Re: Volcano lake turns from blue to red
Carsten Troelsgaard
x-posted to sci.chem
In sci.geo.geology we are stupefied by the coloring of volcanic lake Voui.
Has anyone in sci.chem a qualified opinion on the matter?
Follow link below
Carsten
"Belba Grubb" <trungsi...@yahoo.com> skrev i en meddelelse
news:1149049247.4...@f6g2000cwb.googlegroups.com...
> Jo Schaper wrote:
>
>> So who's got the red picture?
>
> Google Images came through, though I had to spell it "Voui."
>
> http://www.ulb.ac.be/sciences/cvl/aoba/Ambae1.html
>
> Blue and red (5/28/06) at top of page; much information on the rest of
> the page.
>
> Barb
> ----------
> Let us not succumb to nature. We will marshall the clouds and restrain
> tempests; we will bottle up pestilent exhalations; we will probe for
> earthquakes, grub them up, and give vent to the dangerous gas; we will
> disembowel the volcano, and extract its poison, take its seed out. We
> will wash water, and warm fire, and cool ice, and underprop the earth.
> We will teach birds to fly, and fishes to swim, and ruminants to chew
> the cud. It is time we looked into these things.
> -- Henry David Thoreau (1817-1862), U.S. philosopher, author,
> naturalist. "Paradise (To Be) Regained" (1843), in The Writings of
> Henry David Thoreau, vol. 4, p. 283, Houghton Mifflin (1906).)
>
Ernie
the iron oxide that turned the lake red. Sulfur dioxide in the eruption may
have helped leach the iron from the rocks, and the water in the lake is
likely to be very acidic. With time (may be a very long time) the water
may loose some of its acidity, and the iron may precipitate out, and the
lake will loose its red color.
See http://www.redironoxide.net/
Ernie
"Carsten Troelsgaard" <carsten.troe...@mail.dk> wrote in message
news:447d5e88$1$38656$edfa...@dread12.news.tele.dk...
mrda...@gmail.com
Carsten Troelsgaard wrote:
> x-posted to sci.chem
>
> In sci.geo.geology we are stupefied by the coloring of volcanic lake Voui.
> Has anyone in sci.chem a qualified opinion on the matter?
> Follow link below
>
> Carsten
Have you ruled out algae growth from the warm water?
Carsten Troelsgaard
"Ernie" <ErniemanRE...@charter.net> skrev i en meddelelse
news:zjjfg.18$gm...@fe04.lga...
> Magma usually contain significant amount of iron. My guess is that it is
> the iron oxide that turned the lake red. Sulfur dioxide in the eruption
> may
> have helped leach the iron from the rocks, and the water in the lake is
> likely to be very acidic. With time (may be a very long time) the water
> may loose some of its acidity, and the iron may precipitate out, and the
> lake will loose its red color.
Thanks Ernie
I'm only familiar with the precipitates of ironoxide/hematite. None of those
hues are like the ones on the image, but that may have other reasons like
mixture of other colorants, transparancy of the water, reflectance at the
surface or fine particles in it etc.You think it could be dissolved
ironoxyde?
I havn't found any good sources for the 'vergrünerung' present in an array
of
different geological environments/rockbodies - reduced iron likely
participate. I do know an intense darkblue colored (when wet) porcelain-clay
(degraded caolinitic clay) that turns turquish blue on drying, but it looses
is's color completely within a few hundred degrees of burn .. iron is /not/
part of this 'vergrünerung'.
The decay of volcanic ashes are the main source for multilayered
phyllosilicates (smectites, bentonites), but this type of clay is the
uppersit side of caolins on the degradation scale of clayes. If
phyllosilicates are part of the turbidity of the water, there may be a link.
If the green color is some reduced iron compound, then tell me what causes
the massive oxidation.
Yes MrDarrett, algae bloom has been considered likely
George, we have too little 'off the shelf' knowledge about sulphor to
comment.
Carsten
> See http://www.redironoxide.net/
>
> Ernie
>
> "Carsten Troelsgaard" <carsten.troe...@mail.dk> wrote in message
> news:447d5e88$1$38656$edfa...@dread12.news.tele.dk...
>>
>> x-posted to sci.chem
>>
>> In sci.geo.geology we are stupefied by the coloring of volcanic lake
>> Voui.
>> Has anyone in sci.chem a qualified opinion on the matter?
>> Follow link below
>>
>> Carsten
>>
>> "Belba Grubb" <trungsi...@yahoo.com> skrev i en meddelelse
>> news:1149049247.4...@f6g2000cwb.googlegroups.com...
