scholarly journals 1,2-DCA Natural Attenuation Evaluation in Groundwater: Insight by Dual Isotope 13C/37Cl and Molecular Analysis Approach

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 728
Author(s):  
Giovanna Carpani ◽  
Massimo Marchesi ◽  
Ilaria Pietrini ◽  
Luca Alberti ◽  
Luciano Massimo Zaninetta ◽  
...  
Keyword(s):  
Natural Attenuation ◽  
Groundwater Remediation ◽  
Source Area ◽  
Enrichment Factors ◽  
Contaminated Site ◽  
Anaerobic Conditions ◽  
Site Specific ◽  
Main Site ◽  
Dual Isotope ◽  
Reductive Dehalogenase

Natural attenuation (NA) processes represent a valuable option in groundwater remediation. At a heavily 1,2-dichloroethane (1,2-DCA) contaminated site, Compound-Specific Isotope Analysis (CSIA) in combination with Biological Molecular Tools (BMTs) were implemented as a rigorous characterization approach to evaluate the occurrence of Natural Attenuation in the proximity of the source area. By the use of microcosm experiments, the potential for natural and enhanced biodegradation under anaerobic conditions was documented, following the dichloroelimination pathway. Enrichment factors of −9.1‰ and −11.3‰ were obtained for 13C while Geobacter spp. and reductive dehalogenase genes (rdhs) were identified as main site-specific biomarkers. At pilot scale, enrichments of 13.5‰ and 6.3‰ for δ13C and δ37Cl, respectively, high levels of reductive dehalogenase (rdh group VI) along with the dominance of Geobacter spp. indicated the occurrence of significant dichloroelimination processes in groundwater under anaerobic conditions. By using the site-specific enrichment factors, degradation extents over approximately 70–80% were estimated, highlighting the relevant potential of NA in 1,2-DCA degradation in the vicinity of the source area at the site. The proposed fine-tuned protocol, including CSIA and BMTs, is proven to be effective as a groundwater remediation strategy, properly assessing and monitoring NA at site scale.

Hexavalent Chromium Remediation by Bore-Hole Placed Reduction Barriers and Monitored Natural Attenuation

2006 ◽  
Vol 9 (1) ◽  
Author(s):  
Jim V. Rouse ◽  
Richard M. Thomasser ◽  
Cathleen A. Terentieff ◽  
Lisa A. Hall
Keyword(s):  
Hexavalent Chromium ◽  
Natural Attenuation ◽  
Groundwater Remediation ◽  
Central Valley ◽  
Source Area ◽  
Cost Effective ◽  
Integrated Approach ◽  
Permeable Reactive Barriers ◽  
Monitored Natural Attenuation ◽  
Reactive Barriers

AbstractPreviously, the authors have developed the concept of in-situ reduction of hexavalent chromium in contaminated groundwater, using various forms of active reagent delivery, based on site geohydrological conditions. While these approaches are highly successful and cost effective, in some cases, such active approaches may not be appropriate. Rather, it may be appropriate to limit the spread of chromium contamination by formation of permeable reactive barriers or reactive zones through the borehole placement of aqueous reductants. A passive approach, utilizing bore-hole placed reactive barriers and Monitored Natural Attenuation (MNA), offers real advantages for groundwater remediation, especially in situations involving groundwater in fractured or cavernous bedrock, where the water table is at great depth, or where on-going activities in the source area limit access for more active approaches. A geochemical reactive barrier was used at a South Australian timber preservation facility sited over a cavernous limestone. After remedial activities within the plume achieved significant reduction of the mobile chromium mass, the applicable regulatory agency authorized MNA for control of residual contamination. A phased approach has been utilized at a Central Valley, California timber preservation site, to develop data on the radial spread of reductant injection through diffusion, and the longevity of the effect of such injection, and a full-scale remedial approach designed, recognizing limitations on injection imposed by limited access. The paper discusses the requirements to demonstrate the effectiveness of MNA. Case histories of successful application of the integrated approach of passive reduction and MNA are presented, as a cost-effective and environmentally-protective means of accomplishing remediation of hexavalent chromium in groundwater.

The potential of anaerobic bacteria to degrade chlorinated compounds

2001 ◽  
Vol 44 (8) ◽  
pp. 49-56 ◽  
Author(s):  
M.H.A. van Eekert ◽  
G. Schraa
Keyword(s):  
Anaerobic Bacteria ◽  
Granular Sludge ◽  
Chlorinated Ethenes ◽  
Contaminated Sites ◽  
Contaminated Site ◽  
Anaerobic Conditions ◽  
Chlorinated Aromatics ◽  
Start Up ◽  
Acetogenic Bacteria ◽  
Uasb Reactors

Chlorinated ethenes and chlorinated aromatics are often found as pollutants in sediments, groundwater, and wastewater. These compounds were long considered to be recalcitrant under anaerobic conditions. In the past years however, dechlorination of these compounds has been found to occur under anaerobic conditions at contaminated sites and in wastewater treatment systems. This dechlorination is mainly attributed to halo-respiring bacteria, which are able to couple this dechlorination to energy conservation via electron transport coupled phosphorylation. The dechlorinating activities of the halo-respiring bacteria seem to be confined to the dechlorination of chloroethenes and chlorinated aromatic compounds. In addition, methanogenic and acetogenic bacteria are also able to reduce the chlorinated ethenes via a-specific cometabolic pathways. Although these latter reactions may not be important in the remediation of contaminated sites, they may be of substantial influence in the start-up of remediation processes and in the application of granular sludge from UASB reactors. Specific halo-respiring bacteria may be used to increase the dechlorination activities via bioaugmentation in the case that the appropriate microorganisms are not present at the contaminated site or in the sludge.

