Degradation Of Chlorpyrifos In Soil Research Articles

Comparison of peroxodisulfate and peroxymonosulfate activated by microwave for degradation of chlorpyrifos in soil: Effects of microwaves, reaction mechanisms and degradation products

The combination of microwave (MW) and persulfate (PS, including peroxodisulfate (PDS) and peroxymonosulfate (PMS)) has been proved to be a potential method for degradation of organic pollutant. In this study, the degradation of chlorpyrifos (CPF) in soil by MW/PDS and MW/PMS was investigated. As a result, a synergistic effect was created between MW and PS. Compared with conventional heating (CH) providing thermal effect, MW also played a special non-thermal effect for PDS activation, causing superior CPF degradation by MW/PDS. However, the similar degradation efficiency of CPF in MW/PMS system and CH/PMS system indicated mainly a thermal effect was played by MW in MW/PMS system. The generation of reactive oxygen species (ROS) was explored in detail, SO4•− and •OH, generated in water, was the main ROS in MW/PDS system, and 1O2, generated in soil/water interface, was the main ROS in MW/PMS system. 100:1 of PS to CPF molar ratio, 1:1 of water and soil mass ratio were selected as appropriate reaction conditions. Environmental factors including pH and humic acid showed different effects on CPF degradation in MW/PDS system and MW/PMS system. Moreover, the degradation products were different due to different selectivity of ROS, reaction pathways were predicted based on Gaussian calculation and detected products. In addition, toxicity prediction, energy estimation and the applicability in different types of soils were investigated for practical significance of CPF degradation by MW/PS. Therefore, MW/PS provides a promising approach for remediation of CPF-contaminated soils.

Comparison of Mw/Pds System and Mw/Pms System for Degradation of Chlorpyrifos in Soil: Mechanism and Products

Comparison of Mw/Pds System and Mw/Pms System for Degradation of Chlorpyrifos in Soil: Mechanism and Products

Degradation of chlorpyrifos in soil using laccase immobilized iron oxide nanoparticles and their competent role in deterring the mobility of chlorpyrifos.

Covalent-immobilization of the laccase enzyme onto the iron oxide nanoparticles was achieved using N-(3-Dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDAC) as cross-linkers. The presence of sulphur moeity in the laccase immobilized nanoparticles (LNPs) observed through Scanning Electron Microscopy- Energy dispersive X-ray spectroscopy (SEM-EDS) spectra confirmed the immobilization of laccase enzyme. The TEM analysis of iron oxide nanoparticles (FNPs), chitosan coated iron nanoparticles (CNPs) and laccase immobilized nanoparticles (LNPs) confirmed their sizes around 12, 15 and 20nm, respectively. The effect of LNPs in degrading chlorpyrifos under field conditions was studied by simulating the conditions in a column. Column A, which was used as control showed more leaching of chlorpyrifos as compared to column B containing LNPs. The sorption coefficient (Kd) value obtained for control (column A) and LNPs containing column B were 21.6 and 112.3L/kg, respectively. LNPs altered the Kd values of soil thereby showing lesser leaching potential. Higher the Kd value, lesser will be the leaching potential in the ground water. Copper in laccase enzyme resulted in hydrolysis of chlorpyrifos. Chitosan used for coating on FNPs and soil organic matter resulted in the adsoption of chlorpyrifos. Current results will allow a better assessment of the role of LNPs as a competent deterrent in chlorpyrifos mobility and degradation.

