solubility of gases

Phototic Zone

-sunlit upper layer of the ocean.

-Goes to about 200m down.

-Lots of photosynthesis - ↑ O2 concentration

-Warm - heat from sunlight.

-90% of all marine life is found in this area.

aphotic zone

-No sunlight

-Chemosynthesis

-Cold

-Nutrient rich

Solubility of gases in seawater

-Gases (nitrogen, carbon, and oxygen) dioxide in the atmosphere (carbon dioxide) are in a state of equilibrium with the gases dissolved in ocean water

-If the [gases] in the atmosphere↑, [gases] in the ocean ↑ too

Percentage of gases in the atmosphere

-78% nitrogen.

-21% oxygen

-carbon dioxide .04%

-other gases (mostly argon) .96%

Factors that contribute to the concentration of gases in sea water

-gas solubility.

-water temperature

-atmospheric pressure

-water pressure due to depth

-salinity of the seawater

Gas solubility

Carbon dioxide: -Very soluble in seawater because of its ability to form carbonic acid .

Oxygen: -Low solubility in seawater because it can't chemically combine with the water molecules

-meaning the level of carbon dioxide held by seawater is higher than that of oxygen

conditions that affect gas solubility

-water temperature

water temperature

-Cold water can dissolve more gas than water at warmer temperature.

-applying heat makes molecules move faster

-Dissolved gas molecules evaporate from the surface water more quickly

Ex: Why water near the poles dissolve more oxygen than water in the tropics?

-Because water found near the poles will dissolve more oxygen than the water found in the tropics

atmospheric temperature

Changes of atmospheric pressure affect the equilibrium of gases in the atmosphere and in the ocean

High atmospheric pressure - Example: when concentration of gases in the atmosphere increases - Pushes more gas molecules to dissolve in water

Low atmospheric pressure - Example: hurricane/tropical cyclone Dissolved gas molecules escape to the atmosphere

water pressure due to depth

oWater pressure is higher as the depth is deeper

oWater pressure increases due to sheer mass of the water

oSolubility of gases increases as the water pressure increases

oThe pressure force the gas to stay dissolved in water

↑ depth ↑ water pressure ↑ solubility

Salinity of seawater

Gases are better able to dissolve in water with lower levels of salinity because there are less solutes taking up space between the water molecules and so more water molecules are able to interact with gas molecules and dissolve them.

Ex- as the fresh water mixes with salt water in the sea, the solubility of these gases decreases.

↓ salinity ↑ gas solubility

↑ salinity ↓ solubility

The Impact of Solubility

on Marine Life

At the surtace, producers take in dissolved carbon dioxide for use in photosynthesis and then release oxvgen as a result.

oCO2 and O2 are both necessary for the survival of marine organism

oCO2 - for photosynthesis

oO2 - for respiration

Variations of water

Turbidity- irregular changes in the speed and direction of fluid movement

high - Coastal waters have cloudy water .

•plankton, sediment, bacteria, decaying plants

-low - Open ocean ecosystems have clear water → low turbidity

Nutrient levels

-substances that provide nourishment for organisms.

-are highest near coastlines, as rivers dump nitrogen and phosphorus into the ocean

Nitrogen gas

bacteria that makes the nitrogen easier for other organisms to use for protein creation

chemosynthesis

the biological process by which chemical energy is converted into carbohydrates for the organism's food.