MOE Key Laboratory on Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, China.
School of Resources and Environmental Engineering, Shandong University of Technology, Zibo, 255000, China.
J Hazard Mater. 2020 Jun 15;392:122260. doi: 10.1016/j.jhazmat.2020.122260. Epub 2020 Feb 9.
Molecular fractionation of dissolved organic matter (DOM) induced by the sorption on soil minerals is a common geochemical process in soil, which has been well documented on natural DOM. Biochar is an emerging soil amendment and can continuously release DOM into the soil. However, reports regarding the interactions of soil minerals and biochar-derived DOM are limited. Herein, the molecular fractionation of DOMs derived from biochar samples obtained by pyrolyzing maize straw (MS) at 300 and 500 °C (M3 and M5) and MS (selected as the control) after sorption on ferrihydrite, a common soil mineral, was investigated for the first time. Results showed that biochar-derived DOMs contained greater aromatic and less aliphatic and O-containing structure compared to MSDOM. The sorption affinities of ferrihydrite for the three DOMs were in the order of M5DOM > M3DOM > MSDOM. A greater decrease in zeta potential and more external CO species were observed in ferrihydrite after sorption of M5DOM than after sorption of MSDOM or M3DOM. DOM components with high molecular weights and high contents of unsaturated oxidized or aromatic structures were preferentially sorbed by ferrihydrite via hydrophobic partition, H-bonding and electrostatic interactions. Polycyclic aromatics and polyphenols in MSDOM and M3DOM were the primary components sorbed by ferrihydrite, while the highly unsaturated and phenolic compounds in M5DOM showed stronger affinity to ferrihydrite. The oxygen-containing functional groups and unsaturation level are the primary parameters controlling the molecular fractionation of biochar-derived DOM on ferrihydrite. The results of this study help to get deep insight on the environmental behavior of straw- and biochar-derived DOMs in soil.
土壤矿物对溶解有机质（DOM）的吸附作用导致其分子分馏是一种常见的地球化学过程，在天然 DOM 中已有充分的记录。生物炭是一种新兴的土壤改良剂，可以不断向土壤中释放 DOM。然而，关于土壤矿物与生物炭衍生 DOM 相互作用的报道却很有限。本研究首次考察了玉米秸秆（MS）在 300 和 500°C 热解得到的生物炭（M3 和 M5）和 MS（作为对照）在吸附于赤铁矿（一种常见的土壤矿物）后衍生的 DOM 的分子分馏。结果表明，与 MS-DOM 相比，生物炭衍生的 DOM 含有更多的芳香结构和更少的脂肪族和含氧结构。赤铁矿对三种 DOM 的吸附亲和力顺序为 M5DOM＞M3DOM＞MSDOM。与吸附 MS-DOM 或 M3DOM 相比，吸附 M5DOM 后赤铁矿的 ζ 电位下降更大，外部 CO 物种更多。赤铁矿通过疏水分配、氢键和静电相互作用优先吸附具有高分子量和高不饱和氧化或芳香结构的 DOM 组分。MS-DOM 和 M3DOM 中的多环芳烃和多酚类是赤铁矿吸附的主要成分，而 M5DOM 中高度不饱和和酚类化合物与赤铁矿具有更强的亲和力。含氧官能团和不饱和程度是控制生物炭衍生 DOM 在赤铁矿上分子分馏的主要参数。本研究结果有助于深入了解秸秆和生物炭衍生 DOM 在土壤中的环境行为。
