1. Chapter 16 Oceans & Coastlines Earth Science and the Environment (4th ed) Thompson & Turk

2. 16.1 Geography of oceans Oceans are all connected So really just 1 big ocean! 5 ocean basins Atlantic Pacific Arctic Antarctic Indian 3. Fig. 16.1, p.400 4. 16.2 Seawater Salinity total amount of dissolved salts expressed as a percentage Six main ions: Cl, Na, Mg, SO4, Ca, K Also contains gases; CO2 & O2 mainly Gases in equilibrium w/atmosphere Salinity not uniform Average is 3.5% (35 parts per 1000) 5. Fig. 16.3, p.401 6. What Affects Salinity? Salinity INCREASES: Volume of water decreases Evaporation & freezing Salinity DECREASES Volume of water increases Precipitation & melting Saltiest water Cold arctic/antarctic waters Warm subtropical waters 7. Fig. 16.4, p.402 8. 16.2 Seawater Temperature in oceans is layered Warm surface 450m Thermocline next 2 km, temperature drops off rapidly with depth Cold deep layer below thermocline and extends to poles, 1oC to 2.5oC 9. Fig. 16.5, p.402 10. Density of ocean water D = M/V Temperature affects volume As temperature goes up volume goes up and thus density goes DOWN As temperature goes down volume goes down and density goes UP Salinity affects mass As salinity goes up density goes UP As salinity goes down density goes DOWN Therefore Most dense water is Salty and cold Least dense water is warm and less salty 11. 16.6 Ocean currents Current continuous flow of water in a given direction Surface currents wind-driven flow in the top 400m of seas Commonly used to aid ocean transport Gulf Stream 80km wide by 650m deep, 5km velocity (at fastest) Westerlies and trade winds produce gyres broad loop currents 12. Fig. 16.14, p.407 13. Fig. 16.13, p.407 14. 16.6 Ocean currents Coriolis effect objects moving in a fluid are curved due to earths rotation. Eckman transport another twist imparted to currents due to constant Coriolis and decreasing wind effects, with depth 15. Fig. 16.15, p.408 16. 16.6 Ocean currents Deep-sea currents move both vertically and horizontally Thermohaline circulation vertical currents caused by density differentials Cooling cold water is more dense than warm Salinity more salt = denser water Surface currents change in both temperature and salinity as they move Water takes 500 2,000 years to make a vertical loop Deep current flow is responsible for the exchange of heat energy around the globe. 17. Fig. 16.12, p.406 18. 16.6 Ocean currents Upwelling upward flow in response to water sinking elsewhere Winds blowing offshore or along shore can cause upwelling Brings cold water up Also brings nutrients up Exchanges gases with the atmoshere Redistributes heat Weak Coriolis force at low latitudes causes equatorial upwelling 19. Fig. 16.16, p.409 20. Estuaries enclosed body of water formed where freshwater from rivers and streams flows into the ocean, mixing with the salty sea water places of transition from land to sea, and from fresh to salt water influenced by the tides, but protected from the full force of ocean waves, winds, and storms by the reefs, barrier islands, or fingers of land, mud, or sand that define an estuary's seaward boundary 21. Estuaries Subdivided into three types based upon the relative importance of river inflow and tidal mixing. Salt-wedge estuaries are dominated by the outflow from rivers. Partially-mixed estuaries are dominated by neither river inflow nor tidal mixing. In well-mixed estuaries tidal turbulence destroys the halocline and water stratification. 22. Estuaries Estuaries are extremely fertile because nutrients are brought in by rivers and recycled from the bottom because of the turbulence. Stressful conditions and abundant nutrients result in low species diversity, but great abundance of the species present. Despite abundance of nutrients, phytoplankton blooms are irregular and the base of the food chain is detritus washed in from adjacent salt marshes. 23. Functions of Estuaries Estuaries are sometimes called marine nurseries habitats for many juvenile organisms, especially for fishes many fish are born and grow up in estuaries migrate to the open ocean Wildlife Habitat Recreation 24. NC Coast to Sea Rivers and streams flow to sea Empty into bays, estuaries and sounds Sometimes protected by barrier islands Coastal areas are vulnerable 25. 16.9 Beaches Development along sandy shores Beachfront property & barrier islands are hot property Many resorts, hotels, etc. built in these areas Problems with beach development Erosion of the coast Sea level rise pollution 26. Fig. 16.22, p.413 27. Fig. 16.31, p.419 28. 16.8 Emergent and submergent coastlines Factor affecting sea-level Tectonic processes Isostatic adjustment Eustatic sea-level change Growth or melting of glaciers Changes in water temperature Changes water volume via thermal expansion/contraction Changes in volumes of mid-ocean ridges Rapid spreading creates a higher ridge zone, displacing more water