Effect of leaching of DOC on pore characteristic of a sandy soil

Changes of microstructural properties of a sandy soil from a former sewage farm due to the leaching of dissolved organic carbon (DOC) were studied. The leaching of DOC at various pH values was induced using sodium hydroxide or hydrochloric acid solutions. The removal of DOC altered the pore properties of the remaining solid. The average pore radius measured from water vapor desorption isotherms (micropores range) increased with the increase of the removed DOC under alkaline conditions and did practically not alter under acid treatment. The average pore radius measured by the mercury intrusion porosimetry (mesopores range), decreases, however, for low amounts of the DOC extracted and increases on extracting higher DOC amounts. The mesopores appeared to be fractal. At moderate amounts of the DOC leached the finer mesopores occurred having the higher fractal dimensions than the coarser mesopores.