Degradation of 14C-carbofuran in soil using a continuous flow system

Degradation and Persistence of Carbofuran in Peanut and Soil in Field Trails as Determined by GC-MS

This paper investigated the analytical method of degradation and persistence of carbofuran, its metabolite 3-hydroxy carbofuran in peanut seeds, fronds and soils in field trial using gas chromatography mass spectrometry (GC-MS). Carbofuran 3GR formulation (3g a.i./100g) was applied at dosages of 2250 and 3375g ha-1in furrow at sowing peanut seeds in the fields of Langfang, Hebei province and Jinan, Shandong province, China, respectively. The soil and the plant samples were collected at different intervals and the residues of carbofuran and 3-hydroxy carbofuran were analyzed by GC-MS. The degradation kinetic result showed that the degradation of carbofuran in peanut fronds in Jinan and Langfang can be well predicted with equation: C=1.2839e-0.1733tand C=0.5731e-0.1567t, with a half-life about 4.0 and 4.4 days respectively. For the degradation of carbofuran in soils, the result coincides well with equations: C= 4.2057e-0.2229t, and C= 5.4014e-0.1499t, with half-life of 3.1 and 4.6 days for Jinan and Langfang, respectively. The pH, organic matter and clay content as well as the climatic temperature play an important role in the degradation of carbofuran in soils. 3-hydroxy carbofuran dissipated rapidly both in peanut fronds and soils, it was not detectable 7 days after treatment for all treatment, the concentration of carbofuran and 3-hydroxy carbofuran in peanut seeds at harvest time were lower than either the maximum residue limit in China or the EUs maximum residue limit of 0.1 mg kg1. Based on the data from this investigation, the use of carbofuran in peanut could be considered to be safe.

Batch Study for Insecticide Carbofuran Adsorption onto Palm-Oil-Fronds-Activated Carbon

The adsorption of insecticide, carbofuran from aqueous solution onto activated carbon derived from palm oil fronds (PFAC) was investigated through batch study. The effects of both initial concentration and pH of the carbofuran over the range of 25 to 250 mg/L and 2 to 12, respectively, on the adsorption of the prepared PFAC were studied in batch experiments. Equilibrium data were fitted to the Langmuir, the Freundlich, and the Temkin isotherm models. The results obtained from application of these models show that the best fits were achieved with the Langmuir model, and a maximum monolayer adsorption capacity of 164 mg/g was obtained at 30°C. The regeneration efficiency of spent activated carbon was studied and it was found to be 90.0–96.4%. The results indicated that PFAC has good capability as adsorbent for the removal of carbofuran from aqueous solutions.

Bioremediation of carbofuran contaminated soil under saturated condition: soil column study

Disturbed soil columns, 5.8 cm in diameter and 25 cm in length, were used as a basic model to simulate the movement of carbofuran in rice field soil under saturated conditions. Bioaugmentation using a specific carbofuran degrader, Burkholderia sp. PCL3, in free and immobilized cell forms and biostimulation using rice straw as organic amendment were applied with the aim of enhancing the degradation of carbofuran in soil and to prevent the movement of carbofuran along with the flow through. In the abiotic control and the treatment with only indigenous microorganisms, the mass recovery percentage of carbofuran in the effluent was 52.1 and 22.5%, respectively. The application of bioaugmentation or biostimulation significantly enhanced carbofuran degradation in soil and reduced the movement of carbofuran as indicated by a low mass recovery percentage of carbofuran in the effluent of 14.6-15.5%. A low efficiency of carbofuran removal was obtained from the soil column with bioaugmentation together with biostimulation treatments in which the mass recovery percentage of carbofuran in the effluent was in the range of 22.1-22.6%. Sorption of carbofuran to soil, rice straw and corncob, formation of carbofuran metabolite and colony forming unit (CFU) and pH variation with the time were also investigated during column operation.

