Behavior Of Dissolved Organic Matter From Landfill Leachate In Soils And Its Impact On Environment

Landfill is the major disposal way of urban waste due to its simple operation and mass manipulation. However, the leachate from landfill would contaminate the surface water and underground water heavily without proper management. Since the past decades, many studies has been conducted with foucus on the quantity and quality of the contaminants derived from landfill leachate, and their formation mechanism and disposal technologies. However, few information is available about the behavior of dissolved organic matter (DOM) from landfill leachate in soil and consequence impact on surrounding environment,. Thus, A series of experiments including soil incubation, sorption-desorption study, soil column trial and greenhouse pot experiment were performed in this study with a different ages of landfill leachate from a fresh leachate to a 12-year's leachate). The aim of this study is to explore the sorption/desorption, and translocation behavior of landfill leachate DOM in the acidic and calcareous soils, and to elucidate the effect of these DOM on the mobilization, immigration downward, and bioavailability of heavy metal born in the soils. The obtained results were shown as follow:1 The sorption equilibrium isotherms of landfill leachate DOM with different ages in the acidic and calcareous soils could be described well by the "initial mass approach" with a higher decision coefficiency (R~2>0.98). For the same initial concentration of landfill leachate DOM, the average net sorption of landfill leachate DOM onto acidic soil was 1.74 times higher than that onto the calcareous soil. The older the landfill leachate DOM, the greater the affinity of DOM with soils. It was observed that the affinity of landfill leachate DOM with the two soils was negatively correlated to the proportion of the hydrophilic or small molecular size fractions occupied in landfill leachate DOM. Besides, pH was also one of the key factors affecting the sorption of landfill leachate DOM onto soils. The increase of pH would reduce DOM sorption onto soils.