HPU NCS2200 Earth science for elementary education majors summer 2014 online class oceans and esutaries

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

11. 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

12. 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

13. Fig. 16.14, p.407

14. Fig. 16.13, p.407

15. 16.6 Ocean currents
 Coriolis effect – objects moving in a fluid are
curved due to earth’s rotation.
 Eckman transport – another “twist” imparted to
currents due to constant Coriolis and decreasing
wind effects, with depth

16. Fig. 16.15, p.408

17. 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.

18. Fig. 16.12, p.406

19. 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

20. Fig. 16.16, p.409

21. 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

22. 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.

23. 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.

24. 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

25. 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

26. 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

27. Fig. 16.22, p.413

28. Fig. 16.31, p.419

29. 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