Publication Date:
2022-05-25
Description:
Author Posting. © The Author(s), 2018. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Limnology and Oceanography Methods 16 (2018): 286-298, doi:10.1002/lom3.10245.
Description:
Compositional changes in marine particulate organic carbon (POC) throughout the water column trace important processes that underlie the biological pump’s efficiency. While labor-intensive, particle sampling efforts offer potential to expand the empirical POC archive at different stages in the water column, provided that organic composition is sufficiently preserved between sampling and analysis. The standard procedure for preserving organic matter composition in marine samples is to immediately store particles at -80°C to -20°C until they can be freeze-dried for analysis. This report investigates the effect of warmer drying and storage temperatures on POC composition, which applies to the majority of POC samples collected in the field without intention for organic analysis. Particle samples collected off Woods Hole, MA were immediately dried at 56°C, at room temperature, or stored at -80°C until being freeze-dried. Results show that oven- and air-drying did not shift the bulk composition (i.e., carbon and nitrogen content and stable isotope composition) of POC in the samples relative to freeze-drying. Similarly, warmer drying temperatures did not affect POC thermal stability, as inferred by ramped pyrolysis/oxidation (RPO), a growing technique that uses a continuous temperature ramp to differentiate components of organic carbon by their decomposition temperature. Oven- and air-drying did depress lipid abundances relative to freeze-drying, the extent of which depended on compound size and structure. The data suggest that field samples dried at room temperatures and 56°C are appropriate for assessing bulk POC composition and thermal stability, but physical mechanisms such as molecular volatilization bias their lipid composition.
Description:
This research was funded by the National Science Foundation (NSF) Graduate Research Fellowship program and the NSF Cooperative Agreement for the Operation of a National Ocean Sciences Accelerator Mass Spectrometry Facility (OCE-0753487).
Keywords:
Particulate organic carbon composition
;
Sample drying treatment
;
Ramped oxidation
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
