Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China; Key Lab of Northwest Water Resource, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an, 710055, China.
Xi'an Botanical Garden of Shaanxi Province, Botanical Institute of Shaanxi Province, Xi'an, 710061, China.
Environ Res. 2024 Oct 15;259:119523. doi: 10.1016/j.envres.2024.119523. Epub 2024 Jul 2.
Strengthening rhizosphere effects to enhance pollutant removal is a hotspot of constructed wetlands (CWs) research in recent years, and improving the root traits and metabolic capacity of macrophytes is crucial for strengthening rhizosphere effects. In the field experiment, two types of subsurface flow (SSF) CWs (CW10 and CW20, with substrate depths of 10 and 20 cm, respectively) under the vertical spatial stress of roots (VSSR) and two types of non-VSSR SSF CWs (CW40 and CW60) were adopted with Typha orientalis as cultivated plants to investigate the variability of root development, metabolism, and pollutant removal at different substrate depths. VSSR induced substantial redundant root development, which significantly increased root-shoot ratio, fine and lateral root biomass, root porosity, and root activity, with lateral and fine root biomass of CW20 reaching 409.17 and 237.42 g/m, respectively, which were 3.18 and 5.28 times those of CW60. The radical oxygen loss (ROL) and dissolved organic carbon (DOC) levels of CW20 single plant were 1.36 and 4.57 times higher than those of CW60, respectively, and more types of root exudates were determined (e.g., aldehydes, ketones and amides). More aerobic heterotrophs (e.g., Massilia, Planomicrobium), nitrification bacteria (e.g., Ellin6067, Nitrospira), aerobic denitrification bacteria (e.g., Bacillu, Chryseobacterium, Pseudomonas) and denitrification phosphorus accumulating organisms (e.g., Flavobacterium) were enriched in the rhizosphere of CW20. This changed the main transformation pathways of pollutants and enhanced the removal of pollutants, with the COD, TN and TP average removal rates of CW20 increasing by 9.99%, 13.28% and 8.92%, respectively, compared with CW60. The ideotype root system architecture CW (RSACW; CW20) constructed in this study, which consists of a large number of fine and lateral roots, can stimulate more efficient rhizosphere effects stably and continuously.
强化根际效应以增强污染物去除是近年来人工湿地（CWs）研究的热点，而改善植物根系的特性和代谢能力对于强化根际效应至关重要。在田间试验中，采用两种不同基质深度（10cm 和 20cm）的下向流 CW（CW10 和 CW20）和两种无垂直空间根应力（VSSR）的下向流 CW（CW40 和 CW60）作为垂直空间根应力下的下向流 CW（VSSR），以香蒲为栽培植物，研究了不同基质深度下根系发育、代谢和污染物去除的变化。VSSR 诱导了大量冗余的根系发育，显著增加了根冠比、细根和侧根生物量、根孔隙率和根活力，其中 CW20 的侧根和细根生物量分别达到 409.17 和 237.42g/m，是 CW60 的 3.18 倍和 5.28 倍。CW20 单株的自由基氧损失（ROL）和溶解有机碳（DOC）水平分别比 CW60 高 1.36 倍和 4.57 倍，并且确定了更多类型的根分泌物（如醛、酮和酰胺）。更多的好氧异养菌（如 Massilia、Planomicrobium）、硝化菌（如 Ellin6067、Nitrospira）、好氧反硝化菌（如 Bacillus、Chryseobacterium、Pseudomonas）和反硝化除磷菌（如 Flavobacterium）在 CW20 的根际中得到了富集。这改变了污染物的主要转化途径，增强了污染物的去除效果，与 CW60 相比，CW20 的 COD、TN 和 TP 平均去除率分别提高了 9.99%、13.28%和 8.92%。本研究构建的理想根系形态 CW（RSACW；CW20）由大量细根和侧根组成，能够稳定持续地激发更有效的根际效应。
