Degradation Of Aldicarb Research Articles

Advanced removal of pesticides, herbicides, and pharmaceutical residues from surface water

ABSTRACT This work is interested in studying the removal of 27 harmful pollutants from drinking water in the Rosetta branch of the River Nile by advanced treatment processes (i.e. photo-catalysis under natural conditions and normal pH of surface water). The concentration levels of the selected pesticides (11 compounds) in raw water by the spiking method ranged from 1.57–0.40 µg/L, while the concentration of pharmaceuticals (10 compounds) ranged from 41.56–5.95 µg/L and the herbicides (6 compounds) in the range of 1.89–1.37 µg/L. For this purpose, TiO2-Hombikat/alumina (T/A) was prepared by a two-step method; sonication followed by the hydrothermal method. Cu/TiO2-Hombikat/alumina was prepared hydrothermally (H-Cu/T/Al) and by the wet impregnation method (Ma-Cu/T/Al). The prepared materials were characterized by XRD and SEM. The use of advanced treatment could successfully remove selected pollutants. In the case of pharmaceutical residues, the prepared catalysts showed a powerful efficiency in the complete removal of sulfamethazine, while only (T/A) and (H-Cu/T/Al) showed such an efficiency in the complete removal of diclofenac sodium. On the other hand, lower efficiencies were observed with caffeine (17.99% (T/A) and 24.05% (H-Cu/T/Al)). In the case of pesticides, a high removal of pendimethalin (93.77%) using (H-Cu/T/Al) and 86.03% by using (Mb-Cu/T/Al), whereas lower efficiencies were observed for T/A toward the degradation of aldicarb (15.6%) (l) and H-Cu/T/Al (26.07%). In the case of herbicides, the catalysts showed no more than 57% efficiency in the removal of these pollutants.

Photocatalytic degradation of organic pollutant aldicarb by non-metal-doped nanotitania: synthesis and characterization.

The current study focused on pollution control by titania through photocatalytic degradation of aldicarb pesticide in aqueous medium. Titania, which is an efficient photocatalyst, can bring about degradation of aqueous organic pollutants under UV and visible light irradiation. Here, we prepared titania by sol-gel method from titanium tetraisopropoxide and doped non-metals like N and S from sources such as urea and thiourea, respectively. The prepared catalyst was characterized by XRD, UV-Vis.DRS, TEM, XPS, etc. Photocatalytic activity of the catalyst was evaluated from extend of degradation of aldicarb pesticide by measuring its concentration with the help of HPLC. It was found that the modified catalyst showed better photocatalytic degradation than pure titania in visible light.

Photocatalytic self-detoxification by coaxially electrospun fiber containing titanium dioxide nanoparticles

Electrospun nanofibers containing titanium dioxide (TiO2) were investigated as a self-detoxifying system consisting of polyacrylonitrile (PAN) and anatase TiO2 nanoparticles. Fibers were prepared by uniaxial and coaxial electrospinning to study the effect of nanoparticle placement on the detoxification activities of the photocatalyst. Coaxially spun fibers had the particles selectively placed in the sheath layer by electrospinning pure PAN solution and PAN/TiO2 solution as the core and sheath layer, respectively. Using scanning electron microscopy, X-ray microanalysis and X-ray photoelectron spectroscopy, it was confirmed that the coaxial approach resulted in the location of nanoparticles near the surface of the fibers compared to the uniform distribution obtained for uniaxial fibers. Photocatalytic activity of the fibers under ultraviolet irradiation was demonstrated by the degradation of aldicarb, as measured by high-performance liquid chromatography. In terms of degradation kinetics, the distribution density of TiO2 nanoparticles in the fiber surface region significantly affected the initial degradation rate, while the final decomposition amounts after 3 h did not differ significantly.

