. Are sodium-rich dust inputs from shrinking lakes diminishing southern South American soil fertility?

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

Simposio; Blowing South: Southern Hemiphere Dust Symposium; 2021

Dry lake beds exposed by shrinking water bodies in arid regions constitute sodium (Na)-rich mineral dustemission hotspots that may potentially affect agriculture. While several studies have proposed this linkbased on the dispersive properties of Na, no mass balance has so far been attempted. We modeled 13 yearsof dust emission from Mar Chiquita (MC), the most extensive saline lake in South America, which hasexperienced recent shrinking in response to climate variability and anthropogenic water diversion in theupper tributaries. Based on the chemistry of dust, we found that on average between 2005-2017, ~15-150mg m-2 of MC-derived soluble Na was deposited 300 km from the source in August plus September, theseason of strongest MC dust emissions. We compared these values against exchangeable Na stocksmeasured on agricultural soils at 13 sites across the Pampean plains, with differing rainfall regimes andwater holding capacity. We found that infiltrated rainfall water in equilibrium with Na from deposited dusthas a low to non-existent short-term, seasonal sodification risk, except in close proximity to the MC dustsource (