不同镉污染农田土壤上秸秆和炭化秸秆分解动态及其对土壤镉的吸附特征

Decomposition dynamic and Cd adsorption characteristic of crop straw and biochar in different Cd-contaminated farmland soils

通过温室土壤培养实验，研究不同镉污染农田土壤上不同的作物秸秆和炭化作物秸秆还田后的分解动态和还田秸秆材料对污染土壤中镉的吸附特征，探讨秸秆和炭化秸秆还田做为重金属镉污染农田土壤修复剂的可行性。实验结果表明，还田的油菜秸秆和玉米秸秆在2种镉污染水稻土壤上6个月分解了43％-65％，秸秆炭化后还田则很稳定，2种镉污染土壤上还田6个月时累计分解量小于5％。2种镉污染土壤上还田的秸秆和炭化秸秆随还田时间延长镉含量逐渐增加。模拟镉污染土壤上，相同时期油菜秸秆中镉含量显著高于玉米秸秆，油菜秸秆炭中镉含量显著高于玉米秸秆炭。在镉污染土壤上，还田的玉米秸秆、油菜秸秆、玉米秸秆炭和油菜秸秆炭对土壤镉的净吸附量相近，均小于1．1μg／g。在模拟镉污染土壤上还田的油菜秸秆和油莱秸秆炭对土壤镉净吸附量最高分别达到2．74μg／g和7．03μg／g，分别是玉米秸秆和玉米秸秆炭的2倍，且显著高于其在镉污染土壤上的净吸附量，具有高的吸附能力。

Soil incubation experiments were conducted under greenhouse condition to investigate the dy- namic of crop straw and biochar decomposition and adsorption to Cd in different Cd-contaminated soils. Results showed that 43% -65% of maize and oilseed rape straw returned to the Cd-contaminated soils were decomposed in 6 months, while biochar from maize and oilseed rape straw decomposed less than 5%. The Cd concentrations of straw and biochar returned to Cd-contaminated soils increased with the increase of incubation time. The Cd concentrations of straw and biochar from oilseed rape were significantly higher than that from maize at the same incubation time. The highest net adsorption amounts of Cd from simulation Cd-contaminated soil by straw and biochar from oilseed rape straw were 2.74 μg/g and 7.03μg/g, respectively and which were higher than that from Cd-contaminated soil and straw and biochar from maize.