Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs / Key Laboratory of Original Agro-Environmental Pollution Prevention and Control, MARA / Tianjin Key Laboratory of Agro-Environment and Agro-Product Safety, Tianjin 300191, PR China; Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs / Key Laboratory of Original Agro-Environmental Pollution Prevention and Control, MARA / Tianjin Key Laboratory of Agro-Environment and Agro-Product Safety, Tianjin 300191, PR China.
Sci Total Environ. 2021 Sep 1;785:147163. doi: 10.1016/j.scitotenv.2021.147163. Epub 2021 Apr 17.
Arsenic (As) and cadmium (Cd) are nonessential toxic metal(loids) that are carcinogenic to humans. Hence, reducing the bioavailability of these metal(loids) in soils and decreasing their accumulation in rice grains is essential for agroecology, food safety, and human health. Iron (Fe)-enriched corncob biochar (FCB), Fe-enriched charred eggshell (FEB), and Fe-enriched corncob-eggshell biochar (FCEB) were prepared for soil amelioration. The amendment materials were applied at 1% and 2% application rates to observe their alleviation effects on As and Cd loads in rice paddy tissues and yield improvements using pot trials. The FCEB treatment increased paddy yields compared to those of FCB (9-12%) and FEB (3-36%); this could be because it contains more plant essential nutrients than FCB and a lower calcite content than that of FEB. In addition, FCEB significantly reduced brown rice As (As, 29-60%) and Cd (Cd, 57-81%) contents compared to those of the untreated control (CON). At a 2% application rate, FCEB reduced the average mobility of As (56%) and Cd (62%) in rhizosphere porewater and enhanced root Fe-plaque formation (76%) compared to those of CON. Moreover, the enhanced Fe-plaque sequestered a substantial amount of As (171.4%) and Cd (90.8%) in the 2% FCEB amendment compared to that of CON. Pearson correlation coefficients and regression analysis indicated that two key mechanisms likely control As and Cd accumulations. First, rhizosphere soil pH and Eh controlled As and Cd availabilities in porewaters and their speciation in the soil. Second, greater Fe-plaque formation in paddy roots grown in the amended soils provided a barrier for plant uptake of the metal(loids). These observations demonstrate that soil amendment with Fe-enriched corncob-eggshell biochar (e.g., 2% FCEB) is a prospective approach for the remediation of metal accumulation from the soil to grain system while simultaneously increasing paddy yield.
砷（As）和镉（Cd）是非必需的有毒金属（类），对人类具有致癌性。因此，减少土壤中这些金属（类）的生物有效性并降低其在水稻籽粒中的积累对于农业生态、食品安全和人类健康至关重要。富铁玉米芯生物炭（FCB）、富铁烤蛋壳（FEB）和富铁玉米芯-蛋壳生物炭（FCEB）被用于土壤改良。将这些改良剂以 1%和 2%的施用量应用于盆栽试验，观察它们对水稻组织中砷和镉负荷的缓解作用以及对产量的提高。与 FCB（9-12%）和 FEB（3-36%）相比，FCEB 处理增加了稻谷产量；这可能是因为它比 FCB 含有更多的植物必需营养物质，并且比 FEB 含有更低的方解石含量。此外，与未处理对照（CON）相比，FCEB 显著降低了糙米中砷（As，29-60%）和镉（Cd，57-81%）的含量。在 2%的施用量下，与 CON 相比，FCEB 降低了根际孔隙水中砷（56%）和镉（62%）的平均迁移率，并增强了根铁斑的形成（76%）。此外，与 CON 相比，增强的铁斑在 2%FCEB 改良剂中螯合了大量的砷（171.4%）和镉（90.8%）。皮尔逊相关系数和回归分析表明，两个关键机制可能控制着砷和镉的积累。首先，根际土壤 pH 值和 Eh 值控制着孔隙水中砷和镉的可利用性及其在土壤中的形态。其次，在添加土壤中生长的水稻根系中形成更多的铁斑为植物吸收金属（类）提供了障碍。这些观察结果表明，用富铁玉米芯-蛋壳生物炭（例如 2%FCEB）进行土壤改良是一种有前景的方法，可用于修复土壤到谷物系统中的金属积累，同时提高稻谷产量。
