We do not routinely vacumn roast our samples to remove organic matter.
Instead, when we process our sediment material we soak it for 5 -10 minutes in a solution
of 3% hydrogen peroxide and sodium hexametaphosphate. In 1997 we analyzed a set of
rose Bengel stained live benthic forams for Dr. Bruce Corliss at Duke University. These
forams contained a large plug of organic matter inside the shell test. We ran two series
of individuals from core EN293-1-2, 0-0.5 cm, 500-650 um size fraction. The first series
we ran as we normally do, doing nothing to the shell tests. The organic matter was still
visible in the reaction vessel at the end of the reaction time. The file associated with
this data is en293.nothing.
For the second series of analyses we pretreated the shell tests with 3% hydrogen
peroxide and sonication for 10 minutes or until the organic matter was fully oxidized.
The file associated with this data is en293.peroxide.
The following table summarizes the data:
Peroxide and Sonication
Peroxide minus No Pretreatment
|Delta of O18
||Delta of C13|
We believe that the depletion of 0.14 per mil in C13 falls within
the standard deviation of the analysis of the individual shell tests and is not significant.This test was a worst case scenario as most
foraminiferans recovered from the sediments have little organic matter left
in the test.