Degradation Of Carbaryl Research Articles

Excitation-emission-kinetic fluorescence coupled with third-order calibration for quantifying carbaryl and investigating the hydrolysis in effluent water

A novel method for determination of carbaryl in effluent was proposed in this study. The kinetic evolution of excitation-emission matrix fluorescence (EEM) for the pesticide were recorded and come into being a four-way data array. The four-way fluorescence data were analyzed using the parallel factor analysis (PARAFAC). The methodology exploits the second-order advantage of three-order calibration based on quadrilinear parallel factor analysis, allowing analyte concentrations to be estimated even in the presence of an uncalibrated fluorescent background. It gave the satisfactory results for determination of the carbaryl in effluent samples. In addition, the kinetic study of degradation of carbaryl was performed according to the kinetic profile provided by the calibration.

Effect of nonionic surfactants on the oxidation of carbaryl by anodic Fenton treatment

As a potentially promising technology, anodic Fenton treatment (AFT) has been shown to be very successful in pesticide removal. However, the influence of other constituents in the pesticide formulation, such as nonionic surfactants, has not been addressed. In this study, the effect of Triton X (TX) on the degradation kinetics and pathways of carbaryl undergoing AFT was investigated in an effort to facilitate its practical application. The presence of Triton X-100 was found to slow down the carbaryl degradation rate. This result can be attributed to the consumption of hydroxyl radicals ( OH) by surfactants and the formation of a carbaryl⋯TX⋯Fe 3+ complex, resulting in the unavailability of carbaryl to OH attack. The modified AFT kinetic model previously developed in this laboratory shows an excellent fit to the carbaryl degradation profile ( R 2>0.998), supporting the formation of a carbaryl⋯TX⋯Fe 3+ complex. The carbaryl degradation rate decreased as Triton X-100 concentration increased from 20 to 1000 mg L −1. Both OH consumption by surfactants and complex formation are responsible for the degradation rate reduction below the critical micelle concentration (CMC), whereas the complex and micelle formation becomes a more dominant factor above the CMC. The effect of ethylene oxide (EO) numbers of a given nonionic surfactant mainly lies in the consumption of hydroxyl radicals, which increases with the length of the EO chain, but does not significantly affect the formation of the carbaryl⋯TX⋯Fe 3+ complex. Based on the GC–MS and LC–ESI–MS results, no evidence was found that the carbaryl degradation pathway was affected. Carbaryl was typically oxidized to 1-naphthol and 1,4-naphthoquinone similar to what is observed in the absence of surfactants. Triton X-100 was degraded via the breakdown of EO chains and ω-oxidation of the terminal methyl group, which resulted in the production of a series of ethoxylate oligomers.

Modeling Evaluation of Carbaryl Degradation in a Continuously Stirred Tank Reactor by Anodic Fenton Treatment

Anodic Fenton treatment (AFT) has been shown to be effective in removing pesticides from aqueous solution in batch reactors with the formation of less toxic and more biodegradable products. To facilitate practical application of AFT, carbaryl degradation in a continuously stirred tank reactor (CSTR) by AFT was investigated under different experimental conditions, such as carbaryl inlet concentration, Fenton reagent concentration/ratio, and carbaryl feeding flow rate. A higher Fe2+ delivery rate and H2O2 to Fe2+ ratio (H2O2:Fe2+) were found to favor the carbaryl degradation process, whereas flow rate was shown to be a much less significant factor to influence the degradation rate under the evaluated experimental conditions. A kinetic-based semiempirical model was developed to simulate the experimental data, and a very good fit between the model and the raw data was found (R2 > 0.99). A dimensionless parameter (k/q2) was found to be a good indicator of the degradation rate; that is, the higher the k/q2value is, the faster the degradation process is. The rate parameter (k) can be used to evaluate the degradation rate when the flow rate is invariant for a given pesticide. The shape parameter (beta) is most likely related to the availability and reactivity of Fenton reagents and hydroxyl radicals. To compare the degradation rate of different pesticides, more information other than k/q2, k, and beta values, such as the instantaneous degradation rate vs time relationship, needs to be considered.

Expression and Characterization of Carboxylesterase E4 Gene from Peach–Potato Aphid (Myzus persicae) for Degradation of Carbaryl and Malathion

An abridged carboxylesterase E4 (CbE E4) gene was cloned from the peach-potato aphid, Myzus persicae, by reverse transcription-PCR and subcloned into the expression vector pET28b. The abridged CbE E4 gene was successfully expressed in E. coli BL21 (DE3). The recombinant CbE E4 hydrolyzed beta-naphthyl acetate and Carbaryl by 64% within 2.5 h, Malathion by 80% within 1.25 h. However, the hydrolysis of other pesticides (Dichlorovos, Parathion, Pirimicarb and Deltamethrin) was not detected.

