Institute of Resources, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, 1 Weigang, Nanjing 210095, China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, China.
Institute of Resources, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, 1 Weigang, Nanjing 210095, China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, China.
Sci Total Environ. 2022 Aug 25;836:155547. doi: 10.1016/j.scitotenv.2022.155547. Epub 2022 Apr 30.
Biochar has been used as an amendment in Cd-contaminated soils. However, the mechanisms of which biochar reduce Cd mobility and rice (Oryza sativa L.) Cd uptake by modifying the iron and sulfur cycling in soil has rarely been addressed in the literature. A pot experiment has been carried out with two Cd-contaminated paddy soils (FG and DBS) from South China. Rice straw biochar (RSB) and rape straw biochar (RASB) pyrolyzed at 450 °C were applied at 0, 0.5, and 1% (w/w), respectively. The results showed that biochar amendment at a rate of 1% reduced grain Cd concentrations by 29.3-35.2%. Furthermore, biochar significantly reduced the Cd concentration of root, while the decline of Cd concentration by RASB treatment was higher than by RSB treatment. Root Cd in RASB was significantly reduced by 56.4-51.8% compared to than that in RSB at the maturing stage. Biochar reduced soil acid-soluble Cd by 15.9-25.3% with the increase of pH at the maturing stage in FG soil, and 30.1-59.3% by promoting soil into more reductive condition at the heading stage in DBS soil with higher contents of Fe and S. In addition, biochar impeded Cd transport from soil to rice roots by increasing the formation of iron plaque at the flooding stage. Owing to the influence of RASB, DCB-Cd concentration increased significantly, with 99.7% at the heading stage in FG soil and 237.9% at the tillering stage in DBS soil, respectively. Furthermore, RASB with a higher sulfur concentration had a more positive effect on Cd immobilization and iron plaque formation compared to RSB. As a conclusion, this study suggested that biochar might be able to promote the Cd immobilization by affecting the cycling of iron and sulfur in soil.
生物炭已被用作污染土壤中镉的改良剂。然而，生物炭通过改变土壤中铁和硫的循环来降低镉的移动性和水稻（Oryza sativa L.）对镉的吸收的机制在文献中很少被提及。在中国南方进行了一项利用两种受镉污染的稻田土壤（FG 和 DBS）的盆栽实验。分别添加 0、0.5 和 1%（w/w）的水稻秸秆生物炭（RSB）和油菜秸秆生物炭（RASB）。结果表明，1%的生物炭添加量可使稻谷中镉浓度降低 29.3-35.2%。此外，生物炭显著降低了根中的镉浓度，而 RASB 处理的镉浓度下降幅度高于 RSB 处理。与 RSB 相比，在成熟阶段，RASB 处理使根中的 Cd 降低了 56.4-51.8%。在 FG 土壤中，生物炭在成熟阶段通过提高 pH 值使土壤中酸溶性镉降低了 15.9-25.3%，而在 DBS 土壤中，由于铁和硫含量较高，促进土壤向更还原的条件转化，使土壤中酸溶性镉降低了 30.1-59.3%。此外，生物炭在淹水阶段通过增加铁斑的形成，阻碍了镉从土壤向水稻根部的迁移。由于 RASB 的影响，FG 土壤在抽穗期的 DCB-Cd 浓度显著增加，达到 99.7%，DBS 土壤在分蘖期增加到 237.9%。此外，与 RSB 相比，硫含量较高的 RASB 对 Cd 固定和铁斑形成具有更积极的影响。综上所述，本研究表明，生物炭可能通过影响土壤中铁和硫的循环来促进 Cd 的固定。
