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Environmental Science & Technology

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https://www.readbyqxmd.com/read/28812881/predicting-microbial-fuel-cell-biofilm-communities-and-bioreactor-performance-using-artificial-neural-networks
#1
Keaton Larson Lesnik, Hong Liu
The complex interactions that occur in mixed-species bioelectrochemical reactors, like microbial fuel cells (MFCs), make accurate predictions of performance outcomes under untested conditions difficult. While direct correlations between any individual waste stream characteristic or microbial community structure and reactor performance have not been able to be directly established, the increase in sequencing data and readily available computational power enables the development of alternate approaches. In the current study, 33 MFCs were evaluated under a range of conditions including 8 separate substrates and 3 different wastewaters...
August 16, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28810730/hydrogen-isotope-fractionation-during-biodegradation-of-1-2-dichloroethane-potential-for-pathway-identification-using-a-multi-element-c-cl-and-h-isotope-approach
#2
Jordi Palau, Orfan Shouakar-Stash, Siti Hatijah Mortan, Rong Yu, Monica Rosell, Ernest Marco-Urrea, David L Freedman, Ramon Aravena, Albert Soler, Daniel Hunkeler
Even though multi-element isotope fractionation patterns provide crucial information to identify contaminant degradation pathways in the field, those involving hydrogen are still lacking for many halogenated groundwater contaminants and degradation pathways. This study investigates for the first time hydrogen isotope fractionation during both aerobic and anaerobic biodegradation of 1,2-dichloroethane (1,2-DCA) using five microbial cultures. Transformation-associated isotope fractionation values (ε_bulk^H) were: -115 ± 18‰ (aerobic C-H bond oxidation), -34 ± 4‰ and -38 ± 4‰ (aerobic C-Cl bond cleavage via hydrolytic dehalogenation), -57 ± 3‰ and -77 ± 9‰ (anaerobic C-Cl bond cleavage via reductive dihaloelimination)...
August 16, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28763203/shallow-gas-migration-along-hydrocarbon-wells-an-unconsidered-anthropogenic-source-of-biogenic-methane-in-the-north-sea
#3
Lisa Vielstädte, Matthias Haeckel, Jens Karstens, Peter Linke, Mark Schmidt, Lea Steinle, Klaus Wallmann
Shallow gas migration along hydrocarbon wells constitutes a potential methane emission pathway that currently is not recognized in any regulatory framework or greenhouse gas inventory. Recently, the first methane emission measurements at three abandoned offshore wells in the Central North Sea (CNS) were conducted showing that considerable amounts of biogenic methane originating from shallow gas accumulations in the overburden of deep reservoirs were released by the boreholes. Here, we identify numerous wells poking through shallow gas pockets in 3-D seismic data of the CNS indicating that about one-third of the wells may leak, potentially releasing a total of 3-17 kt of methane per year into the North Sea...
August 16, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28753286/species-diversity-hinders-adaptation-to-toxicants
#4
Jeremias Martin Becker, Matthias Liess
Environmental toxicants such as pesticides exert strong selection pressure on many species. While the resulting development of pesticide resistance in agricultural pest species is well-known, reports on the extent of adaptation in exposed nontarget species are contradictory. These contradictory reports highlight a continuing challenge in understanding the relevant ecological mechanisms that facilitate or hinder adaptation to toxicants in the field. Here we show that species diversity hinders the adaptation to toxicants...
August 16, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28753284/exploring-the-role-of-persulfate-in-the-activation-process-radical-precursor-versus-electron-acceptor
#5
Eun-Tae Yun, Ha-Young Yoo, Hyokwan Bae, Hyoung-Il Kim, Jaesang Lee
This study elucidates the mechanism behind persulfate activation by exploring the role of various oxyanions (e.g., peroxymonosulfate, periodate, and peracetate) in two activation systems utilizing iron nanoparticle (nFe(0)) as the reducing agent and single-wall carbon nanotubes (CNTs) as electron transfer mediators. Since the tested oxyanions serve as both electron acceptors and radical precursors in most cases, oxidative degradation of organics was achievable through one-electron reduction of oxyanions on nFe(0) (leading to radical-induced oxidation) and electron transfer mediation from organics to oxyanions on CNTs (leading to oxidative decomposition involving no radical formation)...
