College of Resources and Environmental Sciences, Hunan Normal University, Changsha, 410081, People's Republic of China.
School of Metallurgy and Environment, Central South University, Changsha, 410083, People's Republic of China.
Environ Sci Pollut Res Int. 2019 Dec;26(36):36688-36697. doi: 10.1007/s11356-019-06688-5. Epub 2019 Nov 18.
The alkaline nature of biochar provides a potential for soil arsenic (As) mobilization and, hence, enhancing efficiency of As phytoextraction by combining with As hyperaccumulator. To testify the feasibility and potential risk of the above strategy, biochar effect on As transfer in a paddy soil and accumulation in P. vittata was investigated in a pot experiment. By leaching soil (total As concentration 141.17 mg/kg) with simulated acid rain (pH 4.2), As the concentration in leaching eluate increased proportionally with increasing biochar ratio. Coincident with elevated soil As mobility, apparent enhancement in As uptake and translocation in P. vittata was determined with 1-5% biochar amendment after 40 days of plant growth. Furthermore, diffusive gradients in thin film (DGT) technique were employed to characterize any potential risk in vertical downward migration of As at 2-mm resolution. A significantly increasing profile of DGT-As ranging from on average 20 μg/L in CK to 50-100 μg/L in 1-3% biochar treatments was recorded over 0-60 mm depth, with 25-71% lower labile As in the rhizosphere than non-rhizosphere zone with few exceptions. As compared to Chinese quality standard for groundwater (Class IV 50 μg/L), biochar ratio at ≤ 1% was suggested for local water safety while actual application should take the physicochemical characteristic of tested soil into account. Our results demonstrated the biochar-assisted P. vittata phytoremediation can serve as an emerging pathway to enhance efficiency of soil As phytoextraction. The combination of DGT techniques and greenhouse assay provided a powerful tool for evaluating the gradient distribution of heavy metal in rhizosphere and accessing corresponding ecological risk at more precise scale.
生物炭的碱性为土壤砷（As）的迁移提供了潜力，因此，通过与砷超积累植物结合，提高了砷植物提取的效率。为了验证该策略的可行性和潜在风险，本研究采用盆栽试验研究了生物炭对水稻土中砷的迁移和蜈蚣草（Pteris vittata）积累的影响。通过淋洗土壤（总砷浓度为 141.17mg/kg）用模拟酸雨（pH4.2），淋出液中砷浓度随生物炭比例的增加而呈比例增加。随着土壤砷的迁移性增加，在植物生长 40 天后，用 1-5%的生物炭进行改良，发现蜈蚣草对砷的吸收和转运明显增强。此外，采用薄膜扩散梯度（DGT）技术以 2mm 的分辨率对砷垂直向下迁移的任何潜在风险进行了特征描述。在 0-60mm 的深度范围内，DGT-As 的浓度剖面显著增加，从 CK 中的平均 20μg/L 增加到 1-3%生物炭处理中的 50-100μg/L，根际区的可利用态砷比非根际区低 25-71%，但也有少数例外。与中国地下水质量标准（IV 类 50μg/L）相比，建议在 1%以下的生物炭比例用于当地的水安全，而实际应用应考虑到受测土壤的物理化学特性。与中国地下水质量标准（IV 类 50μg/L）相比，建议在 1%以下的生物炭比例用于当地的水安全，而实际应用应考虑到受测土壤的物理化学特性。我们的结果表明，生物炭辅助蜈蚣草修复可以作为一种新兴途径，提高土壤砷植物提取的效率。DGT 技术和温室试验的结合为评估重金属在根际的梯度分布和在更精确的尺度上评估相应的生态风险提供了有力工具。
