AICE MARINE 1.2

What does Turbulence do?

-At the surface layer, mixing by wave action (turbulence) causes gases to dissolve into seawater.

-the upper 200m have a higher concentration of CO2 and O2

Sodium chloride dissolve easily in water

through dissolution of ions

Sodium chloride placed in water ->

ionic bonds are broken by the water molecule

Partially positive hydrogen ends of the water molecule surround the

negatively charged chlorine atoms

Partially negative oxygen ends of watermolecule will surround the

positively charged sodium atoms

Solubility is impacted by physical factors, especially

temperature

-as temperature of seawater rises, the rate of

dissolution of salts increases. (warm water is saltier)

As water heats up, molecules move faster and it's easier to

break ionic bonds

Salinity

the concentration of dissolved salts in seawater - measured in parts per thousand (ppt)

measured using total dissolved solids (TDS)method -

boil 1000g of sea water until all water has evaporated; measure the salts left behind.

Average salinity of open ocean

35ppt.

water salinity varies

at any location

Precipitation and runoff do what to salinity?

decrease salinity(Reason: freshwater is added to the solution)

Evaporation does what to salinity?

increase salinity (Reason:freshwater is removed from the solution

Areas with high salinity concentration are

called hypersaline (salinity greater than 40‰)

pH

a measure of the concentration of hydrogen ions in water; a quantitative measure of the acidity or alkalinity of a solution on a logarithmic scale

Acidic solution:

high concentration of hydrogen ions; pH is bellow 7

Alkaline/basic solutions -

low concentration of hydrogen ions; pH is above 7

Neutral solution pH

pH is 7 H+ = OH-

Ocean pH=

8.2 (recently 8.1)

litmus indicator

litmus indicator - only indicates if is acid or alkali, doesn't show how level of acidity

universal indicator -

shows a range of strength (number, but not accurate

pH probes-

most accurate, show the hydrogen-ion concentration

The concentration of N2 , CO2, & O2 gases in the atmosphere are in a

state of equilibrium with the dissolved gases in seawater

If the concentration of a gas in the atmosphere increases then,

the concentration of that gas in the sea water will also increase.

What factors influence the concentration of gases in sea water?

Turbulence

Gas solubility

Water temperature

Atmospheric pressure

Water pressure due to depth

Salinity

Turbulence-

(irregular movement of fluid) and wave action

Soluble gas: O2:

Used in Respiration / released by photosynthetic organisms

Low solubility b/c it does not react with water molecules

Soluble gas: CO2:

Used for photosynthesis / released by respiration

Easily dissolvable because it makes carbonic acid (H2CO3) when it reacts with water

Causing CO2 levels to be higher than O2 levels in seawater

Soluble gas: N2

Used for making proteins / must be converted by nitrogen-fixing microorganisms first

Water temp: cold water dissolves ___ gas than warm water

more

Atmospheric pressure : increase pressure causes

increase in gas solubility and stay dissolved

High pressure systems, gasses

are added to ocean water because this pushes more of those gas molecules to dissolve in seawater,

Low pressure systems (hurricanes), gasses

are lost from ocean to atmosphere because ) more dissolved gasses from the water escape into the atmosphere.

Water pressure due to depth -

pressure increases with depth and that causes an increase in gas solubility (gases are not easily lost)

Salinity -

lower salinity dissolves more gasses

Fresh water dissolves more gasses as they contain less dissolved solutes

more oxygen in estuaries than in the open ocean.

Most of dissolved oxygen

is found in the top 100 m of water (super saturation).

as temp increases, DO ___

decreases

tropical waters have __ DO than cold polar waters;

less

Inputs of DO at surface layer:

from photosynthesis & water/wave motion(more waves=more O2

Outputs of DO at surface layer

Cellular respiration by all organisms (algae, bacteria, fish,etc.)

Decomposition by bacteria, AKA respiration

;As depth increases O2 decreases until it reaches the

Oxygen minimum layer

Oxygen Minimum Layer-

At a depth of about 100m -1000m the dissolved oxygen is at its lowest

Why does the Oxygen min layer occur?

Lack of photosynthesis; exchange with atmosphere; no inputs

Respiration and decomposition still removes DO

Organisms here must adapt to low O2 by having gills great for extracting O2 and/or be mostly inactive.

After the OML, concentrations begins to increase. Why?

Less respiration being carried out by the decomposer (bacteria). Decomposition of detritus has been completed.

Lack of food sources for organisms living below the OML zone, less respiration occurs

O2 solubility increases as the temperature decreases so more O2 can stay dissolved

Pressure increases more O2 is dissolved

Tropical oceans -

higher salinities due to increased evaporation

Polar oceans-

- lower salinities due to slower rates of evaporation and melting ice

salinity drops right near the equator due to

increased cloud cover and rainfall(precipitation > evaporation

Atmospheric solution

-dissolved gases which are kept in balance between the atmosphere and the sea water by mixing of the surface due to wind and waves

Volcanic eruptions

- emits gasses when eruptions occur

Run off

- freshwater w/ minerals (ions) deposited into the ocean

CO2 in the atmosphere dissolves in the sea water

creating H2CO2(carbonic acid) which lowers the water's pH

Ocean acidification prevents corals form absorbing all

the CaCO3 they need to build their skeletal structures -> This leads to skeletal loss as their skeletons dissolve in the more acidic waters

Gases are LESS SOLUBLE in warm waters , why?

faster moving H2O molecules at surface allow gas molecules to escape faster/ evaporate)

Increases in H2O temp can affect the amount of dissolved O2 needed

for organisms

O2 is slightly

O2 slightly less soluble in salt water than in fresh water

Ocean sink:

more gases dissolve into the seawater

ocean source:

more gases escape the seawater and enter the atmosphere

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