Is dust derived from shrinking saline lakes a risk to soil sodification in southern South America?

LAURA GABRIELA BORDA; NICOLÁS COSENTINO ; LAURA ANTONELA ITURRI; MARÍA GABRIELA GARCÍA; DIEGO GAIERO

Journal of geophysical research: Earth surface

John Wiley and Sons

Lugar: Nueva Jersey; Año: 2022

Dry lakebeds exposed by shrinking water bodies in arid regions constitute sodium (Na)-rich mineral dust emission hotspots that may potentially affect agriculture through soil sodification. However, no soluble Na mass balance has so far been attempted. We modeled 13 years (2005-2017) of dust emission from Mar Chiquita (MC), the most extensive shrinking saline lake in South America. Based on a chemical characterization of dust, we found that a mean ~15-150 mg m-2 of soluble Na was deposited 300 km from the source during the season of strongest dust emissions. We estimated the impact of this atmospheric input on 13 agricultural soils, with different rainfall regimes and water holding capacity. At most sites, dust-equilibrated infiltrated rainfall water had a Na concentration 8-7000 times lower than the lowest concentration threshold proposed to trigger sodification. Additionally, this rainfall water is diluted ~2-20 times as it infiltrates in saturated soils, and its sodium adsorption ratio is probably reduced due to the abundance of soluble calcium and magnesium in the soil solution. Thus, there is no risk of short-term, seasonal sodification, except possibly at two sites and in close proximity to the dust source (