During routine [(3)H]thymidine incorporation measurements of environmental samples, significant a... more During routine [(3)H]thymidine incorporation measurements of environmental samples, significant amounts of radioactivity are often incorporated into macromolecules other than DNA. Although the percentage of nonspecific labeling varies both temporally and spatially, the cause(s) of these variations remain unknown. Correlations between the percent incorporated radioactivity in DNA and a variety of experimental and environmental parameters measured in the Alfia River, Crystal River, Medard Reservoir, and Bayboro Harbor were examined. The amount of radioactivity incorporated into DNA ranged from 6 to 95% ([Formula: see text]; n=121). Nonspecific labeling began immediately upon the addition of [(3)H]thymidine and was linear over time. Labeling patterns were independent of both the amount of thymidine added and cell-size fraction. A two year study of Bayboro Harbor indicated no conclusive relationship between nonspecific labeling and seasonality. The amount of radioactivity incorporated into DNA was inversely correlated with total rates of thymidine incorporation and a strong diurnal pattern was observed in the Crystal River. No consistent relationship was observed between labeling patterns and primary productivity, chlorophylla, particulate DNA, dissolved DNA, bacterial cell numbers, temperature, salinity, and dissolved organic carbon. The only relationship with dissolved inorganic nutrients (N and P) occurred in the Crystal River. In this phosphate limited river, the percent of radioactivity incorporated into DNA was positively correlated with phosphate concentrations. These results indicate that nonspecific labeling is not dependent on any one parameter but may be a function of many interacting environmental factors or a function of the specific ambient bacterial population.
Sixty push-pull experiments were conducted in a shallow coastal plain aquifer to determine the fa... more Sixty push-pull experiments were conducted in a shallow coastal plain aquifer to determine the fate of nitrate under stimulated and in situ conditions. The experiments were conducted in 5 wells equipped with multi-level samplers (MLS's), each with 12 ports equally spaced over 3.6 m. The injections included: 1) Br, and nitrate, 2) Br, nitrate, and lactate, 3) Br, nitrate, lactate,
Field-scale push-pull experiments were conducted to determine the factors controlling Fe(III) and... more Field-scale push-pull experiments were conducted to determine the factors controlling Fe(III) and Mn(IV) reduction in the well-characterized, shallow, coastal plain aquifer near Oyster, VA. Sixty push-pull experiments were simultaneously conducted in 5 wells equipped with multi-level samplers (MLSs), each with 12 ports equally spaced from 4.4 to 8 m below ground surface; a zone that sampled a heterogeneous portion of
A novel approach to examining the mechanisms controlling the velocity and attachment of bacteria ... more A novel approach to examining the mechanisms controlling the velocity and attachment of bacteria in porous media was developed for the South Oyster Bacterial Transport Field Site. Instead of performing bacterial transport experiments in the lab using repacked materials and artificial water, samples of sediment core, 7 cm. in length, were connected to multi-level samplers at the field site, the
A novel approach to examining the mechanisms controlling the velocity and attachment of bacteria ... more A novel approach to examining the mechanisms controlling the velocity and attachment of bacteria in porous media was developed for the South Oyster Bacterial Transport Field Site. Instead of performing bacterial transport experiments in the lab using repacked materials and artificial water, samples of sediment core, 7 cm. in length, were connected to multi-level samplers at the field site, the
Proceedings of the Water Environment Federation, 2008
ABSTRACT This study was conducted to estimate the human health risks from recreational use of the... more ABSTRACT This study was conducted to estimate the human health risks from recreational use of the Chicago Waterway System (CWS) receiving treated, but non-disinfected, effluent from the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC or District) North Side, Stickney and Calumet water reclamation plants (WRPs). Dry and wet weather samples were collected within the recreational season and analyzed for indicator and pathogen bacteria, protozoa and viruses. The dry and wet weather microbial results were integrated in a probabilistic microbial risk assessment (MRA). Recreational activities considered were canoeing, boating and fishing. Exposure parameters were developed from the primary literature and local use surveys. Overall rates of illness for receptors were all below the USEPA limit of 14 illnesses per 1000 exposure events for freshwater recreational use. Higher rates of illness were predicted during wet weather events. Disinfection of WRP effluent alone has marginal effects on overall recreational illness rates.
Hydrochlorofluorocarbons (HCFCs), proposed as alternatives to the ozone-depleting chlorofluorocar... more Hydrochlorofluorocarbons (HCFCs), proposed as alternatives to the ozone-depleting chlorofluorocarbons (CFCs), have been considered recalcitrant to biological degradation. We report the aerobic degradation by a methanotrophic bacterium of three out of five HCFCs and one out of three hydrofluorocarbons (HFCs) tested. The ability of Methylosinus trichosporium OB3b to degrade these compounds depended on the degree and position of halogen substitution. Gas chromatography, mass spectrometry, and ion chromatography were used to verify the transformation of the HCFCs and HFCs. The stoichiometric release of free chloride and fluoride ions indicated complete mineralization by the reaction. The wide dissemination and abundance of methanotrophs in the environment suggest that these organisms may provide a natural sink for some the CFC replacement compounds.
