Hurricanes alter Be-10 concentrations in tropical river sediment but do not change regional erosion rate estimates

Abstract

Tropical islands, including many in island arcs, are subjected to recurring disturbances from extreme storms such as tropical cyclones. To test whether such storms influence cosmogenic nuclide concentrations such that they do not reflect long-term rates of erosion, we measured meteoric and in situ 10Be in river sediment samples from Dominica, an andesitic island in the Caribbean, before and after category five Hurricane Maria (in 2017). Populations of before- and after-storm concentrations are statistically indistinguishable (n = 7 pairs for in-situ 10Be, n = 11 pairs for meteoric 10Be). 10Be concentrations vary from −138% to +73% within before–after sample pairs relative to the mean of the pair. These new data suggest that the effects of extreme storms on the depth and amount of near-surface erosion on Dominica vary spatially. Our data support the calculations of Niemi et al. (2005) and Yanites et al. (2009) suggesting that basin-by-basin comparisons of erosion rates based on cosmogenic nuclides should be approached with caution in small (<~100 km2) watersheds affected by mass movements and extreme storms. Erosion rates determined from in-situ 10Be on Dominica (geometric mean = 0.102 mm y−1, n = 12) are low compared to similarly steep and wet areas globally and correlate positively with the spatial density of mass movements.

Publisher

Wiley

Publication Date

4-1-2022

Publication Title

Earth Surface Processes and Landforms

Department

Geology

Document Type

Article

DOI

https://dx.doi.org/10.1002/esp.5310

Keywords

Caribbean, Cosmogenic radionuclides, Detrital, Erosion rate, Tropical storm, Situ cosmogenic BE-10, Long-term erosion, Denudation rates, In-situ, Meteoric BE-10

Language

English

Format

text

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