Limits...
Natural attenuation model and biodegradation for 1,1,1-trichloroethane contaminant in shallow groundwater.

Lu Q, Zhu RL, Yang J, Li H, Liu YD, Lu SG, Luo QS, Lin KF - Front Microbiol (2015)

Bottom Line: The results indicated that the majority of the contaminant mass was present at 2-6 m in depth, the contaminated area was approximately 1000 m × 1000 m, and natural attenuation processes were occurring at the site.The effluent breakthrough curves from the column experiments demonstrated that the effectiveness of TCA natural attenuation in the groundwater accorded with the advection-dispersion-reaction equation.The contamination plume was predicted to diminish and the maximum concentration of TCA decreased to 280 μg/L.

View Article: PubMed Central - PubMed

Affiliation: State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resource and Environmental Engineering, East China University of Science and Technology , Shanghai, China.

ABSTRACT
Natural attenuation is an effective and feasible technology for controlling groundwater contamination. This study investigated the potential effectiveness and mechanisms of natural attenuation of 1,1,1-trichloroethane (TCA) contaminants in shallow groundwater in Shanghai by using a column simulation experiment, reactive transport model, and 16S rRNA gene clone library. The results indicated that the majority of the contaminant mass was present at 2-6 m in depth, the contaminated area was approximately 1000 m × 1000 m, and natural attenuation processes were occurring at the site. The effluent breakthrough curves from the column experiments demonstrated that the effectiveness of TCA natural attenuation in the groundwater accorded with the advection-dispersion-reaction equation. The kinetic parameter of adsorption and biotic dehydrochlorination of TCA was 0.068 m(3)/kg and 0.0045 d(-1). The contamination plume was predicted to diminish and the maximum concentration of TCA decreased to 280 μg/L. The bacterial community during TCA degradation in groundwater belonged to Trichococcus, Geobacteraceae, Geobacter, Mucilaginibacter, and Arthrobacter.

No MeSH data available.


Phylogenetic tree of the V6 partial sequence of bacterial 16S rRNA from the bacteria in groundwater shown in boldface and the referred sequences in the EMBL database with the putative divisions listed to the right. The topology show was calculated with the Neighbor-joining method. Bootstrap values n = 1000 replicates. Of ≥50% were reported near the corresponding nodes. The scale bar represented 0.05 nuclear acid substitutions per nucleotide position.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4548683&req=5

Figure 5: Phylogenetic tree of the V6 partial sequence of bacterial 16S rRNA from the bacteria in groundwater shown in boldface and the referred sequences in the EMBL database with the putative divisions listed to the right. The topology show was calculated with the Neighbor-joining method. Bootstrap values n = 1000 replicates. Of ≥50% were reported near the corresponding nodes. The scale bar represented 0.05 nuclear acid substitutions per nucleotide position.

Mentions: The degradation community was the primary reason for reductions in contamination in groundwater and its structure was investigated using a clone library. A total of 34 positive clones were clustered into five operational taxonomic unit (OTUs) at 97% similarity by Mothur 1.32. The rarefaction curve flattened to the right, demonstrating that a reasonable individuals in the community were sampled. The phylogenetic tree showed that the dominant enriched species fell into four major groups: Deltaproteobacteria (13/34, 38.24%, two OTUs), Bacilli (16/34, 47.06%, one OTU), Actinobacteridae (2/34, 5.88%, one OTU), and Flavobacteriia (3/34, 8.82%, one OTU; Figure 5). TCA-3 exhibited 99.0% similarity to Firmicutes clone B-UP-T0 OTU4 (FM204984) found in a 1,2-DCA-contaminated groundwater. TCA-1 exhibited 99.0% similarity to Geobacter lovleyi strain Geo7.1A (JN982204), which was isolated from an anaerobic microbial enrichment culture of organohalide-respiring and could dechlorinate tetrachloroethylene (PCE) and TCA. TCA-2 exhibited 94.0% similarity to uncultured bacterium TfC20L52 (EU362313), which was able to reductively dechlorinate PCE to trans-DCE (Kittelmann and Friedrich, 2008). TCA-5 exhibited 99.0% similarity to bacterium BR20 (GQ461628) presented in a trichloroethylene (TCE) anaerobic dechlorinating culture. TCA-4 exhibited 99.0% similarity to clone ccspost2208 (AY133106) that was isolated from a TCE-contaminated site. Analysis of the dominant species, which consisted of anaerobic dechlorinating culture, may indicate the natural attenuation capability of TCA in groundwater.


