Characterizing variability in geochemistry and mineralogy of western US dust sources

Authors: MANGUM, ABBY - Brigham Young University; CARLING, GREGORY - Brigham Young University; BICKMORE, BARRY - Brigham Young University; Webb, Nicholas - Nick; LEIFI, DETIARE - Brigham Young University; BRAHNEY, JANICE - Utah State University; FERNANDEZ, DIEGO - Utah State University; REY, KEVIN - Brigham Young University; NELSON, STEPHEN - Brigham Young University; BURGENER, LANDON - Brigham Young University; LEMONTE, JOSHUA - Brigham Young University; THOMPSON, ALYSSA - Brigham Young University; Newingham, Beth; DUNIWAY, MICHAEL - Us Geological Survey (USGS); AANDERUD, ZACHARY - Brigham Young University

Submitted to: Aeolian Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/16/2024
Publication Date: 9/21/2024
Citation: Mangum, A., Carling, G., Bickmore, B., Webb, N.P., Leifi, D., Brahney, J., Fernandez, D., Rey, K., Nelson, S., Burgener, L., Lemonte, J., Thompson, A., Newingham, B.A., Duniway, M.C., Aanderud, Z. 2024. Characterizing variability in geochemistry and mineralogy of western US dust sources. Aeolian Research. 70-71:Article 100941. https://doi.org/10.1016/j.aeolia.2024.100941.
DOI: https://doi.org/10.1016/j.aeolia.2024.100941

Interpretive Summary: Dust events originate from a variety of sources in arid and semi-regions, yet dust is difficult to trace back to the source. To test the viability of source tracking via dust fingerprinting, we used dust samples from the National Wind Erosion Research Network (NWERN) to characterize the geochemical and mineralogical composition of key dust sources across the western US. Our results show that the composition of dust varies across the sites and is related to differences in underlying bedrock and soil type, with particularly distinct dust at or near playas with abundant evaporite minerals. Other sites, however, had similar geochemical and mineralogical composition that could not initially be distinguished. A linear discriminant analysis (LDA) successfully separated all sites based on their geochemistry, suggesting that LDA may prove useful for fingerprinting dust samples with seemingly similar composition. Further, an LDA based on mineralogical data separated most sites using only a limited number of mineral phases that were readily explained by the local geologic setting. Dust composition varied seasonally at many of the sites, but within-site variability was smaller than across-site variability, indicating that the fingerprints are robust over time. Taken together, the geochemical and mineralogical measurements generated distinct fingerprints for dust emissions across NWERN sites. If expanded to include a broader range of sites across the western US, a library of geochemical and mineralogical data may serve as a basis for fingerprints to potentially track dust from source to sink.

Technical Abstract: Dust events originate from multiple sources in arid and semi-arid regions, making it difficult to quantify source contributions. Dust geochemical/mineralogical composition, if the sources are sufficiently distinct, can be used to quantify the contributions from different sources. To test the viability of using geochemical and mineralogical measurements to separate dust-emitting sites, we used dust samples collected between 2018 and 2020 from ten National Wind Erosion Research Network (NWERN) sites that are representative of western United States (US) dust sources. Dust composition varied seasonally at many of the sites, but within-site variability was smaller than across-site variability, indicating that the geochemical signatures are robust over time. It was not possible to separate all the sites using commonly applied principal component analysis (PCA) and cluster analysis because of overlap in dust geochemistry. However, a linear discriminant analysis (LDA) successfully separated all sites based on their geochemistry, suggesting that LDA may prove useful for separating dust sources that cannot be separated using PCA or other methods. Further, an LDA based on mineralogical data separated most sites using only a limited number of mineral phases that were readily explained by the local geologic setting. Taken together, the geochemical and mineralogical measurements generated distinct signatures of dust emissions across NWERN sites. If expanded to include a broader range of sites across the western US, a library of geochemical and mineralogical data may serve as a basis to track and quantify dust contributions from these sources.