Composition of the oceans

1
Composition of the oceans

• At least 72 chemical elements present (top four
  sodium, chloride, sulfate, magnesium)
• Enough salt to cover earths surface 40-story
  thick
• Affected by waves, melting, runoff, evap., etc.
• Red Sea and Persian Gulf saltiest

2
Composition of Seawater
Water (96.5 ) Dissolved substances (3.5 ) (see
page ) Chloride (55) Sodium (30 ) Sulfate
(8) Magnesium (4 )
Sources of salt Weathering of crust and washed by
rain (original source) Volcanic eruptions Hot
water seafloor vents/ridges/trenches
3
Why are oceans salty?

• Gradual processes of weathering and erosion and
  then dissolved material carried by rivers and/or
  rain
• Dissolved from rocks below the sea floor
• Dissolved material from sea floor vents
• Processes occurred for millions of years

4
The salt cycle
5
Does the saltiness change?

• Although rivers dump primarily fresh water,
  still contains dissolved minerals. This actually
  adds salt to ocean. However, some salt sinks to
  floor as sediment as well as being left behind
  from evaporation. Therefore, incoming and
  outgoing salt about equal (although in favor of
  the input).