>> > Jo Schaper wrote:
>> >
>> >> So who's got the red picture?
>> >
>> > Google Images came through, though I had to spell it "Voui."
>> >
>> > http://www.ulb.ac.be/sciences/cvl/aoba/Ambae1.html
>> >
>> > Blue and red (5/28/06) at top of page; much information on the rest of
>> > the page.
>> >
>> > Barb
snip
Ernie
I am a chemist and not a geologist, and what I say may be of limited
application to geology. I think of ferrous (iron of plus 2 oxidation state)
compounds as off-white, yellow, and light green, while ferric (iron of plus
3 oxidation state) tend to be reddish. But, this is not a general rule,
because there are many exceptions to this generalizations: for example,
ferrous oxide is black, and ferric sulfate, Fe2(SO4)3, is greenish white,
but ferric subsulfate solution, Fe4(OH)2(SO4)5 is reddish-brown.
Ferrous compounds are oxidized by air to ferric. Bacteria may reduce
Fe+++ to Fe++, but air will oxidize it back up to Fe+++.
Can you measure the pH of the lake, and get a water samples? Is the source
of color in
solution or is it a very finely dispersed precipitate?
Get a chemical composition of the water - Inductively Coupled Plasma
(usually
called ICP) would be a good method to start with, but request sulfur (S)
analysis as well. If in addition to iron, there is a significant amount
(more than 0.001% ) of
copper, nickel, cobalt, manganese, etc, in the water samples, then the
number
of possible color combinations becomes many fold.
Ernie
"Carsten Troelsgaard" <carsten.troe...@mail.dk> wrote in message
news:447df1b3$0$38664$edfa...@dread12.news.tele.dk...
Aidan Karley
> Can you measure the pH of the lake, and get a water samples?
>
We're working from news reports because the volcano lake in question is
in Vanuatu, on a very small island.
And most people, sensibly, are keeping clear. Satellite
photography shows vegetation killed off for some hundreds of metres
from the lake.
A temperature and monitoring ground station died after a year or
so of working and hasn't (yet) been replaced.
Current information appears to come through
http://www.ulb.ac.be/sciences/cvl/aoba/Ambae1.html
--
Aidan Karley, FGS
Aberdeen, Scotland
Written at Thu, 01 Jun 2006 06:48 +0100, but posted later.
Carsten Troelsgaard
> Carsten,
>
> I am a chemist and not a geologist, and what I say may be of limited
> application to geology. I think of ferrous (iron of plus 2 oxidation
> state)
> compounds as off-white, yellow, and light green, while ferric (iron of
> plus
> 3 oxidation state) tend to be reddish. But, this is not a general rule,
> because there are many exceptions to this generalizations: for example,
> ferrous oxide is black, and ferric sulfate, Fe2(SO4)3, is greenish white,
> but ferric subsulfate solution, Fe4(OH)2(SO4)5 is reddish-brown.
Another poster in this thread writes
quote
A pH of 1.6 requires a strong acid. Primordial H2S is converted into
SO2/SO3 by atmospheric oxygen and returns to the lake to form
sulfuric acid, H2SO4. There are two major sulfate minerals capable
of coloring a lake blue: blue vitriol CuSO4.5H2O and green vitriol
FeSO4.7H2O:
http://www.hongqingchem.com/product.htm
I favor the ferrous sulfate (green vitriol) because it allows for an
interchange of colors, that is a conversion of a lake from blue
-green to red color and from red color back to blue-green as
illustrated by the crater lake at Irazu, Costa Rica.
www.hotelmartino.com/tours/irazu.htm
Ferrous iron(II) at the surface of the lake is oxidized to Ferric(III)
by atmospheric oxygen, thus changing the lakes surface from
blue-green to red of hematite.
In the absence of agitation, hematite settles out and the blue
-green color of excess ferrous sulfate rises to the surface.
John Curtis
Unquote
I think the two of you has got to the essentials. My slobby recollection is
in accordance with John Curtis' ... the red lake has a lower temperature and
less agitation could be expected and make way for an atmospheric oxidation
of the Ferrous compounds at the surface.
Carsten
Aidan Karley
> I havn't found any good sources for the 'vergrünerung' present in an array
> of
> different geological environments/rockbodies
>
iron-manganese oxides that forms in weathering of iron-rich rocks,
particularly in desert environments (and is often preserved and visible in
grains in sediments from such environments).
There's something that looks familiar about that word, but I can't
bring the word it reminds me of to the surface.
