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quantum yield of contaminant

Thanh Hoai Tran, Einav Mayzlish Gati, Amram Eshel, Gidon Winters
Along the arid Arava, southern Israel, acacia trees (Acacia raddiana and Acacia tortilis) are considered keystone species. Yet they are threatened by the ongoing aquifer depletion for agriculture, the conversion of natural land to agricultural land, seed infestation by bruchid beetles, and the reduction in precipitation level in the region. In the acacia dominated Evrona reserve (southern Arava), adding to these threats are recurrent oil spills from an underground pipeline. We report here a study of the effects of contaminated soils, from a recent (December 2014) and a much older (1975) oil spills...
December 7, 2017: Environmental Pollution
Yang-Er Chen, Hao-Tian Mao, Jie Ma, Nan Wu, Chao-Ming Zhang, Yan-Qiu Su, Zhong-Wei Zhang, Ming Yuan, Huai-Yu Zhang, Xian-Yin Zeng, Shu Yuan
We systematically compared the impacts of four Cr salts (chromic chloride, chromic nitrate, potassium chromate and potassium bichromate) on physiological parameters and chlorophyll fluorescence in indigenous moss Taxiphyllum taxirameum. Among the four Cr salts, K2Cr2O7 treatment resulted in the most significant decrease in photosynthetic efficiency and antioxidant enzymes, increase in reactive oxygen species (ROS), and obvious cell death. Different form the higher plants, although hexavalent Cr(VI) salt treatments resulted in higher accumulation levels of Cr and were more toxic than Cr(III) salts, Cr(III) also induced significant changes in moss physiological parameters and chlorophyll fluorescence...
December 1, 2017: Chemosphere
Ľubica Vetráková, Vít Ladányi, Jamaludin Al Anshori, Pavel Dvořák, Jakob Wirz, Dominik Heger
Azobenzene is a prototypical photochromic molecule existing in two isomeric forms, which has numerous photochemical applications that rely on a precise knowledge of the molar absorption coefficients (ε). Careful analysis revealed that the previously reported absorption spectra of the "pure" isomers were in fact mutually contaminated by small amounts of the other isomer. Therefore, the absorption spectra of both trans- and cis-azobenzene in methanol were re-determined at temperatures of 5-45 °C. The thermodynamically more stable trans-azobenzene was prepared by warming the solution in the dark...
November 24, 2017: Photochemical & Photobiological Sciences
Keer Yu, Xuchun Li, Liwei Chen, Jingyun Fang, Huali Chen, Qiangbiao Li, Nianping Chi, Jun Ma
Advanced reduction by the extremely strong reducing species, hydrated electron (eaq(-)), is a promising and viable approach to eliminate a wide variety of persistent and toxic contaminants. In this study, we proposed a sulfite/iodide/UV process, which offered efficient production of eaq(-) for contaminant reduction. Using monochloroacetic acid (MCAA) as a simple eaq(-) probe, the availability of eaq(-) was assessed, and the mechanism involving the roles of S(IV) and iodide in the process was elucidated. A pronounced synergistic effect of S(IV) and iodide was observed in MCAA reductive dechlorination...
November 15, 2017: Water Research
Meiquan Cai, Peizhe Sun, Liqiu Zhang, Ching-Hua Huang
Peracetic acid (PAA) is a widely used disinfectant, and combined UV light with PAA (i.e. UV/PAA) can be a novel advanced oxidation process for elimination of water contaminants. This study is among the first to evaluate the photolysis of PAA under UV irradiation (254 nm) and degradation of pharmaceuticals by UV/PAA. PAA exhibited high quantum yields (Φ254nm = 1.20 and 2.09 mol·Einstein-1 for the neutral (PAA0) and anionic (PAA-) species, respectively) and also showed scavenging effects on hydroxyl radicals (k•OH/PAA0 = (9...
November 17, 2017: Environmental Science & Technology
Yi-Hsueh Chuang, Serena Chen, Curtis J Chinn, William A Mitch
Utilities incorporating the potable reuse of municipal wastewater are interested in converting from the UV/H2O2 to the UV/free chlorine advanced oxidation process (AOP). The AOP treatment of reverse osmosis (RO) permeate often includes the de facto UV/chloramine AOP because chloramines applied upstream permeate RO membranes. Models are needed that accurately predict oxidant photolysis and subsequent radical reactions. By combining radical scavengers and kinetic modeling, we have derived quantum yields for radical generation by the UV photolysis of HOCl, OCl(-), and NH2Cl of 0...