Comprehensive studies of aldicarb degradation in various oxidant systems using high performance liquid chromatography coupled with UV detection and quadrupole ion trap mass spectrometry

Aldicarb, a carbamate pesticide, is commonly used in agriculture and can be naturally degraded to metabolites, resulting in their occurrence in drinking water supplies. The disinfection process using different oxidants for the treatment of drinking water provides the opportunity to degrade aldicarb and its metabolites to byproducts that may pose more human health risk than the parent compounds. A comprehensive study of aldicarb and its metabolites involving treatment with free chlorine (FC), monochloramine (MCA), ozone (O3), chlorine dioxide (ClO2), hydrogen peroxide, permanganate () and UV radiation was performed to identify the degradation products. Free chlorine, high-dosage UV radiation and permanganate exhibited stronger oxidation capacity than the other oxidants studied, with chlorine dioxide showing the weakest oxidation ability among them. Aldicarb sulfoxide was formed as the degradation product of aldicarb by oxidation with free chlorine, MCA, ozone, and hydrogen peroxide. Aldicarb sulfone was identified as an oxidation byproduct of both aldicarb and aldicarb sulfoxide by permanganate. N-chloro-aldicarb sulfone was formed as an oxidation byproduct of aldicarb sulfone by free chlorine. The comprehensive information is very valuable for water treatment facilities and environmental researchers.

Potential enhancement of degradation of the nematicides aldicarb, oxamyl and fosthiazate in UK agricultural soils through repeated applications

The potential for enhanced degradation of the carbamoyloxime nematicides aldicarb and oxamyl and the organophosphate fosthiazate was investigated in 35 UK agricultural soils. Under laboratory conditions, soil samples received three successive applications of nematicide at 25 day intervals. The second and third applications of aldicarb were degraded at a faster rate than the first application in six of the 15 aldicarb-treated soils, and a further three soils demonstrated rapid degradation of all three applications. High organic matter content and low pH had an inhibitory effect on the rate of aldicarb degradation. Rapid degradation was observed in nine out of the ten soils treated with oxamyl. In contrast, none of the fosthiazate-treated soils demonstrated enhanced degradation. The potential for enhanced degradation of aldicarb and oxamyl was demonstrated in nine out of 15 and nine out of ten soils respectively that had previously been treated with these active substances. Degradation of fosthiazate occurred at a much slower rate, with no evidence of enhanced degradation. Fosthiazate may provide a useful alternative in cases where the efficacy of aldicarb and oxamyl has been reduced as a result of enhanced degradation.

Aldicarb and carbofuran transport in a Hapludalf influenced by differential antecedent soil water content and irrigation delay

Pesticide use in agroecosystems can adversely impact groundwater quality via chemical leaching through soils. Few studies have investigated the effects of antecedent soil water content (SWC) and timing of initial irrigation (TII) after chemical application on pesticide transport and degradation. The objectives of this study were to investigate the effects of antecedent soil water content (wet vs dry) and timing of initial irrigation (0 h Delay vs 24 h Delay) on aldicarb [( EZ)-2-methyl-2-(methylthio)propionaldehyde O-methylcarbamoyloxime] and carbofuran [2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate] transport and degradation parameters at a field site with Menfro silt loam (fine-silty, mixed, superactive, mesic Typic Hapludalf) soils. Aldicarb and carbofuran were applied to plots near field capacity (wet) or near permanent wilting point (dry). Half of the dry and wet plots received irrigation water immediately after chemical application and the remaining plots were irrigated after a 24 h Delay. The transport and degradation parameters were estimated using the method of moments. Statistical significance determined for SWC included averages across TII levels, and significance determined for TII included averages across SWC levels. For the dry treatment, aldicarb was detected 0.10 m deeper ( P < 0.01) on two of the four sampling dates and carbofuran was detected at least 0.10 m deeper ( P < 0.05) on all of the sampling dates compared to the wet treatment. Pore water velocity was found to be higher ( P < 0.10) in the dry vs wet treatments on three of four dates for aldicarb and two of four dates for carbofuran. Retardation coefficients for both pesticides showed similar evidence of reduced values for the dry vs wet treatments. These results indicate deeper pesticide movement in the initially dry treatment. For aldicarb and carbofuran, estimated values of the degradation rate were approximately 40–49% lower in the initially dry plots compared to the initially wet plots, respectively. When the initial irrigation was delayed for 24 h, irrespective of antecedent moisture conditions, a 30% reduction in aldicarb degradation occurred. This study illustrates the deeper transport of pesticides and their increased persistence when applied to initially dry soils.