August 16, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28745895/reactivity-of-triplet-excited-states-of-dissolved-natural-organic-matter-in-stormflow-from-mixed-use-watersheds
#6
Andrew J McCabe, William A Arnold
Dissolved organic matter (DOM) quantity and composition control the rate of formation (Rf,T) of triplet excited states of dissolved natural organic matter ((3)DOM*) and the efficiency of (3)DOM* formation (the apparent quantum yield, AQYT). Here, the reactivity of (3)DOM* in stormflow samples collected from watersheds with variable land covers is examined. Stormflow DOM reflects variability in DOM quantity and composition as a function of land cover and may be important in controlling the fate of cotransported pollutants...
August 16, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28727446/reductive-outer-sphere-single-electron-transfer-is-an-exception-rather-than-the-rule-in-natural-and-engineered-chlorinated-ethene-dehalogenation
#7
Benjamin Heckel, Stefan Cretnik, Sarah Kliegman, Orfan Shouakar-Stash, Kristopher McNeill, Martin Elsner
Chlorinated ethenes (CEs) such as perchloroethylene, trichloroethylene and dichloroethylene are notorious groundwater contaminants. Although reductive dehalogenation is key to their environmental and engineered degradation, underlying reaction mechanisms remain elusive. Outer-sphere reductive single electron transfer (OS-SET) has been proposed for such different processes as Vitamin B12-dependent biodegradation and zerovalent metal-mediated dehalogenation. Compound-specific isotope effect ((13)C/(12)C, (37)Cl/(35)Cl) analysis offers a new opportunity to test these hypotheses...
August 16, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28699742/quantitative-analysis-of-reactive-oxygen-species-photogenerated-on-metal-oxide-nanoparticles-and-their-bacteria-toxicity-the-role-of-superoxide-radicals
#8
Dan Wang, Lixia Zhao, Haiyan Ma, Hui Zhang, Liang-Hong Guo
Ecotoxicity of engineered nanoparticles (NPs) has become the focus of considerable attention because of their wide applications. Reactive oxygen species (ROS) play important roles in the toxicity mechanisms of engineered metal oxide NPs. This work aimed to understand quantitatively the contribution of photogenerated ROS on metal oxide NPs to their toxicity. The dynamic generation of O2(•-), (•)OH, and H2O2 in aqueous suspensions of photoilluminated metal oxide nano- and bulk particles (TiO2, ZnO, V2O5, CeO2, Fe2O3, and Al2O3) was measured by a continuous-flow chemiluminescence (CFCL) detection system...
August 16, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28809556/radical-chemistry-and-structural-relationships-of-ppcp-degradation-by-uv-chlorine-treatment-in-simulated-drinking-water
#9
Kaiheng Guo, Zihao Wu, Chii Shang, Bo Yao, Shaodong Hou, Xin Yang, Weihua Song, Jingyun Fang
The UV/chlorine process is an emerging advanced oxidation process (AOP) used for the degradation of micropollutants. However, the radical chemistry of this AOP is largely unknown for the degradation of numerous structurally diverse micropollutants in water matrices of varying quality. These issues were addressed by grouping 34 pharmaceuticals and personal care products (PPCPs) according to the radical chemistry of their degradation in the UV/chlorine process at practical PPCP concentrations (1 μg L-1) and in different water matrices...
August 15, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28809549/mesocosm-studies-on-the-efficacy-of-bioamended-activated-carbon-for-treating-pcb-impacted-sediment
#10
Rayford B Payne, Upal Ghosh, Harold Douglas May, Christopher W Marshall, Kevin R Sowers
This report describes results of a bench-scale treatability study to evaluate the efficacy of bioaugmentation with bioamended activated carbon (AC) for in-situ treatment of polychlorinated biphenyl (PCB) impacted sediments. To this end, the ability of PCB transforming microorganisms to degrade and reduce the overall concentration of PCBs in sediment was determined in 2 L recirculating mesocosms designed to simulate conditions in Abraham's Creek in Quantico, Virginia. Ten sediment mesocosms were tested for the effects of AC alone, AC with slow release electron donor (cellulose) and different concentrations and combinations of PCB dehalogenating and degrading microorganisms added as bioamendments...
