The six gases covered by the Kyoto Protocol are carbon dioxide (CO2),
methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs),
perfluorocarbons (PFCs), and sulphur hexafluoride (SF6). Question:
Can any, or all, of these gases be measured while in solution
contained in a pig farm holding pond? A chemist says that if you know
the solubility index of the particular gas then you can measure the
amount. Where can an instrument be purchased that will measure these gases? |
Request for Question Clarification by
pafalafa-ga
on
28 May 2004 09:58 PDT
Hello christophergsmith-ga,
Thanks for a most interesting question.
I am an environmental scientist with many years of experience in
monitoring issues. I can probably provide an answer to your question
as you have written it, but it would perhaps be even better if you
could add some context.
Is there anything you can let us know about why you want this
information, or what you hope to do with such monitoring data?
There are several reasons for my asking.
Several of the Kyoto Protocol gases -- especially CO2 and methane --
are produced in pig farm settings by biological processes involving
bacteria. The amounts of such dissolved gases in the holding pond
itself may have little bearing to the degree of overall emissions of
such gases to the atmosphere.
The fluourinated compounds (HFCs, PFCs and SF6) are industrial
chemicals, and not likely to be present in significant amounts in pig
farm wastes (unless there's a leaky refrigeration unit about).
Knowing the solubility index of a gas in pure water may not mean very
much in terms of its solubility in a complex gloop one would likely
find on a pig farm.
If you want to know the amount of gases for the sake of curiousity,
that's one thing. But if you want to measure the gases because of
some sort of regulatory issue, then you probably need to follow strict
protocol established by the regulating agencies for types of
equipment, measuring techniques, and data integrity.
Anyway...knowing a bit more about the situation you're in would be
helpful in crafting the best answer possible for your question.
Thanks.
pafalafa-ga
|
Clarification of Question by
christophergsmith-ga
on
28 May 2004 11:14 PDT
Ponds, pig and others, evidently produce large amounts of green house
gases. My client wants to be able to establish a baseline of the
amount of gases generated by the ponds and then thereafter measure the
reduction of the gases after treatment of the pond fluids. It was
suggested that if the measurments were in situ rather than above the
ponds then there would be less likelihood of contamination - hence the
question of an instrument capable of measuring the amount of dissolved
gases in the fluids.
|
Request for Question Clarification by
pafalafa-ga
on
28 May 2004 19:42 PDT
Christopher,
The more I look into this, the more interesting it gets.
On the one hand, your client is pretty much on the forefront of
environmental concepts. No less of an authority than the National
Academy of Sciences recently completed a study of air emissions from
animal feedlots, and concluded that there's a lot of air emissions
from animal farming operations, and very little technology to actually
measure them.
The report is called "Air Emissions from Animal Feeding Operations:
Current Knowledge, Future Needs" and you can read a bit about it here:
http://www4.nationalacademies.org/news.nsf/isbn/0309087058?OpenDocument
On the other hand, tryng to measure the dissolved greenhouse gases in
the holding pond strikes me as way off base in terms of the overall
issues because:
1) A lot of the greenhouse gas emissions are from the animals
themselves (if you get my drift) rather than solely from the
ponds...the ponds are generally seen as more of a source of water
pollution than air pollution, though they certainly contribute to air
problems as well.
2) Not all the air emissions are greenhouse gases. Ammonia is also a
big air pollutant from pig farms and similar facilities. They also
kick up an awful lot of particulates. These are not greenhouse
contributors, but are serious air pollution problems just the same.
3) As the NAS report covers in great detail, the technology for
measuring overall air emission from pig farms is just not there yet.
The Academy recommends a fairly large-scale program to develop the
appropriate tools, but right now, there's an awful lot of guesswork
involved. It seems, at best, premature to be trying to make the type
of measurements you're asking about.
4) Some of the greenhouse gases like HFCs are just not very likely to
originate from pig farms, and are probably not worth monitoring for.
My suggestion would be to alter your original question somewhat, to
allow me to take a few days to really put together a thorough overview
of air pollution issues from animal feedlots, and to identify some of
the main measures that farms are undertaking to reduce the
environmental impacts to air from their operations.
If this sounds like a reasonable approach, let me know (and also tell
me a bit more about the farm -- how large, what state, etc), and I'll
be glad to get started.
But if it's not the type of answer you want, please let the
researchers here know how you would like us to proceed, especially in
the light of the information I mentioned above.
