Earth Sciences Division
Research
Environmental Remediation Technology Program
Objectives
Characterization Of VOC Biodegradation On Rock Surfaces By SR FTIR Imaging
Annual Report 1998-1999
Results
Designing stra t e gies for using Global features of SR FTIR spectra intrinsic microorganisms to successfor the intrinsic micro o rganisms, Hoi-Ying N. Holman, Jil Geller, fully biodegrade and detoxify VOCs toluene and toluene metabolites were Jennie C. Hunter-Cevera ( volatile organic contaminants) consistent with those reported in the and Karsten Pruess requires a thorough characterization literature. Detailed comparative analyContact: of key reactions at a molecular level sis of spectra recorded on microbial Hoi-Ying Holman on mineral surfaces occupied with surfaces of the coated-gold mirrors (510) 486-5943, hyholman@lbl.gov microorganisms. This study show s and on the cleaved basalt samples that synchrotron radiation-based (SR) Fourier transform infrared indicates the existence of distinct SR FTIR absorption bands as (FTIR) spectromicroscopy — with a spatial resolution of 5–10 markers indicative of the presence of biomolecule markers (biomarkers) and of toluene and toluene metabolites. microns and strong signal to noise levels — can readily be Fi g u re 1 shows the spatial distribution of IR absorption bioapplied to imaging characterization of the complex progress of m a rkers associated with protein Amide I of intrinsic micro o rg a nVOC biodegradation on basaltic rock surfaces, especially the isms (1687 cm-1) .The mapping was re c o rded on one of the basalt progress of the initial biodegradation. specimens after it was exposed to 100-ppm toluene vapor at 100% relative humidity for five days.The high intensity of the IR Approach absorption band at 1687 cm-1 implies that the intrinsic micro o rganisms in the basalt ro ck from INEEL could grow extremely Vesicular basalt rock samples and intrinsic microorganisms quickly and form biofilms under our experimental conditions were taken from a site where VOC contamination has threatened within five days.The striking similarities between the IR absorpthe Snake River Aquifer near the Department of Energy’s Idaho tion and the optical images of the biofilms on the surface of the National Engineering and Environmental Laboratory (INEEL). ro ck chip confi rmed that SR FTIR spectro m i c ro s c o py is adequate Toluene vapor was used as a model VOC that can be directly for detecting the presence of biofilms on ro ck surfaces. metabolized by intrinsic microorganisms. The SR FTIR spectra The spatial distributions of IR absorption associated with for films of microorganisms, toluene and possible toluene toluene (1029 cm-1), and metabolites benzyl alcohol (1022 cmmetabolites were measured and validated by comparison with 1) and catechol (1096 cm-1) were mapped and are presented in those in the spectral literature. Basalt specimens were incubated Figure 2.The presence of these metabolites implies that intrinsic microorganisms probably degraded toluene via the pathway in a closed system in the dark for a number of days.The biodegradescribed in Figure 3.The absence of benzyl aldehyde and bendation of toluene on specimen surfaces was monitored using SR zoic acid in our sample implies that the bottlenecks in the FTIR spectromicroscopy.
Figure 1. SR FTIR mapping of intrinsic microbes on vesicular basalt.
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