August 15, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28809540/simplified-modeling-of-organic-contaminant-adsorption-by-activated-carbon-and-biochar-in-the-presence-of-dissolved-organic-matter-and-other-competing-adsorbates
#11
Kyle Koyu Shimabuku, Julian M Paige, Marisol Luna Agüero, R Scott Summers
Cyclohexanol, phenol, benzoic acid, and phenanthrene fractional removal (italicized words are defined within the main text) by pulverized granular activated carbon and biochar adsorption in deionized water and stormwater was independent of target-adsorbate initial concentrations (C0) when C0s were below concentration thresholds. This permits a simple-modeling approach. C0-independent removal in deionized water at low-target-adsorbate concentrations potentially suggests that DOM in the deionized water induce a competitive effect that causes deviations from the Freundlich model...
August 15, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28809480/rapid-life-cycle-impact-screening-using-artificial-neural-networks
#12
Runsheng Song, Arturo A Keller, Sangwon Suh
The number of chemicals in the market is rapidly increasing, while our understanding of the life-cycle impacts of these chemicals lags considerably. To address this, we developed deep Artificial Neural Network (ANN) models to estimate life-cycle impacts of chemicals. Using molecular structure information, we trained multilayer ANNs for life-cycle impacts of chemicals using six impact categories, including cumulative energy demand, global warming (IPCC 2007), acidification (TRACI), human health (Impact2000+), ecosystem quality (Impact2000+), and eco-indicator 99 (I,I, total)...
August 15, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28809115/an-intuitive-approach-for-predicting-potential-human-health-risk-with-the-tox21-10k-library
#13
Nisha S Sipes, John F Wambaugh, Robert Pearce, Scott S Auerbach, Barbara Anne Wetmore, Jui-Hua Hsieh, Andrew J Shapiro, Daniel Svoboda, Michael J DeVito, Stephen S Ferguson
In vitro-in vivo extrapolation (IVIVE) analyses translating high-throughput screening (HTS) data to human relevance have been limited. This study represents the first report applying IVIVE approaches and exposure comparisons using the entirety of the Tox21 federal collaboration chemical screening data, incorporating assay response efficacy and quality of concentration-response fits, and providing quantitative anchoring to first address the likelihood of human in vivo interactions with Tox21 compounds. This likelihood was assessed using a maximum blood concentration to in vitro response ratio approach (Cmax/AC50), analogous to decision-making methods for clinical drug-drug interactions...
August 15, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28749652/evaluating-benthic-recovery-decades-after-a-major-oil-spill-in-the-laurentian-great-lakes
#14
Karine Bertrand, Landis Hare
The long-term effects of oil spills on freshwater organisms have been little studied. In 1950, a large oil spill (10 million L) covered the harbor area of Parry Sound, Ontario, the deepest port in the Laurentian Great Lakes. Ecological impacts were not studied at the time, but 25 years later three-quarters of the Chironomus cucini larvae (Insecta, Diptera, Chironomidae) living in the harbor area were reported to be deformed. We returned six decades after the spill and found that the frequency of deformities had returned to background levels and that the community of burrowing invertebrates has largely recovered...
August 15, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28745506/structure-dependent-hematological-effects-of-per-and-polyfluoroalkyl-substances-on-activation-of-plasma-kallikrein-kinin-system-cascade
#15
Qian S Liu, Yuzhen Sun, Guangbo Qu, Yanmin Long, Xingchen Zhao, Aiqian Zhang, Qunfang Zhou, Ligang Hu, Guibin Jiang
Per- and polyfluoroalkyl substances (PFASs) are a global concern because of their ubiquitous occurrence and high persistence in human blood, and increasing amounts of unidentified fluorinated compounds are now becoming new exposure issues. This study aims to investigate the structure-related effects of PFASs on the activation of the plasma kallikrein-kinin system (KKS). The effects of 20 PFASs and the related long-chain aliphatic compounds were screened, and their binding affinities for the initial zymogen, Hagmen factor XII (FXII) in the KKS, were evaluated by molecular docking analysis...
