of continents Weathering of continents Volcanic eruptions Volcanic eruptions Hydrothermal vents Hydrothermal vents

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32 Oxygen Concentration Solubility depends on T and Salinity Solubility depends on T and Salinity Warm, saline water holds less O 2 Warm, saline water holds less O 2 Oxygen consumption in water column Oxygen consumption in water column Respiration by animals Respiration by animals Mixing rate of oceans Mixing rate of oceans Sluggish mixing - low rate of O 2 replenishment Sluggish mixing - low rate of O 2 replenishment

33 Carbon Dioxide Concentration Solubility depends on T and S Solubility depends on T and S CO 2 is released by animals CO 2 is released by animals Mixing rate of oceans Mixing rate of oceans Affects pH of seawater (What is its pH?) Affects pH of seawater (What is its pH?) Similar to concentration profiles of nutrients (PO 4 -3, NO 3 - ) Similar to concentration profiles of nutrients (PO 4 -3, NO 3 - )

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37 pH - function of dissolved CO 2 Reacts with water to produce carbonic acid, which releases H + ions CO 2 + H 2 O H 2 CO 3 H + + HCO 3 - H + + CO 3 -2 H 2 CO 3 is carbonic acid, HCO 3 - is the bicarbonate ion and CO 3 -2 is the carbonate ion CO 2 in Seawater

38 Carbonate system - buffers against large shifts in pH Carbonates dissolve in deep water Higher CO 2 makes the water less alkaline (pH 7.8) Warm, shallow water has less dissolved CO 2 More alkaline than deep water (pH 8.2) Carbonate sediments are abundant CO 2 in Seawater

39 Carbonate System

40 Precipitation of CaCO 3 ---- HCO 3 - + OH - => CO 3 = + H 2 O

41 Calcite (or Calcium Carbonate) Compensation Depth (CCD) CaCO 3 dissolves in deeper water due to higher CO 2 content in deep water CaCO 3 dissolves in deeper water due to higher CO 2 content in deep water Deepest sediments have little or no CaCO 3 Deepest sediments have little or no CaCO 3 CCD is deeper (less dissolution) in the Atlantic Ocean than in the Pacific CCD is deeper (less dissolution) in the Atlantic Ocean than in the PacificWhy?

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43 The Carbonate System

44 Changes in the CCD for the Past 100 m.y.


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