Zn2+ and Cd2+ assisted photo-catalytic degradation of chlorpyrifos in soil

The Cd2+ and Zn2+ assisted photo-catalytic degradation of soil incorporated chlorpyrifos (CLP) was reported in current study. The soil samples fortified with CLP and metals were irradiated in photo-reactor for different time intervals to check maximum degradation. Soil samples extracted with acetonitrile were analyzed by HPLC. The results of the study revealed a complete mineralization of insecticide from soil that followed first–order Langmuir-Hinshelwood (L-H) kinetic model. The CLP degradation rate in soil was higher in photoreactor than control with variation in half-life from 41 days to 20 days. The degradation of CLP in photoreactor was 5 fold augmented after Zn2+ fortification of soil while Cd2+ had negligible effect on CLP photodegradation. Thus Zn2+ fortification of soil will not only replenish the important nutrient for plant growth but will also help in alleviating the harmful effects of CLP on soil flora and fauna by enhancing its rate of photodegradation.

Use of okara in the bioremediation of chlorpyrifos in soil: Effects on soil biochemical properties

The main objective of this manuscript was to study the bioremediation capacity of okara (a byproduct of soy milk production) in soils contaminated by organic xenobiotics. To this aim, and under controlled laboratory conditions, a soil was contaminated with chlorpyrifos insecticide at a dose of 5lha−1. Okara was added to this contaminated soil in two different manners: (1) pure okara (Op); and (2) a biostimulant/biofertilizer made from pure okara using the pH-stat technique. Several enzymatic activities (dehydrogenase, urease, β-glucosidase and phosphatase) and the evolution of the insecticide in soil were studied over an 80-day period. The results suggested that both forms of okara stimulated soil microorganisms and accelerated the degradation of chlorpyrifos in soil. It was, however, the biostimulant/biofertilizer that showed the greatest acceleration in insecticide degradation, possibly due to its higher content in low molecular weight (<300Da) peptides, easily available to soil microorganisms.

Bacterial community analysis in chlorpyrifos enrichment cultures via DGGE and use of bacterial consortium for CP biodegradation.

The organophosphate pesticide chlorpyrifos (CP) has been used extensively since the 1960s for insect control. However, its toxic effects on mammals and persistence in environment necessitate its removal from contaminated sites, biodegradation studies of CP-degrading microbes are therefore of immense importance. Samples from a Pakistani agricultural soil with an extensive history of CP application were used to prepare enrichment cultures using CP as sole carbon source for bacterial community analysis and isolation of CP metabolizing bacteria. Bacterial community analysis (denaturing gradient gel electrophoresis) revealed that the dominant genera enriched under these conditions were Pseudomonas, Acinetobacter and Stenotrophomonas, along with lower numbers of Sphingomonas, Agrobacterium and Burkholderia. Furthermore, it revealed that members of Bacteroidetes, Firmicutes, α- and γ-Proteobacteria and Actinobacteria were present at initial steps of enrichment whereas β-Proteobacteria appeared in later steps and only Proteobacteria were selected by enrichment culturing. However, when CP-degrading strains were isolated from this enrichment culture, the most active organisms were strains of Acinetobacter calcoaceticus, Pseudomonas mendocina and Pseudomonas aeruginosa. These strains degraded 6-7.4 mg L(-1) day(-1) of CP when cultivated in mineral medium, while the consortium of all four strains degraded 9.2 mg L(-1) day(-1) of CP (100 mg L(-1)). Addition of glucose as an additional C source increased the degradation capacity by 8-14 %. After inoculation of contaminated soil with CP (200 mg kg(-1)) disappearance rates were 3.83-4.30 mg kg(-1) day(-1) for individual strains and 4.76 mg kg(-1) day(-1) for the consortium. These results indicate that these organisms are involved in the degradation of CP in soil and represent valuable candidates for in situ bioremediation of contaminated soils and waters.

