Key Laboratory of Arable Land Conservation (North China), Ministry of Agriculture, College of Land Science and Technology, China Agricultural University, Beijing, 100193, China.
School of Ecology and Environment Studies, Nalanda University, Rajgir, Nalanda, Bihar, India.
Chemosphere. 2022 Nov;306:135555. doi: 10.1016/j.chemosphere.2022.135555. Epub 2022 Jun 30.
The aggregation and transport of biochar colloids (BCs) in the soil and groundwater are critical for applying biochar in the field and assessing long-term environmental risk. This research aimed to study the influence of dissolved organic matter (DOM) with different molecular weights (including humic acid, HA; bovine serum albumin, BSA; deoxyribonucleic acid, DNA) and three minerals (including kaolinite, goethite, and hematite) on the aggregation and transport behaviors of BCs. The adsorption of DOM on the surface of BCs increased the stability, inhibited aggregation, and promoted the transport of BCs. As the molecular weight of DOM increased, the thicknesses of the adsorption layer of HA, BSA, and DNA on BCs surface were 2.2 nm, 5.3 nm, and 5.6 nm, respectively, resulting in increasing steric hindrance and improving the stability and mobility of BCs. Kaolinite also significantly enhanced the stability and mobility of BCs by increasing the electrostatic repulsion. Goethite and hematite quickly combined with BCs through electrostatic attraction, resulting in stronger aggregation and retention of BCs. Compared to hematite, goethite provided more adsorption sites for BCs due to its needle-like shape, so goethite caused a larger heteroaggregation rate. Overall, the presence of DOM with different molecular weights and the minerals with varying surface charges in the soil environment had a significant and distinct impact on the stability, aggregation, and transport of BCs, which advances the knowledge of colloidal biochar fate in the soil and groundwater.
生物炭胶体（BCs）在土壤和地下水中的聚集和迁移对于生物炭在田间的应用和评估其长期环境风险至关重要。本研究旨在研究不同分子量的溶解有机质（DOM，包括腐殖酸（HA）、牛血清白蛋白（BSA）、脱氧核糖核酸（DNA））和三种矿物质（包括高岭土、针铁矿和赤铁矿）对 BCs 聚集和迁移行为的影响。DOM 在 BCs 表面的吸附增加了 BCs 的稳定性，抑制了聚集，并促进了 BCs 的迁移。随着 DOM 分子量的增加，HA、BSA 和 DNA 在 BCs 表面的吸附层厚度分别为 2.2nm、5.3nm 和 5.6nm，从而增加了空间位阻，提高了 BCs 的稳定性和迁移性。高岭土通过增加静电排斥也显著提高了 BCs 的稳定性和迁移性。针铁矿和赤铁矿通过静电吸引迅速与 BCs 结合，导致 BCs 的聚集和保留更强。与赤铁矿相比，针铁矿由于其针状形状为 BCs 提供了更多的吸附位点，因此针铁矿导致更大的异质聚集率。总的来说，土壤环境中不同分子量的 DOM 和具有不同表面电荷的矿物质的存在对 BCs 的稳定性、聚集和迁移有显著而明显的影响，这推进了胶体生物炭在土壤和地下水中命运的知识。