November 22, 2017: Environmental Science & Technology
Xiaoji Fan, Jiahui Xu, Michel Lavoie, W J G M Peijnenburg, Youchao Zhu, Tao Lu, Zhengwei Fu, Tingheng Zhu, Haifeng Qian
Carbon nanotubes can be either toxic or beneficial to plant growth and can also modulate toxicity of organic contaminants through surface sorption. The complex interacting toxic effects of carbon nanotubes and organic contaminants in plants have received little attention in the literature to date. In this study, the toxicity of multiwall carbon nanotubes (MWCNT, 50 mg/L) and paraquat (MV, 0.82 mg/L), separately or in combination, were evaluated at the physiological and the proteomic level in Arabidopsis thaliana for 7-14 days...
November 3, 2017: Environmental Pollution
Daniel Beckett, Marc Edelmann, Jonathan D Raff, Krishnan Raghavachari
Nitroxyl (HNO) and hydrogen peroxide have both been implicated in a variety of reactions relevant to environmental and physiological processes and may contribute to a unique, unexplored, pathway for the production of nitrous acid (HONO) in soil. To investigate the potential for this reaction, we report an in-depth investigation of the reaction pathway of H2O2 and HNO forming HONO and water. We find the breaking of the peroxide bond and a coupled proton transfer in the first step leads to hydrogen nitryl (HNO2) and an endogenous water, with an extrapolated NEVPT2 (multireference perturbation theory) barrier of 29...
November 8, 2017: Physical Chemistry Chemical Physics: PCCP
Dingdong Liu, Huijun Liu, Shengtao Wang, Jiazheng Chen, Yilu Xia
Although ionic liquids (ILs) are unlikely to act as air contaminants, their high solubility and slow degradation make them a potential threat to the aquatic environment. The IL 1-decylpyridinium bromide ([DPy]Br) is a common type of pyridine IL, which has varied applications such as in extraction, separation, and catalytic synthesis. Herein, the toxicity of [DPy]Br to S. obliquus is determined. Growth was inhibited by high-concentration [DPy]Br, whereas it had a hormetic effect at low concentrations. The IC50-96h was approximately 0...
October 18, 2017: Science of the Total Environment
Élise Smedbol, Marc Lucotte, Michel Labrecque, Laurent Lepage, Philippe Juneau
The use of glyphosate-based herbicides in agriculture has increased steadily since the mid 90's and there is now evidence of glyphosate leaching and contamination of aquatic ecosystems. The aim of this study was to evaluate the effects of a glyphosate-based herbicide (Factor 540(®)) on growth and photosynthetic capacity of algae and cyanobacteria. Six algal and three cyanobacterial species/strains, of three different taxonomic groups, were exposed to five glyphosate concentrations (10, 50, 100, 500 and 1000μgl(-1)) during 48h...
September 28, 2017: Aquatic Toxicology
John Mumbo, Dominik Deyerling, Bernhard Henkelmann, Gerd Pfister, Karl-Werner Schramm
Bromocarbazoles and chlorocarbazoles are emerging environmental contaminants that have been reported to be persistent and possessing dioxin-like toxicity; however, their photodegradative fate in water is unknown. The photodegradation of 3-bromocarbazole, 3-chlorocarbazole, and 3,6-dichlorocarbazole was determined in ultrapure water. They proceeded by direct photolysis and followed first-order kinetics. The rate constants (k) were 0.4838, 0.3454, and 0.4422 h(-1) corresponding to half-lives (t 1/2) 1.81, 2...
October 5, 2017: Environmental Science and Pollution Research International
Li Wang, Gang Wang, Congdi Shang, Rui Kang, Yu Fang
A naphthalimide-based low-molecular-mass fluorophore (NA) was designed and synthesized by introducing an azetidine unit onto the aromatic ring of the compound as an electron-donating structure, and a hydrophilic (2-(2-aminoethyl-amino)ethanol) moiety into the "N-imide site" of the core structure. UV-vis absorption and fluorescence measurements revealed that the fluorophore is soluble in water and shows a fluorescent quantum yield of ∼20% and lifetime of ∼3.7 ns in the solvent within a wide pH range. Moreover, the fluorescence emission and anisotropy of the fluorophore as produced are both dependent upon the viscosity and polarity of the medium...
October 11, 2017: ACS Applied Materials & Interfaces
Dorota Jarmużek, Tomasz Pedzinski, Marcin Hoffmann, Tomasz Siodła, Kinga Salus, Donata Pluskota-Karwatka
Fluvastatin (FLV) belongs to the group of compounds referred to as statins, also known as 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors. Statins act as cholesterol-lowering agents and are among the most frequently prescribed drugs. They upregulate low-density lipoprotein receptors in the liver by binding to the active site of HMG-CoA reductase, which is the key enzyme in cholesterol biosynthesis. Statins have been detected as contaminants in natural waters and are susceptible to degradation upon exposure to light...
