How Much Does the Sea Weigh?

I was reading through one of the my A-level chemistry book when I came across an estimate that they had recorded for the total volume of the sea, which they worked out to be 1.37x109Km3 or 1370000000Km3 and this intrigued me somewhat, so I had a rummage through the internet to see if I could find an estimate for the average density of saline water, which I found I think on yahoo answers (Not exactly a solid peer reviewed source) and thought I’d do some calculations. Here’s what I came up with.


Estimated Volume of the sea = 1.37x109Km3


Average density of saline water = 1027Kgm-3


1.37x109Km3 = 1000000000(1.37x109m3)
                        = 1.37x1018m3


Mass = 1027Kgm-3(1.37x1018m-3)
         = 1.40699x1021Kg = 1.40699x1018tonnes
         = 1,406,990,000,000,000,000 tonnes


This number is 1.4 Quintillion tonnes.


Of course this figure is extremely rough with error bounds probably somewhere in the trillions of tonnes thanks to soluble debris from river and human activities, but still it gives you an idea of just how huge the oceans are.


Sources


Volume of Ocean from Salters Advanced Chemistry’s Chemical Storylines A2, Third Edition, published by Heinemann books, page 126


Average Density of Sea Water taken from a discussion on Yahoo answers but later found on website http://hypertextbook.com/facts/2002/EdwardLaValley.shtml data recorded by several reputable sources.