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Dechlorination

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https://www.readbyqxmd.com/read/28328216/natural-attenuation-in-streambed-sediment-receiving-chlorinated-solvents-from-underlying-fracture-networks
#1
Burcu Simsir, Jun Yan, Jeongdae Im, Duane Graves, Frank E Löffler
Contaminant discharge from fractured bedrock formations remains a remediation challenge. We applied an integrated approach to assess the natural attenuation potential of sediment that forms the transition zone between upwelling groundwater from a chlorinated solvent-contaminated fractured bedrock aquifer and the receiving surface water. In situ measurements demonstrated that reductive dechlorination in the sediment attenuated chlorinated compounds before reaching the water column. Microcosms established with creek sediment or in situ incubated Bio-Sep beads degraded C1-C3 chlorinated solvents to less chlorinated or innocuous products...
March 22, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28321700/thermoactivated-persulfate-oxidation-of-pesticide-chlorpyrifos-in-aquatic-system-kinetic-and-mechanistic-investigations
#2
Lei Zhou, Ya Zhang, Rongrong Ying, Guoqing Wang, Tao Long, Jianhua Li, Yusuo Lin
The widespread occurrence of organophosphorus pesticides (OPPs) in the environment poses risks to both ecologic system as well as human health. This study investigated the oxidation kinetics of chlorpyrifos (CP), one of the typical OPPs, by thermoactivated persulfate (PS) oxidation process, and evaluated the influence of key kinetic factors, such as PS concentrations, pH, temperature, bicarbonate, and chloride ions. The reaction pathways and mechanisms were also proposed based on products identification by LC-MS techniques...
March 20, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28320527/characterization-and-genome-functional-analysis-of-the-ddt-degrading-bacterium-ochrobactrum-sp-ddt-2
#3
Xiong Pan, Tianheng Xu, Haoyu Xu, Hua Fang, Yunlong Yu
A strain of Ochrobactrum sp. DDT-2 that was capable of degrading DDT as the sole carbon and energy source was isolated and sequenced, and its biodegradation characteristics and metabolism mechanism were examined. The genome sequence of the isolate DDT-2 was composed of 4,630,303bp with a GC content of 55.99% and 4454 coding genes. The degradation rate of DDT by the isolate DDT-2 increased with the increasing substrate concentration (0.1-10mg/l) and temperature (20-40°C). The degradation half-life of DDT in the presence of the isolate DDT-2 at pH7...
March 17, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28319739/mechanism-and-kinetics-of-halogenated-compound-removal-by-metallic-iron-transport-in-solution-diffusion-and-reduction-within-corrosion-films
#4
Shun Tang, Xiao-Mao Wang, Shi-Ting Liu, Hong-Wei Yang, Yuefeng F Xie, Xiao-Yi Yang
A detailed kinetic model comprised of mass transport (ktra), pore diffusion (kdif), adsorption and reduction reaction (krea), was developed to quantitatively evaluate the effect of corrosion films on the removal rate (kobs) of halogenated compounds by metallic iron. Different corrosion conditions were controlled by adjusting the iron aging time (0 or 1 yr) and dissolved oxygen concentration (0-7.09 mg/L DO). The kobs values for bromate, mono-, di- and tri-chloroacetic acids (BrO3(-), MCAA, DCAA and TCAA) were 0...
March 6, 2017: Chemosphere
https://www.readbyqxmd.com/read/28292737/in-vivo-metabolism-of-organophosphate-flame-retardants-and-distribution-of-their-main-metabolites-in-adult-zebrafish
#5
Guowei Wang, Hanyan Chen, Zhongkun Du, Jianhua Li, Zunyao Wang, Shixiang Gao
Understanding the metabolism of chemicals as well as the distribution and depuration of their main metabolites in tissues are essential for evaluating their fate and potential toxicity in vivo. Herein, we investigated the metabolism of six typical organophosphate (OP) flame retardants (tripropyl phosphate (TPRP), tri-n-butyl phosphate (TNBP), tris(2-butoxyethyl) phosphate (TBOEP), tris(2-chloroethyl) phosphate (TCEP), tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) and tri-p-cresyl phosphate (p-TCP)) in adult zebrafish in laboratory at three levels (0, 1/150 LC50 (environmentally relevant level), and 1/30 LC50 per OP analog)...
