Why is it difficult to turn seawater into drinking water?

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Okay, but I didn't get it that way. Felt more like pulling teeth.:D

Irrelevant. I will not allow my lack of clarity to stop me from casting judgment on you.
I have termed you as 'goofy' and goofy you shall stay.
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Well I did say it was a good start and I'll still stick with that. With more survivors you actually increase the number of people that will be in "abject misery" in many places on this Earth.
What you're saying is that so long as a nation is in misery we should try to keep their birthrate down. Not doing that is one of the major causes of the misery in the Third World. We gave them vaccines and antibiotics, without realizing that the average number of children per family to reach puberty was going to skyrocket, and this would lead to a population crisis.
I sometimes wonder if survival is enough?
No, of course it is not enough. But it is essential, because without survival nothing else matters.
I know part of that problem is I am used to the standard of living I have, and I'm just not willing to survive at levels much lower than I'm used to. That's got to be someone else's job if it comes right down to it.
Well then take heart from the fact that the second derivative of population went negative around 1980, because it turns out that the most effective contraceptive is prosperity. The population will reach ten billion around the end of this century and then start falling, for the first time in tens of thousands of years.

Of course then you'll have to worry about the economy. Every economic model since Adam Smith assumes (without comment) that a steadily increasing number of producers and consumers will be its engine of prosperity.
US farm subsidies, the vast fertile mid west, and well meaning groups all actually make life worse in many places in Africa, where locals could grow more food than the population needs. Why don´t they? you may ask. Answer is that the boat loads of food US (and some others) send is not all eaten by the leaders, but sold at prices in local markets which are less than the cost of local production, so even those with land to farm do not, but buy the cheaper food from America (or starve). That is less costly to them than raising their own, which they can not sell at a positive return. Many economies in Africa would be self sustaining if cheap food from America were not allowed into those African countries.
Your argument is persuasive. But then why did I have to launch a food drive for Ethiopia in the early 1980s? Why weren't they munching away on all those cheap American corn flakes that you claim are for sale in every bazaar?
It is little wonder China is winning the battle for the hearts and minds of Africa, with trade now more than the US has, many oil and mineral rights granted, etc.
China has a long history of colonialism that is nothing like the form practiced by the Western nations. Their Buddhist monks brought the Iron Age to Japan and Korea, complete with (their own) written language and (their own) legends and other cultural motifs, without absorbing them into China. Of course Vietnam wasn't so lucky. And neither is Tibet, who already had their own Buddhist monks, written language and Iron Age technology.

We're still expecting China to "rescue" Greece by making an offer they can't refuse.
The RMB is starting be be used, but the dollar is still dominate - but for how long?
The sun sets on every empire eventually. Who knows when it will be our turn? If we don't start electing a better class of politicians, then perhaps within our (yours and mine) lifetime.
 
I did some searching and couldn't find any support for what you just said. Do you have a link we can view in support of that?

Strange, how about the WHO for a reference (referencing amongst others the CDC)

Regular intake of low-mineral content water could be associated with the progressive evolution of the changes discussed above, possibly without manifestation of symptoms or causal symptoms over the years. Nevertheless, severe acute damage, such as hyponatremic shock or delirium, may occur following intense physical efforts and ingestion of several litres of low-mineral water (Basnyat et al. 2000). The so-called "water intoxication" (hyponatremic shock) may also occur with rapid ingestion of excessive amounts not only of low-mineral water but also tap water. The "intoxication" risk increases with decreasing levels of TDS. In the past, acute health problems were reported in mountain climbers who had prepared their beverages with melted snow that was not supplemented with necessary ions. A more severe course of such a condition coupled with brain oedema, convulsions and metabolic acidosis was reported in infants whose drinks had been prepared with distilled or low-mineral bottled
water (CDC 1994).

