Oceanography (2+1)

Composition of sea water

As water is a good solvent most elements on the earth are found disssolved in sea water of the 108 elements discovered so for 84 elements have been found to be in seawater.  

The major constituents comprise about 99.7% of all dissolved materials. The remaining 0.3% comprises of the three categories of dissolved gases,nutrients and trace elements.The concentrations of dissolved gases, nutrients, and trace elements are greatly affected by biological organisms, the climate, and some geochemical processes. Their concentrations are varying so much from place to place and from time to time. As a very rough approximation, the dissolved gases are generally one or two hundred times more abundant that the nutrients, and the nutrients, in turn, are thousands of times more abundant than are trace elements.

In addition to what is in solution seawater also contains some fine particulate matter in suspension. Some of this particulate matter will eventually dissolve, and some will eventually add to the sediment on the ocean bottom. Organic particulate matter has other possible fates. It may be consumed directly by organisms or it may decompose through bacterial action and return to solution as nutrients, reusable by plants in photosynthesis.

The suspended particulate matter has a noticeable effect on the seawater chemistry. The particles may exchange some of their cations or anions with those dissolved in the water. They also provide surfaces on which some dissolved materials may precipitate out of solution and from which other materials may be dissolved into solution. The composition are conveniently grouped into four broad categories.

a. Major constituents

b. Dissolved gases

c. Nutrients or disslolved organic matter

d.Trace elements