Soil bacterial and fungal community successions under the stress of chlorpyrifos application and molecular characterization of chlorpyrifos-degrading isolates using ERIC-PCR

Chlorpyrifos is a widely used insecticide in recent years, and it will produce adverse effects on soil when applied on crops or mixed with soil. In this study, nested polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) were combined to explore the bacterial and fungal community successions in soil treated with 5 and 20 mg/kg of chlorpyrifos. Furthermore, isolates capable of efficiently decomposing chlorpyrifos were molecular-typed using enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR). Under the experimental conditions, degradation of chlorpyrifos in soil was interpreted with the first-order kinetics, and the half-lives of chlorpyrifos at 5 and 20 mg/kg doses were calculated to be 8.25 and 8.29 d, respectively. DGGE fingerprint and principal component analysis (PCA) indicated that the composition of the fungal community was obviously changed with the chlorpyrifos treatment, and that samples of chlorpyrifos treatment were significantly separated from those of the control from the beginning to the end. While for the bacterial community, chlorpyrifos-treated soil samples were apparently different in the first 30 d and recovered to a similar level of the control up until 60 d, and the distance in the PCA between the chlorpyrifos-treated samples and the control was getting shorter through time and was finally clustered into one group. Together, our results demonstrated that the application of chlorpyrifos could affect the fungal community structure in a quick and lasting way, while only affecting the bacterial community in a temporary way. Finally, nine typical ERIC types of chlorpyrifos-degrading isolates were screened.

Study on the Degradation of Chlorpyrifos by Immobilized &lt;i&gt;Bacillus&lt;/i&gt;

Pesticide pollutions have become increasingly severe. Especially the extensive production and application of chlorpyrifos have resulted in the environmental pollution and ecological damage. The employment of the immobilized microorganism degradation of chlorpyrifos in soil is a kind of effective technology without secondary pollution. The best ratio of immobilized carrier has been determined by comparison among different carriers for chlorpyrifos degradation. Based upon the adoption of Bacillus LLBD4, pH value, temperature and initial concentration of chlorpyrifos were studied in this experiment. The results showed that the combination of 10% of PVC, 1% of activated carbon and 0.5% sodium alginate can be served as the best carrier, furthermore, chlorpyrifos degradation efficiency reached the peak when the pH was set to 7.0, the initial concentration of chlorpyrifos was 100 mg·L-1at 30°C, reaching about 83%.

Plasmid-mediated bioaugmentation for the degradation of chlorpyrifos in soil

To overcome the poor survival and low activity of the bacteria used for bioremediation, a plasmid-mediated bioaugmentation method was investigated, which could result in a persistent capacity for the degradation of chlorpyrifos in soil. The results indicate that the pDOC plasmid could transfer into soil bacteria, including members of the Pseudomonas and Staphylococcus genera. The soil bacteria acquired the ability to degrade chlorpyrifos within 5 days of the transfer of pDOC. The efficiency of the pDOC transfer in the soil, as measured by the chlorpyrifos degradation efficiency and the most probable number (MPN) of chlorpyrifos degraders, was influenced by the soil temperature, moisture level and type. The best performance for the transfer of pDOC was observed under conditions of 30°C and 60% water-holding capacity (WHC). The results presented in this paper show that the transfer of pDOC can enhance the degradation of chlorpyrifos in various soils, although the degradation efficiency did vary with the soil type. It may be concluded that the introduction of plasmids encoding enzymes that can degrade xenobiotics or donor strains harboring these plasmids is an alternative approach in bioaugmentation.

Salinity effects on chlorpyrifos degradation and phosphorus fractionation in reclaimed coastal tideland soils

