The Naked Scientists

The Naked Scientists Forum

Author Topic: what makes water blue  (Read 12051 times)

Offline huwston

  • Jr. Member
  • **
  • Posts: 26
    • View Profile
what makes water blue
« on: 12/01/2007 19:19:30 »
whit is it in water that makes it blue?

is it the oxygen?

or hydrogen?
« Last Edit: 12/01/2007 21:38:27 by huwston »


 

Offline simpsonsman

  • Jr. Member
  • **
  • Posts: 12
    • View Profile
what makes water blue
« Reply #1 on: 13/01/2007 01:53:38 »
its not blue
 

Offline huwston

  • Jr. Member
  • **
  • Posts: 26
    • View Profile
what makes water blue
« Reply #2 on: 13/01/2007 10:24:55 »
ok sorry it not blue, then what makes it appear blue?
 

Offline ukmicky

  • Moderator
  • Neilep Level Member
  • *****
  • Posts: 3011
    • View Profile
    • http://www.space-talk.com/
what makes water blue
« Reply #3 on: 13/01/2007 15:51:47 »
Reflection from the sky I i would have thought but the cleanliness of the water would have a big say on the shade of the blue.
 

Offline WylieE

  • Sr. Member
  • ****
  • Posts: 236
    • View Profile
what makes water blue
« Reply #4 on: 13/01/2007 16:50:58 »
Really?
 I thought water did have an intrinsic color, and that was blue- a very faint blue, but if you had enough water this would be visible.  I thought it was due to the light exciting the vibrational energy of the water molecules. 
  But it was a long time ago, in a galaxy far away that I heard this, so maybe it was just an urban legend or has since been shown to be incorrect. . .
If so, I'd love to hear why this is incorrect.
Colleen
 

Offline ukmicky

  • Moderator
  • Neilep Level Member
  • *****
  • Posts: 3011
    • View Profile
    • http://www.space-talk.com/
what makes water blue
« Reply #5 on: 13/01/2007 17:03:26 »
No not really but possible
 

Offline chris

  • Neilep Level Member
  • ******
  • Posts: 5339
  • Thanked: 65 times
  • The Naked Scientist
    • View Profile
    • The Naked Scientists
what makes water blue
« Reply #6 on: 13/01/2007 17:40:00 »
Everything underwater looks very blue doesn't it? The reason for this, and hence the "blueness" of the sea, is similar in some ways to the reason that the sky is blue.

Water molecules resemble tiny boomerangs, with a central oxygen atom at the apex and two hydrogen atoms at the tips. These molecules can soak up light in the infrared (heat) end of the spectrum. This is why water vapour in the atmosphere is a more potent greenhouse gas than carbon dioxide.

But in the ocean, where water molecules are surrounded by many other water molecules, a phonomenon called hydrogen bonding occurs. These are weak "inter-molecular" attractive forces; put simply, water is what's known as a "polarised molecule". The central oxygen pulls the electrons of the two hydrogens towards itself, making the hydrogens slightly plus and the oxygen slightly minus. Since unlike charges attract, a hydrogen on one molecule will be attracted to the oxygen of another, adjacent, water molecule. This makes water sticky and accounts for its wonderful life-sustaining properties.

The consequence of this hydrogen bonding is that it makes the molecules "stiffer" so when light hits water, instead of absorbing just in the infrared it begins to absorb more strongly at visible red wavelengths too. Because red wavelengths are being soaked up, leaving relatively more blue light behind, the water looks blue. And the deeper you go the more pronounced this effect, so the "bluer" everything looks.

Ice also does this, which is why the thick walls of ice at the Earth's poles, and on glaciers, have that beautiful blue hue.

Chris
 

Offline WylieE

  • Sr. Member
  • ****
  • Posts: 236
    • View Profile
what makes water blue
« Reply #7 on: 15/01/2007 02:50:20 »
Thanks for the answer! 
It makes sense now.
Colleen
 

Offline Karen W.

  • Moderator
  • Naked Science Forum GOD!
  • *****
  • Posts: 31653
  • Thanked: 5 times
  • "come fly with me"
    • View Profile
what makes water blue
« Reply #8 on: 15/01/2007 03:48:59 »
Everything underwater looks very blue doesn't it? The reason for this, and hence the "blueness" of the sea, is similar in some ways to the reason that the sky is blue.