Then there is the issues with low calcium and magnesium

2.2 Practically zero calcium and magnesium intake from lowmineral
water
Calcium and magnesium are both essential elements. Calcium is a substantial
component of bones and teeth. In addition, it plays a role in neuromuscular
excitability (i.e., decreases , the proper function of the conducting myocardial
system, heart and muscle contractility, intracellular information transmission
and the coagulability of blood. Magnesium plays an important role as a cofactor
and activator of more than 300 enzymatic reactions including glycolysis, ATP
metabolism, transport of elements such as sodium, potassium, and calcium
through membranes, synthesis of proteins and nucleic acids, neuromuscular
excitability and muscle contraction.
Although drinking water is not the major source of our calcium and
magnesium intake, the health significance of supplemental intake of these
elements from drinking water may outweigh its nutritional contribution
expressed as the proportion of the total daily intake of these elements. Even in
industrialized countries, diets not deficient in terms of the quantity of calcium
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and magnesium, may not be able to fully compensate for the absence of calcium
and, in particular, magnesium, in drinking water.
Since the early 1960’s, epidemiological studies in many countries all over the
world have reported that soft water (i.e., water low in calcium and magnesium)
and water low in magnesium is associated with increased morbidity and
mortality from cardiovascular disease (CVD) compared to hard water and water
high in magnesium. An overview of epidemiological evidence is provided by
recent review articles (Sauvant and Pepin 2002; Donato et al. 2003; Monarca et
al. 2003; Nardi et al. 2003) and is summarized in other chapters of this
monograph (Calderon and Craun, Monarca et al.). Recent studies also suggest
that the intake of soft water, i.e. water low in calcium, may be associated with
higher risk of fracture in children (Verd Vallespir et al. 1992), certain
neurodegenerative diseases (Jacqmin et al. 1994), pre-term birth and low weight
at birth (Yang et al. 2002) and some types of cancer (Yang et al. 1997; Yang et
al. 1998). In addition to an increased risk of sudden death (Eisenberg 1992;
Bernardi et al. 1995; Garzon and Eisenberg 1998), the intake of water low in
magnesium seems to be associated with a higher risk of motor neuronal disease
(Iwami et al. 1994), pregnancy disorders (so-called preeclampsia) (Melles &
Kiss 1992), and some types of cancer (Yang et al. 1999a; Yang et al. 1999b;
Yang et al. 1999c; Yang et al. 2000).

http://www.who.int/water_sanitation_health/dwq/nutdemineralized.pdf
 
Strange, how about the WHO for a reference (referencing amongst others the CDC)

Then there is the issues with low calcium and magnesium

http://www.who.int/water_sanitation_health/dwq/nutdemineralized.pdf

But I just read a report that said you could get all the minerals you need in your diet. So the only time pure water would be much of an issue is if you have a sub-nutritional diet. I know many millions of people in this world do have a sub-nutritional diet. Currently I do not.
 
But I just read a report that said you could get all the minerals you need in your diet. So the only time pure water would be much of an issue is if you have a sub-nutritional diet. I know many millions of people in this world do have a sub-nutritional diet. Currently I do not.

Did you read the article? Paticually the bit I posted about the magnesium and calcuium in diet not making up for deficiency and the deficiency is a separate mater from water intoxication which is a lethal condition caused by the intake of to much pure water. Follow the link I posted and actually read it
 
... But then why did I have to launch a food drive for Ethiopia in the early 1980s? Why weren't they munching away on all those cheap American corn flakes that you claim are for sale in every bazaar? ...
During atypical times, like draughts, westerners with surplus food should help feed the hungry and starving; but not chronically supply food. During the draught, it is the lack of rain, not cheaper food available than local production can provide that is why adequate food is not produced locally.

I don´t think boxes of cereal are sent, bulk items like rice etc. that are part of the native diet are sent now. This supply is not always available. Basically mainly when there are production surpluses that can not be more profitable sold. Soon, if not already the destruction of local farming by well meaning organizations will end. There are ever more people of means in China, etc. and they are eating more meat too. Thus, the demand is or soon will be chronically greater than even the fertile Mid West can produce with its very industrialized mass production agriculture - a modern miracle.

