Re: Glaciers

The quick answer to your question is think about where the iceberg came 
from, rather than where it might float to.  By your subject line it looks
like you know that icebergs are "calves" of glaciers; they're just chunks
that break off from the glacier.  The glaciers are formed from 
precipitation that has fallen at some point in the past as fresh water.
So icebergs come originally from rain and snow, rather than seawater that
freezes.

But even if icebergs originally came from salt water, they would still be
mostly fresh.  Salt water freezes at a lower temperature than fresh water,
and as it freezes it excludes the salts from the ice.  The end result is 
ice that is mostly pure water with pockets of concentrated salts in it.

A quick web search located a site with more information of glaciology.  It
can be found at http://www.antdiv.gov.au/aad/sci/glacio/glacio.html

Good luck with your search for more information!