Persistence of selected organophosphate and carbamate insecticides in waters from a coastal watershed

Organophosphate and carbamate compounds are among the most widely used pesticides. Contamination of surface water by these compounds is of concern because of potential toxicity to aquatic organisms, especially those at lower trophic levels. In this study we evaluated the persistence of diazinon, chlorpyrifos, malathion, and carbaryl in waters from various sites in the Newport Bay-San Diego Creek watershed in southern California (USA). The persistence of diazinon and chlorpyrifos was much longer than that of malathion or carbaryl and was further prolonged in seawater. Microbial degradation contributed significantly to the dissipation of diazinon and chlorpyrifos in freshwater, but was inhibited in seawater, leading to increased persistence. In contrast, degradation of malathion and carbaryl was rapid and primarily abiotic. A greater temperature dependence was observed for carbaryl degradation in all waters and for diazinon degradation in freshwater. The interactions of pesticide persistence with water location, temperature, and type of pesticides suggest that site- and compound-specific information is needed when evaluating the overall ecotoxicological risks of pesticide pollution in a watershed. Because the persistence of diazinon and chlorpyrifos may increase significantly in seawater, mitigation should occur before the pesticides reach seawater. The relatively short persistence of these compounds in freshwater suggests that practices aimed at extending residence time (e.g., diversion to wetlands) may effectively reduce pesticide output to downstream water bodies.

Determination of a N-methylcarbamate pesticide in environmental samples based on the application of photodecomposition and peroxyoxalate chemiluminescent detection

A new sensitive analytical procedure for the determination of a N-methylcarbamate pesticide (carbaryl) is presented, based on the participation of a fluorescent derivative of the pesticide in the peroxyoxalate chemiluminescent (PO–CL) system using imidazole as a catalyst. The chemiluminescent emission is detected in a flow injection (FI) manifold, employing sodium dodecyl sulfate micellar medium as carrier, which avoids the rapid degradation of a PO in water. The formation of the fluorescent derivative implies the previous decomposition of carbaryl to methylamine (MA) by UV irradiation and subsequent derivatisation with o-phthalaldehyde (OPA), carried out off-line. Photodecomposition allows a rapid degradation of carbaryl in MA, which implies some advantages in relation to the traditional hydrolysis in alkaline medium, such shorter analysis time and easier application. The optimisation of the operational and chemical variables affecting the CL response was carried out by using experimental design strategies. The method has been successfully applied to different natural waters and vegetal sample, obtaining satisfactory recoveries in both cases, with detection limits in compliance with the maximum limit of residues (MLR) permitted.

Shadecovers Affect Degradation of Carbaryl on Field-grown Pakchoi

The effect of shade covers on degradation of insecticide, carbaryl on field-grown pakchoi (Brassica rapa subsp. chinensis) was examined by a commercial enzyme-linked immunosorbent assay (ELISA) kit. Carbaryl at a.i. 10.6 g·L-1 (1.42 oz/gal) was applied to the plants grown under five different shade treatments including control without any coverings. The experiment was arranged in a randomized complete block design with three replications. Pesticide residue on leaf tissues was examined on dates of 1, 3, 5, and 7 days after pesticide application. On all sampling dates, pesticide residue was greater with treatments with higher shade percentage. Both linear and quadratic relationship of shade (independent variable) and the concentration of remained carbaryl (dependent variable) were significant (P < 0.05). The half-life of carbaryl on pakchoi leaves ranged from 2 days for control to 9 days for the heaviest shade (75%) treatment with rain protection.

Radiation absorption and rate constants for carbaryl photocatalytic degradation in a solar collector

We discuss an analytical model for the evaluation of radiation absorption in a tubular photocatalytic reactor. The model has no adjustable parameters and takes into account scattering in all directions. We compare the results of this model with those of Monte Carlo (MC) simulations and of a Lambert–Beer (LB) approximation, for a reactor illuminated by a parabolic solar concentrator. A good correspondence is found with the MC simulations. In particular, the model displays the correct saturation behavior of absorption for large catalyst particle concentrations, which is not obtained with the LB approximation. We have carried out experiments for the degradation of carbaryl in a solar parabolic collector (PC). The model is used to calculate the rate constant for this degradation from the experimental data. The theoretical model predictions reproduce well, the trends observed in the experiments.