What will be interesting to follow, is when poor Americans can not even afford “Franks & Beans” as the Chinese, etc. can and will be bidding the prices up with demand greater than supply. Imports by China of basic grains (to feed their pigs - more than all in the rest of the world! etc.) are increasing at about 15% per year now.

In the US´s capitalistic system, it will be hard to tell privately owned Cargill they can not sell to the highest bidder. There may be food riots, and serious political changes coming in the next decade. The Chinese curse (May you live in interesting times) is being made real by the Chinese both in food demand and dollar problems.

Just to put in a few "on topic" words, I note (and very few know) that there is more energy stored in a barrel of salt* than in a barrel of oil but no one has yet figured out how to utilize it and great quantities of fresh water would be required plus the power level would be low. The osmotic pressure across a membrane of pure salt against pure water will lift a column of water several hundred (I forget exact value) feet high. I.e. greater hydrostatic pressures than most hydroelectric dams have available.

* This may seem more plausible to you when you think of the solar energy absorbed to turn a inland sea into a salt flat. When some salt enters into water solution it "falls down" into a very deep energy hole. Fundamentally, this is why it takes a lot of energy to separate salt from H2O. Again, it is sad that no one has discovered how to economically capture the energy being released, as we can when a rock falls down into a deep gravity hole. A few salt / water motors exist, but they are just toys.
 
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Can we us seawater for irrigation?
Will it kill the crops?

You ever herd of soil salinity problems, huge sections of farm land in Australia have been destroyed because of salt from rising water table caused by irrigation. What do you think would happen if that irrigation water was also brine.

You ever seen a salt farm on the coast line, sea water is allowed to flow in and then evaporate leaving the salt. You think anything will grow there apart from salt bush?
 
Why is seawater salty? Where is the source of NaCl for seawater?
NaCl dissolves in rivers and ends up in the sea.

About 200 years ago, when the age of the Earth was a subject of much discussion (Religious folk stating it was less than 6000 years old as that is what the bible tells) a calculation, not badly done*, was made to get a scientific estimate of the age of the Earth, based on the salt content and flow rates of many rivers. (Assuming that at "T=0" the oceans were pure H2O.)

* Giving a very much too small answer; however, very much greater than 6000 years.
 
{Post 33 in part} US farm subsidies, the vast fertile mid west, and well meaning groups all actually make life worse in many places in Africa, where locals could grow more food than the population needs. Why don´t they? you may ask.

Answer is that the boat loads of food US (and some others) send is not all eaten by the leaders, but sold at prices in local markets which are less than the cost of local production, so even those with land to farm do not, but buy the cheaper food from America (or starve). That is less costly to them than raising their own, which they can not sell at a positive return. Many economies in Africa would be self sustaining if cheap food from America were not allowed into those African countries. ...

Here is some graphical data showing how Africa is ever more dependent upon the US´s surpluses being dumped there, instead of becoming self sufficient in food with local production:
060412.jpg
The road to hell is paved with good intentions! (Let´s feed the hungry.)
 
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What will be interesting to follow, is when poor Americans can not even afford “Franks & Beans” . . . .
That will not happen soon. It's well documented that the greatest nutritional problem among America's poor is obesity! When foreigners tell me they want to come to America and interview our poor people to find out for themselves what their lives are like, I always tell them that the easiest way to find a large number of poor Americans is to go to McDonalds.

The only poor people who are undernourished are the ones with mental issues. In the 1960s and 70s, we decided as a society that it was unfair to lock people up in mental institutions against their will just because they were not taking care of their health. So today you have to let them out after three days.

I understand. It seems that most homeless people eventually end up in Los Angeles because you can sleep outside there about 330 days a year. I'd rather sleep in a park in L.A. and panhandle for food than be locked up in a psych ward. (My wife worked in one for many years so she feels the same way. Just being there not locked up was horrible.)