Water molecules resemble tiny boomerangs, with a central oxygen atom at the apex and two hydrogen atoms at the tips. These molecules can soak up light in the infrared (heat) end of the spectrum. This is why water vapour in the atmosphere is a more potent greenhouse gas than carbon dioxide.

But in the ocean, where water molecules are surrounded by many other water molecules, a phenomenon called hydrogen bonding occurs. These are weak "inter-molecular" attractive forces; put simply, water is what's known as a "polarised molecule". The central oxygen pulls the electrons of the two hydrogens towards itself, making the hydrogens slightly plus and the oxygen slightly minus. Since unlike charges attract, a hydrogen on one molecule will be attracted to the oxygen of another, adjacent, water molecule. This makes water sticky and accounts for its wonderful life-sustaining properties.

The consequence of this hydrogen bonding is that it makes the molecules "stiffer" so when light hits water, instead of absorbing just in the infrared it begins to absorb more strongly at visible red wavelengths too. Because red wavelengths are being soaked up, leaving relatively more blue light behind, the water looks blue. And the deeper you go the more pronounced this effect, so the "bluer" everything looks.

Ice also does this, which is why the thick walls of ice at the Earth's poles, and on glaciers, have that beautiful blue hue.

Chris

Chris I am amazed by your knowledge.. It is very interesting. I have noticed here in the rivers, during the winter the rivers get muddy for obvious reasons, but in the spring that clears and the rivers look a beautiful  sheer green and more clear. When the sun becomes more intense, I notice in the summer that the waters become a different green Has this something to do with algae growth in the waters..?? 
 

Offline chris

  • Neilep Level Member
  • ******
  • Posts: 5339
  • Thanked: 65 times
  • The Naked Scientist
    • View Profile
    • The Naked Scientists
what makes water blue
« Reply #9 on: 15/01/2007 11:19:21 »
Yes, it's algae. Algae are tiny single-celled plants and use the green pigment chlorophyll to soak up sunlight and turn it into chemical energy (sugars).

The chemical reactions driven by photosynthesis are sensitive to temperature and how much light there is. So when summer comes, and both increase, the rate of photosynthesis shoots up. The algae have more energy, so they can grow more rapidly. This increases their population and the water becomes a deep green - the colour of the algal cells...

Chris
 

Offline Karen W.

  • Moderator
  • Naked Science Forum GOD!
  • *****
  • Posts: 31653
  • Thanked: 5 times
  • "come fly with me"
    • View Profile
what makes water blue
« Reply #10 on: 15/01/2007 16:00:20 »
Thank you Chris, I was wondering that, as When We built our Pond in the front yard, we decided to make it pretty big but we started out about 15 ft long by about 8 to 10 ft across, of course it was not rectangular we just kind of did a freestlye shape.. anyway we started out with nothing in the yard to shade the pond so in the summer when the sun was so bright, we had a dickens of a time keeping the algae at bay so we could see the fish. Then in the winter it would become more clear, I assumed it was due to the fact that the cloud cover and rain were keeping the pond clearer, with the darker skies and cold keeping algae growth down and the rain kind of constantly replenishing the water..IE, it rains a lot here in the winter! Well I bought a couple of maple trees and as they have grown, they began to provide shade for the pond . This seemed to help as far as the upper part of the pond was concerned.. The lower half was a separate unit, a liner, and it had no shade still. So My aunt had a catalpa tree at her house that was always dropping seed so I was able to get a couple of seeds that took off like crazy when I planted them in a pot. after a few months I transferred them into the ground and boy did they take off. Right now it is providing wonderful shade for the pond and the algae growth has really been slowed down during the summer.Is there anyway without chemical alteration to further reduce the algae during those months? Are there Plants or natural things I can use which will not harm the fish..?
« Last Edit: 15/01/2007 16:04:25 by Karen W. »
 

Offline WylieE

  • Sr. Member
  • ****
  • Posts: 236
    • View Profile
what makes water blue
« Reply #11 on: 15/01/2007 22:53:21 »
Oh I'm jealous, you have catalpa trees. . any good worms?  If so you'll have tons of fish!
Colleen
 

Offline Karen W.

  • Moderator
  • Naked Science Forum GOD!
  • *****
  • Posts: 31653
  • Thanked: 5 times
  • "come fly with me"
    • View Profile
what makes water blue
« Reply #12 on: 16/01/2007 01:34:35 »
 Colleen, We have two ponds on the property but they are both stalked with ornamental fish. They are not huge ponds..Our pond is stalked with little pet store feeder fish which have grown to be about 6 to 8 inches long each and a coi.  Worms are great...LOL but you have walk down to the river to fish, my pond houses my little pets not dinner!! LOL The two catalpa trees are doing great.. We love them as The leaves are so large and beautiful. I love in the fall when the big cigar pods get ready to fall they look so funny hanging from the branches. They grow very well here in northern California.