March 11, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28274623/oxygen-exposure-effects-on-the-dechlorinating-activities-of-a-trichloroethene-dechlorination-microbial-consortium
#6
Na Liu, Haijun Li, Mengyan Li, Longzhen Ding, Chih-Huang Weng, Cheng-Di Dong
The aim of this work was to study the effects of the presence of oxygen on the dechlorination of trichloroethene by a microbial consortium containing D. mccartyi. The 16S rRNA and reductive dechlorination genes of the functional bacteria and the non-dechlorinators were monitored. Exposing the consortium to oxygen altered the overall biotransformation rate of the dechlorination process, biotransformation processes prolonged with oxygen concentrations changing from 0 to 7.2mg/L, however, trichloroethylene was eventually dechlorinated to ethene...
February 28, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28273571/detoxification-of-1-1-2-trichloroethane-to-ethene-in-a-bioreactor-co-culture-of-dehalogenimonas-and-dehalococcoides-mccartyi-strains
#7
Siti Hatijah Mortan, Lucía Martín-González, Teresa Vicent, Gloria Caminal, Ivonne Nijenhuis, Lorenz Adrian, Ernest Marco-Urrea
1,1,2-Trichloroethane (1,1,2-TCA) is a non-flammable organic solvent and common environmental contaminant in groundwater. Organohalide-respiring bacteria are key microorganisms to remediate 1,1,2-TCA because they can gain metabolic energy during its dechlorination under anaerobic conditions. However, all current isolates produce hazardous end products such as vinyl chloride, monochloroethane or 1,2-dichloroethane that accumulate in the medium. Here, we constructed a syntrophic co-culture of Dehalogenimonas and Dehalococcoides mccartyi strains to achieve complete detoxification of 1,1,2-TCA to ethene...
February 27, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/28264061/wheat-straw-biochar-supported-nanoscale-zerovalent-iron-for-removal-of-trichloroethylene-from-groundwater
#8
Hui Li, Ya Qin Chen, Shuai Chen, Xiao Li Wang, Shu Guo, Yue Feng Qiu, Yong Di Liu, Xiao Li Duan, Yun Jiang Yu
This study synthesized the wheat straw biochar-supported nanoscale zerovalent iron (BC-nZVI) via in-situ reduction with NaBH4 and biochar pyrolyzed at 600°C. Wheat straw biochar, as a carrier, significantly enhanced the removal of trichloroethylene (TCE) by nZVI. The pseudo-first-order rate constant of TCE removal by BC-nZVI (1.079 h-1) within 260 min was 1.4 times higher and 539.5 times higher than that of biochar and nZVI, respectively. TCE was 79% dechlorinated by BC-nZVI within 15 h, but only 11% dechlorinated by unsupported nZVI, and no TCE dechlorination occurred with unmodified biochar...
2017: PloS One
https://www.readbyqxmd.com/read/28257813/reverse-osmosis-and-ultrafiltration-for-recovery-and-reuse-of-larval-rearing-water-in-anopheles-arabiensis-mass-production-effect-of-water-quality-on-larval-development-and-fitness-of-emerging-adults
#9
Wadaka Mamai, Rebecca Hood-Nowotny, Hamidou Maiga, Adel Barakat Ali, Nanwintoun S Bimbile-Somda, Diloma Dieudonné Soma, Hanano Yamada, Rosemary Susan Lees, Jeremie R L Gilles
BACKGROUND: Countries around the world are showing increased interest in applying the sterile insect technique against mosquito disease vectors. Many countries in which mosquitoes are endemic, and so where vector control using the sterile insect technique may be considered, are located in arid zones where water provision can be costly or unreliable. Water reuse provides an alternate form of water supply. In order to reduce the cost of mass rearing of Anopheles arabiensis mosquitoes, the possibility of recycling and reusing larval rearing water was explored...
March 1, 2017: Acta Tropica
https://www.readbyqxmd.com/read/28244752/amino-acid-assisted-dehalogenation-of-carbon-tetrachloride-by-green-rust-inhibition-of-chloroform-production
#10
Weizhao Yin, Bjarne W Strobel, Hans Christian B Hansen
Layered Fe(II)-Fe(III) hydroxides (green rusts, GRs) are promising reactants for reductive dechlorination of chlorinated solvents due to high reaction rates and the opportunity to inject reactive slurries of the compounds into contaminant plumes. However, it is necessary to develop strategies that reduce the formation of toxic byproducts such as chloroform (CF). In this study, carbon tetrachloride (CT) dehalogenation by the chloride form of GR (GRCl) was tested in the presence of glycine (GLY) and other selected amino acids...
