The use of magnesium-enriched brine for stabilization of highly erodible playa surfaces: A comparative study with sodium alginate and sodium silicate

Newly formed playas, such as those resulting from the desiccation of Lake Urmia (LU) in northwest Iran, are significant global dust sources with implications for human health and the environment. Stabilizing these surfaces affordably can be achieved using locally sourced magnesium-enriched brine. To evaluate this approach, for LU playa, we examined the accumulation of ions, minerals deposition, and salt crust (Cr) formation in LU brine under both natural and laboratory conditions. We then assessed the effect of brines with varying Mg2+ concentrations (B0 approximate to 1.97, B5 approximate to 2.72, and B15 approximate to 3.62 mol/L) on the stabilization of two highly erodible soils (sand sheets and sandy salt crust), comparing them with commercial stabilizers: sodium alginate (Na-A) and sodium silicate (Na-S). The crusts were evaluated based on thickness, compressive strength, and soil loss in wind tunnel experiments. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS) was employed to analyze crust morphology and elemental composition. The results indicated that in the pure crusts, halite was the dominant mineral in salt crusts, while bischofite (MgCl2 center dot 6H2O) and epsomite (MgSO4 center dot 7H2O) formed during different stages of brine evaporation. Bischofite appeared at the pond margins, indicating deposition from less concentrated brines (B0 and B5), while epsomite dominated the center during the final evaporation stages. Brine treatments significantly reduced soil loss to 1.2%, outperforming Na-A (4.88%), Na-S (30.35%), and the control (34.18%). SEM analysis confirmed aggregate formation due to NaCl and MgCl2 precipitation. In conclusion, Mg-enriched LU brine demonstrated effectiveness comparable to commercial stabilizers in enhancing the resilience of highly erodible playa surfaces.