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Photochemical processing of aldrin and dieldrin in frozen aqueous solutions under arctic field conditions 总被引:1,自引:0,他引:1
Rowland GA Bausch AR Grannas AM 《Environmental pollution (Barking, Essex : 1987)》2011,159(5):1076-1084
Organochlorine (OC) contaminants are transported to the Polar Regions, where they have the potential to bioaccumulate, presenting a threat to the health of wildlife and indigenous communities. They deposit onto snowpack during winter, and accumulate until spring, when they experience prolonged solar irradiation until snowmelt occurs. Photochemical degradation rates for aldrin and dieldrin, in frozen aqueous solution made from MilliQ water, 500 μM hydrogen peroxide solution or locally-collected melted snow were measured in a field campaign near Barrow, AK, during spring-summer 2008. Significant photoprocessing of both pesticides occurs; the reactions depend on temperature, depth within the snowpack and whether the predominant phase is ice or liquid water. The effect of species present in natural snowpack is comparable to 500 μM hydrogen peroxide, pointing to the potential significance of snowpack-mediated reactions. Aldrin samples frozen at near 0 °C were more reactive than comparable liquid samples, implying that the microenvironments experienced on frozen ice surfaces are an important consideration. 相似文献
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Photoexcitation of complexes between cyclophane 1 and 1- or 2-chloronaphthalene in aqueous solution leads to rapid dechlorination of the guest, a reaction driven by electron transfer from host to excited guest. The main photoproducts contain a naphthyl group covalently attached to the host framework. The results may lead to new approaches for remediating water contaminated with chlorinated aromatic compounds. 相似文献
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We have performed the photolysis of 2‐methyloxy‐, 2‐ethyloxy‐, 2‐propyloxy‐, 2‐isopropyloxy‐, 2‐(l‐methylbutyl)oxy‐, 2‐cyclohexyloxy‐ and 2‐propargyloxybenzothiazole derivatives. We have studied the influence of polarity of the solvent and presence or absence of oxygen on the course of their photochemical transformations. In general it can be concluded that the cleavage of the substituent‐oxygen bonds occurs preferentially, whereby the main product was identified in most cases to be 2‐benzothiazolinone. The rate of photolysis and the composition of the reaction mixture was dependent upon the presence or absence of oxygen. Photoreactivity of above benzo‐thiazole derivatives was also strongly dependent on the structure of the substituents in the position 2. 相似文献
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Swapan Khanra Claudio Minero Valter Maurino Ezio Pelizzetti Binay K. Dutta Davide Vione 《Environmental Chemistry Letters》2008,6(1):29-34
Here we show that the photolysis of FeCl2+ upon UV irradiation of Fe(III) at pH 0.5, yielding Cl• and then Cl2−•, upon further reaction with Cl−, induces phenol degradation. The photolysis of FeCl2+ can be highlighted and studied as the huge interference by FeOH2+ can be avoided under such conditions. Our data allowed the assessment of a photolysis quantum yield for FeCl2+ of 5.8 × 10−4 under UVA irradiation, much lower compared to the literature value of 0.5. The discrepancy can be explained if the photolysis
process is efficient but photoformed Fe2+ and Cl• undergo recombination inside the solvent cage. 相似文献
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Salah Eddine Sbai Chunlin Li Antoinette Boreave Nicolas Charbonnel Sebastien Perrier Philippe Vernoux Farida Bentaye Christian George Sonia Gil 《环境科学学报(英文版)》2021,33(1):311-323
Photochemical aging of volatile organic compounds (VOCs) in the atmosphere is an important source of secondary organic aerosol (SOA). To evaluate the formation potential of SOA at an urban site in Lyon (France), an outdoor experiment using a Potential Aerosol Mass (PAM) oxidation flow reactor (OFR) was conducted throughout entire days during January-February 2017. Diurnal variation of SOA formations and their correlation with OH radical exposure (OHexp), ambient pollutants (VOCs and particulate matters, PM), Relative Humidity (RH), and temperature were explored in this study. Ambient urban air was exposed to high concentration of OH radicals with OHexp in range of (0.2–1.2)×1012 molecule/(cm3?sec), corresponding to several days to weeks of equivalent atmospheric photochemical aging. The results informed that urban air at Lyon has high potency to contribute to SOA, and these SOA productions were favored from OH radical photochemical oxidation rather than via ozonolysis. Maximum SOA formation (36 µg/m3) was obtained at OHexp of about 7.4 × 1011molecule/(cm3?sec), equivalent to approximately 5 days of atmospheric oxidation. The correlation between SOA formation and ambient environment conditions (RH & temperature, VOCs and PM) was observed. It was the first time to estimate SOA formation potential from ambient air over a long period in urban environment of Lyon. 相似文献
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G. T. Brooks 《Journal of environmental science and health. Part. B》2013,48(6):755-793
Abstract The wide‐spread use of pesticides in modern agriculture has created a need to investigate the chemical transformation of pesticides in plants and animals. This paper reviews the chemical and biochemical fate of various pesticides and other xenobiotics. Photochemical mechanisms appear to be the most common pathways for the abiotic transformation of these chemicals. Biotic transformation includes a large group of biochemical reactions which may result in either deactivation (detoxication) or activation (toxication) of bioactive compounds. The need for quality control in the production of pesticides is also discussed. 相似文献