Natural attenuation model and biodegradation for 1,1,1-trichloroethane contaminant in shallow groundwater.

Lu Q, Zhu RL, Yang J, Li H, Liu YD, Lu SG, Luo QS, Lin KF - Front Microbiol (2015)

Phylogenetic tree of the V6 partial sequence of bacterial 16S rRNA from the bacteria in groundwater shown in boldface and the referred sequences in the EMBL database with the putative divisions listed to the right. The topology show was calculated with the Neighbor-joining method. Bootstrap values n = 1000 replicates. Of ≥50% were reported near the corresponding nodes. The scale bar represented 0.05 nuclear acid substitutions per nucleotide position.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4548683&req=5

Figure 5: Phylogenetic tree of the V6 partial sequence of bacterial 16S rRNA from the bacteria in groundwater shown in boldface and the referred sequences in the EMBL database with the putative divisions listed to the right. The topology show was calculated with the Neighbor-joining method. Bootstrap values n = 1000 replicates. Of ≥50% were reported near the corresponding nodes. The scale bar represented 0.05 nuclear acid substitutions per nucleotide position.
Mentions: The degradation community was the primary reason for reductions in contamination in groundwater and its structure was investigated using a clone library. A total of 34 positive clones were clustered into five operational taxonomic unit (OTUs) at 97% similarity by Mothur 1.32. The rarefaction curve flattened to the right, demonstrating that a reasonable individuals in the community were sampled. The phylogenetic tree showed that the dominant enriched species fell into four major groups: Deltaproteobacteria (13/34, 38.24%, two OTUs), Bacilli (16/34, 47.06%, one OTU), Actinobacteridae (2/34, 5.88%, one OTU), and Flavobacteriia (3/34, 8.82%, one OTU; Figure 5). TCA-3 exhibited 99.0% similarity to Firmicutes clone B-UP-T0 OTU4 (FM204984) found in a 1,2-DCA-contaminated groundwater. TCA-1 exhibited 99.0% similarity to Geobacter lovleyi strain Geo7.1A (JN982204), which was isolated from an anaerobic microbial enrichment culture of organohalide-respiring and could dechlorinate tetrachloroethylene (PCE) and TCA. TCA-2 exhibited 94.0% similarity to uncultured bacterium TfC20L52 (EU362313), which was able to reductively dechlorinate PCE to trans-DCE (Kittelmann and Friedrich, 2008). TCA-5 exhibited 99.0% similarity to bacterium BR20 (GQ461628) presented in a trichloroethylene (TCE) anaerobic dechlorinating culture. TCA-4 exhibited 99.0% similarity to clone ccspost2208 (AY133106) that was isolated from a TCE-contaminated site. Analysis of the dominant species, which consisted of anaerobic dechlorinating culture, may indicate the natural attenuation capability of TCA in groundwater.

Bottom Line: The results indicated that the majority of the contaminant mass was present at 2-6 m in depth, the contaminated area was approximately 1000 m × 1000 m, and natural attenuation processes were occurring at the site.The effluent breakthrough curves from the column experiments demonstrated that the effectiveness of TCA natural attenuation in the groundwater accorded with the advection-dispersion-reaction equation.The contamination plume was predicted to diminish and the maximum concentration of TCA decreased to 280 μg/L.

View Article: PubMed Central - PubMed

Affiliation: State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resource and Environmental Engineering, East China University of Science and Technology , Shanghai, China.

ABSTRACT
Natural attenuation is an effective and feasible technology for controlling groundwater contamination. This study investigated the potential effectiveness and mechanisms of natural attenuation of 1,1,1-trichloroethane (TCA) contaminants in shallow groundwater in Shanghai by using a column simulation experiment, reactive transport model, and 16S rRNA gene clone library. The results indicated that the majority of the contaminant mass was present at 2-6 m in depth, the contaminated area was approximately 1000 m × 1000 m, and natural attenuation processes were occurring at the site. The effluent breakthrough curves from the column experiments demonstrated that the effectiveness of TCA natural attenuation in the groundwater accorded with the advection-dispersion-reaction equation. The kinetic parameter of adsorption and biotic dehydrochlorination of TCA was 0.068 m(3)/kg and 0.0045 d(-1). The contamination plume was predicted to diminish and the maximum concentration of TCA decreased to 280 μg/L. The bacterial community during TCA degradation in groundwater belonged to Trichococcus, Geobacteraceae, Geobacter, Mucilaginibacter, and Arthrobacter.

No MeSH data available.