One thing really caught my attention in Dex’s article.
Security experts have been predicting that water rights in the Middle East, especially where Israel and its neighbors are concerned, will be the most serious aggravation of conflict in the not too distant future.
This makes developing a low cost desalinization technology a matter of urgency. Maybe it would be wise to invest in desalinization companies’ stocks.
Regarding the article’s take on sea mammals and drinking seawater. Popular writer Gardner Soule, in his book The Mystery Monsters, asked how it was that whales stayed alive drinking sea water. Did they, he asked, know about secret springs? Did they have some secret organ that removed salt that has this far eluded whalers?
It was a damned stupid set of questions. Soule should simply have asked whale biolohists. In The Year of the Whale, Victor B. Schaeffer notes that whales simply have better kidneys for this purpose than humans. They’re the “secret organ”, not exactly hidden from whalers.
The article’s claim that whales don’t need to drink strikes me as odd – if whales have a problem, it’s probably too much water. Whales can hardly help ingesting water when they eat, especialy the filter-feeding baleen whales. They probably don’t stop specifically to drink, but they’re probably taking in seawater all the time anyway.
Not so fast. I found the guy’s name… Alain Bombard. See here: http://www.sailnet.com/collections/seamanship/index.cfm?articleID=sailne0773%20%20
A quote from the article…
Run a Google search on him, though most pages are either in French, or link to pages about Bombard inflatable rafts.
I have a survival manual “Survival–How to Survive in Hostile Environments” written by Xavier Maniguet. This book includes a section on drinking seawater. Among other suggestions, Maniguet says one should first begin diluting freshwater (if available)…“adding a glass of seawater to a liter of fresh water will produce a liquid with the same osmotic pressure as beer”. He adds that if seawater must be consumed, some of the guidelines are: drink before you start to feel thirsty; intake should be divided up into about 10 portions of two or three mouthfuls each per day, limit consumption to no more that five to seven days to avoid exceeding the limits of renal function. If after this length of time you have been successful in obtaining freshwater from fish, turtles, algae or rain, you can again drink seawater in small doses for another five to seven days. Also suggested: alternate consumption of sea and freshwater (if available) and, most interestingly, saltwater enemas, as the mucous lining of the colon has a filtering system that other mucous membranes lack. Maniguet’s conclusion is “If seawater is drunk, hydration remains normal for about seven days, though death still occurs around the eighth or ninth day. However, the main point is that the individual remains perfectly conscious for seven days…this enables a person to get organized, allows an ecosystem to develop under the boat…and enables the individual to study his surroundings. After the seventh day, decompensation will set in rapidly, but seven days of relative comfort will have been gained.”
I was once stranded at sea, and though fresh water was in scant supply, the boat was more than adequately stocked with dry champagne. Sounds much better than it was.
Man, I went to the wrong high school
I know a little of physiology. The osmotic gradient of saltwater is much greater (3.5/1) than the human body. If you are in Seawater, the water in your body will “try” to dilute the salt in the ocean and you will dehydrate.
I have a very hard time believing that the blood vessels are permeable to water. If they were, then all the blood would leak out (or at least the plasma). By what mechanism would water be able to enter the blood vessels, but not leave them?
According to the master in his question to “Why do your fingers and toes wrinkle in the bathtub?”
(emphasis mine)
If the tissue under the stratum corneum cannot absorb water (which makes sense because otherwise you would really be a soggy lump after soaking in the hot tub for a while) you couldn’t get water to your blood vessels to absorb.
Regardless, there are hundreds, if not thousands, of stories about how dehydrated rescued sailors are after they have been immersed in the ocean for long periods of time. For example, take a look at the sailors of the USS Indianapolis. They were in the water for 9 days and many that survived the sinking of the ship became delusional and mad from dehydration–which then lead many to drink seawater. If blevy’s theory is correct, why did that happen?
This website, Dehydration, Osmosis and the 2nd Law of Thermodynamics, explains how simply immersing your self in salt water to get water is against the 2nd Law of Thermodynamics. I cannot vouch for the veracity of this website, but it sounds correct to me.
Thanks guys. I’ve been a little feverish and dehydrated this past week myself, so forgive any slips of my logic.