We examined the effect of soil salinity on the degradation of chlorpyrifos and the residual effect of chlorpyrifos and its metabolites on soil P fractionation during 60-day aerobic incubation. A sandy loam soil (Typic Psammaquents) was collected from the Daeho reclaimed tideland and two-thirds of the soil was applied with Na salt to get three different soil salinity levels: 4.6 (low, EL), 9.7 (medium, EM), and 14.4 (high, EH) dS m−1. Estimated half-lives for chlorpyrifos degradation were 7.1 in EL, 10.0 in EM and 16.9 days in EH soils. During the degradation of chlorpyrifos in soil, microbial activity decreased by increasing soil salinity and its inhibitory effect increased with time. In contrast, the addition of chlorpyrifos did not inhibit soil alkaline phosphatase (SAP) activity, which was higher in EH than in control soils. Chlorpyrifos added at a rate of 5.0 mg a.i. kg−1 dry soil did not affect the distribution pattern of P fractions in control soils. Both an increase in soil salinity and soil sterilization increased the Ca-bound P fraction and decreased the occluded Fe + Al-bound P fraction with a significant interaction between soil salinity and sterilization. With time, the Ca-bound P fraction increased and organic- and occluded Fe + Al-bound P fractions decreased, while total-P, available-P, and non-occluded + adsorbed P fraction remained unchanged. Particularly, organic-P was mineralized more in EH than in control soils and the Ca-bound P fraction contained the highest inorganic P released. Mineralization of organic P and partitioning of released P in the recalcitrant Ca-bound P fraction increased by increasing soil salinity, while available P fraction remained unchanged, suggesting that the addition of chlorpyrifos at the currently recommended dosage level did not seem to considerably affect the available P fraction with low P leaching potential to waterways.

Starch-encapsulated chlorpyrifos: release rate, insecticidal activity and degradation in soil

Incorporation of chlorpyrifos into starch matrices was achieved by thermal gelatinization. The level of amylose content in the starch matrices (10 and 52%) and the addition of auxiliary agents, i.e. solvent, emulsifiers or both, were varied and eight different formulations were prepared. According to differential scanning calorimetry (DSC) and X-ray diffraction measurements, chlorpyrifos was partly present in a crystalline form in all the starch formulations. The formulations had controlled release properties, and the release rate into water could be described by a linear model. In a bioassay, the formulations killed all larvae of the cabbage root fly at a dosing of 1.4 kg a.i. per ha. The degradation of chlorpyrifos in soil from the starch formulations could be described in a nonlinear logistic model and the half-life was predicted to be 88 days. Differences in the amount of amylose in the starch as well as the addition of solvent and emulsifiers in the preparation procedure had no systematic influence on the release rate, the insecticidal effect and the degradation rate. No correlation between release rate into water and degradation in soil could be established. Two commercial chlorpyrifos formulations Lorsban#174; 15 G (granular) and Cyfos#174; 500 gl -1 (emulsifiable concentrate), were included in the study for comparison.

Factors Affecting the Hydrolytic Degradation of Chlorpyrifos in Soil

The abiotic hydrolysis of the organophosphorus insecticide chlorpyrifos was examined in 37 different soils, which were chosen to represent a wide variety of physicochemical characteristics (e.g., pH 3.8−8.5). Samples of soil were sterilized via γ-irradiation, treated with [14C]chlorpyrifos at 10 μg/g, and incubated under standardized conditions (25 °C, field moisture capacity, darkness) for up to 4 months. Chlorpyrifos hydrolysis proceeded at a slow rate (<0.008 day-1) in acidic soils (pH ≤ 7). In alkaline soils, however, hydrolytic rate constants varied greatly (0.004−0.063 day-1). Corresponding hydrolytic half-lives for acidic and alkaline soils ranged from 92 to 341 and 11 to 200 days, respectively. Correlation analyses indicated that soil pH was the independent variable displaying the strongest association with hydrolytic rate constant (r = 0.55), but multiple regression models based on combinations of this parameter with other soil properties, including phosphatase enzyme activities, did not offer strongly predictive models for explaining the variability in kinetics observed (best fit r2 = 0.59). Incubation of chlorpyrifos with both sterile and nonsterile soils revealed that although both microbial and hydrolytic mechanisms contributed to chlorpyrifos degradation in all soils, there were clearly soils in which hydrolysis constituted the major route of degradation. Chlorpyrifos hydrolysis was greatly accelerated under low moisture conditions, both in acidic and alkaline soils. Additional experiments in several soils that displayed rapid chlorpyrifos hydrolysis at 10 μg/g provided evidence that the hydrolytic reaction was inhibited at higher concentration (1000 μg/g). Results highlight the importance but also the complex nature of the hydrolytic breakdown of chlorpyrifos in soil. Under certain conditions (e.g., some alkaline soils, air-dry soils) hydrolysis may be the driving factor modulating chlorpyrifos persistence. Keywords: Chlorpyrifos; soil; hydrolysis; degradation

