early 1970s to early 1990s) was used to calculate CFC profiles and time lags. We compared the ana... more early 1970s to early 1990s) was used to calculate CFC profiles and time lags. We compared the analytical results with numerical simulations. metersthickness,diffusionandbarometricpumpingsuf- The time lags in the 15-m-deep unsaturated zone increase from 4.2 to ficiently mix the gases in the unsaturated zone so soil- between 5.2 and 6.1 yr and from 3.4 to 3.9 yr for CFC-11 and CFC-12,
We used current knowledge of cellular processes involved in reductive dechlorination to develop a... more We used current knowledge of cellular processes involved in reductive dechlorination to develop a conceptual model to describe the regulatory system of dechlorination at the cell level; the model links bacterial growth and substrate consumption to the abundance of messenger RNA of functional genes involved in the dechlorination process. The applicability of the model was tested on a treatability study of biostimulated and bioaugmented microcosms. Using quantitative real time PCR, high-resolution expression profiles of the functional reductive dehalogenase genes bvcA and vcrA were obtained during two consecutive dechlorination events of trichlorethene, cis-dichlorethene and vinyl chloride. Up-regulation of the bvcA (for the biostimulated microcosms) and vcrA (for the bioaugmented microcosms) gene expression fitted well with high rates of dechlorination of vinyl chloride, while no known transcripts could be measured during trichloroethene and cis-dichlorethene dechlorination. Maximum concentrations of 2.1 and 1.7 transcripts per gene of the bvcA and vcrA genes, respectively, were measured at the same time points as maximum dechlorination rates were observed. The developed model compared well with the experimental data for both biostimulated and bioaugmented microcosms under non-steady state conditions and was supported by results from a recently published study under steady state conditions.
A molecular study on how the abundance of the dechlorinating culture KB-1 affects dechlorination ... more A molecular study on how the abundance of the dechlorinating culture KB-1 affects dechlorination rates in clay till is presented. DNA extracts showed changes in abundance of specific dechlorinators as well as their functional genes. Independently of the KB-1 added, the microbial dechlorinator abundance increased to the same level in all treatments. In the non-bioaugmented microcosms the reductive dehalogenase gene bvcA increased in abundance, but when KB-1 was added the related vcrA gene increased while bvcA genes did not increase. Modeling showed higher vinyl-chloride dechlorination rates and shorter time for complete dechlorination to ethene with higher initial concentration of KB-1 culture, while cis-dichloroethene dechlorination rates were not affected by KB-1 concentrations. This study provides high resolution abundance profiles of Dehalococcoides spp. (DHC) and functional genes, highlights the ecological behavior of KB-1 in clay till, and reinforces the importance of using mul...
... from lakes is therefore needed for environmental management or restoration of lake ecosystems... more ... from lakes is therefore needed for environmental management or restoration of lake ecosystems (Hayashi and Rosenberry, 2002; Sophocleous, 2002; Gleeson et ... 25 061 000, Robertson Geologging, Deganwy, UK) using a 50-by 25-mm scintillation crystal as a natural detector. ...
early 1970s to early 1990s) was used to calculate CFC profiles and time lags. We compared the ana... more early 1970s to early 1990s) was used to calculate CFC profiles and time lags. We compared the analytical results with numerical simulations. metersthickness,diffusionandbarometricpumpingsuf- The time lags in the 15-m-deep unsaturated zone increase from 4.2 to ficiently mix the gases in the unsaturated zone so soil- between 5.2 and 6.1 yr and from 3.4 to 3.9 yr for CFC-11 and CFC-12,
... and seepages of biogenic gas in Northern Denmark TROELS LAIER,* NIELS OLUF JORGENSEN,t BJORN ... more ... and seepages of biogenic gas in Northern Denmark TROELS LAIER,* NIELS OLUF JORGENSEN,t BJORN BUCHARDT,~ TOMMY CEDERBERG~ and ... and isotopic composition has been found by the authors in several on-land shallow (100-120 m) wells These marine ...
