6 Rate of Addition or Removal Residence TimeTime to replace a substance in a reservoir, or average length of time a substance exists in a reservoirTotal AmountRate of Addition or RemovalWater in atm. = 11 daysWater on land = 1 yearWater in oceans = 3500 years
7 Importance of Water Cycle to the Earth System Transfers heatSea level changeGreenhouse gasGlobal warming will affect itRenewable resource; energy sourceWeathering and erosion agentInteracts with the Carbon Cycle
8 Energy Absorbed and Released During Phase Changes of Water
24 Chemical Weathering Limestones H2CO3 + CaCO3 <==> Ca+2 + 2HCO3- Silicates2H2CO3 + NaAlSi3O8 ==> Na+ + 2HCO3-+ clay minerals2H2CO3 + CaAl2Si2O8 ==> Ca+2 + 2HCO3-What happens to CO2 during chemical weathering?Role of water? pH of river water? Seawater?
32 Oxygen Concentration Solubility depends on T and Salinity Warm, saline water holds less O2Oxygen consumption in water columnRespiration by animalsMixing rate of oceansSluggish mixing - low rate of O2 replenishment
33 Carbon Dioxide Concentration Solubility depends on T and SCO2 is released by animalsMixing rate of oceansAffects pH of seawater (What is its pH?)Similar to concentration profiles of nutrients (PO4-3, NO3-)
37 CO2 in Seawater pH - function of dissolved CO2 Reacts with water to produce carbonic acid, which releases H+ ionsCO2 + H2O H2CO3 H+ + HCO3- H+ + CO3-2H2CO3 is carbonic acid, HCO3- is the bicarbonate ion and CO3-2 is the carbonate ion
38 CO2 in Seawater Carbonate system - buffers against large shifts in pH Carbonates dissolve in deep waterHigher CO2 makes the water less alkaline (pH ≈ 7.8)Warm, shallow water has less dissolved CO2More alkaline than deep water (pH ≈ 8.2)Carbonate sediments are abundant
40 Precipitation of CaCO3----HCO3- + OH- => CO3= + H2O
41 Calcite (or Calcium Carbonate) Compensation Depth (CCD) CaCO3 dissolves in deeper water due to higher CO2 content in deep waterDeepest sediments have little or no CaCO3CCD is deeper (less dissolution) in the Atlantic Ocean than in the PacificWhy?