Environmental Scanning Electron Microscopy Application for Brackish Water Irrigation Impact on Soil

We investigated soil response to irrigation with slightly brackish water (1200 mg L−1 total dissolved solids on average) in a semiarid environment at the microscopic scale using environmental scanning electron microscopy (ESEM) applied in static and dynamic modes, which allowed comparison between nonirrigated and 3-yr-irrigated soil samples to determine the impact of applied brackish water. Results indicate that (i) there was a change in soil hydrophilic behavior by the continuous accumulation of water-borne salt in the soil matrix, (ii) compared with nonirrigated samples, the wetting process occurred more gradually for the 3-yr-irrigated sample, (iii) the wetting process started at a lower vapor pressure for the 3-yr-irrigated sample, (iv) water vapor pressure in the chamber at full saturation was lower for the 3-yr-irrigated sample, and (v) the presence of heavy metals in the soil was more frequent in irrigated samples. Our results show that ESEM is a useful technique to determine the impacts on soil of irrigation with slightly brackish water.