Development and validation of a HPLC method for the determination of aldicarb, aldicarb sulfoxide and aldicarb sulfone in liquid samples from anaerobic reactors

This study describes the development and validation of a high-performance liquid chromatography (HPLC) method for detecting aldicarb and its residues in liquid samples without pretreatment. The HPLC system was equipped with a C-18 column and the mobile phase was composed of a mixture of water and acetonitrile using a linear gradient elution. The UV detector was utilized at 210 nm. Methomyl was used as an internal standard. Water and synthetic medium were used as solvents. The method was linear from 0.49-15.0 mg L-1 (r2 > 0.9985), 0.1-5.0 mg L-1 (r2 > 0.9974) and 0.1-5.0 mg L-1 (r2 > 0.9987) for aldicarb, aldicarb sulfoxide and aldicarb sulfone, respectively. The linearity of the method was confirmed by the ANOVA F-test through adjustment of the linear model, validity of the regression and efficiency of the regression tests. The limit of detection in water and synthetic medium were of 0.391/0.440 mg L-1, 0.069/0.192 mg L-1 and 0.033/0.068 mg L-1 for aldicarb, aldicarb sulfoxide and aldicarb sulfone, respectively. Total time of analysis was of 22 min. In the application of the method, the aldicarb degradation in horizontal-flow anaerobic immobilized biomass (HAIB) reactor was evaluated under different conditions (methanogenic, sulfidogenic and denitrifying).

Pulsed Losses and Degradation of Aldicarb in a South Florida Agricultural Watershed

The objectives of these studies were to characterize patterns of movement of aldicarb, aldicarb sulfoxide, and aldicarb sulfone from a typical canalized South Florida watershed and to evaluate aldicarb dissipation in surface water in situ within a citrus grove. Surface water samples were collected daily or every other day from the discharge point for the watershed beginning May 15, 2001, through August 15, 2002. Of 457 samples collected, aldicarb, aldicarb sulfoxide, and aldicarb sulfone were detected in 6, 1, and 13, respectively. Aldicarb was detected from February through May 2002, corresponding to the legal application season of January 1 through April 30 in Florida. Aldicarb concentrations ranged from <0.16 to 4.97 ng ml(-1). A single detection (0.99 ng ml(-1)) of aldicarb sulfoxide occurred in March 2001. The majority of aldicarb sulfone detections occurred during June and July, 2001, after the application season, and ranged from <0.22 to 0.89 ng ml(-1). The half-life for aldicarb in fortified, native surface water ranged from 1.86 to 3.64 days depending on the source of water and the presence of sediments. These results demonstrated the utility of sampling on a frequent basis (compared with monthly or quarterly) for better characterizing pesticide discharges, especially in flashy systems such as canal-drained watersheds within South Florida.

Plant uptake of aldicarb from contaminated soil and its enhanced degradation in the rhizosphere

Experiments were conducted to investigate the degradation of aldicarb, an oxime carbamate insecticide, in sterile, non-sterile and plant-grown soils, and the capability of different plant species to accumulate the pesticide. The degradation of aldicarb in soil followed first-order kinetics. Half lives ( t 1/2) of aldicarb in sterile and non-sterile soil were 12.0 and 2.7 days, respectively, which indicated that microorganisms played an important part in the degradation of aldicarb in soil. Aldicarb disappeared more quickly ( p⩽0.05) in the soil with the presence of plants, and t 1/2 of the pesticide were 1.6, 1.4 and 1.7 days in the soil grown with corn, mung bean and cowpea, respectively. Comparison of plant-promoted degradation and plant uptake showed that the enhanced removal of aldicarb in plant-grown soil was mainly due to plant-promoted degradation in the rhizosphere.

Experimental Study on Effect of Anion Surfactant on Degradation Rate of Aldicarb in Soil

Degradation kinetics of aldicarb [2‐methyl‐2‐(methylthio) propionaldehyde O‐(methyl carbamoyl) oxime] in surface and subsurface soil containing different levels of sodium dodecylbenzenesulfonate (SDBS) were determined to understand complex effect of SDBS on aldicarb degradation process. The results showed that degradation curves of aldicarb in soil can be described with first order kinetics formula and the degradation rate constant, k (d− 1), in surface soil was larger than that in subsurface soil. SDBS can accelerate the degradation of aldicarb in soil and there was a good linear relationship between degradation rate constant and the logarithm of SDBS concentration. The possible reasons were that SDBS could change pH value of soil, have solubilization effect on aldicarb, and be used as carbon source of microorganisms. But SDBS had a larger promotion to the degradation of aldicarb in surface than in subsurface soil. When SDBS concentration was 1000 mg/kg of dried soil the first order degradation rate constant of aldicarb could be increased by 56.6 percent in surface soil and by 27.6 percent in subsurface soil, respectively.

