Chen Ming, He Lei, Wang Dengjun, Xie Limei, Zhang Yue, Xu Nan, Jiang Jing, Li Bowen
School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, China; Jiangsu Key Laboratory of Environmental Functional Materials, Suzhou University of Science and Technology, Suzhou 215009, China.
School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, China; Jiangsu Key Laboratory of Environmental Functional Materials, Suzhou University of Science and Technology, Suzhou 215009, China.
Sci Total Environ. 2025 Feb 15;965:178693. doi: 10.1016/j.scitotenv.2025.178693. Epub 2025 Jan 31.
Little is known about the transport of heavy metals such as cadmium (Cd(II)) with aged biochar colloids in natural soils. Herein, we investigated the cotransport behaviors of Cd(II) with ultraviolet-irradiation aged biochar colloids pyrolyzed at 400 °C (ABC400) and 700 °C (ABC700) in saturated paddy soils. Pristine biochar colloids were included for comparison. Our results showed that Cd(II) transport was significantly facilitated by pristine and aged biochar colloids in saturated paddy soils, compared to the negligible breakthrough of Cd(II) without biochar colloids. This is likely because biochar colloids acted as vehicles carrying adsorbed Cd(II) during cotransport. Compared with pristine biochar colloids, the aged biochar colloids (especially ABC400) exhibited a greater enhancement effect, with 1.4-3.7 times Cd(II) transport in soils, likely due to stronger sorption affinity and higher mobility of aged biochar colloids towards Cd(II). Synergistic transport of aged biochar colloids with Cd(II) was relatively lower in the red soil than that in the huangni soil, probably related to the higher content of iron oxides, larger specific surface area, and lower content of soil organic matter in the red soil. A two-site kinetic retention model was employed to successfully simulate the cotransport of aged biochar colloids with Cd(II) in paddy soils. Our findings illustrate that light irradiation could accelerate the mobility of biochar colloids, as well as their synergistic carrier of Cd(II). This could trigger the potential cotransport risks when biochar is applied for field remediation of Cd-contaminated soils over a long period of time.
关于镉（Cd(II)）等重金属与老化生物炭胶体在天然土壤中的迁移情况，人们了解甚少。在此，我们研究了在饱和水稻土中，Cd(II)与在400℃（ABC400）和700℃（ABC700）下热解的紫外线辐照老化生物炭胶体的共迁移行为。纳入了原始生物炭胶体作为对照。我们的结果表明，与没有生物炭胶体时Cd(II)可忽略不计的穿透情况相比，原始和老化生物炭胶体在饱和水稻土中显著促进了Cd(II)的迁移。这可能是因为生物炭胶体在共迁移过程中充当了携带吸附的Cd(II)的载体。与原始生物炭胶体相比，老化生物炭胶体（尤其是ABC400）表现出更大的增强效果，土壤中Cd(II)的迁移量是其1.4至3.7倍，这可能是由于老化生物炭胶体对Cd(II)具有更强的吸附亲和力和更高的迁移率。老化生物炭胶体与Cd(II)的协同迁移在红壤中相对低于黄泥田，这可能与红壤中较高的铁氧化物含量、较大的比表面积和较低的土壤有机质含量有关。采用双位点动力学保留模型成功模拟了老化生物炭胶体与Cd(II)在水稻土中的共迁移。我们的研究结果表明，光照可加速生物炭胶体的迁移率及其作为Cd(II)协同载体的能力。当长期将生物炭用于镉污染土壤的田间修复时，这可能引发潜在的共迁移风险。
