Evaluation of dust production efficiencies in sandy sediments

Several studies have shown that dust emission (vertical flux, F) can be considered a constant fraction (k) of the saltating flux (horizontal flux, Q), that is, F=kQ. This coefficient of proportionality, or dust production efficiency factor, is often called the 'k factor' and is fundamentally related to soil properties especially soil texture. Beyond regional and global modeling applications, a practical utility of k is for air quality regulatory agencies where k can be used to estimate F based on only measurements of Q, which is more easily measured in the field. Only a few studies have directly estimated the k factor from soils within potential dust sources even though dust models that represent the sandblasting process typically utilize k. The goal of this study was to compare two methods to calculate k from sandy sediments and compare those estimates with an empirical method of calculating the k factor. The first method (method 1) used the difference between F calculated from two sets of sediment samplers whereas the second method (method 2) used a set of aerosol monitors to measure F. We found that the range of k values from our study are consistent with soil texture-based estimates of k and also have the correct order of magnitude. Thus, any of the methods described in our study are appropriate for estimation of k for sandy soils.