INCITAP   20787
INSTITUTO DE CIENCIAS DE LA TIERRA Y AMBIENTALES DE LA PAMPA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Highlights of the study on aeolian dust emitted from agricultural soils of Argentina
Autor/es:
JUAN ESTEBAN PANEBIANCO; MÉNDEZ, MARIANO JAVIER; DANIEL EDUARDO BUSCHIAZZO; LAURA ANTONELA ITURRI; AIMAR, SILVIA BEATRIZ; FERNANDO AVECILLA; DE ORO, LAURA ANDREA
Lugar:
Santa Rosa
Reunión:
Simposio; Blowing South: Southern Hemiphere Dust Symposium; 2021
Resumen:
Although some precedents exist, strong research on wind erosion in Argentina started around 1995. The firstworks focused on the measurement of wind erosion. Some mass flux profile models turned out not to bemathematically feasible to calculate the horizontal mass transport, hence producing important biases. Evenwhen using the models that can represent better the mass distribution with height, such as exponentialfunctions or linear interpolation, we found differences of up to 50% in the calculated mass transportdepending on the sampling set up. Considering this, soil losses measured in loessic soils from centralArgentina were up to 1.5 kg m-2 day-1 (or 27 Mg ha-1 year-1). Generally, much lower values were measuredin other soil types across the country. Mean threshold wind speed was 7.5 m s-1 for loessic soils, butgenerally higher for other soil types in more arid and windy regions. After studying wind erosion, work wasoriented towards dust or particulate matter less than ten microns in diameter (PM10) emitted fromagricultural soils and from other wind-erosion prone surfaces in rural areas. Very sandy surfaces such asunpaved roads were found to emit less dust per unit of transported mass, but to emit much more absolutequantities because horizontal mass transport was much higher than on soils. Using concentration gradients,average potential PM10 vertical emission for loessic soils from central Argentina was estimated to bebetween 2x10-4 g m-2 s-1 and 8x10-4 g m-2 s-1. According to our findings, abrasion predominates in sandysurfaces, and lifting of loose particles prevails in finer surfaces. Higher emission values were observed forloamy textures due to the overlapping of abrasion, lifting, and fragmentation of aggregates during saltation.Aggregates that move most actively by saltation on loamy-textured soils are, on average, 110 microns indiameter. We also observed that around 250 metres of bare surface are needed for the development of a dustplume from full fragmentation of the saltating soil aggregates on a loamy sand soil. Particles that we haveconsistently found to actively contribute to the emission of dust are up to around 62.5 microns, becauseparticles in this size range are much more affected by vertical forces than bigger ones. On average, 12% ofthese particles were found to be lost by vertical movement over a distance of 200 meters. The highest PM10emission rates under field conditions were observed when relative humidity was below 20% and the airtemperature was higher than 30°C, especially when the wind speed exceeded 8 m s−1. Interaction betweenclimate, soil and tillage produces high variability of dust emission. Dust is generally enriched in chemicalelements as compared to the bulk soil. Nutrient content in PM10 from eroded sediment from these soils wasfound to be up to 60 g/kg C, 5 g/kg N, 900 mg/kg S; and up to 250 mg/kg Ca and Mg. C y N are transportedhigher than Ca and Mg, especially on less structured surfaces, and S showed a more homogenousdistribution with height.