Document Type

Article

Publication Date

9-2022

DOI

10.1016/j.chemgeo.2022.121006

Publication Title

Chemical Geology

Volume

607

Pages

121006 (1-11 pp.)

Abstract

The use of 228Th has seen limited application for determining sedimentation and mass accumulation rates in coastal and marine environments. Recent analytical advances have enabled rapid, precise measurements of particle-bound 228Th using a radium delayed coincidence counting system (RaDeCC). Herein we review the 228Th cycle in the marine environment and revisit the historical use of 228Th as a tracer for determining sediment vertical accretion and mass accumulation rates in light of new measurement techniques. Case studies comparing accumulation rates from 228Th and 210Pb are presented for a micro-tidal salt marsh and a marginal sea environment. 228Th and 210Pb have been previously measured in mangrove, deltaic, continental shelf and ocean basin environments, and a literature synthesis reveals that 228Th (measured via alpha or gamma spectrometry) derived accumulation rates are generally equal to or greater than estimates derived from 210Pb, reflecting different integration periods. Use of 228Th is well-suited for shallow (<15 cm) cores over decadal timescales. Application is limited to relatively homogenous sediment profiles with minor variations in grain size and minimal bioturbation. When appropriate conditions are met, complimentary use of 228Th and 210Pb can demonstrate that the upper layers of a core are undisturbed and can improve spatial coverage in mapping accumulation rates due to the higher sample throughput for sediment 228Th.

Comments

© 2022 The Authors. Published by Elsevier B.V.

This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Original Publication Citation

Tamborski, J. J., Cai, P., Eagle, M., Henderson, P., & Charette, M. A. (2022). Revisiting 228Th as a tool for determining sedimentation and mass accumulation rates. Chemical Geology, 607, Article 121006. https://doi.org/10.1016/j.chemgeo.2022.121006

ORCID

0000-0003-2422-3252 (Tamborski)

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