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Chapter 21, section 1
H2O basics →
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Properties of Ocean Water
Water is a good solvent (it is good at dissolving stuff)
The ocean is salty because salts and nutrients are dissolved in the water,
although pure water is colorless and tasteless
Composition of ocean
water →
Billions of kilograms of dissolved substances are carried into the ocean
by rivers and streams. When water evaporates from the ocean the salt
is left behind
Gases, such as carbon dioxide, are dissolved into the ocean from the
atmosphere and from volcanic eruptions under the ocean
Elements in ocean
Ocean water is made of about 96% H2O, 2% Chlorine, 1% Sodium and less
water →
than 1% magnesium, sulfur, calcium, potassium, gold, zinc, & phosphorous
Dissolved gases in
ocean water →
The three main gases dissolved in the ocean are the same three main
gases that make up the atmosphere; nitrogen, oxygen, and carbon dioxide
Carbon dioxide dissolves easily into water and is therefore the most
abundant gas in the ocean
Salinity of ocean
X water →
Salinity- the amount of dissolved solids in ocean water (# of grams of
dissolved solids / kg of ocean water)
Usually written in parts per thousand (‰) because the mass of dissolved
solids is small compared to the mass of water
Salinity is increased by evaporation and freezing. In both cases pure
water is removed, so the dissolved solids remain in the ocean
Tropical waters have a higher salinity because more evaporation occurs,
although at the equator there is more rain fall which lowers the salinity
Polar waters have a higher salinity because more freezing occurs
Ocean temperature →
The surface of the ocean is heated by absorbing infrared radiation from
the sun
The equator receives more direct radiation and so the ocean waters are
warmer than the waters further from the equator
Because the sun can only penetrate a few hundred meters of ocean water
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there is a sudden change of temperature below this point
Thermocline- the rapid temperature change that occurs with increasing
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Ocean density →
ocean depth
Below the thermocline water temperature continues to drop until just
above the point of freezing
Density is mass per volume (m/v)
There are two factors that effect the density of ocean water; salinity and
temperature
If the salinity is high, the water is more dense because the ratio of
dissolved particles to water is higher
If the temperature is low, the water is more dense because the molecules
that make up the water are packed closely together
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