August 23, 2017: Physical Chemistry Chemical Physics: PCCP
Marcela Prado Silva, Arlen Mabel Lastre-Acosta, Simón Mostafa, Garrett McKay, Karl G Linden, Fernando L Rosario-Ortiz, Antonio Carlos Silva Costa Teixeira
Singlet oxygen ((1)O2), hydroxyl radicals ((•)OH), and excited triplet states of organic matter ((3)OM(*)) play a key role in the degradation of pollutants in aquatic environments. The formation rates and quantum yields (Φ) of these reactive intermediates (RI) through photosensitized reactions of dissolved organic matter (DOM) have been reported in the literature for decades. Urban biowaste-derived substances (UW-BOS), a form of organic matter derived from vegetative and urban waste, have recently been shown to be efficient sensitizers in the photo-degradation of different contaminants...
June 23, 2017: Environmental Science and Pollution Research International
Jason L J Dearling, Alan B Packard
BACKGROUND: Measurement of trace metal contamination is critical in the production of radiometals, such as 64Cu, for protein labeling. ICP-MS provides these data with high sensitivity and high specificity, but at high (instrument) cost. TETA (1,4,8,11-tetraazacyclotetradecane-1,4,8,11- tetraacetic acid) titration provides high sensitivity at low cost but with low specificity. A method that allowed the measurement of trace metals with high sensitivity but also at relatively low cost would, therefore, be very useful in the development of new radiometal production methods...
2017: Current Radiopharmaceuticals
Andrew C Maizel, Christina K Remucal
The photochemical production of reactive species, such as triplet dissolved organic matter ((3)DOM) and singlet oxygen ((1)O2), contributes to the degradation of aquatic contaminants and is related to an array of DOM structural characteristics, notably molecular weight. In order to relate DOM molecular weight, optical properties, and reactive species production, Suwannee River (SRFA) and Pony Lake fulvic acid (PLFA) isolates are fractionated by sequential ultrafiltration, and the resultant fractions are evaluated in terms of molecular composition and photochemical reactivity...
February 21, 2017: Environmental Science & Technology
Noël J Diepens, Evelyne Buffan-Dubau, Hélène Budzinski, Jean Kallerhoff, Georges Merlina, Jérome Silvestre, Isabelle Auby, Nathalie Tapie, Arnaud Elger
Worldwide seagrass declines have been observed due to multiple stressors. One of them is the mixture of pesticides used in intensive agriculture and boat antifouling paints in coastal areas. Effects of mixture toxicity are complex and poorly understood. However, consideration of mixture toxicity is more realistic and ecologically relevant for environmental risk assessment (ERA). The first aim of this study was to determine short-term effects of realistic herbicide mixture exposure on physiological endpoints of Zostera noltei...
March 2017: Environmental Pollution
Sadegh Askari, Atta Ul Haq, Manuel Macias-Montero, Igor Levchenko, Fengjiao Yu, Wuzong Zhou, Kostya Ken Ostrikov, Paul Maguire, Vladimir Svrcek, Davide Mariotti
Highly size-controllable synthesis of free-standing perfectly crystalline silicon carbide nanocrystals has been achieved for the first time through a plasma-based bottom-up process. This low-cost, scalable, ligand-free atmospheric pressure technique allows fabrication of ultra-small (down to 1.5 nm) nanocrystals with very low level of surface contamination, leading to fundamental insights into optical properties of the nanocrystals. This is also confirmed by their exceptional photoluminescence emission yield enhanced by more than 5 times by reducing the nanocrystals sizes in the range of 1-5 nm, which is attributed to quantum confinement in ultra-small nanocrystals...
October 6, 2016: Nanoscale
Jinhua Zhang, Jie Wang, Jia Feng, Junping Lv, Jin Cai, Qi Liu, Shulian Xie
1,4-Dichlorobenzene (1,4-DCB) is a common organic contaminant in water. To determine the effects of this contaminant on photosynthesis in the freshwater alga Chlorella pyrenoidosa, algal cells were treated with 1,4-DCB at different concentrations for various times, and their photosynthetic pigment contents and chlorophyll fluorescence traits were analyzed. The results showed that 1,4-DCB exerted toxic effects on photosynthesis in C. pyrenoidosa, especially at concentrations exceeding 10 mg/L. The inhibitory effects of 1,4-DCB were time- and concentration-dependent...
September 2016: Environmental Monitoring and Assessment
R K Dutta, Ambika Kumar
Detection of ultratrace levels of aqueous uranyl ions without using sophisticated analytical instrumentation and a tedious sample preparation method is a challenge for environmental monitoring and mitigation. Here we present a novel yet simple analytical method for highly sensitive and specific detection of uranyl ions via photoluminescence quenching of CdS quantum dots. We have demonstrated a new approach for synthesizing highly water-soluble and strong photoluminescence-emitting CdS quantum dots (i.e., CdS-MAA and CdS-MAA-TU) of sizes less than 3 nm...
September 20, 2016: Analytical Chemistry
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