Effect of cold temperature on the rate of natural attenuation of benzene, toluene, ethylbenzene, and the three isomers of xylene (BTEX)

2010 ◽  
Vol 47 (5) ◽  
pp. 516-527 ◽  
Author(s):  
Ania C. Ulrich ◽  
Kristen Tappenden ◽  
James Armstrong ◽  
Kevin W. Biggar
Keyword(s):  
Natural Attenuation ◽  
Field Conditions ◽  
Published Data ◽  
Anaerobic Conditions ◽  
Data Set ◽  
Cold Temperatures ◽  
Site Analysis ◽  
Benzene Toluene ◽  
The Impact ◽  
Hydrogeological Information

The impact of cold temperatures on natural attenuation rates is poorly understood and compounded by the lack of published data, particularly under field conditions. This paper presents a collection of data from monitoring and remediation projects completed at cold temperatures. The data set was compiled from 55 studies under anaerobic conditions (46 field and nine laboratory) from sites where groundwater temperatures are typically less than 15 °C. By normalizing the data to +5 and +10 °C, the scatter in rates for BTEX degradation in groundwater was reduced by 33% to 66%. In an attempt to address the paucity of data on natural attenuation rates under cold temperatures, this study has compiled and normalized 101 anaerobic BTEX natural attenuation rates. Eleven of the 55 studies and 43 of the 101 rates presented in this study have not been previously published. Additionally, this study has compiled, for each site, relevant contaminant and hydrogeological information that can be reviewed to choose appropriate rates for preliminary site analysis.

scholarly journals Vegetarian and vegan diets and risks of total and site-specific fractures: results from the prospective EPIC-Oxford study

BMC Medicine ◽  
2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Tammy Y. N. Tong ◽  
Paul N. Appleby ◽  
Miranda E. G. Armstrong ◽  
Georgina K. Fensom ◽  
Anika Knuppel ◽  
...  
Keyword(s):  
Cox Regression ◽  
Diet Group ◽  
Economic Factors ◽  
Death Certificates ◽  
Site Specific ◽  
Main Site ◽  
Specific Fracture ◽  
Fracture Risks ◽  
Socio Economic Factors

Abstract Background There is limited prospective evidence on possible differences in fracture risks between vegetarians, vegans, and non-vegetarians. We aimed to study this in a prospective cohort with a large proportion of non-meat eaters. Methods In EPIC-Oxford, dietary information was collected at baseline (1993–2001) and at follow-up (≈ 2010). Participants were categorised into four diet groups at both time points (with 29,380 meat eaters, 8037 fish eaters, 15,499 vegetarians, and 1982 vegans at baseline in analyses of total fractures). Outcomes were identified through linkage to hospital records or death certificates until mid-2016. Using multivariable Cox regression, we estimated the risks of total (n = 3941) and site-specific fractures (arm, n = 566; wrist, n = 889; hip, n = 945; leg, n = 366; ankle, n = 520; other main sites, i.e. clavicle, rib, and vertebra, n = 467) by diet group over an average of 17.6 years of follow-up. Results Compared with meat eaters and after adjustment for socio-economic factors, lifestyle confounders, and body mass index (BMI), the risks of hip fracture were higher in fish eaters (hazard ratio 1.26; 95% CI 1.02–1.54), vegetarians (1.25; 1.04–1.50), and vegans (2.31; 1.66–3.22), equivalent to rate differences of 2.9 (0.6–5.7), 2.9 (0.9–5.2), and 14.9 (7.9–24.5) more cases for every 1000 people over 10 years, respectively. The vegans also had higher risks of total (1.43; 1.20–1.70), leg (2.05; 1.23–3.41), and other main site fractures (1.59; 1.02–2.50) than meat eaters. Overall, the significant associations appeared to be stronger without adjustment for BMI and were slightly attenuated but remained significant with additional adjustment for dietary calcium and/or total protein. No significant differences were observed in risks of wrist or ankle fractures by diet group with or without BMI adjustment, nor for arm fractures after BMI adjustment. Conclusions Non-meat eaters, especially vegans, had higher risks of either total or some site-specific fractures, particularly hip fractures. This is the first prospective study of diet group with both total and multiple specific fracture sites in vegetarians and vegans, and the findings suggest that bone health in vegans requires further research.

DGT use in contaminated site characterization. The importance of heavy metal site specific behaviour

Chemosphere ◽  
2008 ◽  
Vol 70 (6) ◽  
pp. 1135-1140 ◽  
Author(s):  
Maria Letizia Ruello ◽  
Miriam Sileno ◽  
Daniela Sani ◽  
Gabriele Fava
Keyword(s):  
Heavy Metal ◽  
Site Characterization ◽  
Contaminated Site ◽  
Site Specific ◽  
Metal Site ◽  
Specific Behaviour

Quinoline and Derivatives at a Tar Oil Contaminated Site:  Hydroxylated Products as Indicator for Natural Attenuation?

2007 ◽  
Vol 41 (15) ◽  
pp. 5314-5322 ◽  
Author(s):  
Anne-Kirsten Reineke ◽  
Thomas Göen ◽  
Alfred Preiss ◽  
Juliane Hollender
Keyword(s):  
Natural Attenuation ◽  
Contaminated Site ◽  
Tar Oil
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