Poghosyan A.,University of Illinois at Chicago |
Sturchio N.C.,University of Illinois at Chicago |
Sturchio N.C.,University of Delaware |
Morrison C.G.,University of Illinois at Chicago |
And 5 more authors.
Environmental Science and Technology | Year: 2014
Perchlorate is a persistent and mobile contaminant in the environment with both natural and anthropogenic sources. Stable isotope ratios of oxygen (δ18O, δ17O) and chlorine (δ37Cl) along with the abundance of the radioactive isotope 36Cl were used to trace perchlorate sources and behavior in the Laurentian Great Lakes. These lakes were selected for study as a likely repository of recent atmospheric perchlorate deposition. Perchlorate concentrations in the Great Lakes range from 0.05 to 0.13 μg per liter. δ37Cl values of perchlorate from the Great Lakes range from +3.0‰ (Lake Ontario) to +4.0‰ (Lake Superior), whereas δ18O values range from -4.1‰ (Lake Superior) to +4.0‰ (Lake Erie). Great Lakes perchlorate has mass-independent oxygen isotopic variations with positive δ17O values (+1.6‰ to +2.7‰) divided into two distinct groups: Lake Superior (+2.7‰) and the other four lakes (∼+1.7‰). The stable isotopic results indicate that perchlorate in the Great Lakes is dominantly of natural origin, having isotopic composition resembling that measured for indigenous perchlorate from preindustrial groundwaters of the western USA. The 36Cl/Cl ratio of perchlorate varies widely from 7.4 × 10-12 (Lake Ontario) to 6.7 × 10-11 (Lake Superior). These 36ClO4 - abundances are consistent with an atmospheric origin of perchlorate in the Great Lakes. The relatively high 36ClO4 - abundances in the larger lakes (Lakes Superior and Michigan) could be explained by the presence of 36Cl-enriched perchlorate deposited during the period of elevated atmospheric 36Cl activity following thermonuclear bomb tests in the Pacific Ocean. © 2014 American Chemical Society.
Stedtfeld R.D.,Michigan State University |
Stedtfeld T.M.,Michigan State University |
Kronlein M.,Michigan State University |
Seyrig G.,Michigan State University |
And 3 more authors.
Environmental Science and Technology | Year: 2014
Nucleic acid amplification of biomarkers is increasingly used to measure microbial activity and predict remedial performance in sites with trichloroethene (TCE) contamination. Field-based genetic quantification of microorganisms associated with bioremediation may help increase accuracy that is diminished through transport and processing of groundwater samples. Sterivex cartridges and a previously undescribed mechanism for eluting biomass was used to concentrate cells. DNA extraction-free loop mediated isothermal amplification (LAMP) was monitored in real-time with a point of use device (termed Gene-Z). A detection limit of 105 cells L-1 was obtained, corresponding to sensitivity between 10 to 100 genomic copies per reaction for assays targeting the Dehalococcoides spp. specific 16S rRNA gene and vcrA gene, respectively. The quantity of Dehalococcoides spp. genomic copies measured from two TCE contaminated groundwater samples with conventional means of quantification including filtration, DNA extraction, purification, and qPCR was comparable to the field ready technique. Overall, this method of measuring Dehalococcoides spp. and vcrA genes in groundwater via direct amplification without intentional DNA extraction and purification is demonstrated, which may provide a more accurate mechanism of predicting remediation rates. © 2014 American Chemical Society.
Hatzinger P.B.,Biotechnology Development and Applications Group |
Streger S.H.,Biotechnology Development and Applications Group |
Begley J.F.,MT Environmental Restoration
Journal of Contaminant Hydrology | Year: 2015
1,2-Dibromoethane (ethylene dibromide; EDB) is a probable human carcinogen that was previously used as both a soil fumigant and a scavenger in leaded gasoline. EDB has been observed to persist in soils and groundwater, particularly under oxic conditions. The objective of this study was to evaluate options to enhance the aerobic degradation of EDB in groundwater, with a particular focus on possible in situ remediation strategies. Propane gas and ethane gas were observed to significantly stimulate the biodegradation of EDB in microcosms constructed with aquifer solids and groundwater from the FS-12 EDB plume at Joint Base Cape Cod (Cape Cod, MA), but only after inorganic nutrients were added. Ethene gas was also effective, but rates were appreciably slower than for ethane and propane. EDB was reduced to < 0.02 μg/L, the Massachusetts state Maximum Contaminant Level (MCL), in microcosms that received ethane gas and inorganic nutrients. An enrichment culture (BE-3R) that grew on ethane or propane gas but not EDB was obtained from the site materials. The degradation of EDB by this culture was inhibited by acetylene gas, suggesting that degradation is catalyzed by a monooxygenase enzyme. The BE-3R culture was also observed to biodegrade 1,2-dichloroethane (DCA), a compound commonly used in conjunction with EDB as a lead scavenger in gasoline. The data suggest that addition of ethane or propane gas with inorganic nutrients may be a viable option to enhance degradation of EDB in groundwater aquifers to below current state or federal MCL values. © 2014 Elsevier Ltd. All rights reserved.