The pond is full of fish! They started with ten feeder fish and now there are many dozens and we never feed them as the pond produces enough nutrients bugs etc for the fish to thrive on their own.. It is very nice. I built a bridge out of old redwood house planks that were tongue and groove about 2x6 I would say. They were from an old house I lived in as a small child. The wood had been salvaged. I made it big enough to cross the middle of the pond at a narrower spot where the two levels come together. I like that vantage point of view but that is where I can see the algae problem the most.. Right now it is a bit clearer as it is winter. but if it is indeed algae that colors it in my pond then perhaps there is hope to cut it back enough to make visibility better and yet still provide enough bacteria and nutrients for the fish to thrive!!

The colored wave length's are interesting, I am assuming that this also applies to the red sea the black sea etc. I assume they are named such due to the appearance of the water color, Is this correct?
« Last Edit: 16/01/2007 01:36:37 by Karen W. »
 

Offline WylieE

  • Sr. Member
  • ****
  • Posts: 236
    • View Profile
what makes water blue
« Reply #13 on: 16/01/2007 02:41:18 »
Wow Karen,

That sounds incredible! I hope it is warm enough there now that you can go out and enjoy it a bit.

 I love catalpa trees, very beautiful with their white flowers and yes, there's something about the giant cigars hanging off of them that is quite odd- (and I do love the worms too- they're actually very cute).

 It's a bit off this topic, but one trick for getting rid of algae is to throw barley straw into the pond.  As it decays it helps control algae and it doesn't seem to have any negative effects on fish- although it probably wouldn't help much with the visibility.

Colleen
 

Offline Karen W.

  • Moderator
  • Naked Science Forum GOD!
  • *****
  • Posts: 31653
  • Thanked: 5 times
  • "come fly with me"
    • View Profile
what makes water blue
« Reply #14 on: 16/01/2007 02:49:25 »
Thanks for the tip! It is very cold here this last week. Our evenings and in the wee hours of the mornings are runing 25 to 28 degrees right now. Has been colder then the usual upper 30's low 40's.  Thanks Colleen!
« Last Edit: 17/01/2007 03:39:42 by Karen W. »
 

Offline huwston

  • Jr. Member
  • **
  • Posts: 26
    • View Profile
what makes water blue
« Reply #15 on: 16/01/2007 23:25:43 »
thanks try filling a bath almost full and u can almost see the colour. well, it definately changes the colour of the bath.
 

Offline ukmicky

  • Moderator
  • Neilep Level Member
  • *****
  • Posts: 3011
    • View Profile
    • http://www.space-talk.com/
what makes water blue
« Reply #16 on: 18/01/2007 03:01:55 »
Hi Karen


Algae live near the surface and  blooms are caused by the sun and excessive levels of nutrients moving around in the pond water and their are many of reasons as to why .

The first one could be your fish. I believe carp are bottom feeders and in their search for food they stir up the bottom of the pond causing all that dead stuff sitting at the bottom rotting away to get kicked up spreading nutrients to the upper layers of the water where the algae live ,give any plant nutrients and they will grow.

Even worse a too powerful or badly situated fountain pump, fountain or waterfall  can cause underwater currents to spread nutrients from the bottom once again to the surface layers of the pond giving the algae nutrients to grow .

Or maybe you feed your lawn and some of that feed finds its way into the pond after it rains .

Or maybe to many leaves or fruits from surrounding plants fall into the pond, Easy fix , put a net over the pond.


ITS PROBABLY ALL THE ABOVE

How to stop the blooms

Make the pond healthier by introducing underwater plants maybe Canadian pond weed as its cheap and easy to get, it grows quickly but is very easy to control and is probably the best oxygenater of water you can get. Well oxygenated water has two benefits ,first the fish need well oxygenated water and secondly the bacteria at the bottom of the pond work better and more efficiently and quickly eat up all the dead fish food ,leaves etc which prevents algae blooms as their is less decaying matter/nutrients sitting at the bottom of the pond waiting to be disturbed by the fish or fountain.

Another way is to introduce some Lilly's , enough so they cover a large percentage of the surface area of the pond which cuts down the amount of sun light entering the water ,This is probably the quickest fix.