Photoinduced degradation of carbaryl in a wetland surface water.

The photoinduced degradation of carbaryl (1-naphthyl-N-methyl carbamate) was studied in a wetland's surface water to examine the photochemical processes influencing its transformation. For this particular wetland water, at high pH, it was difficult to delineate the photolytic contribution to the overall degradation of carbaryl. At lower pH values, the extent of the degradation attributable to indirect pathways, that is, in the presence of naturally occurring photosensitizers, increased significantly. Moreover, the photoenhanced degradation at the lower pH values was found to be seasonally and spatially dependent. Analysis of water samples revealed two primary constituents responsible for the observed indirect photolytic processes: nitrate and dissolved natural organic matter (NOM). Nitrate in the wetland appears at high concentrations (> or =1 mM) seasonally after the application of fertilizers in the watershed and promotes contaminant destruction through the photochemical production of the hydroxyl radical (HO*). The extent of the observed indirect photolysis pathway appears to be dependent upon the concentration of nitrates and the presence of HO* scavengers such as dissolved NOM and carbonate alkalinity. Paradoxically, during low-nitrate events (<50 microM), NOM becomes the principal photosensitizer through either the production of HO*, direct energy transfer from the excited triplet state, and/or production of an unidentified transient species.

Oxidation of carbaryl in aqueous solution by membrane anodic fenton treatment.

Carbaryl, a commonly used insecticide, was used in this study as a probe to investigate a new Fenton treatment technology, ion exchange membrane anodic Fenton treatment (membrane AFT). It was found that the degradation kinetics of carbaryl by membrane AFT obeys a previously published AFT model quite well. The NaCl (electrolyte) concentration in two half-cells was optimized for two kinds of membrane. Effects of the H(2)O(2)/Fe(2+) ratio and the Fenton reagent delivery rate were also investigated. The treatment efficiency for anion membrane AFT is higher than for salt-bridge AFT under the same operating conditions. Decreasing the delivery rate of Fenton reagents and increasing the treatment temperature also increase the treatment efficiency. The activation energy for carbaryl degradation by anion membrane AFT was estimated to be 14.7 kJ x mol(-1). 1-Naphthol, 1,4-naphthoquinone, and (phthalic acid-O-)yl N-methylcarbamate were detected by GC-MS as the degradation products of carbaryl by Fenton treatment. No decrease in carbaryl degradation rate was found during repeated use (100 times) of the anion exchange membrane. High and stable treatment efficiency can be achieved using an anion exchange membrane rather than a salt-bridge in the AFT system. Because of its effectiveness and convenience, the use of an ion exchange membrane as a substitute for the salt-bridge used in the previous AFT system has brought the AFT technology a major step closer to practical application.

Photoluminescence and Raman Spectroscopy as Probes to Investigate Silver and Gold Dicyanide Clusters Doped in A-Zeolite and Their Photoassisted Degradation of Carbaryl

Dicyanoaurate and dicyanoargentate ions doped in A-type zeolite were prepared and analyzed spectroscopically. Data from luminescence and Raman spectroscopies along with extended Huckel calculations indicate the formation of [M(CN)2-]n oligomers (M = Ag, Au) in the zeolite host. Variations in luminescent properties as a function of excitation wavelength, dopant concentration inside the zeolite host, and temperature facilitate assignment of cluster structures. The data obtained from a comparison of Ag- and Au-doped silica and γ-alumina show that the [M(CN)2-]n clusters form in the channels of the zeolite rather than on the surface. The [M(CN)2-]n clusters in A zeolite show strong catalytic activities toward the photodecomposition of carbaryl in aqueous solution. The photodecomposition of carbaryl at room temperature shows different decomposition products in the presence and absence of the M(CN)2- doped A zeolite catalyst. In addition, the decomposition rate constants increase as the metal content increases....

Reductive degradation of carbaryl in water by Zero-valent iron

Reduction of carbaryl solution by zero-valent iron powder (ZVIP) was studied in a rotator batch system (70 rpm) in order to evaluate the utility of this reaction in remediation of carbamate contaminated water. Degradation with different amount of ZVIP: 0.01, 0.02, 0.03, 0.04 g/ml at pH 6.6 and at ambient temperature was investigated. The results show that the process exhibits a degradation rate appearing to be directly proportional to the surface contact area of ZVIP (325-mesh) with the carbaryl molecules. Three analytical techniques were used to monitor carbaryl degradation: (1) A UV–Vis diode array spectrophotometer was used to record all spectra. (2) A high performance liquid chromatography was used to separate by-products and examine the evolution of breakdown products. (3) A home-built spectrophosphorimeter that uses the solid surface room temperature phosphorescence (SSRTP) was employed to observe selectively the decline of the carbaryl concentration at different amount of ZVIP on Whatman no. 1 filter paper. Results show that the reducing degradation of carbaryl with ZVIP as the source of electrons is effective with a half-life close to several minutes.