early 1970s to early 1990s) was used to calculate CFC profiles and time lags. We compared the ana... more early 1970s to early 1990s) was used to calculate CFC profiles and time lags. We compared the analytical results with numerical simulations. metersthickness,diffusionandbarometricpumpingsuf- The time lags in the 15-m-deep unsaturated zone increase from 4.2 to ficiently mix the gases in the unsaturated zone so soil- between 5.2 and 6.1 yr and from 3.4 to 3.9 yr for CFC-11 and CFC-12,
We used current knowledge of cellular processes involved in reductive dechlorination to develop a... more We used current knowledge of cellular processes involved in reductive dechlorination to develop a conceptual model to describe the regulatory system of dechlorination at the cell level; the model links bacterial growth and substrate consumption to the abundance of messenger RNA of functional genes involved in the dechlorination process. The applicability of the model was tested on a treatability study of biostimulated and bioaugmented microcosms. Using quantitative real time PCR, high-resolution expression profiles of the functional reductive dehalogenase genes bvcA and vcrA were obtained during two consecutive dechlorination events of trichlorethene, cis-dichlorethene and vinyl chloride. Up-regulation of the bvcA (for the biostimulated microcosms) and vcrA (for the bioaugmented microcosms) gene expression fitted well with high rates of dechlorination of vinyl chloride, while no known transcripts could be measured during trichloroethene and cis-dichlorethene dechlorination. Maximum concentrations of 2.1 and 1.7 transcripts per gene of the bvcA and vcrA genes, respectively, were measured at the same time points as maximum dechlorination rates were observed. The developed model compared well with the experimental data for both biostimulated and bioaugmented microcosms under non-steady state conditions and was supported by results from a recently published study under steady state conditions.
A molecular study on how the abundance of the dechlorinating culture KB-1 affects dechlorination ... more A molecular study on how the abundance of the dechlorinating culture KB-1 affects dechlorination rates in clay till is presented. DNA extracts showed changes in abundance of specific dechlorinators as well as their functional genes. Independently of the KB-1 added, the microbial dechlorinator abundance increased to the same level in all treatments. In the non-bioaugmented microcosms the reductive dehalogenase gene bvcA increased in abundance, but when KB-1 was added the related vcrA gene increased while bvcA genes did not increase. Modeling showed higher vinyl-chloride dechlorination rates and shorter time for complete dechlorination to ethene with higher initial concentration of KB-1 culture, while cis-dichloroethene dechlorination rates were not affected by KB-1 concentrations. This study provides high resolution abundance profiles of Dehalococcoides spp. (DHC) and functional genes, highlights the ecological behavior of KB-1 in clay till, and reinforces the importance of using mul...
... from lakes is therefore needed for environmental management or restoration of lake ecosystems... more ... from lakes is therefore needed for environmental management or restoration of lake ecosystems (Hayashi and Rosenberry, 2002; Sophocleous, 2002; Gleeson et ... 25 061 000, Robertson Geologging, Deganwy, UK) using a 50-by 25-mm scintillation crystal as a natural detector. ...
early 1970s to early 1990s) was used to calculate CFC profiles and time lags. We compared the ana... more early 1970s to early 1990s) was used to calculate CFC profiles and time lags. We compared the analytical results with numerical simulations. metersthickness,diffusionandbarometricpumpingsuf- The time lags in the 15-m-deep unsaturated zone increase from 4.2 to ficiently mix the gases in the unsaturated zone so soil- between 5.2 and 6.1 yr and from 3.4 to 3.9 yr for CFC-11 and CFC-12,
... and seepages of biogenic gas in Northern Denmark TROELS LAIER,* NIELS OLUF JORGENSEN,t BJORN ... more ... and seepages of biogenic gas in Northern Denmark TROELS LAIER,* NIELS OLUF JORGENSEN,t BJORN BUCHARDT,~ TOMMY CEDERBERG~ and ... and isotopic composition has been found by the authors in several on-land shallow (100-120 m) wells These marine ...
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