Environmental science and pollution research international, Jan 30, 2014
High concentrations of uranium(VI) in the Witwatersrand Basin, South Africa from mining leachate ... more High concentrations of uranium(VI) in the Witwatersrand Basin, South Africa from mining leachate is a serious environmental concern. Treatment systems are often ineffective. Therefore, optimization of a bioremediation system that facilitates the bioreduction of U(VI) based on biostimulation of indigenous bacterial communities can be a viable alternative. Tolerance of the indigenous bacteria to high concentrations of U and the amount of citric acid required for U removal was optimized. Two bioreactor studies which showed effective U(VI) removal more than 99 % from low (0.0037 mg L(-1)) and high (10 mg L(-1)) concentrations of U to below the limit allowed by South African National Standards for drinking water (0.0015 mg L(-1)). The second bioreactor was able to successfully adapt even with increasing levels of U(VI) feed water up to 10 mg L(-1), provided that enough electron donor was available. Molecular biology analyses identified Desulfovibrio sp. and Geobacter sp. among known spec...
The Chicago Area Waterway System (CAWS) is a man-made channel, which serves the Chicago area for ... more The Chicago Area Waterway System (CAWS) is a man-made channel, which serves the Chicago area for the drainage of urban storm water and the conveyance of secondary treated effluent from the Metropolitan Water Reclamation District of Greater Chicago's (District) North Side, Stickney and Calumet water reclamation plants (WRPs). A microbial characterization of the CAWS upstream and downstream of the WRPs and from the WRP outfall was initiated by collecting dry and wet weather samples and analyzing for indicators and pathogens. During dry weather, indicator bacteria (fecal coliform [FC], E. coli [EC], enterococci [EN]) were the most abundant microbial species detected in the CAWS compared to pathogens (Salmonella spp [SA], enteric viruses [EV], adenovirus [AV], norovirus [NV] and Giardia and Cryptosporidium). Pseudomonas aeruginosa [PA] levels in the outfall samples were either lower or equivalent to the CAWS. The wet weather samples had a higher frequency of detection of indicator b...
During routine [(3)H]thymidine incorporation measurements of environmental samples, significant a... more During routine [(3)H]thymidine incorporation measurements of environmental samples, significant amounts of radioactivity are often incorporated into macromolecules other than DNA. Although the percentage of nonspecific labeling varies both temporally and spatially, the cause(s) of these variations remain unknown. Correlations between the percent incorporated radioactivity in DNA and a variety of experimental and environmental parameters measured in the Alfia River, Crystal River, Medard Reservoir, and Bayboro Harbor were examined. The amount of radioactivity incorporated into DNA ranged from 6 to 95% ([Formula: see text]; n=121). Nonspecific labeling began immediately upon the addition of [(3)H]thymidine and was linear over time. Labeling patterns were independent of both the amount of thymidine added and cell-size fraction. A two year study of Bayboro Harbor indicated no conclusive relationship between nonspecific labeling and seasonality. The amount of radioactivity incorporated into DNA was inversely correlated with total rates of thymidine incorporation and a strong diurnal pattern was observed in the Crystal River. No consistent relationship was observed between labeling patterns and primary productivity, chlorophylla, particulate DNA, dissolved DNA, bacterial cell numbers, temperature, salinity, and dissolved organic carbon. The only relationship with dissolved inorganic nutrients (N and P) occurred in the Crystal River. In this phosphate limited river, the percent of radioactivity incorporated into DNA was positively correlated with phosphate concentrations. These results indicate that nonspecific labeling is not dependent on any one parameter but may be a function of many interacting environmental factors or a function of the specific ambient bacterial population.
