School of Environment, South China Normal University, Guangzhou, 510006, China.
South China Institute of Environmental Sciences, Ministry of Ecology and Environment, 510655, China.
Chemosphere. 2022 Aug;301:134738. doi: 10.1016/j.chemosphere.2022.134738. Epub 2022 Apr 27.
Although the benefits of biochar amendment for heavy metal(loid) immobilization in soil have been widely recognized, its migration in soil and the resultant effects on the risk of downward migration of metal(loid)s are still poorly understood. In this study, based on biochar derived dissolved organic matter (DOM), excitation-emission matrix coupled with parallel factor analysis (EEM-PARAFAC) technique was employed to trace biochar migration within one year in 0-100 cm soil profiles in the field. The vertical co-migration of Pb, Cu and As was also analyzed. With biochar amended, DOM, humification index (HIX) and biological index (BIX) in 0-60 cm soil profiles increased significantly, while pH only increased in the topsoil. The identified water-extracted DOM components showed that biochar could enhance the content of fulvic acids and humic acids in soil DOM and biochar might migrate downward to 60 cm soil profiles. Furthermore, toluene/methanol-extracted DOM also confirmed the migration extent of biochar, which was more suitable to trace biochar migration because of its high resistance to the long-term ageing in the field. Moreover, we found that biochar reduced the content of Cu in 0-60 cm soil profiles, but increased the available Pb and As in the 20-40 cm soil layers. The Pearson's correlation study confirmed a strong correlation (0.568**≤R ≤ 0.803**) between the content of heavy metal(loid)s and humic-like components of soil DOM, which suggested that biochar co-migrated with Pb, Cu and As, and the potential environmental risks of biochar should be fully evaluated while it was applied for soil metal(loid) remediation.
尽管生物炭改良对土壤重金属（类）固定化的益处已得到广泛认可，但生物炭在土壤中的迁移及其对金属（类）向下迁移风险的影响仍知之甚少。在这项研究中，基于生物炭衍生的溶解有机质（DOM），采用激发-发射矩阵耦合平行因子分析（EEM-PARAFAC）技术，在田间 0-100 cm 土壤剖面中追踪了一年内生物炭的迁移。还分析了 Pb、Cu 和 As 的垂直共迁移。添加生物炭后，0-60 cm 土壤剖面中 DOM、腐殖化指数（HIX）和生物指数（BIX）显著增加，而 pH 仅在上层土壤中增加。鉴定出的水提取 DOM 组分表明，生物炭可以增加土壤 DOM 中富里酸和腐殖酸的含量，生物炭可能向下迁移到 60 cm 土壤剖面。此外，甲苯/甲醇提取 DOM 也证实了生物炭的迁移程度，由于其在田间长期老化的高抗性，更适合追踪生物炭的迁移。此外，我们发现生物炭降低了 0-60 cm 土壤剖面中 Cu 的含量，但增加了 20-40 cm 土壤层中可利用的 Pb 和 As。Pearson 相关性研究证实了土壤 DOM 中重金属（类）和类腐殖质成分之间存在很强的相关性（0.568**≤R≤0.803**），这表明生物炭与 Pb、Cu 和 As 共迁移，在应用生物炭进行土壤金属（类）修复时，应充分评估其潜在的环境风险。
