Lecture 1 - Water Properties Flashcards
What proportion of the Earth’s surface is covered by oceans?
Over 70%
What is the average ocean depth?
3,730m
What is the average ocean volume?
1,328 km3
What percentage of the living space on the planet does the ocean provide?
99%
What percent of water available on the globe is contained in the ocean?
97%
What proportion of animal phyla are found in marine environments?
32/33
Name the only animal phyla that can’t be found in marine environments.
Onychorphora
Give the microorganisms found in a single 1ml drop of seawater.
- 10 million viruses
- 1 million bacteria
- A thousand protozoans and algae
How many species of marine plants and animals are there?
Nearly 250,000
Why is sea life older than life on land?
Because life originated in the sea
What percentage of the Earth’s biomass is made up of marine microbes?
50%
What proportion of the Earth’s surface area is taken up by coral reefs?
0.1%
What percentage of marine biodiversity is hosted by coral reefs?
25%
What percentage of marine biodiversity is composed of invertebrates?
80%
What percentage of oxygen we breathe comes from the ocean?
How?
30-50%
Phytoplankton absorb CO2 and release oxygen into the air.
Without the heat-absorbing capacity of the ocean, how much would the atmosphere have warmed from climate change?
36 degrees
What percentage of global protein use by humans comes from oceans?
7%
What percent of the world’s population lies on the coast?
What percent is expected to lie on the coast by 2025?
- Currently: 50%
- 2025: 75%
What proportion of the Great Barrier Reef died last year?
A third.
How has the Arctic changed due to global warming?
- Should be multi-year ice.
- Changing to seasonal first-year ice system.
What proportion of ion content in the ocean is
a) chloride?
b) sodium?
a) Chloride = 55%
b) Sodium = 7.7%
Why is seawater salty?
Due to the erosion of minerals from continents, hydrothermal vents and submarine volcanoes.
What is the average concentration of salts in the ocean by
a) Weight
b) Parts per thousand
a) Weight = 3.5%
b) Parts per thousand = 35
How is salinity measured?
By
- conductivity (a ratio)
- Practical salinity units (psu)
What is the formal definition of salinity?
(conductivity of a seawater sample) / (conductivity of a standard KCL solution)
What is silica in the ocean used for?
To form the cases of Diatoms
What is the freezing point of seawater?
-1.8C
What kinds of water sink?
- Cold water
- Salty water
They are denser.
What are upwellings?
Deep water brought up due to the action of wind, reducing sea surface temperature and bringing nutrients to the surface.
What is a halocline?
Where salinity changes dramatically with depth.
What is a thermocline?
Where temperature changes dramatically with depth.
Do thermoclines or haloclines tend to occur together or separately?
Together.
What is a pynocline?
Changes in the density of water with depth
Where do seasonal thermoclines occur?
In temperate waters
What is a seasonal thermocline?
A layer of the ocean that experiences a rapid change in temperatures within just a few metres of depth.
What is the name given to the surface area of a thermocline?
The ‘mixed layer’
What can the conductivity of water be measured using?
A CTD-profiler
What percentage of the Earth’s surface is sea ice?
7%
Does water become saltier or less salty with depth?
Saltier
Which zone does the majority of biology occur in?
The Epipelagic Zone (first 200m)
What zone is the average depth of the ocean?
The Bathypelagic Zone
Give the zone where depths up to 11,000m occur.
Hadal zone
How much does pressure increase with every 10m?
1 atmosphere
Which colour penetrates water the least?
How quickly does it disappear?
Red.
Disappears within first 15m of depth.
Which colour penetrates water the best?
How far can it penetrate?
Blue.
Can penetrate up to 200m.
What proportion of atmospheric CO2 is taken in by the ocean?
1/3
Give the two processes that drive the ocean’s ability as a carbon sink.
- Solubility pump; carbon dissolves in seawater and is moved around as water moves.
- Biological processes; e.g. photosynthesis
