Seawater Properties
Which property is best measured using a Secchi disk to assess water quality?
Turbidity
What is the thermocline, and what physical property defines it?
A transitional layer where temperature decreases rapidly with depth
Where is the intertidal zone located at?
Between high and low tide marks, exposed at low tide and underwater at high tide
Deep ocean currents are primarily driven by...
Density differences caused by variations in temperature and salinity
Why is saltwater denser than freshwater?
Dissolved salts increase the mass of the water without significantly increasing its volume
The pH of seawater is approximately 8.1. What does this pH value indicate about seawater?
Seawater is slightly basic (alkaline)
The halocline is best defined as a layer in the ocean where:
Salinity changes rapidly with increasing depth
The epipelagic zone (0–200 meters) is characterized by which conditions?
Sunlit, warm water with high productivity and abundant marine life.
Ocean surface currents are primarily driven by which factors?
Wind, solar heating, and Earth's rotation
At what depth does water pressure increase by approximately 1 atmosphere?
10 meters
What is the average salinity of seawater?
35 ppt
What is the pycnocline?
A layer where density changes rapidly with depth
Which ocean zone is known as the 'twilight zone' due to minimal light penetration?
Mesopelagic zone (200–1,000 meters)
Which is a major function of ocean currents?
They control climate, influence weather, transport nutrients and minerals, and form gyres
Sound travels approximately how many times faster in water than in air?
4 times faster
Which factors cause sound to travel faster in seawater?
Higher salinity, temperature, pressure
Which description best characterizes the deep ocean layer?
It contains most of the ocean's water and is dark, cold, dense, and salty, with nearly constant salinity and density
The photic zone in the ocean is defined by which characteristic?
Sunlight that aids in photosynthesis
Name the 5 major gyres.
North Atlantic
North Pacific
South Atlantic
South Pacific
Indian Ocean
Eutrophication in ocean waters is primarily caused by an excess of what nutrients?
Nitrogen and phosphorus
Ocean acidification occurs when carbon dioxide dissolves in seawater. What compound is formed?
Carbonic acid (H₂CO₃)
The surface mixed layer of the ocean is characterized by what conditions?
Warm temperatures and high dissolved oxygen
The aphotic zone is characterized by what features?
No sunlight for photosynthesis
How are currents, gyres, and the great ocean conveyor belt related?
Currents come together to make gyres, and gyres come together to make the conveyor belt
Why does the ocean appear blue when viewed from above?
It absorbs many colors and reflects blue.