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hippocampus

Joined: 27 Feb 2012 Posts: 126 Location: Bikini Bottom
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Posted: Tue May 15, 2012 7:21 am Post subject: All the Water on Planet Earth |
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I am posting this link so that teachers may share it with their students. It can be used to stimulate discussion on the conscientious use of water. If the country you are in is anything like the one I am in, most people there use water as if it were, well, water... as if it just fell out of the sky for free!
http://apod.nasa.gov/apod/ap120515.html
I think this photo dramatically illustrates how scarce, and how precious, water really is. To paraphrase Henry David Thoreau in Walden: lakes (and oceans) may seem practically bottomless to us, but to a surveyor (like Thoreau was) they are no deeper than saucers when considered in relation to the general height of dry land surrounding them.
Please look it up, I may be misinformed, but it is my understanding that all of the water on Earth was created at one time (in one geological era) and "they're not making it anymore". It can be artificially produced but it is rather infeasible in light of how much people use.
Last edited by hippocampus on Fri May 18, 2012 2:08 am; edited 2 times in total |
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tttompatz

Joined: 06 Mar 2010 Posts: 1951 Location: Talibon, Bohol, Philippines
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Posted: Tue May 15, 2012 10:35 am Post subject: |
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Clean, fresh water as a commodity is certainly in short supply globally and it is a good topic to think/talk about. Creating fresh potable water is neither cheap nor easy on a large scale.
Water as a substance is created and destroyed through various chemical processes (natural and human caused) on a regular basis and with 75% of the planet covered in it there won't be any shortage of it any time in the next aeon or two.
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Glenski

Joined: 15 Jan 2003 Posts: 12844 Location: Hokkaido, JAPAN
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Posted: Tue May 15, 2012 1:02 pm Post subject: |
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tttompatz,
The fact remains that although 75% of the world is covered in water, 99% of that is not freshwater (what we drink, feed to livestock, use for irrigation, etc.).
Water we can use is indeed running low.
Who leaves the faucet running when they brush their teeth or wash dishes? They are wasting water.
Lots of good lesson material on this topic is available on the Internet, and National Geographic had a good article on it recently (for those students with high reading ability). Colleague of mine teaches this topic annually to a group of uni students. |
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tttompatz

Joined: 06 Mar 2010 Posts: 1951 Location: Talibon, Bohol, Philippines
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Posted: Tue May 15, 2012 1:47 pm Post subject: |
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Glenski wrote: |
tttompatz,
The fact remains that although 75% of the world is covered in water, 99% of that is not freshwater (what we drink, feed to livestock, use for irrigation, etc.).
Water we can use is indeed running low. |
So I guess you missed the first sentence
tttompatz wrote: |
Clean, fresh water as a commodity is certainly in short supply globally and it is a good topic to think/talk about. Creating fresh potable water is neither cheap nor easy on a large scale. . |
in your rush to contradict me.
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Sashadroogie

Joined: 17 Apr 2007 Posts: 11061 Location: Moskva, The Workers' Paradise
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Posted: Tue May 15, 2012 6:25 pm Post subject: |
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So long as there's enough left for the vodka distilleries...
Hic! |
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Glenski

Joined: 15 Jan 2003 Posts: 12844 Location: Hokkaido, JAPAN
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Posted: Tue May 15, 2012 10:20 pm Post subject: |
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tttompatz,
No, I didn't miss the first sentence. I just felt you may have contradicted yourself! I mean, what's the point in saying (as we agree) that freshwater supplies are diminishing and are low in the first place, and then in another breath saying we have a lot of water around ("no shortage") when it is too difficult/expensive to convert the majority of water that is on hand? |
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tttompatz

Joined: 06 Mar 2010 Posts: 1951 Location: Talibon, Bohol, Philippines
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Posted: Tue May 15, 2012 10:25 pm Post subject: |
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Glenski wrote: |
tttompatz,
No, I didn't miss the first sentence. I just felt you may have contradicted yourself! I mean, what's the point in saying (as we agree) that freshwater supplies are diminishing and are low in the first place, and then in another breath saying we have a lot of water around ("no shortage") when it is too difficult/expensive to convert the majority of water that is on hand? |
Big difference between science and economics.
Just because it is not economic does not mean it is not there. It just means we are not willing to pay the price.
The OP implied that water is a non renewable resource and that is misleading.
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artemisia

Joined: 04 Nov 2008 Posts: 875 Location: the world
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Posted: Wed May 16, 2012 2:56 am Post subject: |
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Great resource, hippocampus. Thank you! |
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hippocampus

Joined: 27 Feb 2012 Posts: 126 Location: Bikini Bottom
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Sashadroogie