Rapid Degradation of Carbaryl by Two Novel Strains of Arthrobacter spp. Isolated from Forest Soil

Carbaryl is one of the carbamate insecticides widely used in agricultural fields and forests. To restore the environment contaminated with carbaryl application, it is suggested that microbial degradation of carbaryl could be an effective method. Two novel bacterial strains degrading rapidly carbaryl were isolated from forest soil. These strains designated as 19B and 19C were identified as novel species of Arthrobacter, respectively based on main bacterial properties including GC-content, major fatty acid composition, major menaquinone isoprenologue and 16S rRNA gene sequence analysis. Strain 19B started to degrade carbaryl within several hours and completely degraded 50 μg/ml carbaryl in a mineral salt medium within a day. Similarly, strain 19C showed a high degradation ability. Gas chromatography-mass spectrometry analysis showed that the major degradation metabolite is 1-naphthol (M=144) and minor metabolites are 1,4-naphthalenedione (M=158) and 1,4-naphthalenediol (M=160), suggesting a pathway of carbaryl degradation by both strains.

Does carbaryl increase fluctuating asymmetry in damselflies under field conditions? A mesocosm experiment with Xanthocnemis zealandica (Odonata: Zygoptera)

Summary 1. Previous laboratory experiments have shown that the insecticide carbaryl reduces emergence success and increases fluctuating asymmetry in cell patterns of damselfly wings. These effects were validated using mesocosms. Twenty artificial ponds, each containing Xanthocnemis zealandica, were exposed to three replicated (n = 5) concentrations of carbaryl contamination plus controls. Emergence success, level of fluctuating asymmetry in meristic and metric traits of the wings, and average size of the damselflies were measured. 2. The degradation of carbaryl was relatively constant for the first 5 weeks but later increased considerably, probably because of enhanced biodegradation. 3. Carbaryl at 100 p.p.b. (nominal concentration) reduced emergence success 10 days after application, whereas carbaryl at 10 p.p.b. and 1 p.p.b. had no effect. 4. To investigate how the level of fluctuating asymmetry and size were affected by carbaryl, damselflies from ponds with the highest concentration where emergence success was not affected (10 p.p.b.) were analysed over four time periods. Fluctuating asymmetry of the wings increased during the season but was not affected by carbaryl at 10 p.p.b. 5. Size, measured as average length of the front wings, was affected by date of emergence but not by exposure to carbaryl at 10 p.p.b. 6. Three main reasons for the absence of increased levels of fluctuating asymmetry as a result of carbaryl exposure are suggested.

Photocatalytic degradation of carbaryl in aqueous TiO 2 suspensions containing surfactants

The effect of ionic and non-ionic aliphatic surfactants on the photocatalytic degradation of Carbaryl (1-naphtyl-N-methylcarbamate) in aqueous solutions containing suspended TiO 2 (anatase) particles, under irradiation with simulated AM1 solar light, was investigated. A neat inhibitory effect on the degradation rate was observed, depending on the nature of the surfactant and on the initial pH of the solution. The decay profiles of the primary process corresponded to the usual pseudo-first order kinetics for surfactant concentrations below the critical micellar concentration range, whereas a more complicate behaviour was observed in the presence of micellar aggregates. Mineralization of the pesticide to CO 2, NO 3 − and NH 4 + was evidenced also in the presence of added amphiphiles, suggesting the feasibility of photocatalytic treatment of surfactant-containing aqueous wastes.

Involvement of two plasmids in the degradation of carbaryl by Arthrobacter sp. strain RC100.

A bacterium capable of utilizing carbaryl (1-naphthyl N-methylcarbamate) as the sole carbon source was isolated from carbaryl-treated soil. This bacterium was characterized taxonomically as Arthrobacter and was designated strain RC100. RC100 hydrolyzes the N-methylcarbamate linkage to 1-naphthol, which was further metabolized via salicylate and gentisate. Strain RC100 harbored three plasmids (designated pRC1, pRC2, and pRC3). Mutants unable to degrade carbaryl arose at a high frequency after treating the culture with mitomycin C. All carbaryl-hydrolysis-deficient mutants (Cah-) lacked pRC1, and all 1-naphthol-utilization-deficient mutants (Nat-) lacked pRC2. The plasmid-free strain RC107 grew on gentisate as a carbon source. These two plasmids could be transferred to Cah- mutants or Nat- mutants by conjugation, resulting in the restoration of the Cah and Nah phenotypes.

