Analysis of Marine DOC using a Dry Combustion Method
Woods Hole, MA 02543
E. T. Peltzer
Marine Chemistry and Geochemistry
Woods Hole Oceanographic Institutiton
Woods Hole, MA
C. H. Hopkinson, A. Nolin and L. Redmond
Marine Biological Laboratory
Woods Hole, MA 02543
Marine Chemistry (1996) 54: 191-201.
Received: 25 August 1995.
Accepted: 14 February 1996.
Published: October 1996.
* Current address: Biology Dept, Florida International University,
University Park, Miami FL 33199.
As part of a continuing effort to verify and improve measurements of marine
dissolved organic carbon (DOC), we combusted dried sea salts and adhered
organic matter to assay DOC concentrations in representative samples from the
Atlantic and Pacific Oceans. Combustions were performed overnight at
580°C in sealed tubes and oxidation of organic materials occurred via a
novel mechanism, thermal sulfate reduction:
2 H2SO4 + CH2O -- > CO2 + 2
SO2 + 3 H2O.
Measured DOC concentrations ranged from 43-114 µMC, with the highest
values observed in inshore surface samples from Woods Hole Harbor, and the
lowest values observed in twelve deep offshore Atlantic and Pacific waters.
Stable carbon isotope values determined for all samples were near -22 per mil,
consistent with a predominantly marine phytoplankton origin for DOC. A
seasonal study in Woods Hole Harbor showed no significant temporal trends in
nearshore DOC concentrations. Problems associated with samples storage and
contamination during drying steps prevented precise (± 1 µM) DOC
concentration determinations; however, an improved drying and measurement
system is outlined (Appendix 1) for possible future dry-combustion studies of
This research was supported by Department of Energy grant DE-FG-92ER61438 and
National Science Foundation grant OCE 92-16897 to BF; and NSF grants OCE 91-15201
and OCE 92-03953 with funds provided by the Office of Global Programs, National Oceanic
and Atmospheric Administration to ETP. This is contribution number 9172 from
the Woods Hole Oceanographic Institution and US-JGOFS contribution number 215.
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