Salt water contains Na+ and Cl- ions. Because these ions are free to move in the solution, salt water is electrically conductive. Increased conductivity attenuates the radio waves as the freely-moveable ions absorb and reflect the wave.
(see How can I create hindrances to radio waves?)
The same principle explains why metals block radio waves and are not transparent to visible light.
Pure water is a poor conductor, as it is a covalent compound. A very small amount of water dissociates into H+ and HO- ions, but highly purified water can be 1,000,000x less conductive as seawater.
I expect, depending on the salinity of the water and sensitivity of equipment, it would be easily noticeable in experiment.
From the book Freeze Drying by Georg-Wilhelm Oetjen:
Oesterle showed that not only can tBA speed up the sublimation of ice from
amorphous freeze-concentrated mixtures, but also similar effects can be achieved
with volatile ammonium salts such as ammonium acetate, bicarbonate and formate.
In other words, a scientist showed via experimentation that tBA (also known as tetrabutylammonium hydroxide, which is a type of ammonium salt) and other ammonium salts can speed up the sublimation of ice.
Here is some more information on ammonium salts, and here is some more information on tBA.
So, yes, certain salts can speed up the sublimation of ice.
Sources:
I am unable to access Oesterle's full paper, but here is a link to its abstract (the paper was entitled The influence of tertiary butyl alcohol and volatile salts on the sublimation of ice from frozen sucrose solutions: implications for freeze-drying).
Here is a link to a pdf of the book Freeze Drying; the quote above is from page 87.
(I assume you met sublimation as in the first sentence of your question it says "water ice will, over time, sublimate to vapor.")
Update:
Doing some further research, I've found salts that slow down the sublimation of ice (such as NaCl). What I'm finding is that it depends on the salt.
While I'm not sure, I believe I found a sort-of explanation of why salt sometimes affects sublimation - according to a chemistry.SE question (here):
In wood, most or all of the bonds between the individual atoms and fibre units are covalent; making them very strong...In ice, on the other hand, the units of the crystal is held together with comparatively weak hydrogen bonds, meaning that not a lot of energy is required for a surface molecule of water to escape...
In other words, perhaps salts of different kinds do one of the following:
- Don't do anything
- Weaken the bonds between the atoms, therefore speeding up sublimation
- Strengthen the bonds between the atoms, therefore slowing sublimation
From my research, I think that NaCl is one of the third type and ammonium salts like ammonium acetate are of the second type.
Please note that this explanation of the phenomenon is mostly speculation based on what I've found. It is mostly to show where I'm headed in my research on this topic.
Hope this helps!
Best Answer
solutes can also move across concentration gradients. that's why brining meat cannot be explained by osmosis alone (osmosis only involves solvent molecules)--there is diffusion of sodium ions into interstitial space.
as anna v alluded to, the difference between brining thanksgiving turkey and brining yourself is that it is a lot harder to perform the latter because you actually have a functioning renal system which dumps excess salt from your circulatory fluids into your bladder for later disposal. this is a diuretic process, i.e, it dehydrates you instead of making you more juicy. if i read right the paper i linked below, then the skin itself can function as a salt storage which gives some measure against your kidneys even having to deal with short exposure to salt water.
more on brining: net salt absorption from brines through your skin cannot be stopped because it is a diffusion process through the pores. what affects the rate is thickness of the skin, brine concentration, temperature, etc. (brining birds skin on is probably not as consequential as brining beef or pork skin on). the actual muscle cells have membranes ("lipid bilayer") which resist automatic ion diffusion and ion pumps to control ion movement in either direction. what brining actually does is increase the extracellular fluid volume--the amount of liquid trapped between cells rather than intracellular volume. the denaturing effect of salt on proteins undoubtedly increases the trapping effect even during the cooking process, leading to juicier meat. the idea of brining thus seems to be getting as much liquid in the meat before you cook it, and getting most of it to stay there after its done.
http://ndt.oxfordjournals.org/content/24/11/3282.full