How do root exudates of bok choy promote dibutyl phthalate adsorption on mollisol?

• Published in: Ecotoxicology and environmental safety Vol. 161; pp. 129 - 136
• Main Authors: Lin, Yulong, Wang, Lei, Li, Rui, Hu, Songbo, Wang, Yifan, Xue, Yuewen, Yu, Hui, Jiao, Yaqi, Wang, Yahui, Zhang, Ying
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 15.10.2018
• Subjects: Adsorption; Biodegradation, Environmental; Brassica - chemistry; Dibutyl Phthalate - chemistry; Dissolved organic matter (DOM); Fluorescence; Fluorescence spectra; Humic Substances - analysis; Kinetics; Phthalate esters (PAEs); Plant Exudates - chemistry; Plant Proteins - analysis; Rhizosphere; Root exudates; Soil - chemistry; Soil Pollutants - chemistry; Spectrometry, Fluorescence - methods; Spectroscopy, Fourier Transform Infrared; Phthalate esters (PAEs); Dissolved organic matter (DOM); Adsorption; Root exudates; Fluorescence spectra
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2018.05.072

This study investigates the interaction between the bok choy root exudates and dibutyl phthalate (DBP) onto mollisol during the adsorption. The result elucidated that the adsorption reached equilibrium within 12 h, the adsorption capacity of rhizosphere mollisol containing root exudates and ordinary mollisol were 243.46 mg kg−1 and 281.95 mg kg−1, separately. The adsorption kinetics and isotherm model followed the pseudo-second order and the Frendlish model, respectively, which hinted that the adsorption process was multi-layer heterogeneous chemisorption. We characterized the root exudates and analyzed its effects on soil physical and chemical properties and structure. The result revealed that the root exudates contained hydrocarbons, sulfur compounds and acids. Root exudates made the dissolved organic matter (DOM) dissolution from soil and the increase of organic matter, which might be one of the reasons that root exudates promote DBP adsorption on mollisol. We selected three-dimensional excitation-emission matrix (3D-EEM), synchronous fluorescence and Fourier transform infrared spectroscopy (FTIR) to analyze the interactions between root exudates and DBP, DOM and DBP, respectively. Fluorescence spectrum revealed that the main component of root exudates was protein, for DOM was humic acid, the fluorescence of root exudates and DOM gradually disappeared with the increase of DBP concentration. FTIR revealed that -COO in root exudates and -CH2 in DOM respectively reacted with DBP. The results of this study are of great importance to reveal that the root exudates are significant in the environmental behavior of DBP adsorption on mollisol, and also provide more useful information for phytoremediation of organic pollutants in the mollisol. [Display omitted] •The bok choy root exudates have effects on adsorption of DBP onto mollisol and they can promote DOM dissolution.•Innovative adoption of Fluorescence spectroscopies, FTIR to study the interaction between root exudates, DOM and DBP.•The mechanism of the binding of root exudates-DBP and DOM-DBP was testified as static quenching.