I didn’t realize salt water had such a high osmolarity which would of course make my scheme impossible. Sorry about my earlier doubts Chronos. Though by the way, what is the final word on skin water permeability. I understand your point about water leaking, but I don’t think this is the whole story. There are all kinds of size discrimination and molecule specific channels in the body and I’m curious what would happen if you sat in a pool for too long (your skin becomes so soft it can fall off - but how deep a layer is affected??). Looks like you’ve still got to bring water or desalinators on ocean voyages. Shucks.
SPOOFE, I remember reading an article about Alain Bombard too. He said it was nonsense that sea water would dehydrate you and claimed that people should just start drinking it sooner, before they were already dehydrated. The article said he started out his lengthy castaway experience by drinking a cup of seawater daily. But I always assumed that was in addition to fresh water, since a cup of seawater daily doesn’t sound like enough to keep a person alive.
Err…
This sentence can be a tad bit misleading:
“Technology is improving and costs are dropping, though, and there is speculation that desalinization techniques could be used to bring water to irrigate the deserts of the Middle East, for instance.”
The implication is that desalinization plants are not currently used in The Middle east. In fact, some mid-east countries use desalinization extensively. Saudi Arabia, for instance, gets 70% of their fresh water this way and produces 30% of the worlds total desalinized water themselves.
Link for reference:
http://www.water-technology.net/projects/shuaiba/
Regards,
-Bouncer-
The trick is, of course, to mix sea water with fresh water down to an acceptable level of saltiness. So if you don’t know where your next fresh water will come from, mix a cocktail of fresh water, sea water and urine. This will keep you alive until you kill yourself just to get rid of the memory. 
The trick with the plastic sheet for desalination, or even for extracting water from moist materials (plants, mud, etc.) is to have an enclosure with an higher than ambient temperature, closed on top with the plastic sheet. The enclosure should be as air tight as possible to keep the moist air inside. The plastic sheet being close to ambient, and therefore colder than the moist air, will be covered in condensate, which will run down to the low point and drip into your receptacle. The ratio of plastic sheet area and enclosure volume should be as high as possible.
> The U.S. government notes that there have been significant
> efforts at desalinizing seawater, notably in California and
> Florida, where a few towns are using desalinization methods
> to remove the salt from seawater and make it suitable for
> drinking.
I can’t wait until a few years from now when the whole ocean will have been desalinated!
Anyway, as I am a wiseass, I will assume you’re talking about the more normal process of removing the seawater from the ocean first and then desalinating that, and distributing it for consumption. One large problem blocking the mass use of desalinization is that after desalinating water, you are left with a soup of salt, basically, which is just called a brine, and you have to do something with the brine. The most acceptable alternative seems to be to run a big pipe a couple of miles out into the ocean and pump the brine out thataway. For obvious reasons, then, desalinization works only on ocean coastlines and would not be suitable for smaller bodies of water, where the increase in salinity would be toxic. And even on ocean coastlines, sure, that amount of salt would get diluted pretty fast, but the change would presumably be sufficient to kill coral, for example, so you probably only want to pump out the brine into relatively lifeless areas.
Completely on a different topic, but I thought I’d bring in an aspect of the diverse cultures in South Africa. One of the main cultural groupings (tribe is no longer appropriate, IMO) amongst the South African blacks is the Basotho (South Sotho) people. If you’re curious about where they live, try to find Lesotho, the Mountain Kingdom, a sovereign nation inside South Africa. This is where they eventually settled after the tribal wars dispersed the tribes.
But I’m straying. One of their beliefs (mainly held by the older people these days), and I think this is true of several other groups as well, is that drinking sea water is an excellent medicine, especially for stomach problems. But it has to be pure sea water, with sand present.
I remember that until recently, we had to bring several bottles of seawater with sand back to my parents’ farm for the workers, whenever we took a seaside holiday.
Are there any better solutions, like, say, selling the salts commercially? I know lots of people like to buy genuine sea salt at the supermarket … or perhaps it could be sold to people as a traditional upset-stomach remedy, as per Valerion’s post. Or maybe, if the brine left over from desalination is not suitable for human consumption, it could be shipped off to Minnesota for pouring on the roads and whatnot?
I mean, surely there’s got to be some way to get rid of it that doesn’t involve just dumping it back in the water you want to desalinate …?