摘要：To study the Cd stability immobilized by bio-char-remediated soil under acid rain, the Cd-contam-inated soil in an acid rain region of southern China was selected and remediated using biochar. The characteristics of soil Cd leaching and availability and the organic matter content in the leaching solu-tion were studied under acid rain with different acid-ities. The results showed thatthe pH values increased by 0.48-1.45 units ofthe leaching solutions from the biochar-remediated soils compared with soils with-out biochar, while the Cd contents decreased by 3.56%-78.37%. The biochar addition induced de-creases in the content of dissolved organic matter (DOM) in the soil leaching solutions, but increases in the leaching loss of DOM with acid rain acidities increasing and over time. The DOM three-dimen-sional fluorescence spectrum results implied that the highest load of the macromolecular humus compo-nent was in the first collected leaching solution, while that of the small molecule humus component was in the final collected leaching solution. The acid rain generally induced the soil available Cd contents in the 0-5,5-10,10-15 and 15-20 cm soil layers to decrease by 17.44%,17.55%,12.67% and 13.49%. The available Cd content decreases were attributed to the significant decreases in the content of ex-changeable Cd and the increases in the contents of carbonate-,iron-manganese oxide- and organic-bonded Cd. The results indicate that biochar per-forms well in the immobilization of Cd in soil when it serves as a remediator even in acid rain regions.