August 15, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28806506/quantifying-recycling-and-losses-of-cr-and-ni-in-steel-throughout-multiple-life-cycles-using-matrace-alloy
#16
Shinichiro Nakamura, Yasushi Kondo, Kenichi Nakajima, Hajime Ohno, Stefan Pauliuk
Alloying metals are indispensable ingredients of high quality alloy steel such as austenitic stainless steel, the cyclical use of which is vital for sustainable resource management. Under the current practice of recycling, however, different metals are likely to be mixed in an uncontrolled manner, resulting in function losses and dissipation of metals with distinctive functions, and in the contamination of recycled steels. The latter could result in dilution loss, if metal scrap needed dilution with virgin iron to reduce the contamination below critical levels...
August 14, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28806081/chlorination-kinetics-of-11-nor-9-carboxy-%C3%AE-9-tetrahydrocannabinol-effects-of-ph-and-humic-acid
#17
Allison L Mackie, Yuri Park, Graham A Gagnon
The main psychoactive compound in marijuana, Δ9-tetrahydrocannabinol (THC), and its metabolites are emerging organic contaminants that have been detected in waste and surface waters. As legalization of marijuana for medical and recreational use continues, the effects of increased use and potency of marijuana on water and wastewater treatment processes and the environment should be considered. This study examined degradation kinetics of the main urinary metabolite of THC, 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH) with chlorine...
August 14, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28806073/transformation-among-aromatic-iodinated-disinfection-byproducts-in-the-presence-of-monochloramine-from-monoiodophenol-to-triiodophenol-and-diiodonitrophenol
#18
Tingting Gong, Yuxian Tao, Xiangru Zhang, Shaoyang Hu, Jinbao Yin, Qiming Xian, Jian Ma, Bin Xu
Aromatic iodinated disinfection byproducts (DBPs) are a newly identified category of highly toxic DBPs. Among the identified aromatic iodinated DBPs, 2,4,6-triiodophenol and 2,6-diiodo-4-nitro- phenol have shown relatively widespread occurrence and high toxicity. In this study, we found that 4-iodophenol underwent transformation to form 2,4,6-triiodophenol and 2,6-diiodo-4-nitrophenol in the presence of monochloramine. The transformation pathways were investigated, the decomposition kinetics of 4-iodophenol and the formation of 2,4,6-triiodophenol and 2,6-diiodo-4-nitrophenol were studied, the factors affecting the transformation were examined, the toxicity change during the transformation was evaluated, and the occurrence of the proposed transformation pathways during chloramination of source water was verified...
August 14, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28806072/modeling-of-the-passive-permeation-of-mercury-and-methylmercury-complexes-through-a-bacterial-cytoplasmic-membrane
#19
Jing Zhou, Micholas Dean Smith, Sarah J Cooper, Xiaolin Cheng, Jeremy C Smith, Jerry M Parks
Cellular uptake and export are important steps in the biotransformation of mercury (Hg) by microorganisms. However, the mechanisms of transport across biological membranes remain unclear. Membrane-bound transporters are known to be relevant, but passive permeation may also be involved. Inorganic Hg(II) and methylmercury ([CH3Hg]+) are commonly complexed with thiolate ligands. Here, we have performed extensive molecular dynamics simulations of the passive permeation of Hg(II) and [CH3Hg]+ complexes with thiolate ligands through a model bacterial cytoplasmic membrane...
August 14, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28806071/contrasting-effects-of-dissolved-organic-matter-on-mercury-methylation-by-g-sulfurreducens-pca-and-d-desulfuricans-nd132
#20
Linduo Zhao, Hongmei Chen, Xia Lu, Hui Lin, Geoff A Christensen, Eric M Pierce, Baohua Gu
Natural dissolved organic matter (DOM) affects mercury (Hg) redox reactions and anaerobic microbial Hg methylation in the environment. Several studies have shown that DOM can enhance Hg methylation, especially under sulfidic conditions, whereas others show that DOM inhibits Hg methylation due to strong Hg-DOM complexation. In this study, we investigated and compared the effects of DOM on Hg methylation by an iron-reducing bacterium Geobacter sulfurreducens PCA and a sulfate-reducing bacterium Desulfovibrio desulfuricans ND132 under non-sulfidic conditions...
August 14, 2017: Environmental Science & Technology
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