Biodegradation of Chlorobenzene, 1,2-Dichlorobenzene, and 1,4-Dichlorobenzene in the Vadose Zone

Much of the microbial activity in nature takes place at interfaces, which are often associated with redox discontinuities. One example is the oxic/anoxic interface where polluted groundwater interacts with the overlying vadose zone. We tested whether microbes in the vadose zone can use synthetic chemicals as electron donors and thus protect the overlying air and buildings from groundwater pollutants. Samples from the vadose zone of a site contaminated with chlorobenzene (CB), 1,2-dichlorobenzene (12DCB), and 1,4-dichlorobenzene (14DCB) were packed in a multiport column to simulate the interface of the vadose zone with an underlying groundwater plume. A mixture of CB, 12DCB, and 14DCB in anoxic water was pumped continuously through the bottom of column to an outlet below the first sampling port to create an oxic/anoxic interface and a capillary fringe. Removal to below the detection limits by rapid biodegradation with rates of 21 +/- 1 mg of CB . m(-2) . d(-1), 3.7 +/- 0.5 mg of 12DCB . m(-2) . d(-1), and 7.4 +/- 0.7 mg of 1.4 DCB . m(-2) . d(-1) indicated that natural attenuation in the capillary fringe can prevent the migration of CB, 12DCB, and 14DCB vapors. Enumeration of bacteria capable of degrading chlorobenzenes suggested that most of the biodegradation takes place within the first 10 cm above the saturated zone. Biodegradation also increased the upward flux of contaminants and thus enhanced their elimination from the underlying water. The results revealed a substantial biodegradation capacity for chlorinated aromatic compounds at the oxic/anoxic interface and illustrate the role of microbes in creating steep redox gradients.


Biodegradation of cis-Dichloroethene and Vinyl Chloride in the Capillary Fringe
Kurt, Zöhre; Spain, Jim C. (2014-11-18)
Volatile chlorinated compounds are major pollutants in groundwater, and they pose a risk of vapor intrusion into buildings. Vapor intrusion can be prevented by natural attenuation in the vadose zone if biodegradation mechanisms can be established. In this study, we tested the hypothesis that bacteria can use cis-dichloroethene (cis-DCE) or vinyl chloride (VC) as an electron donor in the vadose zone. Anoxic water containing cis-DCE or VC was pumped continuously beneath laboratory columns that represented the...
Natural Attenuation of Nonvolatile Contaminants in the Capillary Fringe
Kurt, Zöhre; Spain, Jim C. (2016-09-20)
When anoxic polluted groundwater encounters the overlying vadose zone an oxic/anoxic interface is created, often near the capillary fringe. Biodegradation of volatile contaminants in the capillary fringe can prevent vapor migration. In contrast, the biodegradation of nonvolatile contaminants in the vadose zone has received comparatively little attention. Nonvolatile compounds do not cause vapor intrusion, but they still move with the groundwater and are major contaminants. Aniline (AN) and diphenylamine (DP...
Synthesis of Iodo-substituted spiro-fused pyridine derivatives
Teke, Ecem; Zora, Metin; Department of Chemistry (2014)
Spiro cyclic molecules have gained significance because of their biological activities and electronic properties. Spiro frameworks are present in importance natural products and optoelectronic materials. Moreover, due to steric strain, the presence of a spiro carbon atom induces easy rearrangements that can lead to different cyclic products. Although there are some methods to synthesize spiro compounds, the synthesis of iodo-substituted spiro-fused pyridines have not been studied. Accordingly, in this thesis...
Özçelikkale, Altuğ (2013-01-01)
In this study, a theoretical model is developed to simulate the biophysical events in the intracellular spaces considering the biphasic, i.e., poroelastic, behavior of the cytoplasm. Most previous studies in the cryobiology literature have modeled the biophysical response of cells to freezing assuming the spatial homogeneity of all physical properties within the intracellular space without considering fluid-structure interaction in both the intracellular and extracellular spaces. However, a few recent studi...
Aptamer-enabled uptake of small molecule ligands
Auwardt, Supipi Liyamali; Seo, Yeon-Jung; İlgü, Müslüm; Ray, Judhajeet; Feldges, Robert R.; Shubham, Shambhavi; Bendickson, Lee; Levine, Howard A.; Nilsen-Hamilton, Marit (Springer Science and Business Media LLC, 2018-10-24)
The relative ease of isolating aptamers with high specificity for target molecules suggests that molecular recognition may be common in the folds of natural RNAs. We show here that, when expressed in cells, aptamers can increase the intracellular concentrations of their small molecule ligands. We have named these aptamers as DRAGINs (Drug Binding Aptamers for Growing Intracellular Numbers). The DRAGIN property, assessed here by the ability to enhance the toxicity of their ligands, was found for some, but no...
Citation Formats
Z. Kurt, “Biodegradation of Chlorobenzene, 1,2-Dichlorobenzene, and 1,4-Dichlorobenzene in the Vadose Zone,” ENVIRONMENTAL SCIENCE & TECHNOLOGY, pp. 6846–6854, 2013, Accessed: 00, 2020. [Online]. Available: