A wind tunnel experiment to explore the feasibility of using beryllium-7 measurements to estimate soil loss by wind erosion

Abstract

Sandy loess from the Wind–Water Erosion Crisscross Region on the Loess Plateau of China, an area with severe wind erosion, was collected for use in a wind tunnel experiment, to explore the feasibility of using 7Be measurements to estimate the amount of soil lost through wind erosion. Wind erosion selectively removes the finer particles of soil. Use of procedures for estimating soil loss from 7Be measurements developed for water erosion, which do not take account of this selective removal of fines, is therefore likely to result in overestimation of the amount of soil lost through wind erosion, because 7Be is preferentially associated with the finer fractions of the soil. The results of the experiment, supplemented by measurements undertaken on two field plots in the study region demonstrated a well-defined power function relationship between Se/So and ABe (where Se is the specific surface area of the soil at the eroded site; So is the SSA of the original soil and ABe is the 7Be activity remaining at the eroded site), with an exponent of ∼0.75. It is proposed that a particle size correction factor P′, based on the term (Se/So)0.75, can be incorporated into the procedure for estimating soil loss by wind erosion from 7Be measurements. The estimates of soil loss obtained using the refined procedure were in close agreement with the measured values. Use of the 7Be measurements to estimate soil loss without incorporating the particle size correction factor P′ resulted in over-estimation of the soil loss by ∼14%. When P′ was incorporated, the overestimation was reduced to ∼2%.