Short and long-term delivery rates of meteoric Be-10 to terrestrial soils

Well-constrained, long-term average meteoric 10Be deposition rates are important when meteoric 10Be is used as a chronometer or tracer of Earth surface processes. To constrain meteoric 10Be delivery to terrestrial soils, we estimate time-integrated 10Be deposition rates from meteoric 10Be inventories measured in dated soils and compare these results to a new synthesis of short-term measurements of 10Be in precipitation. Comparison of these long-term rates to short-term measurements suggests that short-term measurements likely predict long-term meteoric 10Be deposition rates within uncertainties of ~ 20%.

In precipitation measurements, it is possible to deconvolve the contribution of atmospherically-produced “primary” meteoric 10Be from “recycled” meteoric 10Be delivered by terrestrial dust if a second isotope is measured that quantifies either the recycled or primary components of meteoric 10Be deposition. We use dust-concentration dependent differences between 7Be and 10Be measurements to make new estimates of the recycled contribution to total meteoric 10Be flux delivered to the Earth's surface. These dust-corrected data show a strong linear dependence between precipitation amount and primary meteoric 10Be flux. Concentrations of primary meteoric 10Be in mid- and low-latitude precipitation vary predictably by latitude between 0.63 · 104 and 2.05 · 104 atoms/cm3 of precipitation, providing a first-order estimate of primary meteoric 10Be deposition for a given latitude and precipitation rate.

Research Highlights
► Amount of meteoric 10Be fallout sourced from dust is estimated from 7Be measurements. ► Equation predicts 10Be fallout by latitude and precipitation within 10–20% error. ► Meteoric 10Be retained in soil provides long-term average isotope deposition rates. ► Long-term variability likely approximates uncertainty in short-term fallout estimates.