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Environmental Science. Processes & Impacts

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https://www.readbyqxmd.com/read/28234392/prediction-of-acute-toxicity-of-emerging-contaminants-on-the-water-flea-daphnia-magna-by-ant-colony-optimization-support-vector-machine-qstr-models
#1
Reza Aalizadeh, Peter C von der Ohe, Nikolaos S Thomaidis
According to the European REACH Directive, the acute toxicity towards Daphnia magna should be assessed for any industrial chemical with a market volume of more than 1 t/a. Therefore, it is highly recommended to determine the toxicity at a certain confidence level, either experimentally or by applying reliable prediction models. To this end, a large dataset was compiled, with the experimental acute toxicity values (pLC50) of 1353 compounds in Daphnia magna after 48 h of exposure. A novel quantitative structure-toxicity relationship (QSTR) model was developed, using Ant Colony Optimization (ACO) to select the most relevant set of molecular descriptors, and Support Vector Machine (SVM) to correlate the selected descriptors with the toxicity data...
February 24, 2017: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/28233005/a-strategic-screening-approach-to-identify-transformation-products-of-organic-micropollutants-formed-in-natural-waters
#2
Zhe Li, Sarit L Kaserzon, Merle M Plassmann, Anna Sobek, María José Gómez Ramos, Michael Radke
Many transformation products (TPs) from organic micropollutants are not included in routine environmental monitoring programs due to limited knowledge of their occurrence and fate. An efficient method to identify and prioritize critical compounds in terms of environmental relevance is needed. In this study, we applied a strategic screening approach based on a case-control concept to identify TPs formed along wastewater-impacted rivers. Time-integrated samples were collected over one week at both ends of a river stretch downstream of a wastewater treatment plant (WWTP) outfall and were analyzed by ultrahigh performance liquid chromatography interfaced with quadrupole time-of-flight mass spectrometry (UHPLC-QToF-MS/MS)...
February 24, 2017: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/28229155/sulfate-radical-oxidation-of-aromatic-contaminants-a-detailed-assessment-of-density-functional-theory-and-high-level-quantum-chemical-methods
#3
Sangavi Pari, Inger A Wang, Haizhou Liu, Bryan M Wong
Advanced oxidation processes that utilize highly oxidative radicals are widely used in water reuse treatment. In recent years, the application of sulfate radical (SO4˙(-)) as a promising oxidant for water treatment has gained increasing attention. To understand the efficiency of SO4˙(-) in the degradation of organic contaminants in wastewater effluent, it is important to be able to predict the reaction kinetics of various SO4˙(-)-driven oxidation reactions. In this study, we utilize density functional theory (DFT) and high-level wavefunction-based methods (including computationally-intensive coupled cluster methods), to explore the activation energies of SO4˙(-)-driven oxidation reactions on a series of benzene-derived contaminants...
February 23, 2017: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/28229145/oxidation-potentials-of-phenols-and-anilines-correlation-analysis-of-electrochemical-and-theoretical-values
#4
Ania S Pavitt, Eric J Bylaska, Paul G Tratnyek
Phenols and anilines have been studied extensively as reductants of environmental oxidants (such as manganese dioxide) and as reductates (e.g., model contaminants) that are transformed by environmental oxidants (ozone, triple organic matter, etc.). The thermodynamics and kinetics of these reactions have been interpreted using oxidation potentials for substituted phenols and anilines, often using a legacy experimental dataset that is of uncertain quality. Although there are many alternative oxidation potential data, there has been little systematic analysis of the relevance, reliability, and consistency of the data obtained by different methods...
February 23, 2017: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/28229138/eawag-soil-in-envipath-a-new-resource-for-exploring-regulatory-pesticide-soil-biodegradation-pathways-and-half-life-data
#5
Diogo A R S Latino, Jörg Wicker, Martin Gütlein, Emanuel Schmid, Stefan Kramer, Kathrin Fenner
Developing models for the prediction of microbial biotransformation pathways and half-lives of trace organic contaminants in different environments requires as training data easily accessible and sufficiently large collections of respective biotransformation data that are annotated with metadata on study conditions. Here, we present the Eawag-Soil package, a public database that has been developed to contain all freely accessible regulatory data on pesticide degradation in laboratory soil simulation studies for pesticides registered in the EU (282 degradation pathways, 1535 reactions, 1619 compounds and 4716 biotransformation half-life values with corresponding metadata on study conditions)...
February 23, 2017: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/28224154/unexpectedly-high-concentrations-of-monoterpenes-in-a-study-of-uk-homes
#6
Chunting Michelle Wang, Benjamin Barratt, Nicola Carslaw, Artemis Doutsi, Rachel E Dunmore, Martyn W Ward, Alastair C Lewis
The abundance of volatile organic compounds (VOCs) found in homes depends on many factors such as emissions, ventilation and the oxidative environment and these are evolving over time, reflecting changes in chemical use, behaviour and building design/materials. The concentrations of VOCs in 25 UK homes of varying ages, design and occupancy were quantified using continuous indoor air sampling over five days. Air was collected through low flow (1 mL min(-1)) constant flow restrictors into evacuated 6 L internally silica-treated canisters until the canisters reached atmospheric pressure...
