Articles | Volume 22, issue 22
https://doi.org/10.5194/bg-22-6895-2025
https://doi.org/10.5194/bg-22-6895-2025
Research article
 | 
19 Nov 2025
Research article |  | 19 Nov 2025

Balancing water column and sedimentary 234Th fluxes to quantify coastal marine carbon export

Madeline G. Healey, Erin E. Black, Christopher K. Algar, Maria Armstrong, and Stephanie S. Kienast

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This preprint is open for discussion and under review for Biogeosciences (BG).
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Cited articles

Aller, R. C. and Cochran, J. K.: 234Th/238U disequilibrium in near-shore sediment: Particle reworking and diagenetic time scales, Earth and Planetary Science Letters, 29, 37–50, https://doi.org/10.1016/0012-821X(76)90024-8, 1976. 
Amiel, D. and Cochran, J. K.: Terrestrial and marine POC fluxes derived from 234Th distributions and δ13C measurements on the Mackenzie Shelf, Journal of Geophysical Research: Oceans, 113, C03S13, https://doi.org/10.1029/2007JC004260, 2008. 
Baskaran, M., Swarzenski, P. W., and Porcelli, D.: Role of colloidal material in the removal of 234Th in the Canada Basin of the Arctic Ocean, Deep-Sea Research Part I, 50, 1353–1373, https://doi.org/10.1016/S0967-0637(03)00140-7, 2003. 
Bhat, S. G., Krishnaswami, S., Lal, D., Rama, and Moore, W. S.: 234Th/238U ratios in the oceans, Earth and Planetary Science Letters, 5, 483–491, 1969. 
Black, E. E., Algar, C. K., Armstrong, M., and Kienast, S. S.: Insights into constraining coastal carbon export from radioisotopes, Frontiers in Marine Science, 10, 1254316, https://doi.org/10.3389/fmars.2023.1254316, 2023. 
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This study presents new data from 2021–2024 aimed at improving our understanding of coastal carbon export and storage in a temperate fjord in the Northwest Atlantic. By applying natural tracers in seawater and sediment, we assess short-term carbon dynamics and provide quasi-seasonal observations. The results refine carbon flux estimates in a well-studied site that is emerging as a key location for coastal ocean research.
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