Abstract:

The effect of dissolved organic matter (DOM) on Pb leaching in Pb-contaminated soil treated by freeze-thaw action was investigated with the laboratory simulation experiments. The results showed that physiochemical properties of soil and chemical speciation of Pb were significantly changed by freezethaw action; DOM could significantly facilitate Pb leaching in freeze-thaw soil compared with non freeze-thaw soil. The leaching influences of DOM on Pb in Pb-contaminated soil were closely related to the soil type, soil contamination time and contamination degree. The leaching influence of DOM on Pb in brown soil was greater than that of in black soil,and increased with the time and degree of soil contaminated by Pb increasing. The leaching influences of DOM on Pb in Pb-contaminated soil were also closely related to the mass concentration, properties and component of DOM. The leaching amount of Pb was improved by the increase of DOM mass concentration, the lower pH of DOM and the low-molecular-weight hydrophilic fraction of DOM facilitated the leaching of Pb from in soil.

Key words: straw, sludge, dissolved organic matter, freeze-thaw effect, Pb