March 13, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28242253/dechlorination-and-chlorine-rearrangement-of-1-2-5-5-6-9-10-heptachlorodecane-mediated-by-the-whole-pumpkin-seedlings
#11
Yanlin Li, Xingwang Hou, Miao Yu, Qunfang Zhou, Jiyan Liu, Jerald L Schnoor, Guibin Jiang
Short chain chlorinated paraffins (SCCPs) are ubiquitously present as persistent organic pollutants in the environment. However, little information on the interaction of SCCPs with plants is currently available. In this work, young pumpkin plants (Cucurbita maxima × C. Moschata) were hydroponically exposed to the congener of chlorinated decane, 1,2,5,5,6,9,10-heptachlorodecane (1,2,5,5,6,9,10-HepCD), to investigate the uptake, translocation and transformation of chlorinated decanes in the intact plants...
February 24, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/28240850/ascorbate-promoted-surface-iron-cycle-for-efficient-heterogeneous-fenton-alachlor-degradation-with-hematite-nanocrystals
#12
Xiaopeng Huang, Xiaojing Hou, Falong Jia, Fahui Song, Jincai Zhao, Lizhi Zhang
This study reports the H2O2 activation with different hematite nanocrystals and ascorbate ions for the herbicide alachlor degradation at pH 5. We found that hematite nanoplates (HNPs) exposed with {001} facets exhibited better catalytic performance than hematite nanocubes (HNCs) exposed with {012} facets, which was attributed to the formation of inner-sphere iron-ascorbate complexes on the hematite facets. The 3-fold undercoordination Fe cations of {001} facet favors the formation of inner-sphere iron-ascorbate complexes, while the 5-fold undercoordination Fe cations of {012} facet has stereo-hindrance effect, disfavoring the complex formation...
March 6, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28238364/design-and-performance-of-subgrade-biogeochemical-reactors
#13
Jeff Gamlin, Doug Downey, Brad Shearer, Paul Favara
Subgrade biogeochemical reactors (SBGRs), also commonly referred to as in situ bioreactors, are a unique technology for treatment of contaminant source areas and groundwater plume hot spots. SBGRs have most commonly been configured for enhanced reductive dechlorination (ERD) applications for chlorinated solvent treatment. However, they have also been designed for other contaminant classes using alternative treatment media. The SBGR technology typically consists of removal of contaminated soil via excavation or large-diameter augers, and backfill of the soil void with gravel and treatment amendments tailored to the target contaminant(s)...
February 18, 2017: Journal of Environmental Management
https://www.readbyqxmd.com/read/28238079/development-and-application-of-a-rapid-user-friendly-and-inexpensive-method-to-detect-dehalococcoides-sp-reductive-dehalogenase-genes-from-groundwater
#14
Yogendra H Kanitkar, Robert D Stedtfeld, Paul B Hatzinger, Syed A Hashsham, Alison M Cupples
TaqMan probe-based quantitative polymerase chain reaction (qPCR) specific to the biomarker reductive dehalogenase (RDase) genes is a widely accepted molecular biological tool (MBT) for determining the abundance of Dehalococcoides sp. in groundwater samples from chlorinated solvent-contaminated sites. However, there are significant costs associated with this MBT. In this study, we describe an approach that requires only low-cost laboratory equipment (a bench top centrifuge and a water bath) and requires less time and resources compared to qPCR...
February 25, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28213734/dehalococcoides-and-general-bacterial-ecology-of-differentially-trichloroethene-dechlorinating-flow-through-columns
#15
Babur S Mirza, Darwin L Sorensen, Daniel J McGlinn, R Ryan Dupont, Joan E McLean
The diversity of Dehalococcoides mccartyi (Dhc) and/or other organohalide respiring or associated microorganisms in parallel, partial, or complete trichloroethene (TCE) dehalogenating systems has not been well described. The composition of Dhc populations and the associated bacterial community that developed over 7.5 years in the top layer (0-10 cm) of eight TCE-fed columns were examined using pyrosequencing. Columns biostimulated with one of three carbon sources, along with non-stimulated controls, developed into complete (ethene production, whey amended), partial (cis-dichloroethene (DCE) and VC, an emulsified oil with nonionic surfactant), limited (<5 % cis-DCE and 95 % TCE, an emulsified oil), and non- (controls) TCE dehalogenating systems...
