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

• DOI: 10.1130/g33449.1
• Publication Date: 2012-06-30T04:18:01Z
• Authors: Allan R. Bacon; Daniel deB. Richter; Paul R. Bierman; Dylan H. Rood
• Keywords: 13. Climate action; 15. Life on land; 01 natural sciences; 0105 earth and related environmental sciences

We couple meteoric 10 Be measurements with mass balance analysis of 9 Be 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 10 Be inventory to account for observed 9 Be losses, which indicate that more than half of the 9 Be 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 × 10 6 atoms cm −2 yr −1 , respectively), estimates of 10 Be 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 10 Be retention in acidic soil systems cannot always be made; the latter has far-reaching consequences for soil, sediment, river, and ocean research using meteoric 10 Be.