Humic Substances Enhance Chlorothalonil Phototransformation via Photoreduction and Energy Transfer

Porras, Jazmín; Fernández, Jhon J.; Torres-Palma, Ricardo A.; Richard, Claire

doi:10.1021/es404240x

Cited by 43 publications

(34 citation statements)

References 35 publications

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“…A range of techniques has been used to aid in the characterization of HS, particularly Fourier‐transform infrared spectroscopy, 13 C NMR spectroscopy, and, increasingly, synchrotron‐based Fourier‐transform infrared–attenuated total reflectance spectroscopy and carbon near edge X‐ray fine structure spectroscopy (Davis et al, 1999; Kulikova and Perminova, 2002; Solomon et al, 2005; Christl and Kretzschmar, 2007; Amir et al, 2010; Prietzel et al, 2018). The application of these techniques has contributed significantly to our knowledge of the mechanisms responsible for pesticide sorption to HS (Piccolo et al, 1996; Wang et al, 2011; Dutta et al, 2015).…”

Section: Modeling Of Metal Ion Binding In Soilsmentioning

confidence: 99%

Environmental and Agricultural Relevance of Humic Fractions Extracted by Alkali from Soils and Natural Waters

et al. 2019

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To study the structure and function of soil organic matter, soil scientists have performed alkali extractions for soil humic acid (HA) and fulvic acid (FA) fractions for more than 200 years. Over the last few decades aquatic scientists have used similar fractions of dissolved organic matter, extracted by resin adsorption followed by alkali desorption. Critics have claimed that alkaliextractable fractions are laboratory artifacts, hence unsuitable for studying natural organic matter structure and function in field conditions. In response, this review first addresses specific conceptual concerns about humic fractions. Then we discuss several case studies in which HA and FA were extracted from soils, waters, and organic materials to address meaningful problems across diverse research settings. Specifically, one case study demonstrated the importance of humic substances for understanding transport and bioavailability of persistent organic pollutants. An understanding of metal binding sites in FA and HA proved essential to accurately model metal ion behavior in soil and water. In landscape-based studies, pesticides were preferentially bound to HA, reducing their mobility. Compost maturity and acceptability of other organic waste for land application were well evaluated by properties of HA extracted from these materials. A young humic fraction helped understand N cycling in paddy rice (Oryza sativa L.) soils, leading to improved rice management. The HA and FA fractions accurately represent natural organic matter across multiple environments, source materials, and research objectives. Studying them can help resolve important scientific and practical issues.

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Section: Modeling Of Metal Ion Binding In Soilsmentioning

confidence: 99%

Environmental and Agricultural Relevance of Humic Fractions Extracted by Alkali from Soils and Natural Waters

et al. 2019

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“…This result agrees with previous studies which observed little sensitized photoreaction when CDOM was excited with a wavelength longer than 450 nm (photon energy < 266 kJ/mol). 27,34 QY Spectrum of 1 O 2 . The QY of 1 O 2 constantly decreased with increasing light wavelength (Figure 4b), generally agreeing with the observations of the monochromatic approach using a high-power laser and other techniques, 31,35−38 and the 1 O 2 QY varied depending on the CDOM source.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

High Sample Throughput LED Reactor for Facile Characterization of the Quantum Yield Spectrum of Photochemically Produced Reactive Intermediates

Liu

Wang

et al. 2021

Environ. Sci. Technol.

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Photochemically produced reactive intermediates (PPRIs) by natural photosensitizers such as chromophoric dissolved organic matter (CDOM) play numerous key roles in aquatic biogeochemical processes. PPRI productions rely on both the intensity and the spectrum of incident sunlight. While the impacts of sunlight intensity on PPRI productions are well-studied, there remains insufficient understanding of the spectrum-dependence of PPRI productions. Here we designed a high sample throughput reactor equipped with monochromatic LED lights for systematic assessments of wavelength-dependent productions of four important PPRI species, i.e., triplet-state excited CDOM (3CDOM*), singlet oxygen (1O2), hydrogen peroxide (H2O2), and hydroxyl radical (•OH), in CDOM solutions. The quantum yields of PPRIs followed the order: 3CDOM* > 1O2 ≫ H2O2 > •OH. Moreover, PPRI quantum yields decreased with the light wavelength increasing from 375 to 490 nm and sharply decreased to zero above 490 nm, while the shapes of quantum yield spectra differed among PPRI species. Simulations on PPRI productions under varying season, latitude, altitude, and cloud cover conditions show that the sunlight spectrum plays a role as equally important as intensity in determining PPRI productions and PPRI-mediated transformations of aquatic nutrients and micropollutants. Therefore, incorporating the spectrum dependence of PPRI productions will advance our understandings of PPRI-driven biogeochemical processes and pollutant dynamics under varying spatial-temporal and climatic conditions. Regarding this, the high sample throughput LED reactor sheds light on a new approach for the facile characterization of PPRI quantum yield spectrum.

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“…This reaction might be an energy transfer or an electron/H atom transfer reaction. The energy level of 3 CT* was previously estimated to lay at 275 kJ mol -1 based on phosphorescence measurements at 77 K in pentane (Porras et al, 2014). This is lower than the energy level reported for phenol  314-334 kJ.mol -1 (Becker, 1969) making the energy transfer from 3 CT* to T unlikely.…”

Section: Interactions Between Ct and Thyme's Volatilesmentioning

confidence: 89%

Photochemical interactions between pesticides and plant volatiles

Arbid

Sleiman

Richard

2022

Science of The Total Environment

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Among the numerous studies devoted to the photodegradation of pesticides, very scarce are those investigating the effect of plant volatiles. Yet, pesticides can be in contact with plant volatiles after having been spread on crops or when they are transported in surface water, making interactions between the two kind of chemicals possible. The objectives of the present study were to investigate the reactions occuring on plants. We selected thyme as a plant because it is used in green roofs and two pesticides : the fungicide chlorothalonil for its very oxidant excited state and the insecticide imidacloprid for its ability to release the radical NO 2 under irradiation. Pesticides were irradiated with simulated solar light first in a solvent ensuring a high solubility of pesticides and plant volatiles, and then directly on thyme's leaves. Analyses were conducted by headspace gas chromatography-mass spectrometry (HS-GC-MS), GC-MS and liquid chromatography-high resolution mass spectrometry (LC-HRMS). In acetonitrile, chlorothalonil photosensitized the degradation of thymol, -pinene, 3-carene and linalool with high quantum yields ranging from 0.35 to 0.04, and was photoreduced, while thymol underwent oxidation, chlorination and dimerization. On thyme's leave, chlorothalonil was photoreduced again and products arising from oxidation and dimerization of thymol were detected. Imidacloprid photooxidized and photonitrated thymol in acetonitrile, converting it into chemicals of particular concern. Some of these chemicals were also found when imidacloprid was irradiated dispersed on thyme's leaves. These results show that photochemical reactions between pesticides and the plants secondary metabolites 2 can take place in solution as on plants. These findings demonstrate the importance to increase our knowledge on these complex scenarios that concern all the environmental compartments.

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Humic Substances Enhance Chlorothalonil Phototransformation via Photoreduction and Energy Transfer

Cited by 43 publications

References 35 publications

Environmental and Agricultural Relevance of Humic Fractions Extracted by Alkali from Soils and Natural Waters

Environmental and Agricultural Relevance of Humic Fractions Extracted by Alkali from Soils and Natural Waters

High Sample Throughput LED Reactor for Facile Characterization of the Quantum Yield Spectrum of Photochemically Produced Reactive Intermediates

Photochemical interactions between pesticides and plant volatiles

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