Electron spin resonance. Part two: a diagnostic method in the environmental sciences

A review is presented of some of the ways in which electron spin resonance (ESR) spectroscopy may be useful to investigate systems of relevance to the environmental sciences. Specifically considered are: quantititave ESR, photocatalysis for pollution control; sorption and mobility of molecules in zeolites; free radicals produced by mechanical action and by shock waves from explosives; measurement of peroxyl radicals and nitrate radicals in air; determination of particulate matter polyaromatic hydrocarbons (PAH), soot and black carbon in air; estimation of nitrate and nitrite in vegetables and fruit; lipid-peroxidation by solid particles (silica, asbestos, coal dust); ESR of soils and other biogenic substances: formation of soil organic matter carbon capture and sequestration (CCS) and no-till farming; detection of reactive oxygen species in the photosynthetic apparatus of higher plants under light stress; molecular mobility and intracellular glasses in seeds and pollen; molecular mobility in dry cotton; characterisation of the surface of carbon black used for chromatography; ESR dating for archaeology and determining seawater levels; measurement of the quality of tea-leaves by ESR; green-catalysts and catalytic media; studies of petroleum (crude oil); fuels; methane hydrate; fuel cells; photovoltaics; source rocks; kerogen; carbonaceous chondrites to find an ESR-based marker for extraterrestrial origin; samples from the Moon taken on the Apollo 11 and Apollo 12 missions to understand space-weathering; ESR studies of organic matter in regard to oil and gas formation in the North Sea; solvation by ionic liquids as green solvents, ESR in food and nutraceutical research.

Study on the downward movement of carbofuran in two Malaysian soils

The downward movement of carbofuran in two Malaysian soil types was studied using soil columns. The columns were filled with disturbed and undisturbed soils of either the Bagan Datoh soil (clay) or the Labu soil (sandy clay). The average total percentage of carbofuran in the leachate of the undisturbed Labu soil after 14 days of watering (80.8%) was approximately similar to that of the total amount from the disturbed soil (81.4%). However, carbofuran leaching was observed in the disturbed soil after the fourth day of watering whereas for the undisturbed soil, leaching occurred after the first watering. A similar trend was observed in the Bagan Datoh soil where the residue of carbofuran was detected after the first day of watering in the undisturbed soil column but only at the eighth day of watering in the disturbed soil column. The total percentage carbofuran in the leachate of disturbed and undisturbed soil columns from Bagan Datoh after 14 days of watering was 3.6% and 41.7%, respectively. The study showed that less leaching occurred in soil columns with high organic content such as the Bagan Datoh soil and especially so in disturbed soils where the organic matter was homogeneously mixed in all layers.

Formation of pesticide nonextractable (bound) residues in soil: magnitude, controlling factors and reversibility

The analysis of the coherent data on nonextractable (bound) residues (NER) from the literature and EU pesticide registration dossiers allows the identification of general trends, in spite of the large variability and heterogeneity of data. About 50% of the pesticides reviewed exhibit a low proportion of NER (less than 30% of the initial amount) while only 12% of pesticides have a proportion of NER exceeding 70%. The lowest proportion of NER was found for dinitroanilines (<20%), and the largest value was obtained for carbamates, and in particular dithiocarbamates. The presence of chemical reactive groups, such as aniline or phenol, tends to yield a larger proportion of NER. NER originating from N-heteroatomic ring were found to be lower than those from phenyl-ring structures. Among the environmental factors affecting the formation of NER, microbial activity has a direct and significant effect. Concerning the NER uptake or their bioavailability, consistent data suggest that only a small percentage of the total amounts of NER can be released. The analysis of NER formation kinetics showed that incubation experiments are often stopped too early to allow a correct evaluation of the NER maturation phase. Therefore, there is a need for longer term experiments to evaluate the tail of the NER formation kinetics. Still, the heterogeneity of the NER data between pesticides and for specific pesticides calls for great care in the interpretation of the data and their generalization.

Determination of carbosulfan and its metabolites in oranges by liquid chromatography ion-trap triple-stage mass spectrometry

Liquid chromatography ion-trap mass spectrometry LC-MSn has been successfully applied to identify and confirm carbosulfan and seven of its metabolites in oranges after pressurized liquid extraction (PLE) with dichloromethane. Mass spectra of carbosulfan and its metabolites were investigated using multiple stages of mass spectrometry. Although interpretation of the fragmentation pathways, based on mass spectra, enables structural elucidation and identification of these compounds, the proposed fragmentation pathways and ion structures need verification by exact mass measurements. The analytical method--PLE and LC-MS3 --was validated: limits of quantification (LOQ) ranged from 0.01 to 0.07 mg kg(-1); at this level, recoveries were 55-90% with RSDs (five replicate analyses) from 8 to 19%. The degradation of carbosulfan was determined in a laboratory study carried out in mature oranges (Valencia Late) and tangerines (Clementine of Nules) already harvested. Main degradation products of carbosulfan were carbofuran, 3-hydroxycarbofuran, 3-ketocarbofuran and dibutylamine.