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Measuring Carbon-based Contaminant Mineralization Using Combined CO2 Flux and Radiocarbon Analyses
Published on: October 21, 2016
Resource quality affects carbon cycling in deep-sea sediments
Daniel J Mayor1, Barry Thornton, Steve Hay
1Institute of Biological and Environmental Sciences, Oceanlab, University of Aberdeen, Newburgh, Aberdeenshire, UK. dan.mayor@abdn.ac.uk
The ISME Journal
|March 2, 2012
Summary
Organic matter quality significantly impacts deep-sea carbon cycling. High-quality diatom carbon mineralizes over 300% faster than low-quality fecal pellets, affecting carbon residence time on the seabed.
Area of Science:
- Marine biology
- Geochemistry
- Deep-sea ecology
Background:
- Deep-sea sediments cover most of Earth's surface, acting as a crucial link in global carbon cycles.
- Organic matter transport to the deep sea occurs via diatoms and zooplankton fecal pellets, but their differing qualities' impact is unknown.
Purpose of the Study:
- To investigate how qualitatively different organic matter substrates (diatoms vs. fecal pellets) affect carbon fate in deep-sea sediments.
- To quantify carbon mineralization and uptake by benthic organisms.
Main Methods:
- Incubation of (13)C-labeled diatoms and fecal pellets with deep-sea sediment communities (-0.7°C, 1080m depth).
- Quantification of carbon mineralization and uptake by bacteria and macrofauna over six days.
Main Results:
- Diatom-derived carbon mineralized over 300% faster than fecal pellet carbon.
- Benthic bacteria dominated carbon processing but showed lower growth efficiency on diatoms.
- Substrate quality, not resource availability, controlled bacterial growth, while temperature limited overall microbial activity.
Conclusions:
- Qualitative differences in organic matter significantly alter carbon residence times in deep-sea environments.
- Future changes in exported organic matter composition will impact the balance of deep-sea carbon sequestration and mineralization.
- Benthic microbial communities are sensitive to organic matter quality, influencing global carbon budgets.
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