Thanks.
pafalafa-ga
|
Clarification of Question by
christophergsmith-ga
on
01 Jun 2004 15:21 PDT
My client wishes to develope carbon credits from reducing pond
emissions. The first step in that development is to be able to
measure some, not all, of the gases mentioned in the Kyoto Protocol.
I agree with your observations that animals create air pollution and
water pollution. My client wishes only to deal with pond poop. There
is at least one machine available that has paddle blades that is
placed in a pond and it prevents the pond poop from becoming anarobic,
and thus makes it respond to treatment. I just cannot see a reliable
method for measuring gases leaving a pond from above the pond. It
should be much easier to measure the dissolved gases over time to be
able to document any decrease in such gases.
|
Clarification of Question by
christophergsmith-ga
on
01 Jun 2004 15:24 PDT
I did not finish last transmission. The scope of the job is fairly
limited. I agree that no one has dealt with the problem and my client
wishes to start the procedure, hence the need for the apparatus - if
it exists. Thank you
|
Hi christopher
I will focus only on the measurement issue, and will not attempt to
review the related and complex issues which pfalala-ga mentioned
in RFCs - contribution of farm processes to the release of greenhouse gases.
I hope this will fit the scope of your interest.
I also assume that the goal is to determine concentration
of components present in the pond. Transformations which preserve the
composition are allowed and that services of a typical industrial lab
are available.
If assumptions are wrong , or if the question is no longer of interest,
please let me know after this first installment
Alsoyou may specify ifI should be more or less technical.
First I would critique the chemist who says
" if you know the solubility index of the particular gas then you can measure the
amount .."
If you know solubility of a gas, you can calculate how mach gas is dissolved,
ASUMING the solution is at equilibrium with atmosphere. That assumption is
not apropriate in your situation. A gas may be soluble but not present in
the water, depending on history of the solution.
Spectroscopy is preffered thechnique for determining composition of mixtures.
Infrared spectroscopy is not suitable or water based solutions since water
(being strongly polar) is not transparent for infrared light. Therefore in such
cases (e.g. for organic samples) prefered technique is Raman
spectroscopy, which uses
visible light. Chromatography (suggested in comment) combined with Raman
(not mass) spectroscopy would increase accuracy of measurement.
Here is an example of using Raman spectrometer to determine dissolve gases in the
ocean foor.
http://www.spectroscopynow.com/Spy/basehtml/SpyH/1,,0-5-7-0-74876-ezine-0-3,00.html
And here is article on general use of the laser raman spectrometer for
study of ocean geochemistry
http://www.mbari.org/news/homepage/laser-raman.html
Other general technique would be controlled reduction of sample of water to the
gas phase - evaporation into vacuum or into defined atmosphere
(Nitrogen, Argon..) followed
by usual (infrared) spectroscopy. I would expect that to be straightforward,
but this company is claiming a patent (perhaps for improved accuracy)
on one such a method:
http://www.maran.co.uk/technologies/dera/sensors/general/disgas.htm
Whole range of industrial processes use semipermeable membranes, to
determine partial
pressure of dissolved gases. Here is an field instrument for
detrmination of dissolved O2.
These are very useful as total-dissolved-gas sensors, when accuracy is
not critical.
ttp://www.commonsensing.com/tbol.htm
"..In general dissolved gases equilibrate a small sample volume of
air through a semi-permeable membrane.
Chemical absorbents are used to remove a particular gas allowing
the partial pressure of that gas
to be directly measured and recorded. As the primary measurement
is gas pressure, extremely stable results can be obtained.
http://www.pro-oceanus.com/products.htm
A step up would be a 'dissolved gas analyser', such as shown here
http://www.tmt-d.com/technlgy/ctalg/tm0403_e01.pdf
which can monitor continuously 6 gases ( CO H2 CH4 acetylene...).
Technique is variant on the above: injection into vacuum, here applied
to transformer oil, but usable for water solution as well.
To select a specific instrument(s), we would have to consider range of
concentrations
and method of use (continuous record, or occational sample sent to a lab).
There are companies which carry a line of instruments from several manufacturers
and can provide guidance and expert advice selection of inteuments to fit specific
situation. For example:
According to this instrumentation re-seller 10 companies make
Dissolved CO2 Instruments.
Their database will list companies whose instruments can handle given range.
http://sensors-transducers.globalspec.com/SpecSearch/Suppliers/Labware_Scientific_Instruments/Analytical_Instruments/Dissolved_CO2_Sensors
Search Terms: Raman spectrosocpy
Dissolved gas sensors
Hedgie |
