Seawater Chemistry & Ocean Stratification 1

Key Points The salt in seawater is due in part to water’s unique properties. Seawater density is influenced by temperature and salinity. The ocean has layers as a result of different densities.

How did the Ocean get so salty? Through a combination of water’s properties (universal solvent, adhesion) water “picks up” minerals via erosional and weathering processes In other words, water physically and chemically picks up salts Make way to the ocean

Hydrological Cycle (Water Cycle) 4

What types of elements are found in the ocean’s salts?

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How do we measure the amount of salt in the Ocean? Salinity vs. Conductivity CTD Rosette –Conductivity –Temperature –Density 7

Key Points The salt in seawater is due in part to water’s unique properties. Seawater density is influenced by temperature and salinity. The ocean has layers as a result of different densities.

How is the Ocean Like a Red Velvet Cake?

Ocean Model Temperature Depth Surface Deeper WarmerColder 10

Ocean Model 11

“Warm” shallow surface layer Cold deep layer Transition Zone Ocean Model 12 How do the layers form?

Surface Layer Deep Water Transition Zone 13 Homogeneous Ocean

Ocean Temperature Deep Water 90% of the total volume of ocean is this cold, deep water. At depths greater than 1000m, temperature is approximately 4ºC (even in the tropics!!). windows.ucar.edu Why do layers form? Thermocline = Temperature Change Surface Layer Transition Zone 14

Mass per unit volume Lighter g/cm 3 Denser to g/cm 3 hawaiianphotos.net Because of Density Lighter 100 k g/m 3 Denser 19,300 kg/m 3 Slashfood.com

Ocean Density Surface Layer Deep Water Seawater density is controlled by Temperature and Salinity In the ocean, Temperature has a greater effect on density windows.ucar.edu Pycnocline = Density Change Pycnocline Transition Zone 16

Surface Layer Deep Water Boundary Transition Zone Thermocline & Pycnocline 17

Surface Layer Deep Water Boundary 18 Mixed Warmed and lit by sun Photosynthesis Cold, Dark, No Photosynthesis Less Nutrients, More Nutrients

Surface Ocean Warm Lit by the sun Has photosynthesis Less nutrients Deep Ocean Cold Dark No photosynthesis More Nutrients LOTS AND LOTS OF PRESSURE 19 Main Differences…