AICE Marine – Unit 3 Characteristics of Seawater, Solubility in Water, Density and Pressure

Solute

a solid that dissolves in a solvent

Solution

a mixture of a solute dissolved in a solvent

solvent

a substance which is able to dissolve another substance

Solubility

the ability of a solute to dissolve within solvent

Dissolution

the process of being dissolved

What’s in seawater?

dissolved “salts”, dissolved gases, organic molecules, suspended sediment, mainly chloride(CI-) and sodium Na+

Salinity

concentration of dissolved salts in seawater

How is salinity expressed?

ppt

principle of constant proportions

the salinity of seawater varies in different areas of the ocean, but proportions of the major salts in seawater stay about the same everywhere

Decreases salinity

precipitation, runoff, melting of sea ice

Increases salinity

Evaporation, sea ice formation

How is sea ice formed?

from sea water during polar winters

Iceberg

pieces of glacier that broke off

where to glaciers from and what causes them?

on land, from the accumulation and compaction of snow

How does high salinity affect density?

density-higher salinity= higher density

How does high salinity affect freezing temperatures?

Freezing Temperature-Higher salinity=lower temperature freeze

How does high salinity affect electrical conductivity?

Electrical conductivity-Higher salinity= high e.c

how does high salinity affect viscosity?

viscosity-higher salinity=higher viscosity

how does high salinity affect osmotic pressure?

osmotic pressure- higher salinity=higher osmotic pressure

ph scale

an important abiotic factor for the survival of marine organisms

what ion to acids add to the solution? what ion do alkaline substances/basic add to the solution?

H+, OH-

what is the pH of the ocean?

8.2

what substance buffers the ocean?

calcium carbonate(CaCO3)

three main methods of measuring pH are

litmus indicator, universal indicator, pH probes

litmus indicator

a solution commonly used as papers where has been soaked in the solution, determines if acid or base

universal indicator

a solution commonly used as papers where it has been soaked in the solution, determines the range of strengths for acids and bases

pH probe

probes measure the H+ concentration within a solution to provide a numerical readout, much more precise than any other method

Do gases dissolve better in cold or hot water?

cold

do gases dissolve better in high or low pressure?

high

what gases are in the ocean?

nitrogen, oxygen, and carbon dioxide

what gas from the ocean is the most soluble?

CO2

are gases able to dissolve better in lower or higher salinity areas?

lower

during photosynthesis what happens to the O2 and CO2 levels?

O2 increases, CO2 decreases

during respirations what happens to CO2 and O2 levels?

O2 decreases, CO2 increases

what happens at the surface layer?

photosynthesis by plants at the ocean surface(photic zone) causes high levels of O2 and low levels of CO2

what happens in the oxygen minimum layer?

As depth increases, levels of oxygen decrease until it reaches this level

why is there less decomposition in deep water?

not enough oxygen for decomposing bacteria to perform aerobic respiration

why do deep-ocean organisms use less oxygen?

lack of food causes them to need less energy and repsire less

what happens to the solubility of oxygen as temperature decreases?

it increases

what happened to oxygen solubility as pressure increases?

it increases

density formula

mass/volume

different clines?

pycnocline(density, thermocline(temperature), and halocline(salinity)

is colder water denser then warm water?

yes

what is the ocean stratified by?

density

Surface zone(mixed layer)

contains the least-dense water. Temperature and salinity are mixed by waves and currents. Contact with atmosphere and has sunlight.

Pynocline

density increases dramatically with depth here. Acts as a barrier to mixing between surface zone and deep zone

deep zone

little change in density throughout this layer

what layer takes up 80% of the ocean water?

deep zone

thermocline

as temperature increases, density increases

halocline

as salinity increases, density increases

pycnocline

the rapid change of density with depth

why are gradients formed by mixing due to

strong winds and wave action, currents and upwelling pushing water of different densities together

how is density expressed

g/cm3

what factors affect the density of water?

temperature, salinity, pressure

does freshwater freeze at a lower temperature then seawater?

no

average salinity of the ocean

35 ppt

where in the world do we see thermoclines?

temperate and tropical oceans because warm water and cold deep water don’t mix because of different densities

turbulence

chaotic swirling motion of water where the flow isn’t smooth

dissolved oxygen

oxygen mixed into ocean water that fish and other organisms need to breathe