Coupling meteoric 10be with pedogenic losses of 9be to improve soil residence time estimates on an ancient North American interfluve

We couple meteoric ¹⁰Be measurements with mass balance analysis of ⁹Be to estimate the soil residence time (SRT) of a biogeomorphically stable Ultisol in the Southern Piedmont physiographic region of the southeastern United States. We estimate SRT after correcting the meteoric ¹⁰Be inventory to account for observed ⁹Be losses, which indicate that more than half of the ⁹Be weathered from primary minerals has been leached from the upper 18.3 m of the Ultisol. Our estimates of minimum SRT range between 1.3-1.4 Ma and between 2.6-3.1 Ma under high and low (2.0 and 1.3 × 106 atoms cm ^-2 yr ^-1, respectively), estimates of ¹⁰Be delivery. Denudation rates of the physiographic region corroborate our estimates. We redefine pedogenic time constraints in the Southern Piedmont, and demonstrate that the assumption of complete meteoric ¹⁰Be retention in acidic soil systems cannot always be made; the latter has far-reaching consequences for soil, sediment, river, and ocean research using meteoric ¹⁰Be. © 2012 Geological Society of America.

Duke Scholars

Author Daniel D. Richter Earth and Climate Sciences