Nonlethal method for forensic evaluation of aldicarb exposure in wildlife.

Forensic evaluation of aldicarb exposure is difficult due to the rapid hydrolysis and oxidation of the parent compound. Oxidation products-aldicarb sulfoxide and aldicarb sulfone-are commonly analyzed, but hydrolytic products-aldicarb nitrile, aldicarb nitrile sulfoxide, aldicarb nitrile sulfone-are infrequently analyzed even though they are the primary stable products of aldicarb degradation. Nitrile analyses provide an important avenue to verify aldicarb exposure or aldicarb-induced mortality. Our aproach allows lethal and sublethal exposure assessment. Extraction of samples with acetonitrile:water is followed by chromatographic determination. Sublethal exposure assessment utilizes excreta samples, which is nonlethal and requires holding animals in captivity for 12 h or less. Sublethal exposures of northern bobwhite Colinus virginianus to aldicarb can be identified with greater than 80% confidence for 6 h after dosing. By analyzing GI tracts, lethal exposures of bobwhite to aldicarb can be identified with greater than 90% confidence for 4 days post mortem and with 75% confidence for 8 days post mortem. Sublethal exposures to aldicarb was identified in greater than 80% of Peromyscus maniculatis for 6 h after dosing. Aldicarb and its transformation products were detected for 8 days post mortem in all mice that received aldicarb doses at or above the LD50.

Adsorption Effects on Kinetics of Aldicarb Degradation Equilibrium Model and Application to Incubation and Transport Experiments

The assumption of equilibrium adsorption was applied to both batch incubation and soil column leaching experiments to estimate degradation rate constants of the pesticide aldicarb [2‐methyl‐2‐(methylthio) propionaldehyde o‐(methylcarbamoyl) oxim] in the liquid (μl) and sorbed (μs) phases. The estimation was based on the observed Kd–μ relationship yielded in a soil amended with various amounts of activated C (AC), where Kd is the adsorption coefficient, and μ is the composed degradation rate constant from both phases. The inverse dependence of aldicarb degradation on Kd reveals that μl is faster than μs For batch incubation experiments, the calculated μl and μs were 0.1228 and 0.0019 d−1, respectively, differing by a factor of 65. In continuous‐flow columns, μl and μs were both increased, with an estimated value of 0.2063 and 0.0055 d−1, respectively, resulting in an accelerated overall degradation rate of aldicarb by 181% compared with the batch reactors. The results of our study indicate that, although degradation of aldicarb occurred primarily in the soil solution, it did not cease completely on the sorbed chemicals. The relative contributions of the two phases to the total degradation were therefore dependent on both the adsorption coefficient and the relative degradation rate constants for the dissolved and sorbed chemicals.

Biodegradation of aldicarb in a packed-bed reactor by immobilized Methylosinus

Carboxymethylcellulose microspheres cross-linked via aluminum ions were used as a support material for immobilization of Methylosinus isolated from soil contaminated with aldicarb. The degradation capacity of immobilized bacteria, different parameters such as substrate concentration (50–800 ppm), flow rate (10–60 ml h −1), and continuous contact with reaction medium (flow rate, 20 ml h −1 and concentration, 100 ppm) that affect aldicarb degradation were investigated in a packed-bed reactor. Increases in the flow rate decreased the conversion of aldicarb into its metabolites. On the other hand, increasing the substrate concentration up to 400 ppm led to an increase in the amount of aldicarb converted (max 16%). Beyond this, the proportion of aldicarb that converted was decreased, reaching approximately 7% at 800 ppm. The apparent kinetic parameters, K ′ m and V max, were determined to be as 310.11 ppm and 2.29 × 10 −2 ppm s −1, respectively. Operation of the bioreactor in the recycled mode was much more efficient, degrading 50% of the aldicarb in 24 h and 100% in four days.

