Enhanced carbon sequestration in marginal seas through bacterial transformation

Area of Science:

• Marine organic geochemistry
• Microbial ecology
• Biogeochemical cycles

Background:

• Labile organic carbon is a dynamic marine carbon pool.
• Traditionally, it's thought bacteria rapidly respire labile carbon into CO2.
• Direct evidence for this transformation is limited.

Purpose of the Study:

• To investigate the fate of labile particulate organic carbon (POC) in marginal seas.
• To trace the transformation of labile POC into bacterial POC.
• To quantify the contribution of bacterial carbon to organic carbon burial.

Main Methods:

• Utilized D/L-amino acid analysis to trace carbon origins.
• Analyzed labile POC and bacterial POC fractions.
• Estimated annual bacterial organic carbon burial in global marginal seas.

Main Results:

• Labile POC in marginal seas originates primarily from autochthonous primary production.
• Bacterial POC fractions closely mirrored labile POC fractions.
• Bacterial transformation of labile POC is rapid, driven by high bacterial growth efficiency in nutrient-rich marginal seas.

Conclusions:

• Bacterial transformation plays a critical role in carbon sequestration within marginal seas.
• An estimated 0.08 ± 0.03 Pg of bacterial organic carbon is buried annually in global marginal seas, comprising ~40% of total organic carbon burial.
• This process contributes to long-term carbon sequestration and may explain increased CO2 uptake in coastal regions.