Sixty push-pull experiments were conducted in a shallow coastal plain aquifer to determine the fa... more Sixty push-pull experiments were conducted in a shallow coastal plain aquifer to determine the fate of nitrate under stimulated and in situ conditions. The experiments were conducted in 5 wells equipped with multi-level samplers (MLS's), each with 12 ports equally spaced over 3.6 m. The injections included: 1) Br, and nitrate, 2) Br, nitrate, and lactate, 3) Br, nitrate, lactate,
Field-scale push-pull experiments were conducted to determine the factors controlling Fe(III) and... more Field-scale push-pull experiments were conducted to determine the factors controlling Fe(III) and Mn(IV) reduction in the well-characterized, shallow, coastal plain aquifer near Oyster, VA. Sixty push-pull experiments were simultaneously conducted in 5 wells equipped with multi-level samplers (MLSs), each with 12 ports equally spaced from 4.4 to 8 m below ground surface; a zone that sampled a heterogeneous portion of
A novel approach to examining the mechanisms controlling the velocity and attachment of bacteria ... more A novel approach to examining the mechanisms controlling the velocity and attachment of bacteria in porous media was developed for the South Oyster Bacterial Transport Field Site. Instead of performing bacterial transport experiments in the lab using repacked materials and artificial water, samples of sediment core, 7 cm. in length, were connected to multi-level samplers at the field site, the
A novel approach to examining the mechanisms controlling the velocity and attachment of bacteria ... more A novel approach to examining the mechanisms controlling the velocity and attachment of bacteria in porous media was developed for the South Oyster Bacterial Transport Field Site. Instead of performing bacterial transport experiments in the lab using repacked materials and artificial water, samples of sediment core, 7 cm. in length, were connected to multi-level samplers at the field site, the
Proceedings of the Water Environment Federation, 2008
ABSTRACT This study was conducted to estimate the human health risks from recreational use of the... more ABSTRACT This study was conducted to estimate the human health risks from recreational use of the Chicago Waterway System (CWS) receiving treated, but non-disinfected, effluent from the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC or District) North Side, Stickney and Calumet water reclamation plants (WRPs). Dry and wet weather samples were collected within the recreational season and analyzed for indicator and pathogen bacteria, protozoa and viruses. The dry and wet weather microbial results were integrated in a probabilistic microbial risk assessment (MRA). Recreational activities considered were canoeing, boating and fishing. Exposure parameters were developed from the primary literature and local use surveys. Overall rates of illness for receptors were all below the USEPA limit of 14 illnesses per 1000 exposure events for freshwater recreational use. Higher rates of illness were predicted during wet weather events. Disinfection of WRP effluent alone has marginal effects on overall recreational illness rates.
Hydrochlorofluorocarbons (HCFCs), proposed as alternatives to the ozone-depleting chlorofluorocar... more Hydrochlorofluorocarbons (HCFCs), proposed as alternatives to the ozone-depleting chlorofluorocarbons (CFCs), have been considered recalcitrant to biological degradation. We report the aerobic degradation by a methanotrophic bacterium of three out of five HCFCs and one out of three hydrofluorocarbons (HFCs) tested. The ability of Methylosinus trichosporium OB3b to degrade these compounds depended on the degree and position of halogen substitution. Gas chromatography, mass spectrometry, and ion chromatography were used to verify the transformation of the HCFCs and HFCs. The stoichiometric release of free chloride and fluoride ions indicated complete mineralization by the reaction. The wide dissemination and abundance of methanotrophs in the environment suggest that these organisms may provide a natural sink for some the CFC replacement compounds.
Environmental science and pollution research international, Jan 30, 2014
High concentrations of uranium(VI) in the Witwatersrand Basin, South Africa from mining leachate ... more High concentrations of uranium(VI) in the Witwatersrand Basin, South Africa from mining leachate is a serious environmental concern. Treatment systems are often ineffective. Therefore, optimization of a bioremediation system that facilitates the bioreduction of U(VI) based on biostimulation of indigenous bacterial communities can be a viable alternative. Tolerance of the indigenous bacteria to high concentrations of U and the amount of citric acid required for U removal was optimized. Two bioreactor studies which showed effective U(VI) removal more than 99 % from low (0.0037 mg L(-1)) and high (10 mg L(-1)) concentrations of U to below the limit allowed by South African National Standards for drinking water (0.0015 mg L(-1)). The second bioreactor was able to successfully adapt even with increasing levels of U(VI) feed water up to 10 mg L(-1), provided that enough electron donor was available. Molecular biology analyses identified Desulfovibrio sp. and Geobacter sp. among known spec...
The Chicago Area Waterway System (CAWS) is a man-made channel, which serves the Chicago area for ... more The Chicago Area Waterway System (CAWS) is a man-made channel, which serves the Chicago area for the drainage of urban storm water and the conveyance of secondary treated effluent from the Metropolitan Water Reclamation District of Greater Chicago's (District) North Side, Stickney and Calumet water reclamation plants (WRPs). A microbial characterization of the CAWS upstream and downstream of the WRPs and from the WRP outfall was initiated by collecting dry and wet weather samples and analyzing for indicators and pathogens. During dry weather, indicator bacteria (fecal coliform [FC], E. coli [EC], enterococci [EN]) were the most abundant microbial species detected in the CAWS compared to pathogens (Salmonella spp [SA], enteric viruses [EV], adenovirus [AV], norovirus [NV] and Giardia and Cryptosporidium). Pseudomonas aeruginosa [PA] levels in the outfall samples were either lower or equivalent to the CAWS. The wet weather samples had a higher frequency of detection of indicator b...
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