秸秆炭化后还田对不同镉污染农田土壤中镉生物有效性和赋存形态的影响

通过土壤培养试验和生物盆栽试验,研究不同镉污染土壤上作物秸秆炭化后还田对不同镉污染土壤中镉的赋存形态和生物有效性影响,结果表明：在碱性的镉污染土壤上,秸秆炭化后还田降低了玉米地上部生物量,但对玉米地上部镉含量和镉吸收量无显著影响;在酸性的模拟镉污染土壤上秸秆炭化后还田对玉米生长无影响,但还田含镉的油菜秸秆黑炭显著增加了玉米地上部镉含量和镉吸收量;还田不含镉的玉米秸秆黑炭对镉污染土壤中DTPA提取态镉含量没有明显影响,但还田含镉的油菜秸秆黑炭显著增加了镉污染土壤中DTPA提取态镉含量;施用含镉的油菜秸秆黑炭增加了镉污染土壤中水溶和交换态镉含量;施用玉米和油菜秸秆黑炭均显著降低了模拟镉污染土壤中水溶和交换态镉含量;增加了松有机结合态、碳酸盐结合态和紧有机结合态镉含量;模拟镉污染土壤施用玉米和油菜秸秆黑炭6个月后土壤中水溶和交换态镉仍然是土壤镉的主要赋存形态,水溶和交换态镉占土壤全镉的70%以上。综合以上结果可知,秸秆黑炭不能降低污染土壤中镉的生物有效性和植物对土壤镉的吸收量。

Phytoavailability and Chemical Speciation of Cd in Different Cd-contaminated Soils Influenced by Bio-char Incorporation

Greenhouse study was conducted to investigate the phytoavailability and chemical speciation of Cd in two Cd-contaminated soils influenced by bio-char incorporation and to assess the possible remediation by bio-char return to soil.Results showed that bio-char incorporation significantly decreased shoot dry weight but it had no effect on Cd concentration and uptake of maize in Cd-contaminated soil.Biochar incorporation also had no effect on shoot dry weight of maize in artificial Cd-contaminated soil but it significantly increased Cd concentration and uptake of maize with Cd-containing bio-char incorporation.The DTPA extractable Cd concentration increased with the incorporation of Cd-containing bio-char in Cd-contaminated soil.With bio-char incorporating,the water soluble and exchangeable Cd concentration in soil decreased significantly and concentrations of organic bound and carbonate Cd increased significantly in artificial Cd-contaminated soil.While,the water soluble and exchangeable Cd concentration in soil increased significantly with Cd-containing bio-char incorporated into the Cd-contaminated soil.Bio-char incorporation did not decrease the phytoavailability of Cd in both of the two Cd-contaminated soils.