Anish,
Yes. If you wish to charactize the other carbon in sediments that also have
charcoal etc, it is generally suggested that you divide your analysis into
three fractions: inorganic carbon, organic carbon, and black carbon, which
are operationally defined. All of the techniques that I know are all
destructive fractionations, so make sure you have enough homogenous material.
Presumably you have a total carbon analyzer, at least in the form of high
temperature oxidation for mass spectrometry. After the destructive
fractionations, the remaining carbon can be analyzed in your analyzer and the
fractions determined by linear additivity.

There are several good acidifications techniques to remove inorganic carbon;
look in ISOGEOCHEM archives. Almost all give similar results for most
sediments (blush, stammer) and the only real question is equipment and ease.
Similarly chemical oxidation can be used to define non-black carbon, e.g.
Simpson M. J. and Hatcher P. G., 2004. Determination of black carbon in
natural organic matter by chemical oxidation and solid-state 13C nuclear
magnetic resonance spectroscopy. Organic Geochemistry 35: 923-935.

However, in my experience loss on ignition at various increasing temperatures
is the easiest and most reproducible technique. Especially for microcharcoal,
which will instantly oxidize at temperatures well below any important
carbonate decomposition.
Regards,
John

John Furey
Research Physical Scientist
US Army Engineer Research and Development Center
Vicksburg MS 39180

-----Original Message-----
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf
Of Anish Warrier
Sent: Tuesday, December 01, 2009 8:29 AM
To: [log in to unmask]
Subject: Re: [ISOGEOCHEM] Question about collecting POC samples

Dear Colleagues
 
I would like to know a small thing about Carbon isotope work and CHN
analysis...
 
If microcharcoal are present in the sediments then will it affect the D13C
and C/N data???
 
 
Regards
Anish
--
Hard work is like a staircase and luck is like a lift. Lift may fail but
staircase is sure to take you to the top 

Anish Warrier
CSIR-Senior Research Fellow
Department of Marine Geology
Mangalore University
Mangalagangothri - 574 199
INDIA

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