Vegetation density and vapor pressure deficit: Potential controls on dust flux at the Jackpile Uranium Mine, Laguna Pueblo, New Mexico
— Reid Brown and Daniel Cadol

A recent study investigated various processes that control dust transport at a former uranium mine in Laguna Pueblo, New Mexico. Two processes were found to be important in controlling dust transport at the Jackpile mine site: vegetation and soil moisture content inferred from the vapor pressure deficit (VPD). To determine the importance of vegetation, two dominant species were considered: juniper and grass. Dense juniper stands had higher soil uranium concentrations compared to other vegetation types and densities. Moderate and sparse stands had median soil uranium concentrations equal to or less than grass-dominated systems. This suggests that there is a critical stand density that reduces wind speed between individual plants, reducing scour. Designing dust mitigation strategies to maintain stands at this critical density could be important for future site remediation. Seasonal effects on wind speed and soil moisture were also considered. The results showed that dust flux was the greatest in the spring. Unexpectedly, dust flux in the winter showed a marked decrease compared to the other three seasons despite having the highest two recorded wind gusts and a similar sustained winds profile compared to spring. Weather data collected on site was used to calculate the VPD to use as a proxy for soil moisture. The winter experienced the lowest VPD. A low VPD indicates there is more moisture in the air reducing the gradient driving soil moisture evaporation. Based on the positive relationship with dust flux, calculated VPD was able to reproduce seasonal trends of soil moisture reliably and is a good proxy for soil moisture when that data is unavailable.