February 22, 2017: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/28218330/predicting-the-phospholipophilicity-of-monoprotic-positively-charged-amines
#7
S T J Droge, J L M Hermens, S Gutsell, J Rabone, G Hodges
The sorption affinity of eighty-six charged amine structures to phospholipid monolayers (log KIAM) was determined using immobilized artificial membrane high-performance liquid chromatography (IAM-HPLC). The amine compounds covered the most prevalent types of polar groups, widely ranged in structural complexity, and included forty-seven pharmaceuticals, as well as several narcotics and pesticides. Amine type specific corrective increments were used to align log KIAM data with bilayer membrane sorption coefficients (KMW(IAM))...
February 20, 2017: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/28203672/sources-and-fate-of-high-levels-of-ammonium-in-surface-water-and-shallow-groundwater-of-the-jianghan-plain-central-china
#8
Yao Du, Teng Ma, Yamin Deng, Shuai Shen, Zongjie Lu
High levels of ammonium from anthropogenic sources threaten the quality of surface waters and groundwaters in some areas worldwide, but elevated ammonium levels of natural sources also have been identified. High levels of ammonium have been detected in both surface water and shallow groundwater of the Jianghan Plain, an alluvial plain of the Yangtze River. This study used N isotopes coupled with ancillary chemistry to identify ammonium in this region. Ammonium in the Tongshun River (up to 10.25 mg L(-1)) showed a sharp accumulation in the upstream and gradual attenuation in the downstream...
February 16, 2017: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/28197603/general-baseline-toxicity-qsar-for-nonpolar-polar-and-ionisable-chemicals-and-their-mixtures-in-the-bioluminescence-inhibition-assay-with-aliivibrio-fischeri
#9
Beate I Escher, Andreas Baumer, Kai Bittermann, Luise Henneberger, Maria König, Christin Kühnert, Nils Klüver
The Microtox assay, a bioluminescence inhibition assay with the marine bacterium Aliivibrio fischeri, is one of the most popular bioassays for assessing the cytotoxicity of organic chemicals, mixtures and environmental samples. Most environmental chemicals act as baseline toxicants in this short-term screening assay, which is typically run with only 30 min of exposure duration. Numerous Quantitative Structure-Activity Relationships (QSARs) exist for the Microtox assay for nonpolar and polar narcosis. However, typical water pollutants, which have highly diverse structures covering a wide range of hydrophobicity and speciation from neutral to anionic and cationic, are often outside the applicability domain of these QSARs...
February 15, 2017: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/28191571/a-computer-based-prediction-platform-for-the-reaction-of-ozone-with-organic-compounds-in-aqueous-solution-kinetics-and-mechanisms
#10
Minju Lee, Lorenz C Blum, Emanuel Schmid, Kathrin Fenner, Urs von Gunten
Ozonation of secondary wastewater effluents can reduce the discharge of micropollutants by transforming their chemical structures. Therefore, a better understanding of the formation of transformation products during ozonation is important. In this study, a computer-based prediction platform for the kinetics and mechanisms of the reactions of ozone with organic compounds was developed to enable in silico predictions of transformation products. With the developed prediction platform, reaction kinetics expressed as second-order rate constants for the reactions of ozone with selected organic compounds (kO3, M(-1) s(-1)) can be predicted based on an adapted kO3 prediction model from a previous study (Lee et al...
February 13, 2017: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/28186521/diverging-effects-of-isotopic-fractionation-upon-molecular-diffusion-of-noble-gases-in-water-mechanistic-insights-through-ab-initio-molecular-dynamics-simulations
#11
Halua Pinto de Magalhães, Matthias S Brennwald, Rolf Kipfer
Atmospheric noble gases are routinely used as natural tracers to analyze gas transfer processes in aquatic systems. Their isotopic ratios can be employed to discriminate between different physical transport mechanisms by comparison to the unfractionated atmospheric isotope composition. In many applications of aquatic systems molecular diffusion was thought to cause a mass dependent fractionation of noble gases and their isotopes according to the square root ratio of their masses. However, recent experiments focusing on isotopic fractionation within a single element challenged this broadly accepted assumption...
February 10, 2017: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/28165522/classification-of-baseline-toxicants-for-qsar-predictions-to-replace-fish-acute-toxicity-studies
#12
Monika Nendza, Martin Müller, Andrea Wenzel
Fish acute toxicity studies are required for environmental hazard and risk assessment of chemicals by national and international legislations such as REACH, the regulations of plant protection products and biocidal products, or the GHS (globally harmonised system) for classification and labelling of chemicals. Alternative methods like QSARs (quantitative structure-activity relationships) can replace many ecotoxicity tests. However, complete substitution of in vivo animal tests by in silico methods may not be realistic...
