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Universitat Autònoma de Barcelona
Institut de Ciència i Tecnologia Ambientals (ICTA‑UAB)

Key use of short-lived radionuclides as tracers of ocean sinking particles

20 Mar 2024
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The joint application of naturally occurring radionuclides (thorium-234 and polonium-210) as tracers of sinking particles in the ocean can help to better constrain the vertical carbon export driven by the ocean biological carbon pump (BCP).

Short-lived radionuclides as tracers of ocean sinking particles ICTA-UAB

This is the focus of a new article review led by ICTA-UAB scientist Montserrat Roca Martí and recently published in the scientific journal Annual Review of Marine Science.  

The BCP is the suite of biological and physical processes that transfer organic carbon produced on the surface of the ocean by photosynthetic organisms to the ocean interior. Through this mechanism, the ocean removes CO2 from the atmosphere and sequesters it in the deep ocean for hundreds of years or longer, becoming a key component of the global carbon cycle.

The BCP strongly influences climate, but also marine biogeochemical cycles and food webs from phytoplankton to fish. However, despite its global importance, the BCP is poorly constrained and there is a limited understanding of how it will respond to ongoing and future climate change. Here is where radionuclides come into play.  

In this review, Montserrat Roca Martí (ICTA-UAB) and Viena Puigcorbé (ICM-CSIC), present a critical appraisal of the literature in the field of applying radioactive isotopes (radionuclides) as tracers of the movement of particles in the marine environment, in particular to quantify carbon export fluxes in the ocean.  

This research illustrates how radionuclides have become one of the most well-established methods for studying the BCP that exists and highlights how the combined use of 234Th and 210Po can capture carbon flux dynamics that would otherwise be missed. This review provides recommendations and emphasizes where research in this area should go in order to better constrain the spatial and temporal variability of the BCP and reduce the uncertainties associated with oceanic carbon sequestration in the present and future ocean.   


Roca-Martí, M., Puigcorbé, V (2024). Combined use of short-lived radionuclides (234Th and 210Po) as tracers of sinking particles in the ocean. Annual Review of Marine Science, 16:551–575. doi: 10.1146/annurev-marine-041923-013807

Figure reference 

Rodellas, V., Roca-Martí, M., Puigcorbé, V., Castrillejo, M., Casacuberta, N. (2023). Radionuclides as Ocean Tracers. In: Blasco, J., Tovar-Sánchez, A. (eds) Marine Analytical Chemistry. Springer, Cham. https://doi.org/10.1007/978-3-031-14486-8_4