Impact of Hydrocarbon Pollutants on Partially Saturated Soil Media in Batch System: Morphological Analysis Using SEM Techniques

Abstract

Soil surface morphology is an important functional parameter in fate and transport of pollutants in subsurface. Therefore, the aim of present study is to investigate the soil morphological changes using batch experiments having different concentration of a hydrocarbon pollutant, toluene. A series of six batch sets containing 20 g of oven-dried sand with particle size of 0.5–1.0 mm and 40% porosity were prepared at room temperature under partially saturated condition. Various concentrations of dissolved toluene varying from 5 to 100 ppm were considered in the designed batches. After 24 h of the incubation, when the soil water concentration reached to equilibrium, the temporary slides of respective soil samples were prepared. To capture the high magnification at pore scale, scanning electron microscopy (SEM) analysis was conducted at magnification of 10×, 20×, 30× and 40×. The results showed that the level of soil surface losses and the number of cavities on soil surface were increased with increasing hydrocarbon concentration. Furthermore, attenuation in the brightness of the sand particles was observed with increment in hydrocarbon concentration indicating the more adsorption capacity of toluene at high concentration levels. Results of this study are helpful in investigating the geochemical stability of soil, remediation strategy and for upscaling of fate and transport of pollutants in subsurface environment.