Leaching behavior of contaminant in saline-alkali soil amended with sludge

In order to study the leaching behaviors of contaminants in saline-alkali soil amended with dewatered sludge, the changes of nutrients content, heavy metal form distribution and the contents of total organic carbon (TOC), N, P contaminants and heavy metals in leachate were investigated through incubation and leaching experiment. The results show that organic matter, total nitrogen, total phosphorus, available nitrogen, available phosphorus and available potassium in soil amended with sludge are increased by 2.5, 4, 2.4, 3.2, 11.6, and 1.2 times respectively after sludge application and incubation for 0 d. With the extension of incubation time, the total content of nutrients decreases and that of available nutrients increases. Form distribution of heavy metals in soil is less affected by sludge amendment; Zn, Ni, and Pb in exchangeable and carbonate combined states decrease after incubation for 60 d. The contents of TOC, total nitrogen (TN), NH₄⁺-N, Cr, As, Pb, Ni reduce with incubation time. If it rains after incubation period of 60 d, contaminant contents in leachate will be close to the contrast values.