Journal article
Root exudate enhanced contaminant desorption: an abiotic contribution to the rhizosphere effect
Environmental science & technology, Vol.47(20), pp.11545-11553
10/15/2013
DOI: 10.1021/es402446v
PMID: 24047188
Abstract
Despite reports in the literature of superior contaminant degradation in the root-zone of plants, this phenomenon, known as the rhizosphere effect, is poorly understood. We investigated whether root exudates could enhance desorption of residual pollutants, thus improving bioavailability and subsequent biodegradation potential. Root exudates were harvested from three species of hydroponically grown plants, and artificial root exudates (AREs) were created using a literature recipe. Aliquots of the exudates were metabolized by soil bacteria to investigate whether biotransformed exudates exhibited different chemical characteristics or had different effects on contaminant bioavailability than 'raw exudates.' Slurries of naphthalene-aged soil containing raw exudates had a significantly lower soil-water distribution coefficient (Kd) than slurries with metabolized exudates or no-exudate controls, exhibiting median reductions of 50% and 55%, respectively. Raw exudates had a significantly lower surface tension while not increasing overall solubility, indicating the presence of surface-active compounds below the critical micelle concentration; this is a newly observed mechanism of the rhizosphere effect. Exudate samples were characterized by specific UV absorbance, spectral slope, fluorescence index, and excitation-emission matrices. Substantial changes in organic carbon character pre- and postmetabolism, and between harvested exudates and AREs, suggest that AREs are not chemically representative of plant root exudates. Overall, we present evidence that enhanced contaminant desorption in the presence of exudates provides an abiotic contribution to the rhizosphere effect.
Details
- Title: Subtitle
- Root exudate enhanced contaminant desorption: an abiotic contribution to the rhizosphere effect
- Creators
- Gregory H LeFevre - Department of Civil Engineering, University of Minnesota , 500 Pillsbury Drive S.E., Minneapolis, Minnesota 55455, United StatesRaymond M HozalskiPaige J Novak
- Resource Type
- Journal article
- Publication Details
- Environmental science & technology, Vol.47(20), pp.11545-11553
- Publisher
- United States
- DOI
- 10.1021/es402446v
- PMID
- 24047188
- ISSN
- 0013-936X
- eISSN
- 1520-5851
- Language
- English
- Date published
- 10/15/2013
- Academic Unit
- Civil and Environmental Engineering
- Record Identifier
- 9983991950402771
Metrics
12 Record Views