Abstract:Herbicides react with atmospheric OH, producing multiple oxidation products, including HNCO; these products contribute little to secondary organic aerosol.
“…The interaction mechanism of trifluralin on the prepared Ag-citrate/GQDs nano-ink/leaf electrode was based on electrostatic interactions, probably, between the dipole nitro group of trifluralin with negative charge and protonated amine group (R–NH 3 + ) of chitosan which was diluted in acetic acid and also Ag + group of Ag-citrate in the conductive nano-ink [ 23 ]. Trifluralin experiences three types of chemical transformation (oxidation mechanism), including: I) Addition of OH to the aromatic ring, II) abstraction of H by OH radicals of two alkyl chains, and III) dealkylation possibly because of photolysis [ 34 ]. Figure 12 A) CVs, B) DPVs and C) SWVs in the potential range of -1 to +1 V and scan rate of 100 mV/s for Ag-citrate/GQDs nano-ink/leaf electrode in the absence and presence of 1mM trifluralin.…”
Trifluralin is herbicide of the dinitroanilines group in which NO
2
molecules are attached to the benzene ring at diverse positions. Trifluralin affects endocrine function and is listed as an endocrine disrupter in the European Union list. Therefore, its determination is so important in health science. In this study, an easy, sensitive and environmentally friendly method has been developed for determination of trifluralin based on its electrochemical oxidation on a three-electrode system designed on the surface of agricultural products using Ag-citrate/GQDs (graphene quantum dots) nano-ink. The sensor was prepared by direct writing on the surface of the samples. The designed electrodes were dried after 24 h at room temperature and used for trifluralin detection. Under optimized experimental conditions, the Ag-citrate/GQDs nano-ink based sensor was exhibited good sensitivity and specificity for trifluralin detection. The obtained linear range using the cyclic voltammetric (CV) technique is between 0.008 to 1 mM and low limit of quantification (LLOQ) was 0.008 mM. Also, the obtained linear range using differential pulse voltammetric (DPV) and square wave voltammetric (SWV) techniques is 0.005–0.04 mM with LLOQ of 0.005 mM. For further validation of the applicability of the proposed method, it was also used for detection of trifluralin on the surface of apple skin.
“…The interaction mechanism of trifluralin on the prepared Ag-citrate/GQDs nano-ink/leaf electrode was based on electrostatic interactions, probably, between the dipole nitro group of trifluralin with negative charge and protonated amine group (R–NH 3 + ) of chitosan which was diluted in acetic acid and also Ag + group of Ag-citrate in the conductive nano-ink [ 23 ]. Trifluralin experiences three types of chemical transformation (oxidation mechanism), including: I) Addition of OH to the aromatic ring, II) abstraction of H by OH radicals of two alkyl chains, and III) dealkylation possibly because of photolysis [ 34 ]. Figure 12 A) CVs, B) DPVs and C) SWVs in the potential range of -1 to +1 V and scan rate of 100 mV/s for Ag-citrate/GQDs nano-ink/leaf electrode in the absence and presence of 1mM trifluralin.…”
Trifluralin is herbicide of the dinitroanilines group in which NO
2
molecules are attached to the benzene ring at diverse positions. Trifluralin affects endocrine function and is listed as an endocrine disrupter in the European Union list. Therefore, its determination is so important in health science. In this study, an easy, sensitive and environmentally friendly method has been developed for determination of trifluralin based on its electrochemical oxidation on a three-electrode system designed on the surface of agricultural products using Ag-citrate/GQDs (graphene quantum dots) nano-ink. The sensor was prepared by direct writing on the surface of the samples. The designed electrodes were dried after 24 h at room temperature and used for trifluralin detection. Under optimized experimental conditions, the Ag-citrate/GQDs nano-ink based sensor was exhibited good sensitivity and specificity for trifluralin detection. The obtained linear range using the cyclic voltammetric (CV) technique is between 0.008 to 1 mM and low limit of quantification (LLOQ) was 0.008 mM. Also, the obtained linear range using differential pulse voltammetric (DPV) and square wave voltammetric (SWV) techniques is 0.005–0.04 mM with LLOQ of 0.005 mM. For further validation of the applicability of the proposed method, it was also used for detection of trifluralin on the surface of apple skin.
“…105−107 These methods are also suited to track the multiphase oxidative evolution of both the herbicides and their formulation components, including formation of reaction products that may be toxic and/or contribute to the generation of secondary organic aerosols. 80,81 Overall, the impacts of dicamba and 2,4-D to nontarget vegetation in recent years exemplify how new challenges can emerge from changes to the application of herbicides upon the introduction of their tolerance traits, even when the herbicides have been used in another context for decades previously. Because emerging herbicide-tolerance traits dramatically alter how their corresponding herbicides are applied, the new application context must be considered to understand and mitigate environmental impact of these herbicides.…”
In recent years, off-target herbicide drift has been increasingly reported to lead to damage to nontarget vegetation in the U.S. These reports have coincided with the widespread adoption of genetically modified crops with new herbicidetolerance traits. Planting crops with these traits may indirectly lead to increased drift both by increasing the use of the corresponding herbicides and by facilitating their use as postemergence herbicides later in the season. While extensive efforts have aimed to reduce herbicide drift, critical uncertainties remain regarding the physiochemical phenomena that drive the entry of herbicides into the atmosphere as well as the atmospheric processes that may influence short-and long-range transport. Resolving these uncertainties will support the development of effective approaches to reduce herbicide drift.
“…Thus, while the sensitivity of acetate-CIMS is likely insufficient for eddy covariance flux analysis, longer averaging times of 1 or 5 min should yield detection limits adequate for regional agricultural studies during periods of application. The rapid and moderately sensitive measurements are adequate for field applications, such as investigating airborne pesticide drift during and immediately after application by measurements immediately adjacent to application areas, as well as laboratory measurements to determine chemical kinetics and oxidation chemistry [36,37].…”
Section: Discussionmentioning
confidence: 99%
“…Anthropogenic organic compounds, including the phenoxy herbicides described herein, can be oxidized by OH radicals and other oxidants in the atmosphere [36,37]. The calculated OH reactivity from observed concentrations and known rate constants for the two herbicides is small, <0.01 s −1 with MCPA dominating the reactivity.…”
Atmospheric sources of herbicides enable short- and long-range transport of these compounds to off-target areas but the concentrations and mechanisms are poorly understood due, in part, to the challenge of detecting these compounds in the atmosphere. We present chemical ionization time-of-flight mass spectrometry as a sensitive, real-time technique to detect chlorinated phenoxy acid herbicides in the atmosphere, using measurements during and after application over a field at Colorado State University as a case study. Gas-phase 2,4-dichlorophenoxyacetic acid (2,4-D) mixing ratios were greatest during application (up to 20 pptv), consistent with rapid volatilization from spray droplets. In contrast, atmospheric concentrations of 2-methyl-4-chlorophenoxyacetic acid (MCPA) increased for several hours after the initial application, indicative of a slower source than 2,4-D. The maximum observed gas-phase MCPA was 60 pptv, consistent with a post-application volatilization source to the atmosphere. Exposure to applied pesticides in the gas-phase can thus occur both during and at least several hours after application. Spray droplet volatilization and direct volatilization from surfaces may both contribute pesticides to the atmosphere, enabling pesticide transport to off-target and remote regions.
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