Joined: 17 Apr 2007 Posts: 11061 Location: Moskva, The Workers' Paradise
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Posted: Wed May 16, 2012 5:31 am Post subject: |
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Vodka distilled from saltwater is actually pretty good. So I don't really understand what all the bickering is about either, gentlemen. |
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johnslat

Joined: 21 Jan 2003 Posts: 13859 Location: Santa Fe, New Mexico, USA
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Posted: Wed May 16, 2012 12:02 pm Post subject: |
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Dear artemisia,
"Great resource, hippocampus. Thank you!"
But - is it a renewable or a non-renewable resource?
Regards,
John |
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Sashadroogie

Joined: 17 Apr 2007 Posts: 11061 Location: Moskva, The Workers' Paradise
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Posted: Wed May 16, 2012 8:29 pm Post subject: |
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Dear Johnslat
I'd venture that it is at the very least a toastable resource. Here's to you and yours! Hic!
Sasha |
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artemisia

Joined: 04 Nov 2008 Posts: 875 Location: the world
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Posted: Thu May 17, 2012 12:57 am Post subject: |
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johnslat wrote: |
Dear artemisia,
"Great resource, hippocampus. Thank you!"
But - is it a renewable or a non-renewable resource?  |
Dunno, John, but it got my students all excited. I checked the percentage of water that covers the planet with them and drew a circle representing Earth on the board and asked them to imagine all the water of the world � lakes, rivers, oceans � sucked up and put inside a ball. They had to draw circles to show the size of the ball in proportion to Earth (fits in nicely with what we�ve been doing). They drew circles either twice, half or a third of the size of Earth and were then shocked to see the NASA visual.
However, they�re convinced that NASA�s got it all wrong. In a way maybe they�re right because I don�t think the visual would include all the frozen water (glaciers etc.) on the planet.
(BTW, the link�s changed:)
http://apod.nasa.gov/apod/ap120515.html |
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tttompatz

Joined: 06 Mar 2010 Posts: 1951 Location: Talibon, Bohol, Philippines
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Posted: Thu May 17, 2012 2:51 am Post subject: |
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The visual, although misleading, is accurate in terms of mass of water vs the mass of the earth.
The earth is a ball 8000 miles in diameter and the water cover is 75% of the surface area to an average depth (guess here cause I don't have time to google it) of about 2 miles and a maximum depth of about 8 miles.
Considering the crust is, on average, 40 miles thick and there probably is no water in any form below the crust the amount of water in relation to non water mass within the earth would be small.
All of that said, water is indeed a renewable resource. It gets cleaned by nature through evaporation and rainfall (except in places where, due to pollution with sulfur dioxides (coal burning power plants as an example) you get acid rain rather than fresh rain).
Water is also being manufactured and destroyed though natural, chemical processes (vulcanism) and electrolysis (breakdown of water into hydrogen and oxygen).
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hippocampus

Joined: 27 Feb 2012 Posts: 126 Location: Bikini Bottom
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Posted: Fri May 18, 2012 2:20 am Post subject: |
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Thanks Artemisia. I have edited the link in the OP as well.
Again, that's all I want, is to get students thinking about the value of water: the more the better, which is why I am sharing this information here.
tttompatz: I hear you, but I still maintain the opinion that water is non-renewable in that we have a limited supply. Sure it's reusable, but why not try to maintain as much clean water as we can?
I don't know why you would say:
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The visual, although misleading, is accurate in terms of mass of water vs the mass of the earth. |
Kind of self-contradictory isn't it?
I think it doesn't matter how accurate the picture is, I am sure it is close enough. Artemisia, poor sod, apparently doesn't have a computer and projector in his classroom and has to resort to drawing chalk circles - so how accurate are they? Answer: it don't much matter. The students were suitably impressed enough to discuss the issue.
Quote: |
Water is indeed a renewable resource. It gets cleaned by nature through evaporation and rainfall (except in places where, due to pollution with sulfur dioxides (coal burning power plants as an example) you get acid rain rather than fresh rain). |
Quote: |
Water is also being manufactured and destroyed though natural, chemical processes (vulcanism) and electrolysis (breakdown of water into hydrogen and oxygen). |
All this is true, tttompatz, and all the stagnate water, sewage and dead zones like at the mouth of the Mississippi show that humanity is not doing all it can to see that this 'renewable' resource is in fact renewed. That's the problem- water recycling mismanagement and neglect.
Finally, I'd like to remind those of you who will discuss this topic in class that 97% of the world's water is saline. So imagine if 97% of the mass of that water ball in the picture were removed.
It's scary! |
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