Or you can  buy a chemical from your local pond specialist which when added to the water IT kills the algae but not your fish, but is only used as a last resort.

« Last Edit: 18/01/2007 03:41:16 by ukmicky »
 

Offline Karen W.

  • Moderator
  • Naked Science Forum GOD!
  • *****
  • Posts: 31653
  • Thanked: 5 times
  • "come fly with me"
    • View Profile
what makes water blue
« Reply #17 on: 18/01/2007 04:28:14 »
 I have tons of pond lilies in the upper and lower pond and you are right they have helped. We can't hardly see the colorful fish these days.. LOL we have always had lilies. We put the pond in in 97' I tried one of the water treatments last year it was costly with very little results. You really had to keep at it. I worried about all the good stuff it was hurting although I seen no visible damage from its use!

Is canadian Pond weed like duck weed?? We have alot of that. I also have a hge Dinosaur plant I can't remember what its latin name is. It sits in the pond also! I was worried because of how heavy the ice has been this winter if it was to survive.. I forgot to cover it this year! I will look for the plant thing to help. DO you have a Pond Michael? They are very relaxing!
 

Offline chris

  • Neilep Level Member
  • ******
  • Posts: 5339
  • Thanked: 65 times
  • The Naked Scientist
    • View Profile
    • The Naked Scientists
what makes water blue
« Reply #18 on: 20/01/2007 14:20:46 »
Hi Karen

what UKmicky says is correct, that nutrients in the water cause algae to flourish. But what he omits to point out is that the most important nutrient is nitrogen (in the form of ammonium (NH4), and nitrate (NO3) ions), and the best source of that is the urine produced by your fish.

Plants (and animals) lack the necessary metabolic pathways that are required to "fix" atmospheric nitrogen and turn it into bioavailable forms that can be used in their cells. Instead they rely on soil-dwelling "nitrogen fixing" bacteria, which have the necessary chemical know-how.

Some of these microbes are free-living in the soil such as the Azotobacters, Klebsiellae, some Clostridia, Cyanobacteria and so on, but others have developed a much more specialised relationship with the plant world. For instance, the species Rhizobium, when it meets a plant root, releases factors which trigger the roots to grow swellings, called root nodules. These engulf and then nourish and protect the bacterial colony. This image, from a webpage by Jim Deacon at the Institute of Cell and Molecular Biology, Edinburgh University, shows root nodules (arrowed) of a clover plant:




In return for the plant's hospitality the bacteria capture airbourne nitrogen (N2), which is chemically very stable and unexciting, and use an enzyme complex called nitrogenase to turn it into ammonia (NH3). This is much more reactive and therefore easier to involve in chemical reactions. The nitrogen it contains is a critical ingredient in the amino acids that are the building blocks from which proteins are constructed.

This is the nitrogen fixing reaction catalysed by nitrogenase:

N2 + 8H+ + 8e- + 16 ATP → 2NH3 + H2 + 16ADP + 16 Pi

(ATP = adenosine triphosphate, an energy source, Pi = inorganic phosphate)

So animals, including humans, obtain the nitrogen for their proteins by eating other animals and plants, which got it from bacteria, which got it from the air. But when we burn proteins for energy we need to get rid of the excess nitrogen. To do this it's turned into urea in the liver and then excreted in urine from the kidney. Once the urea is back in the environment it gets picked up by plants again as a fertiliser.

So in your pond the fish are peeing out nitrogen (which is in their fish food, assuming you feed them), this is being picke dup by the lilies and the algae, which are flourishing, and your pond goes green!

Chris

University of Edinburgh page on nitrogen fixing bacteria: http://helios.bto.ed.ac.uk/bto/microbes/nitrogen.htm
« Last Edit: 20/01/2007 14:22:36 by chris »
 

Offline Karen W.

  • Moderator
  • Naked Science Forum GOD!
  • *****
  • Posts: 31653
  • Thanked: 5 times
  • "come fly with me"
    • View Profile
what makes water blue
« Reply #19 on: 20/01/2007 18:20:22 »
Chris,
Actually we do not feed the fish. They thrive on what is there in the pond. We of course did when we first started the pond,and that was in 1997, but after a while They were good to go.. They are very healthy and big these days.. Does them eating the insects and mosquitos count as them being fed...????
 

The Naked Scientists Forum

what makes water blue
« Reply #19 on: 20/01/2007 18:20:22 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums