Effects of root exudates on the sorption of polycyclic aromatic hydrocarbons onto biochar

ABSTRACT

The effect of oxalic acid on phenanthrene sorption was varied from that on pyrene sorption. 1.0 mg L^-1 of oxalic acid inhibited phenanthrene sorption, whereas 20, 50 and 100 mg L^-1 of oxalic acid enhanced the sorption. However, pyrene sorption onto biochar was all inhibited among different concentrations of oxalic acid. New functional groups and increased polarity were observed in the biochar coexisted with oxalic acid, moreover, a high concentration of oxalic acid led to an increased specific surface area of the biochar. These changed factors contributed to biochar sorption to phenanthrene, which was dominated by surface adsorption. Weakened aromaticity and increased release of dissolved organic carbon from biochar may have been the main reason for inhibited pyrene sorption onto biochar by oxalic acid. Therefore, this study suggested that root exudates could greatly influence the sorption behavior of biochar towards PAHs in soil rhizosphere, which deserves attention in agricultural systems.

ABSTRACT

KEYWORDS:

• Biochar
• PAHs
• root exudates
• sorption

Acknowledgments

This study was financially supported by the National Key Research and Development Program (2017YFD0800704), Key Program of Frontier Sciences, Chinese Academy of Sciences (QYZDJ-SSW-DQC035), the National Natural Science Foundation of China (41671236).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the the National Natural Science Foundation of China [41671236];the National Key Research and Development Program [2017YFD0800704];Key Program of Frontier Sciences, Chinese Academy of Sciences [QYZDJ-SSW-DQC035].