School of Environmental Studies, China University of Geosciences, 388 Lumo Rd., Wuhan, 430074, Hubei, People's Republic of China.
Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave. W., Waterloo, ON, N2L 3G1, Canada.
Bull Environ Contam Toxicol. 2019 Jul;103(1):175-180. doi: 10.1007/s00128-018-2397-2. Epub 2018 Jul 14.
Previous studies show mercury (Hg) can be effectively removed from solution by biochar, but limited attention was paid on the complexation between Hg and components released from biochars, e.g. dissolved organic matter (DOM). Here, aqueous data from batch-style experiments were modeled using PHREEQC, incorporating thermodynamic constants between Hg and DOM, which was assumed to be composed of thiol, carboxylic, and phenolic functional groups. Modelling results suggest that > 99% Hg complexed with thiol groups in DOM. The modelled concentrations of Hg-DOM complexes from low-T (low-temperature, 300°C) biochars were greater than from high-T (600°C) biochars. The concentrations of Hg-DOM complexes were lower in wood-based than in agricultural residue- and manure-based biochars. Hg-DOM complexes may affect Hg speciation, bioavailability, transport, and methylation processes. This research describes a method to evaluate Hg-DOM interactions, and the results indicate extra caution regarding Hg-DOM complex formation is required in the selection of biochar for Hg remediation.
先前的研究表明，生物炭可以有效地从溶液中去除汞（Hg），但对于 Hg 与生物炭释放的成分（如溶解有机质（DOM））之间的络合作用关注有限。本研究采用 PHREEQC 对批式实验中的水相数据进行建模，模型中包含了 Hg 与 DOM 之间的热力学常数，假设 DOM 由巯基、羧酸和酚基官能团组成。模型结果表明，>99%的 Hg 与 DOM 中的巯基络合。低温（300°C）生物炭形成的 Hg-DOM 络合物的浓度大于高温（600°C）生物炭。与农业残渣和粪便基生物炭相比，木质素基生物炭形成的 Hg-DOM 络合物浓度更低。Hg-DOM 络合物可能会影响 Hg 的形态、生物利用度、迁移和甲基化过程。本研究描述了一种评估 Hg-DOM 相互作用的方法，结果表明，在选择用于 Hg 修复的生物炭时，需要格外注意 Hg-DOM 络合形成的问题。