Sorption, Degradation, and Mineralization of Carbaryl in Soils, for Single‐Pesticide and Multiple‐Pesticide Systems

AbstractSorption, degradation, and mineralization of carbaryl (1‐naphthyl N‐methylcarbamate) alone and in mixtures with atrazine(2‐chloro‐4‐ethylamino‐6‐isopropylamino‐1,3,5‐triazine) and diuron (N′‐(3,4‐dichlorophenyl)‐N,N‐dimethylurea) were characterized for two topsoils and their respective subsoils. In general, differences in sorption and transformation between single and multiple‐pesticide systems were less than differences due to soil type and between topsoil and subsoil. For a given soil, the topsoil containing more organic carbon (OC) than the subsoil exhibited a larger value for the Freundlich sorption coefficient (Kt). Similarly, a larger value for the soil solution degradation rate coefficient (k1) was obtained from topsoil than subsoil, likely due to greater microbial activity in the topsoil. However, for all soils, sorption of carbaryl on soils considerably increased the magnitude of the degradation half‐life (t1/2) for carbaryl in either single‐pesticide or multiple‐pesticide systems. In soils that contained &lt;10 g kg−1 OC content, the effect of multiple‐pesticide systems was to enhance the mineralization of carbaryl. This was attributed to cometabolism. This study shows that carbaryl chemodynamic parameters (Koc and t1/2 values) can be used to adequately analyze the fate of carbaryl in the environment even when carbaryl exists in a mixture with atrazine and diuron.

Rapid determination of carbaryl and 1-naphthol at ppt levels in environmental water samples by automated on-line SPE-LC-DAD-FD

A fully automated method, based on on-line solid phase extraction (SPE) then liquid chromatography with diode-array and fluorescence detection, has been developed for the trace-level determination of carbaryl and 1-naphthol, its primary transformation product, in environmental water samples. By means of rapid enrichment on a 30 mm×4 mm i.d. 10-μm ODS pre-column, using a 10-mL water sample, before LC determination both compounds were recovered satisfactorily from different environmental water samples spiked at various concentrations (0.05–10 μg L−1). Average recoveries were between 93 and 102% with coefficients of variation between 1 and 4%; detection limits as low as 10 and 50 mg L−1 (ppt) were estimated for carbaryl and 1-naphthol, respectively. With this small sample volume, sample throughput was up to 30 samples per day. A carbaryl degradation study was performed by spiking a surface-water sample at 2 μg L−1. After 15 days 80% of the carbaryl was degraded and the presence of 1-naphthol was confirmed by means of its UV spectrum.

Photocatalytic Degradation of Carbaryl in Aqueous Solutions Containing TiO2 Suspensions

The photocatalytic degradation of carbaryl in aqueous TiO2 dispersions irradiated with simulated solar light was investigated. Complete mineralization of the pesticide to CO2 was observed, with the formation of nitrate and ammonium ions as nitrogen-containing end products. Various aromatic intermediates, detected during the process, were identified using HPLC and GC−MS techniques, and their kinetic evolution was also investigated. The formation of the transient compound 1,3-indandione, more persistent than carbaryl, was observed. From obtained analytical and kinetic data, a possible reaction scheme was proposed.

Metabolism of 1‐naphthyl‐N‐methyl carbamate (carbaryl) by bacterial isolates from honey bees and the effect of bacterial inoculations on carbaryl tolerance in bees

I.D. SHARMA AND A. NATH. 1996. The bacteria which inhabit the body of foragers of Apis cerana indica F. were evaluated for degradation of carbaryl (1‐naphthyl‐N‐methyl carbamate). Citrobacter sp., Enterobacter aerogenes and an unidentified isolate could utilize carbaryl as sole carbon and energy source. The enrichment cultures of bacteria could degrade carbaryl 0.019–0.082 in nutrient broth and 0.111–7.895 mg μg‐1 bacterial dry wt in basal salts medium of 1 mmol 1‐1 carbaryl. 1‐Naphthol was the major product of carbaryl degradation. The dip and injection inoculations of foragers (Apis cerana indica F. and Apis mellifera L.) with these bacteria resulted in a significant increase in tolerance to carbaryl. The application of mixed culture to bees induced higher tolerance than the individual isolates. This is the first report of the use of bacteria to decontaminate a living system.