When you get down to the people who are so crazy or so poorly adjusted that they literally can't take care of themselves, then you find people who don't get enough to eat. But that's a ridiculously small segment of the population. I have seen people walk up and stuff hot dogs in their mouths. In a culture like ours where the "average weight" is now what we used to call "overweight," we can't stand the sight of someone who isn't eating enough.

AIDS, gunfights, drug addiction, domestic abuse, drunk driving, yatta yatta, we'll put up with all that. But starvation??? No way! Everybody eats in America. Even our pets are overweight.
The Chinese curse (May you live in interesting times) . . . .
That's an urban legend. It was made up by an Englishman who had never been to China. ;)
 
To Fraggle:

I agree with you- America´s main nutritional problem currently is obesity. That is partly caused by the very cheap food and the profits to be made by selling it. Food is very small part of typical frugal, middle class, American´s budget in part because of the fertile Mid West, but more due to the oil based agriculture that has developed in the US.

There was a study more than 20 years ago that concluded ~95% of the cost of an Idaho potato, eaten in NY City, was the oil (and gas or electricity) used to produce it, ship it, and cook it there (and it is much worse now as back then oil was much cheaper).

If the dollar has collapsed, only the military (and martial law forces) will get much oil derived products. This combined with fact that typical items on your table have traveled more than 1000 miles, often by truck, to get there, will solve America´s obesity problem –to vastly under state the effect of a collapsed dollar on the food consumption in the US.

Part of the problem as I mentioned in recent post, is the US´s capitalistic system is not well designed to tell food processors, like privately owned Cargill, that they can not sell to the highest bidder (which with dollar collapsed and many without jobs in the US, that would be China.)

China is already at the limits of its internal food production capacity and with a population that is rapidly increasing in wealth and eating much more meat. Why their imports of basic food stocks, (grains etc) are growing about 15% annually. Pork is the favorite meat in China; they currently have more pigs than all the rest of the world combined does. Already they cannot feed them without these grain imports. Their demand for food (including animal feed) will only grow worse. “Dr China” will cure the US´s obesity problem in only a few years.

---------------------

“… The number of Americans receiving food stamps rose to a record 41.8 million in July {2010} as the jobless rate hovered near a 27-year high, the government said.

Recipients of Supplemental Nutrition Assistance Program subsidies for food purchases jumped 18 percent from a year earlier and increased 1.4 percent from June, the U.S. Department of Agriculture said today in a statement on its website. Participation has set records for 20 straight months. ..." From October 2010 article here: http://www.bloomberg.com/news/2010-...-41-8-million-americans-in-july-u-s-says.html

With both rapidly growing food needs and rapidly rising prices, how long do you think the US can afford this cost, especially if Republicans get control of either house of Congress. US already has serious budget* problems, with baby boomers now collecting Social Security, instead of being in their peak earning and tax paying years.

* Except the US government is so dysfunctional it does not even have a budget and has not had one for three years!
 
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Actually it can kill you if you drink to much without adding salts or eating a lot of salt.
I did some searching and couldn't find any support for what you just said. Do you have a link we can view in support of that?
Look up electrolyte balance.

The way it can kill you is by knocking your Na, C and K electrolytes out of balance, causing your muscles (such as your heart) to stop working.

It is identical but opposite to dehydration (electrolyte balance is the reason athletes drink vitamin-enhanced drinks instead of (or at least in addition to) plain water).
 
The problem with providing fresh water (and food while we're at it) to the impoverished parts of the world is not one of how to make it or where to get it. The problem is distribution and cost of processes. All those desalination plants and the resources they require for building, transporting and maintaining just cost too much. Impoverished countries can't afford them.

We have solutions, what we don't have is money.

There are two ways to obviate this:
1] Someone must invent a cheap, and inexpensively-maintained-onsite device that can be mass-produced. And until they do,
2] Other nations must donate their money to build, transport and maintain the expensive versions. And that means citizens need to donate.
 
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