Chlorpyrifos degradation in soil at termiticidal application rates

AbstractChlorpyrifos [O,O‐diethyl O‐(3,5,6‐trichloro‐2‐pyridyl) phosphorothioate] is an organophosphorus insecticide applied to soil to control pests both in agricultural and in urban developments. Typical agricultural soil applications (0.56 to 5.6 kg ha−1) result in initial soil surface residues of 0.3 to 32 μg g−1. In contrast, termiticidal soil barrier treatments, a common urban use pattern, often result in initial soil residues of 1000 μg g−1 or greater. The purpose of the present investigation was to understand better the degradation of chlorpyrifos in soil at termiticidal application rates and factors affecting its behaviour. Therefore, studies with [14C]chlorpyrifos were conducted under a variety of conditions in the laboratory. Initially, the degradation of chlorpyrifos at 1000 μg g−1 initial concentration was examined in five different soils from termite‐infested regions (Arizona, Florida, Hawaii, Texas) under standard conditions (25°C, field moisture capacity, darkness). Degradation half‐lives in these soils ranged from 175 to 1576 days. The major metabolite formed in chlorpyrifos‐treated soils was 3,5,6‐trichloro‐2‐pyrid‐inol, which represented up to 61% of applied radiocarbon after 13 months of incubation. Minor quantities of [14C]carbon dioxide (&lt; 5%) and soil‐bound residues (⩽ 12%) were also present at that time. Subsequently, a factorial experiment examining chlorpyrifos degradation as affected by initial concentration (10, 100, 1000 μg g−1), soil moisture (field moisture capacity, 1.5 MPa, air dry), and temperature 15, 25, 35°C) was conducted in the two soils which had displayed the most (Texas) and least (Florida) rapid rates of degradation. Chlorpyrifos degradation was significantly retarded at the 1000 μg g−1 rate as compared to the 10 μg g−1 rate. Temperature also had a dramatic effect on degradation rate, which approximately doubled with each 10°C increase in temperature. Results suggest that the extended (3–24 + years) termiticidal efficacy of chlorpyrifos observed in the field may be due both to the high initial concentrations employed (termite LC 50 = 0.2– 2 μg g−1) and the extended persistence which results from employment of these rates. The study also highlights the importance of investigating the behaviour of a pesticide under the diversity of agricultural and urban use scenarios in which it is employed.

Degradation of Chlorpyrifos in Soil: Influence of Autoclaving, Soil Moisture, and Temperature1

The decomposition of 14C-ring-labeled chlorpyrifos was followed in 2 soils for a 32-week period under laboratory conditions at 25°C. Time required for 50% loss of parent compound in Chehalis clay loam and Sultan silt loam was 4 and 12 weeks, respectively. Faster breakdown of the insecticide in the clay loam was due to microbial degradation since initial halflives of 24 weeks were observed in both autoclaved soils. Radioactivity from degraded chlorpyrifos was recovered as 3,5,6-trichloro-2-pyridinol, as expired CO2, and as a nonextractable soil-bound residue component. After 32 weeks, 47% of the radioactivity from degraded insecticide were recovered as CO2 in the clay loam as compared to only 8% in the silt loam. Temperature had a pronounced effect on the decay rate of chlorpyrifos in Sultan silt loam during a 24-week incubation period at 15°, 25°, and 35°C; initial half-lives were 25, 13, and 6 weeks, respectively. Soil moisture contents ranging from 3–20% did not affect insecticide degradation rates in the Sultan silt loam.