Hello pdy-ga,
Thank-you for your question.
First of all I should note here that it is difficult for these numbers
to be exact because of a number of factors; most notably the volume of
saline water on the Earth is only an estimate and the density of
saline water can also alter (depending on a number of factors). That
being said we can calculate the mass of saline water on Earth using a
few simple facts.
An estimate of the total volume of saline water on the Earth can be
calculated from this page:
http://ga.water.usgs.gov/edu/earthwherewater.html
The table gives:
Oceans, Seas, & Bays - 1,338,000,000 km3
Saline Groundwater - 12,870,000 km3
Saline Lakes - 85,400 km3
This is a total of 1350955400 km3 of saline water.
Using OnlineConversion.com we know that 1 km3 is the same as
1000000000 m3. Therefore the total volume of water in cubic meters is
1350955400 x 1000000000 m3 or 1350955400000000000 m3.
According to the Wikipedia the concentration of sea water (which makes
up the vast majority of the saline water in the world) varies from
1020-1030 kg m-3.
http://en.wikipedia.org/wiki/Sea_water
Therefore we can calculate an approximate upper and lower limit from
this density figure.
Lower: 1020 kg m-3 x 1350955400000000000 m3 = 1377974508000000000000 kg
Higher: 1030 kg m-3 x 1350955400000000000 m3 = 1391484062000000000000 kg
One metric ton is equal to 1000 kg. This gives our lower estimate a
value of 1377974508000000000 tons and the higher estimate a value of
1391484062000000000 tons!
Because of the inaccuracy of these numbers (see my opening comments)
we should probably quote the mass of salty water to be approximately
1.38x10^18 tons.
I hope that this answers your question. Should you require any
further assistance on this matter please do not hesitate to ask for
clarification. |