--
Aidan Karley, FGS
Aberdeen, Scotland
rek...@gmail.com
wouldn't focus too much on the 'blue' color. Most importantly, it is
opaque, not clear. This is most likely just an optical effect of light
scattering off of small particles in the lake. Opaque = particulates.
It appears blue because blue has most intensely scattered wavelengths
(look up "Rayleigh scattering" for an explanation, although size of the
particles and your angle with respect to the water is also a factor).
So don't focus too much on finding blue-colored aqueous solutions -
those are clear solutions. SO2 sounds like a very logical reason for
the color shifting to red. The lake looks just like heavily
concentrated SO2 solution with particulate junk in it.
Carsten Troelsgaard
"Aidan Karley" <doIlookDAFT...@validEMAILaddressTOa.NEWS.group>
skrev i en meddelelse
news:VA.00000ee...@validemailaddresstoa.news.group...
> In article <447df1b3$0$38664$edfa...@dread12.news.tele.dk>, Carsten
> Troelsgaard wrote:
>> I havn't found any good sources for the 'vergrünerung' present in an
>> array
>> of
>> different geological environments/rockbodies
>>
> "verdigris" from Latin? Or "wad" referring to a dark skin of
> iron-manganese oxides that forms in weathering of iron-rich rocks,
> particularly in desert environments (and is often preserved and visible in
> grains in sediments from such environments).
> There's something that looks familiar about that word, but I can't
> bring the word it reminds me of to the surface.
It sounds as you talk about 'desert-varnish'
My 'vergrünerung' is german for english greening. The french 'verdissement'
is achtually the term I've picked up for the general greening of sedimenatry
or solid rocks .. I've only met 'vergrünerung' in conjunction with
paleozoic/aged gabbro (diabase, dolorite).
Carsten
Aidan Karley
> My 'vergrünerung' is german for english greening. The french 'verdissement'
> is achtually the term I've picked up for the general greening of sedimenatry
> or solid rocks .. I've only met 'vergrünerung' in conjunction with
> paleozoic/aged gabbro (diabase, dolorite).
>
moulds, lichens, algae etc onto a rock weathering in daylight. We do mark a
contrast in caving between the clean and (relatively) high friction underground
rocks and the greenish rocks in daylight parts of cave entrances - the daylight
is not necessarily obvious if you come out at night. Unfortunately we just
describe the "green coating" on the rocks as being "slime".
--
Aberdeen, Scotland
Carsten Troelsgaard
"Aidan Karley" <doIlookDAFT...@validEMAILaddressTOa.NEWS.group>
skrev i en meddelelse
news:VA.00000ee...@validemailaddresstoa.news.group...
> Troelsgaard wrote:
>> My 'vergrünerung' is german for english greening. The french
>> 'verdissement'
>> is achtually the term I've picked up for the general greening of
>> sedimenatry
>> or solid rocks .. I've only met 'vergrünerung' in conjunction with
>> paleozoic/aged gabbro (diabase, dolorite).
>>
> Hmmm, I can't think off-hand of a word to express the accumulation
> of
> moulds, lichens, algae etc onto a rock weathering in daylight. We do mark
> a
> contrast in caving between the clean and (relatively) high friction
> underground
> rocks and the greenish rocks in daylight parts of cave entrances - the
> daylight
> is not necessarily obvious if you come out at night. Unfortunately we just
> describe the "green coating" on the rocks as being "slime".
The greening is referring to mineralogical/rock color, not biology.
My best guess is that I've picked up 'verdissement' from the foremost french
clay sedimentologist Georges Millot. I'm sorry for having been so opaque in
choise of wording.
Carsten
Jean
Carsten Troelsgaard a écrit dans le message
<448032b3$0$175$edfa...@dread16.news.tele.dk>...
verdissement ,nm LITT , Fait de devenir vert. Larousse 1998 This a
general term meaning to have turned green. It does not depend on the
mechanism. This could be by biological, mineralogical or other process. It
is often used to describe spoiled meat.
http://criaa.rennes.inra.fr/vigie-viande/question_verdissement_foie_boeuf.ph
p
Interesting page concerned in part with Georges Millot
http://charlatans.free.fr/berthault.shtml
".Georges Millot, géologue et membre de l'Académie des sciences, disparu en
1991. Comme nous le verrons, il refusa pendant plus de quinze ans à M.
Berthault l'accès aux Comptes Rendus, ses communications étant jugées sans
intérêt ni nouveauté."
When I hear of a solution turning from blue to red the first thing I think
of is a change of pH and that likely the solution has one of many chemicals
that will respond in this fashion.
JL