Is Dust Derived From Shrinking Saline Lakes a Risk to Soil Sodification in Southern South America?

Abstract

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 capacities. At most sites, dust‐equilibrated infiltrated rainfall water had a Na concentration 8–7,000 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 (<50 km), where dust deposition is maximum. At these sites, we estimated potential dust‐related rises in the proportion of soil exchangeable Na. Under scenarios of enhanced salt‐rich dust emissions from shrinking lakes in the twenty‐first century, agricultural soils close to salt‐rich dust sources worldwide should be monitored for potential Na enrichment related to Na‐rich dust.

Insights into Variations and Potential Long-Range Transport of Atmospheric Aerosols from the Aral Sea Basin in Central Asia

“…In semi-arid and arid regions across the world, saline lakes have been disappearing at an alarming rate in recent decades as a result of environmental change and unsustainable exploitation of water sources [5][6][7], leading to the emergence of a new type of dust source in these regions, especially in the arid regions. Many lake basins, such as Ebinur Lake in the northwest of the Junggar Basin [8,9], the Aral Sea in arid central Asia [10][11][12], Urmia Lake and Hamoun Lake in Iran [13,14], Chad Lake in north Africa [15,16], Eyre Lake in south Australia [17], Owens Lake in America [18], and Mar Chiquita Lake in Argentina [19,20], are facing severe and rapid desertification processes and severe dust and sand storms [21]. The newly exposed dry lakebeds have become a substantial source of fine dust and saltdust [22], long-range transport of which will harm animals and plants and also pose a great threat to the eco-environment in downwind areas regionally [23].…”

“…Ebinur Lake in the northwest of the Junggar Basin [8,9], the Aral Sea in arid central Asia [10][11][12], Urmia Lake and Hamoun Lake in Iran [13,14], Chad Lake in north Africa [15,16], Eyre Lake in south Australia [17], Owens Lake in America [18], and Mar Chiquita Lake in Argentina [19,20], are facing severe and rapid desertification processes and severe dust and sand storms [21]. The newly exposed dry lakebeds have become a substantial source of fine dust and salt-dust [22], long-range transport of which will harm animals and plants and also pose a great threat to the eco-environment in downwind areas regionally [23].…”