Large effect of leaching of DOC on water adsorption properties of a sandy soil

In this study, changes of adsorption properties of a sandy soil from a former sewage farm due to the leaching of dissolved organic carbon (DOG) were examined. The leaching of DOC at various pH levels was simulated in laboratory experiment using sodium hydroxide as the leaching agent. An increase of pH resulted in an increase of the amount of DOC in the studied soil. The removal of DOC altered the surface properties of the remaining solid. In particular, the surface area was reduced and the water vapour adsorption energy distribution function was shifted to lower energy ranges, thus showing the increase of the hydrophobic character of the soil, The intensity of these changes was more pronounced when the soil had been previously acidified.