Reactivity of neonicotinoid insecticides with carbonate radicals

“NOTICE: this is the author’s version of a work that was accepted for publication in Water Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in WATER RESEARCH, [VOL46, ISSUE11, jul 2012] DOI10.1016/j.watres.2012.03.051¨ ©IWA Publishing 2012. The definitive peer-reviewed and edited version of this article is published in Water Research 46 11 3476-3489 2012 10.1016/j.watres.2012.03.051 and is available at www.iwapublishing.comThe reaction of three chloronicotinoid insecticides, namely Imidacloprid (IMD), Thiacloprid (THIA) and Acetamiprid (ACT), with carbonate radicals (CO3 center dot-) was investigated. The second order rate constants (4 +/- 1) x 10(6), (2.8 +/- 0.5) x 10(5), and (1.5 +/- 1) x 10(5) M-1 s(-1) were determined for IMD, THIA and ACT, respectively. The absorption spectra of the organic intermediates formed after CO3 center dot- is approximately equal to attack to IMD is in line with those reported for alpha-aminoalkyl radicals. A reaction mechanism involving an initial charge transfer from the amidine nitrogen of the insecticides to CO3 center dot- is proposed and further supported by the identified reaction products. The pyridine moiety of the insecticides remains unaffected until nicotinic acid is formed. CO3 center dot- radical reactivity towards IMD, ACT, and THIA is low compared to that of HO center dot radicals, excited triplet states, and O-1(2), and is therefore little effective in depleting neonicotinoid insecticides. (C) 2012 Elsevier Ltd. All rights reserved.This research was financially supported by Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Agencia Nacional de Promocion Cientifica y Tecnologica (Argentina, project PICT 2007 number 00308), and Agencia Espanola de Cooperacion Internacional (project A/8199/07). M.L.D. thanks CONICET for a graduate studentship. M.C.G. is a research member of CONICET. D.O.M. is a research member of Comision de Investigaciones Cientificas de la Provincia de Buenos Aires (CIC), Argentina. L.S.J. acknowledges Ministerio de Ciencia e Innovacion for his Juan de la Cierva scholarship.Dell'arciprete, ML.; Soler Escoda, JM.; Santos-Juanes Jordá, L.; Arques Sanz, A.; Martire, DO.; Furlong, JP.; González, MC. (2012). Reactivity of neonicotinoid insecticides with carbonate radicals. Water Research. 46(11):3476-3489. https://doi.org/10.1016/j.watres.2012.03.051S34763489461

Species-Specific Effects of Epigeic Earthworms on Microbial Community Structure during First Stages of Decomposition of Organic Matter

Background: Epigeic earthworms are key organisms in organic matter decomposition because of the interactions they establish with microorganisms. The earthworm species and the quality and/or substrate availability are expected to be major factors influencing the outcome of these interactions. Here we tested whether and to what extent the epigeic earthworms Eisenia andrei, Eisenia fetida and Perionyx excavatus, widely used in vermicomposting, are capable of altering the microbiological properties of fresh organic matter in the short-term. We also questioned if the earthworm-induced modifications to the microbial communities are dependent on the type of substrate ingested. Methodology/Principal Findings: To address these questions we determined the microbial community structure (phospholipid fatty acid profiles) and microbial activity (basal respiration and microbial growth rates) of three types of animal manure (cow, horse and rabbit) that differed in microbial composition, after being processed by each species of earthworm for one month. No differences were found between earthworm-worked samples with regards to microbial community structure, irrespective of type of manure, which suggests the existence of a bottleneck effect of worm digestion on microbial populations of the original material consumed. Moreover, in mesocosms containing cow manure the presence of E. andrei resulted not only in a decrease in bacterial and fungal biomass, but also in a reduced bacterial growth rate and total microbial activity, while no such reduction was found with E. fetida and P. excavatus

Spectrometric Study of the Nitrile-Ketenimine Tautomerism

Mass spectrometry is used to evaluate the occurrence of the nitrile-ketenimine tautomerism. Mass spectra of two differently substituted nitriles, ethyl-4,4-dicyano-3-methyl-3-butenoate and diethyl-2-cyano-3-methyl-2-pentenodiate are examined looking for common mass spectral behaviors. Ion fragmentation assignments for specific tautomers allow to predict the presence of the corresponding structures. Additionally, the mass spectrum and nuclear magnetic resonance spectra of ethyl-4,4-dicyano-2,2-diethyl-3-methyl-3-butenoate and that of the corresponding amination product support the occurrence of the ketenimine tautomer in the equilibrium

Enol and Enethiol Occurrence for Some Ketones and Thioketones. Mass Spectrometry and Theoretical Calculations

Abstract: The mass spectra of ketones can provide valuable information with regards to keto-enol equilibria occurring in the gas phase. Mass spectra of selected ketones and thioketones have been analysed and specific fragmentation assignments have been done to characterised and weigh co-existing keto and enol tautomers. Thioketones are of particular interest due to their tendency to shift the tautomeric equilibrium towards the enethiol form. The predictive value of this methodology is not only supported by the influence of these compound’s nature and size of the substituent on these equilibria but also by the good correlation found between the selected fragments abundances ratio and semi-empirical calculation (AM1) of the corresponding heats of tautomerization