February 17, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28210952/two-dechlorinated-chlordecone-derivatives-formed-by-in-situ-chemical-reduction-are-devoid-of-genotoxicity-and-mutagenicity-and-have-lower-proangiogenic-properties-compared-to-the-parent-compound
#16
Samuel Legeay, Pierre-André Billat, Nicolas Clere, Fabrice Nesslany, Sébastien Bristeau, Sébastien Faure, Christophe Mouvet
Chlordecone (CLD) is a chlorinated hydrocarbon insecticide, now classified as a persistent organic pollutant. Several studies have previously reported that chronic exposure to CLD leads to hepatotoxicity, neurotoxicity, raises early child development and pregnancy complications, and increases the risk of liver and prostate cancer. In situ chemical reduction (ISCR) has been identified as a possible way for the remediation of soils contaminated by CLD. In the present study, the objectives were (i) to evaluate the genotoxicity and the mutagenicity of two CLD metabolites formed by ISCR, CLD-5a-hydro, or CLD-5-hydro (5a- or 5- according to CAS nomenclature; CLD-1Cl) and tri-hydroCLD (CLD-3Cl), and (ii) to explore the angiogenic properties of these molecules...
February 16, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28188205/metagenomic-and-metatranscriptomic-analyses-reveal-structure-and-dynamics-of-a-dechlorinating-community-containing-dehalococcoides-mccartyi-and-corrinoid-providing-microorganisms-under-cobalamin-limited-condition
#17
Yujie Men, Ke Yu, Jacob Bælum, Ying Gao, Julien Tremblay, Emmanuel Prestat, Ben Stenuit, Susannah G Tringe, Janet Jansson, Tong Zhang, Lisa Alvarez-Cohen
The aim of this study is to obtain a systems level understanding of the interactions between Dehalococcoides and corrinoid-supplying microorganisms by analyzing community structures and functional compositions, activities and dynamics in trichloroethene (TCE) - dechlorinating enrichments. Metagenomes and metatranscriptomes of the dechlorinating enrichments with and without exogenous cobalamin were compared. Seven putative draft genomes were binned from the metagenomes. At an early stage (2 d), more transcripts of genes in the Veillonellaceae bin-genome were detected in the metatranscriptome of the enrichment with exogenous cobalamin compared to the one without cobalamin addition...
February 10, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28159841/kinetic-mechanism-of-the-dechlorinating-flavin-dependent-monooxygenase-hada
#18
Panu Pimviriyakul, Kittisak Thotsaporn, Jeerus Sucharitakul, Pimchai Chaiyen
The accumulation of chlorophenols (CPs) in the environment, due to their wide use as agrochemicals, has become a serious environmental problem. These organic halides can be degraded by aerobic microorganisms, where the initial steps of various biodegradation pathways include an oxidative dechlorinating process in which chloride is replaced by a hydroxyl substituent. Harnessing these dechlorinating processes could provide an opportunity for environmental remediation, but detailed catalytic mechanisms for these enzymes are not yet known...
February 3, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28159790/the-effects-of-sulfate-reduction-on-tce-dechlorination-by-dehalococcoides-containing-microbial-communities
#19
Xinwei Mao, Alexandra Polasko, Lisa Alvarez-Cohen
In order to elucidate interactions between sulfate reduction and dechlorination, we systematically evaluated the effects of different concentrations of sulfate and sulfide on reductive dechlorination by isolates, constructed consortia and enrichments containing Dehalococcoides sp. Sulfate (up to 5 mM) did not inhibit growth or metabolism of pure cultures of dechlorinator Dehalococcoides mccartyi 195, sulfate reducer Desulfovibrio vulgaris Hildenborough (DvH) or syntroph Syntrophomonas wolfei (S. wolfei). In contrast, sulfide (5mM) exhibited inhibitory effects on growth of the sulfate reducer and the syntroph, as well as on both dechlorination and growth rates of D...
February 3, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28140362/self-catalyzed-gaas-nanowires-on-silicon-by-hydride-vapor-phase-epitaxy
#20
Zhenning Dong, Yamina André, Vladimir G Dubrovskii, Catherine Bougerol, Christine Leroux, Mohammed R Ramdani, Guillaume Monier, Agnès Trassoudaine, Dominique Castelluci, Evelyne Gil
Gold-free GaAs nanowires on silicon substrates can pave the way for monolithic integration of photonic nanodevices with silicon electronic platforms. It is extensively documented that the self-catalyzed approach works well in molecular beam epitaxy but is much more difficult to implement in vapor phase epitaxies. Here, we report the first gallium-catalyzed hydride vapor phase epitaxy growth of long (more than 10 μm) GaAs nanowires on Si(111) substrates with a high integrated growth rate up to 60 μm h(-1) and pure zincblende crystal structure...
March 24, 2017: Nanotechnology
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