Abstract
Many soils throughout the world are currently associated with soil erosion by wind and dust emissions. Dust emission processes have major implications for loss of soil resources (such as clays and nutrients) and human exposure to air pollution. This work provides a review on field experiments of dust emission based on previous studies, with new insight into the role of soil aggregation. The work focuses on dust processes in semi-arid soils that are subjected to increased agricultural land use. A boundary-layer wind tunnel has been used to study dust emission and soil loss by simulation and quantification of high-resolution wind processes. Field experiments were conducted in soil plots representing long-term and short-term influences of land uses such as agriculture, grazing, and natural preserves. The results show the impacts of soil disturbances by human activities on the soil aggregation and dust fluxes and provide quantitative estimates of soil loss over time. Substantial loss of PM10 (particulate matter [PM] that is less than 10 micrometers in diameter) was recorded in most experimental conditions. The measured PM10 fluxes highlight the significant implications for soil nutrient resources in annual balance and management strategies, as well as for PM loading to the atmosphere and the risk of air pollution.
Highlights
Soil erosion by wind and the related dust emission from the soil to the atmosphere have significant impacts on Earth systems and human environments
Annual global dust emissions from soils into the atmosphere are estimated to be as high as 3000 million tons, including particulate matter (PM) that is less than 10 micrometers in diameter (PM10)
The emission of PM10 from soils is important for several reasons: (i) PM10 is composed of clays and organic carbon, enabling water and nutrients to be adsorbed in the soil [3]; (ii) PM10 has a major role in aerosol radiative forcing [4]; and (iii) it is considered a key air pollutant associated with health risks [5,6,7]
Summary
Soil erosion by wind and the related dust emission from the soil to the atmosphere have significant impacts on Earth systems and human environments. Dust emission is enabled above a critical value of wind (shear) velocity at which the aerodynamic force is enough to dislodge particles from the surface [10]. The cohesive forces are generally much larger than the aerodynamic and gravitational forces, thereby preventing dust from being lifted directly by wind [8]. In this case, dust entrainment is strongly connected with the saltation process. The impact of the saltation of particles enables the Agronomy 2020, 10, 89; doi:10.3390/agronomy10010089 www.mdpi.com/journal/agronomy
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