February 6, 2017: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/28165516/the-degradation-mechanism-of-sulfamethoxazole-under-ozonation-a-dft-study
#13
Hang Yu, Pu Ge, Jingwen Chen, Hongbin Xie, Yi Luo
Sulfamethoxazole (SMX), a kind of antibiotic, remains in the environment and threatens public health. Ozone as a strong and green oxidant was widely used for selective oxidation degradation of residual SMX. However, it is hard to elucidate the detailed oxidation mechanism through current experimental approaches. A theoretical study has been carried out herein for exploring possible ozonation pathways of SMX. Two reaction mechanisms, viz., direct addition (DA) and H atom transfer (HAT), are considered. The results show that the primary oxidation of aromatic rings (benzene or isoxazole rings) of SMX follows the DA mechanism, featuring an electrophilic addition...
February 6, 2017: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/28165513/linear-free-energy-relationships-for-the-adsorption-of-volatile-organic-compounds-onto-multiwalled-carbon-nanotubes-at-different-relative-humidities-comparison-with-organoclays-and-activated-carbon
#14
Mei-Syue Li, Reuben Wang, Dave Ta Fu Kuo, Yang-Hsin Shih
Accurate prediction of the sorption coefficients of volatile organic compounds (VOCs) on carbon nanotubes (CNTs) is of major importance for developing an effective VOC removal process and risk assessment of released nanomaterial-carrying contaminants. The linear free energy relationship (LFER) approach was applied to investigate the adsorption mechanisms of VOCs on multiwalled CNTs (MWCNTs). The gas-solid partition coefficients (log Kd) of 17 VOCs were determined at 0%, 55%, and 90% relative humidity (RH)...
February 6, 2017: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/28155951/quantifying-the-equilibrium-partitioning-of-substituted-polycyclic-aromatic-hydrocarbons-in-aerosols-and-clouds-using-cosmotherm
#15
Boluwatife Awonaike, Chen Wang, Kai-Uwe Goss, Frank Wania
Functional groups attached to polycyclic aromatic hydrocarbons (PAHs) can significantly modify the environmental fate of the parent compound. Equilibrium partition coefficients, which are essential for describing the environmental phase distribution of a compound, are largely unavailable for substituted PAHs (SPAHs). Here, COSMOtherm, a software based on quantum-chemical calculations is used to estimate the atmospherically relevant partition coefficients between the gas phase, the aqueous bulk phase, the water surface and the water insoluble organic matter phase, as well as the salting-out coefficients, for naphthalene, anthracene, phenanthrene, benz(a)anthracene, benzo(a)pyrene and dibenz(a,h)anthracene and 62 of their substituted counterparts...
February 3, 2017: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/28154864/development-of-polyparameter-linear-free-energy-relationship-models-for-octanol-air-partition-coefficients-of-diverse-chemicals
#16
Xiaochen Jin, Zhiqiang Fu, Xuehua Li, Jingwen Chen
The octanol-air partition coefficient (KOA) is a key parameter describing the partition behavior of organic chemicals between air and environmental organic phases. As the experimental determination of KOA is costly, time-consuming and sometimes limited by the availability of authentic chemical standards for the compounds to be determined, it becomes necessary to develop credible predictive models for KOA. In this study, a polyparameter linear free energy relationship (pp-LFER) model for predicting KOA at 298...
February 3, 2017: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/28149995/trophic-transfer-of-hexabromocyclododecane-in-the-terrestrial-and-aquatic-food-webs-from-an-e-waste-dismantling-region-in-east-china
#17
Chaofei Zhu, Pu Wang, Yingming Li, Zhaojing Chen, Honghua Li, Patrick Ssebugere, Qinghua Zhang, Guibin Jiang
Trophic transfer of hexabromocyclododecane (HBCD) was investigated in both the terrestrial and aquatic food webs from an e-waste dismantling region in East China. The mean Σ3HBCD concentrations in the terrestrial species varied from 0.91 (0.16-1.85) ng g(-1) lipid weight (lw) in dragonflies (Pantala flavescens) to 40.3 (22.1-51.1) ng g(-1) lw in rats (Rattus norvegicus). The isomeric profile indicated that α-HBCD presented a decreasing trend along the trophic level (TL) (from 97.2% to 16.3% of Σ3HBCDs), while γ-HBCD showed a reverse trend (from 2...
February 2, 2017: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/28094829/news-from-environmental-science-processes-impacts
#18
EDITORIAL
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January 17, 2017: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/28094827/meet-the-editorial-board
#19
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January 17, 2017: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/28091681/microbial-rrna-sequencing-analysis-of-evaporative-cooler-indoor-environments-located-in-the-great-basin-desert-region-of-the-united-states
#20
Angela R Lemons, Mary Beth Hogan, Ruth A Gault, Kathleen Holland, Edward Sobek, Kimberly A Olsen-Wilson, Yeonmi Park, Ju-Hyeong Park, Ja Kook Gu, Michael L Kashon, Brett J Green
Recent studies conducted in the Great Basin Desert region of the United States have shown that skin test reactivity to fungal and dust mite allergens are increased in children with asthma or allergy living in homes with evaporative coolers (EC). The objective of this study was to determine if the increased humidity previously reported in EC homes leads to varying microbial populations compared to homes with air conditioners (AC). Children with physician-diagnosed allergic rhinitis living in EC or AC environments were recruited into the study...
January 16, 2017: Environmental Science. Processes & Impacts
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