不同惰性有机碳物料对土壤镉赋存形态和生物有效性的影响

通过温室盆栽试验和土壤培养试验,研究镉污染土壤和模拟镉污染土壤中加入草炭、活性碳和风化煤3种物料对土壤镉赋存形态和生物有效性的影响,探讨其作为重金属镉污染土壤修复剂的可行性。研究结果表明：3种有机碳物料均降低了土壤pH值,镉污染土壤加入不同惰性有机碳修复剂后,土壤中醋酸铵提取态Cd含量和DTPA提取态Cd含量变化不明显。在模拟Cd污染土壤上则不同,加入不同惰性有机碳修复剂后土壤中醋酸铵提取态Cd含量和DTPA提取态Cd含量均明显降低,降低幅度以风化煤最高,且随加入时间延长降低幅度增加。土壤中加入风化煤和草炭可显著增加土壤中轻组有机质含量,风化煤对土壤中镉有较强富集作用。两种土壤镉赋存形态均为酸提取态〉可还原态〉可氧化态,镉污染土壤加入有机物料后酸提取态镉含量无显著性变化,可还原态镉草炭和活性碳处理显著降低,草炭处理可氧化态镉也显著降低,模拟镉污染土壤加入有机物料后,酸提取态镉风化煤处理显著性降低,可还原态镉活性碳处理显著提高,可氧化态镉无显著性变化。在镉污染土壤上,3种有机碳物料对玉米生长没有显著影响,但增加了玉米体内镉含量;风化煤处理显著降低了白菜生物量,增加了白菜体内镉含量。模拟镉污染土壤上3种有机碳物料对白菜和玉米的生长和体内镉含量均没有显著影响。

Effects of Materials Containing Different Inert Organic Carbon on Cd Speciation and Bio-Availability in Soil

Pot experiments and soil incubation experiments were conducted under greenhouse conditions to investigate the effects of different organic carbon materials added into Cd-contaminated soil and Cd-amended soil on Cd speciation and bio-availability,and discussed the feasibility to improve soil Cd pollution as soil remediation agent.The results showed that soil pH reduced after three organic materials added.In Cd-contaminated soil,there were no significant differences in concentrations of NH4OAc-and DTPA-extractable Cd after three organic materials added into soil.But under the organic materials treatments in Cd-amended soil,the concentrations of NH4OAc-and DTPA-extractable Cd decreased markedly,and the weathered coal addition reduced the most,rate of decline increasing with time.Content of light fraction organic matter in soil increased significantly after weathered coal and peat adding into soil and weathered coal had a stronger enrichment of soil Cd.Chemical forms of Cd in both soils were acid-extractable reducible oxidizable Cd.Acid-extractable Cd concentration had no significant change by adding organic material to Cd-contaminated soil,otherwise,reducible Cd concentration decreased obviously after adding peat and active carbon into soil and oxidizable Cd concentration reduced significantly under peat treatment.Acid-extractable Cd concentration decreased significantly after adding weathered coal into Cd-amended soil,but reducible Cd concentration increased obviously under active carbon treatment and oxidizable Cd concentration had no significant change under the three treatments.In Cd-contaminated soil,the three organic carbon materials had no obvious effect on maize growth but increased the Cd content of maize.Chinese cabbage biomass reduced significantly and Cd content increased obviously after weathered coal added into Cd-contaminated soil.In Cd-amended soil,there were no significant effect on Chinese cabbage and maize growth and Cd content under the three materials treatments.