Question

notes b

• breathing underwater

○ water holds 20x less o₂ than air does

• salinity

○ salinity - amount of salt dissolved in the water

• critical question: how do you think the ocean got so salty?
• video notes...

1.
2.

• salinity varies with latitude

○ low @ high latitude (near poles) because of
○ high @ mid latitudes because of
○ low @ low latitudes because of

• also varies with depth

○ in general, salinity increases with depth
(
→
→

• haloclines

○
○ haloclines, together with thermoclines (
create pycnoclines (

Explanation:

1. Ocean salinity source: Rivers carry dissolved salts from the land into the ocean. Volcanic eruptions also release salts into the ocean. Evaporation of seawater leaves behind salts, gradually increasing the salinity over long - term geological processes.
2. Salinity and latitude: At high latitudes near the poles, salinity is low because of melting ice which adds fresh water. At mid - latitudes, high evaporation rates with less precipitation lead to high salinity. At low latitudes, high precipitation dilutes the seawater, resulting in lower salinity.
3. Salinity and depth: In general, salinity increases with depth as water at greater depths has been isolated from surface processes like precipitation and evaporation for a long time, and also due to the dissolution of salts from the ocean floor over time. Haloclines are layers in the ocean where there is a rapid change in salinity with depth. Together with thermoclines (layers of rapid temperature change), they create pycnoclines (layers of rapid density change) as salinity and temperature affect water density.

Answer:

1. How the ocean got so salty: Rivers bring salts from land, volcanic eruptions contribute salts, and evaporation leaves salts behind over time.
2. Salinity at high latitudes: Low because of melting ice adding fresh water.
3. Salinity at mid - latitudes: High due to high evaporation and less precipitation.
4. Salinity at low latitudes: Low because of high precipitation.
5. Haloclines: Layers of rapid salinity change with depth. They, along with thermoclines, create pycnoclines which are layers of rapid density change in the ocean.