Effect of Water Table Management on the Fate of the Pesticide Aldicarb

The fate of agricultural chemicals applied to cultivated fields with subsurface drains is an environmental concern. The transport of the pesticide aldicarb in the soil and groundwater in an agricultural field with subsurface drains was simulated using the computer model VS2DT. A Portsmouth soil from Plymouth, North Carolina, was simulated with five water table management treatmentsconventional or free drainage, controlled drainage, subirrigation, free drainage with surface irrigation, and controlled drainage with surface irrigation. Five drain spacings, 15.2, 22.8, 30.4, 38.1, and 45.7 m, were investigated. Two aldicarb degradation rates, 7- and 30-day half life, were simulated. Free drainage with surface irrigation produced the highest predicted aldicarb losses for all drain spacings while the controlled drainage treatment without surface irrigation consistently resulted in the lowest amount of aldicarb lost through tile outflow.

Microbial aldicarb transformation in aquifer, lake, and salt marsh sediments

The microbial transformation of [N-methyl-(sup14)C]aldicarb, a carbamate pesticide, occurred in aquifer, lake, and salt marsh sediments. Microbial degradation of aldicarb took place within 21 days in aquifer sediments from sites previously exposed to aldicarb (Jamesport, Long Island, N.Y.) but did not occur in sediments which were not previously exposed (Connetquot State Park, Long Island, N.Y.). At the Jamesport sites, higher aldicarb transformation rates occurred in deep, anoxic sediments than in shallow, oxic sediments. There was a significant negative relationship (P < 0.05) between transformation rates and ambient dissolved O(inf2) levels. Aldicarb hydrolysis rates in Jamesport sediments were 10- to 1,000-fold lower than rates previously reported for soils. In addition, aldicarb degradation rates were not significantly correlated with measurements of bacterial activity and density previously determined in the same sediments. Substantially higher aldicarb degradation rates were found in anoxic lake and salt marsh than in aquifer sediments. Furthermore, we investigated the anaerobic microbial processes involved in aldicarb transformation by adding organic substrates (acetate, glucose), an alternative electron acceptor (nitrate), and microbial inhibitors (molybdate, 2-bromoethanesulfonic acid) to anoxic aquifer, lake, and salt marsh sediments. The results suggest that a methanogenic consortium was important in aldicarb transformation or in the use of aldicarb-derived products such as methylamine. In addition, microbial aldicarb transformation proceeded via different pathways under oxic and anoxic conditions. In the presence of O(inf2), aldicarb transformation was mainly via an oxidation pathway, while in the absence of O(inf2), degradation took place through a hydrolytic pathway (including the formation of methylamine precursors). Under anoxic conditions, therefore, aldicarb can be transformed by microbial consortia to yield products which can be of direct benefit to natural populations of methanogens present in sediments.

Degradation of Pesticides in Subsurface Soils, Unsaturated Zone—a Review Of Methods and Results

Abstract Methods and results from degradation studies in subsoils, unsaturated zone, were reviewed for mecoprop, 2,4-D, atrazine, alachlor, aldicarb, carbofuran, linuron, oxamyl, methomyl, MCPA, dichlorprop, monochlorprop, dichlorphenol, TCA, parathion, metribuzin, metolachlor and fenamiphos. Most of the investigations were laboratory studies where small soil samples were sieved and pesticides were added in concentrations from 0.5-5 μg.g−1. A few of the studies mentioned the importance of working with undisturbed samples; another few studies used isotope-labelled pesticides which made it possible to work with concentrations as low as 0.02 μg.g−1. Subsoil samples were characterized according to factors as microbial activity, soil temperature, water content, oxygen content, concentration of pesticide, pretreatment of the soil and soil type, factors considered to have influence on degradation of pesticides. Chemical hydrolysis was considered to be the most dominant pathway in the degradation of aldicarb in subsoil in one of the published papers; all other investigations considered the degradation of pesticides in subsoil to be primarily microbiological. Only a few of the investigations measured the biomass or biological activity of the subsoil samples.

Measurement of aldicarb degradation and movement in upstate New York and Massachusetts potato fields (U.S.A.)

