Changes in physicochemical properties of old stabilized sand dunes due to atmospheric sediments and diversity of clay minerals in a dry area

Abstract

Abstract Sand dune hills were stabilized by petroleum mulch and biological methods in southwest Iran. The present study aims to identify the effects of these landscapes on airborne dust entrapment in five regions, including uphill (UH), downhill (DH), and canopy tree positions after 54 years. These locations were at different distances from dust sources and prevailing winds. The results revealed that salinity in the study areas showed the following trend: canopy > UH > DH. Silt particles were entrapped in the corner 4 times greater than the inner areas. Moreover, silt deposition flux ranged from 54 gm−2 yr−1 (the minimum) in the inner site (Al-Baji) to 207.4 g m−2 yr−1 (the maximum) in the corner site (SG). Unlike silt, clay flux was maximal in both inner (124.4) and corner (123.4) locations due to the movement of fine materials in high elevations. The total deposition of materials (silt + clay) was maximal (330.8) and minimal (155.6 g m−2 yr−1) in the corner and inner sites, respectively. The clay mineralogy indicated that these hills had two groups of minerals. Primary minerals, i.e. carbonates and silicates, were inherited from parent materials. Secondary minerals were identified in surface soil, and peaks in the subsurface were very weak. Wind sediments added these clays to the surfaces. The abundance of these clays showed the following trend: palygorskite > smectite > vermiculite. It was found that these areas do not disturb the atmosphere by dust and play an important role in air purification because the surface roughness of these hills was promoted by artificially planted trees.