Publication Date:
2022-05-25
Description:
Author Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Marine Chemistry 100 (2006): 234-249, doi:10.1016/j.marchem.2005.10.014.
Description:
Over the past few decades, the radioisotope pair of 238U/234Th has been widely and
increasingly used to describe particle dynamics and particle export fluxes in a variety of
aquatic systems. The present paper is one of five review articles dedicated to 234Th. It is
focused on the models associated with 234Th whereas the companion papers (same issue) are
focused on present and future methodologies and techniques (Rutgers van der Loeff et al.),
C/234Th ratios (Buesseler et al.), 234Th speciation (Santschi et al.) and present and future
applications of 234Th (Waples et al.). In this paper, we review current 234Th scavenging
models and discuss the relative importance of the non steady state and physical terms
associated with the most commonly used model to estimate 234Th flux. Based on this
discussion we recommend that for future work the use of models should be accompanied by
a discussion of the effect that model and data uncertainty have on the model results. We also
suggest that future field work incorporate repeat occupations of sample sites on time scales of
1-4 weeks in order to evaluate steady state versus non steady state estimates of 234Th export,
especially during high flux events (〉 ca. 800 dpm m-2 d-1). Finally, knowledge of the physical
oceanography of the study area is essential, particularly in ocean margins and in areas of
established upwelling (e.g. Equatorial Pacific). These suggestions will greatly enhance the
application of 234Th as a tracer of particle dynamics and flux in more complicated regimes.
Description:
This paper grew out of discussion held at the “Future Applications of 234Th in Aquatic
Systems” workshop held at Woods Hole Oceanographic Institution in August, 2004 (see: http://www.geol.sc.edu/cbnelson/Thmeeting/). We are grateful to the US National Science
Foundation Chemical Oceanography Program (OCE 0354757) for its support of the
workshop. We thank the US National Science Foundation, the National
Oceanic and Atmospheric Administration and the Belgian Science Policy for their support of
many of the field and modeling efforts described in this paper.
Keywords:
Th-234
;
Model
;
Scavenging
;
Export
;
Particle dynamics
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
2096326 bytes
Format:
application/pdf
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