PM2.5 and PM10 emissions by abrasion of agricultural soils

Authors: Tatarko, John; KUCHARSKI, MATTHEW - Former ARS Employee; LI, HONGLI - Shandong Agricultural University; LI, HUIRU - Beijing Normal University

Submitted to: Soil and Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/4/2020
Publication Date: 3/4/2020
Citation: Tatarko, J., Kucharski, M., Li, H., Li, H. 2020. PM2.5 and PM10 emissions by abrasion of agricultural soils. Soil and Tillage Research. 200:104601. https://doi.org/10.1016/j.still.2020.104601.
DOI: https://doi.org/10.1016/j.still.2020.104601

Interpretive Summary: Abrasion of soil clods by blowing sand during wind erosion is one process that contributes to fine dust in the air, which lowers air quality. Little is known about the abrasion process that generates fine dust of sizes less than 0.0001 inches or those less than 0.0004 inches. Both of these dust sizes are regulated by the US Environmental Protection Agency as health hazards. In a laboratory wind tunnel, we studied the dust generated by abrasion of 15 soils from across the U.S that contained soil clods. We tested a mixture soil clod sizes in trays as well as sets of clods sitting on the wind tunnel floor and subjected them to fine sand blown at a wind speed of 29 miles per hour. Fine dust emissions were found to depend on soil type. Sandy soils had the weakest clods as well as lowest fine dust contents but were found to have the highest dust emission under abrasion. By contrast, soils higher in clay had lower emissions under abrasion. We also compared fine dust generated from abrasion for five soils that had long-term tillage histories of either conventional tillage (CT) or no-till (NT) agricultural management. CT management tended to show greater dust from abrasion compared to NT management for the same soil. We developed equations that predict fine dust generated for soils and individual clods alone. The results of this research of fine dust generation and can be used to predict fine dust emissions through abrasion on agricultural soils.

Technical Abstract: Abrasion of soil clods by wind erosion is one process contributing to fine particulate dust emissions air, which degrades air quality. Little is known about the abrasion process that generates and emits particulate matter with aerodynamic diameter of less than 2.5 µm (PM2.5) or those less than 10 µm (PM10). Both PM2.5 and PM10 are regulated by the US-Environmental Protection Agency as health hazards. We used a laboratory wind tunnel to study the abrasion induced emissions of 15 aggregated soils from across the U.S. We subjected aggregated soils in trays as well as sets of aggregates placed on the wind tunnel floor to abrader sand (0.29 to 0.42 mm diameter) blown at 13 m s-1. PM2.5 and PM10 emissions were found to vary by soil type. Sandy soils had the poorest aggregation as well as lowest primary fine particulate contents and were found to have the greatest abrasion coefficients (AC) and highest emission of PM2.5 and PM10 under abrasion. By contrast, soils higher in clay had lower AC and emissions under abrasion. In addition, five of the soils tested had long-term histories of both conventional tillage (CT) and no-till (NT) management for paired comparisons of emission based on CT and NT managements. CT management tended to show higher AC values and greater abrasion emissions compared to NT management for the same soil, although only three of five management pairs were significant. Dry aggregate stability parameters were found to have an exponential relationship to AC with break force being a better AC predictor (R2 = 0.936) than dry stability (R2 = 0.894). We also developed equations that predict PM2.5 emissions as a fraction of PM10 emissions for aggregated soils (R2=0.932) and individual aggregates alone (R2=0.854). This research contributes to the understanding and prediction of PM2.5 and PM10 emission through the abrasion process.