Journal
SCIENCE OF THE TOTAL ENVIRONMENT
Volume 616, Issue -, Pages 386-396Publisher
ELSEVIER
DOI: 10.1016/j.scitotenv.2017.10.304
Keywords
Phosphorus; Sediment; Aquatic plant; Rhizosphere; DGT
Categories
Funding
- National Scientific Foundation of China [51279060, 41621002, 41571465, 41322011]
- National Program for Support of Top-Notch Young Professionals [W02070234]
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There are few studies about the processes and mechanisms for aquatic plants to take up phosphorus (P) in wetland soils and sediments. Direct observation of P mobilization in rhizosphere is lacking. In this study, high-resolution dialysis (HR-Peeper) and diffusive gradients in thin films (DGT) techniques were used to capture the small-scale changes of soluble reactive P (SRP) and soluble Fe, and labile P in the rhizosphere of Vallisneria natans (V. natans), respectively. The results showed 5.92- and 3.12-fold enrichments of P and Fe in the Fe plaques formed on the root surfaces, respectively, in comparison with the P and Fe concentrations in the non-rhizosphere sediments. Moreover, simultaneous releases of P and Fe appeared in rhizosphere and the SRP concentration showed up to 114-fold increases compared to the non-rhizosphere sediments. Five kinds of low-molecular weight organic acids (LMWOAs) were detected in the root exudates; oxalic acid accounted for 87.5% of the total. Extraction of Fe and P in the Fe plaques was greatly enhanced by root exudates compared to deionized water, and oxalic acid contributed to 67% and 75% of the total extracted Fe and P, respectively. The coupling processes of Fe plaque enrichment of P and oxalic acid complexation of Fe(III) led to significantly enhanced P acquisition in the rhizosphere of V. natans. (c) 2017 Elsevier B.V. All rights reserved.
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