The degradation and movement of aldicarb residues from an emergence application was measured in soil and groundwater beneath potato fields near Deerfield, Massachusetts, and Savannah, New York. Soil samples collected following the application showed that aldicarb residues degraded at a rate corresponding to a half-life of ∼1.1 months. This half-life is consistent with previous studies. At the Massachusetts location, residues in half of the plot were confined to the upper 1.2 m of soil. In the other half of the plot which was temporarily flooded due to an overflow of a nearby pond, residue movement exceeded 4.8 m and residues up to 21 μg L −1 were observed in the upper 1.5 m of the saturated zone. No residues were observed in wells installed farther than 40 m from the treated area and residues in all wells dropped below 10 μg L −1 within 16 months of the aldicarb application. At the New York site, aldicarb residues entered shallow groundwater after a period of heavy rainfall in late November and early December of 1986. During the study, aldicarb residues were confined to shallow groundwater directly beneath or within 5 m of the treatment area. Aldicarb residues in excess of 10 μg L −1 were not found deeper than ∼2.5 m below the water table. Aldicarb residues had declined to below 1 μg L −1 in all monitoring wells within 5 yr, implying an average half-life of aldicarb residues in groundwater of <1 yr.

Degradation of aldicarb, aldicarb sulfoxide, and aldicarb sulfone in chlorinated water

The three insecticidal species of Temik, aldicarb (I), aldicarb sulfoxide (II), and aldicarb sulfone (III), degrade rapidly in chlorinated water. I is sulfoxidized to II, while II forms III, (chloromethyl)sulfonyl species, and N-chloro-II. III forms N-chloro-III, which decomposes to III acid and dichloromethylamine. Over the pH range of 6-9, the degradation rates of I-III in chlorinated water are several orders of magnitude faster than base hydrolysis, the primary detoxification mechanism in water

Sorption and Degradation of Aldicarb and its Oxidation Products in a Soil‐water Flow System as a Function of pH and Temperature

AbstractThe sorption and degradation of aldicarb [2‐methyl‐2‐(methylthio) propionaldehyde O‐(methylcarbamoyl)oxime], aldicarb sulfoxide [2‐methyl‐2‐(methylsulfinyl)propionaldehyde O‐(methylcarbamoyl)oxime], and aldicarb sulfone [2‐methyl‐2‐(methylsulfonyl)propionaldehyde O‐(methylcarbamoyl) oxime] in a sandy loam soil were determined under varying pH and temperature conditions. The experiments were performed using a soil‐column methodology, which allows a steady state water flow and nonsteady state addition of pesticide. The edition curve (concentration vs. time) was interpreted using analytical solutions to the convection‐dispersion equation that included linear sorption and pseudo‐first‐order degradation. The sorption of the three species changes slightly with pH over the range studied (pH 5–8).The degradation varies with pH, but not in the same manner as found in aqueous solution studies. Sorption decreases as the temperature is increased from 15 to 35°C. Degradation is also temperature dependent in this range and for aldicarb sulfone can be represented by a linear Arrhenius plot from which activation energies can be derived. There is good agreement between the calculated activation energy for aldicarb sulfone and that obtained in aqueous solution studies. The results of this study have provided information about the thermodynamics of the aldicarb system and have demonstrated the usefulness of the soil‐column flow method as a good laboratory model for chemical transport and transformation in soil.

Movement and degradation of aldicarb residues in South Carolina loamy sand soil

The movement and degradation of aldicarb (2-methyl-2-(methylthio)propionaldehyde O-(methylcarbamoyl)oxime) residues was measured in a Dotham loamy sand soil in Barnwell County in southern South Carolina. The experiment was designed to compare movement in a fallow plot versus a soya bean plot and to compare residue results from soil suction lysimeters and soil samples. The soil sample data indicate that aldicarb degraded at a rate corresponding to a half life of approximately 9 days with essentially no residues present 4 months after application. This degradation rate is faster than the 14–39-day half-life measured in nearby states. Because this relatively rapid degradation rate generally constrained residue movement to the upper 0.3 m in both plots (resulting in no significant residues in the lysimeters and monitoring wells), comparison between data from soil cores and suction lysimeters was not possible and the reduced evapotranspiration in the fallow plot had little effect on residue movement. Simulations using the unsaturated zone model PRZM with rainfall records from 15 years were used to illustrate that aldicarb residues should be limited to the upper 1.5 m, regardless of year-to-year variations in rainfall.