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Q: How much carbon dioxide is produced in the biological breakdown of hydrocarbons ( Answered,   0 Comments )
Subject: How much carbon dioxide is produced in the biological breakdown of hydrocarbons
Category: Science > Earth Sciences
Asked by: drjohn48-ga
List Price: $50.00
Posted: 17 Feb 2003 04:17 PST
Expires: 19 Mar 2003 04:17 PST
Question ID: 162466
we are bioremediation contractors and have been asked, how much
carbondioxide is produced through the biological oxydisation of the
hydrocarbons in the soil, we specialise in the Insitu technology, the
question is being asked, are there any papers on this subject.
Subject: Re: How much carbon dioxide is produced in the biological breakdown of hydrocarbons
Answered By: pafalafa-ga on 17 Feb 2003 09:30 PST
Hello Dr. John,

Thanks for a very interesting -- and ultimately frustrating --
question.  The global warming/carbon cycle debate is just that...a
debate.  While there is consensus on some of the broad outlines, there
is very little agreement on the details.  Certainly, the detail of the
role of soil microbes in the uptake and release of carbon is one of
the areas that is up for grabs in the scientific community.

By the way, I am a biologist myself with 25 years experience as an
environmental scientist.  If anything I've offered here is unclear, or
needs more elaboration, please don't hesitate to ask for more detail. 
Just use the "Request for Clarification" button to let me know what
you need.

Listed below are some key documents explaining the role of soil and
soil microbes in the carbon cycle.  I've included both qualitative and
quantitative information.

These should be helpful to you, but again, don't hesitate to ask for
follow-up information.  Test is taken directly from the sites, except
for text in brackets, which I added myself.


Soil Organic Carbon and the Global Carbon Cycle

July 2002

"Soils vary in the amount of soil organic carbon they contain, ranging
from less than 1 percent in many sandy soils to greater than 20
percent in soils found in wetlands or bogs."

[Figure 1 shows that soils release 1,500 gigatons per year of carbon
to the atmosphere]


Biogeochemical Cycles [contains a good overview of the relationship
between soil microbes and carbon uptake and release]


Soils are estimated to contain about 75% of all terrestrial
carbon...Cultivated soil is exposed to the air, so during
decomposition by soil microbes, the soil organic matter is oxidized,
and the carbon is released to the atmosphere as carbon dioxide.


This USEPA document "The U.S. Greenhouse Gas Inventory" give specific
quantitative information of the amount of carbon sequestered in soils
and forests in the U.S.

This is a summary document, but the full inventory of the information
can be founcd here:$File/ghgbrochure.pdf


Experiment hints that not much extra carbon dioxide will be locked up
in future forests' wood or soils

Results from continuing experiments near Duke University where forest
plots grow in the higher atmospheric levels of carbon dioxide expected
by the mid 21st century suggest that trees and soil may not sop up
much of the extra gas over the long term under real-world conditions.


Scientists Find That Grasslands Can Act as 'Carbon Sinks' 

"Our data indicate that soil microbes quickly respond to changes in
carbon and nitrogen availability and may play critical roles in
determining the potential of grasslands — and other terrestrial
ecosystems, too — to act as a carbon sink," Hu said.


[experimental and theoretical considerations for determining soil
microbe activity pertaining to carbon]

Request for Answer Clarification by drjohn48-ga on 24 Feb 2003 03:48 PST
Is there anything specific that deals with the augmentation of the
soils by introducing an enhanced microbial cocktail into hydrocarbon
contaminated soils. Do you know of any research that has or is being
done, that may show how the Co2 is sequested or utilised by various
means, and what is released to the atmospher. Many thanks.

Clarification of Answer by pafalafa-ga on 24 Feb 2003 09:45 PST
Dr. John,

I haven't seen anything along the lines of your question, but I can
possibly help in clarifying how little is known on this topic, and in
steering you towards experts in the field.

A recent report by the American Society for Microbiology, entitled
Environmental Change -- Microbial Contributions, Microbial Solutions"
can be found here:

The report describes the role of microrganisms in both unintentional
and intentional sources and sinks of CO2 and other global climate
change gasses.  In general, intentional addition of nutrients to the
ocean as a means of spurring algal growth, and adding to CO@ uptake
capacity, has been fairly well-studied.  But similar applications on
land -- particularly in the context of bioremediation -- have not
been.  The report states, in part:

"Yet it is conceivable that algal blooms might be
managed to reduce the impact of human-related
CO2 emissions. The intentional addition of iron
nutrients in some areas of the ocean might stimulate
algae to convert more atmospheric CO2 into
biomass. Ultimately this could lower CO2 concentrations
and reduce the greenhouse effect. Similar
management of microbes and plants in terrestrial
systems might also help to mitigate CO2 accumulation.
However, the complexities of numerous
direct and subtle linkages among nutrient pollution,
algal blooms, aquatic bacteria, disease, trace
gases such as methane and nitrous oxide, climate,
and human disturbances are only now beginning
to be understood. Much more work is necessary
before algal, plant and microbe management can
be considered as a tool for climate control."

The authors of the report are listed as:

Gary M. King, Ph.D., Chair, Subcommittee on Global Environmental
University of Maine

David Kirchman, Ph.D., University of Delaware

Abigail A. Salyers, Ph.D., University of Illinois

William Schlesinger, Ph.D., Duke University

James M.Tiedje, Ph.D., Chair, Committee on Environmental Microbiology
Michigan State University

You might want to contact any or all of them to learn of any not-yet
published work that is underway on this topic.  But as for published
literature, there appears to be very little that directly addresses
you follow-up question.

I do want to direct you to the following document, however, "Workshop
The Role of Biotechnology in Mitigating Greenhouse Gas

There is an entire section in the report on "Terrestrial Carbon
Sequestration" using microbes.  Again, there is a good listing of the
experts in the field that may be worth a follow-up contact.  But also,
again, there is no specific focus on remedial technologies, and a
general acknowledgement that our collective understanding of this
topic is based on minimal information.

As I'm sure you are well aware, there is extensive literature about
using microorganisms as a remediation tool for decontaminating
polluted sites.  But there has not yet been, to my knowledge, a
specific focus on CO2 uptake or release in this regard.

I hope this information meets your needs, but don't hesitate to
request another clarification, if there is a specific question you
feel I can address.
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