Determination and identification of metabolites of the fungicides Iprodione and Procymidone in compost

Compound-Specific Isotope Analysis Provides Direct Evidence for Identifying the Source of Residual Pesticides Diazinon and Procymidone in the Soil-Plant System

Compound-specific isotope analysis stands as a promising tool for unveiling the behavior of pesticides in agricultural environments. Using the commercial formulations of persistent fungicide procymidone (PRO) and less persistent insecticide diazinon (DIA), respectively, we analyzed the concentration and carbon isotope composition (δ13C) of the residual pesticides through soil incubation experiments in a greenhouse (for 150 days) and lab conditions (for 50-70 days). Our results showed that the magnitude of δ13C variation depends on pesticide specificity, in which PRO in the soil exhibited little variation in δ13C values over the entire incubation times, while DIA demonstrated an increased δ13C value, with the extent of δ13C variability affected by different spiking concentrations, plant presence, and light conditions. Moreover, the pesticides extracted from soils were isotopically overlapped with those from crop lettuce. Ultimately, the isotope composition of pesticides could infer the degradation and translocation processes and might contribute to identifying the source(s) of pesticide formulation in agricultural fields.

Developmental toxicity of procymidone to larval zebrafish based on physiological and transcriptomic analysis

As a broad-spectrum with low toxicity, procymidone (PCM), is widely used in agriculture and frequently observed in aquatic system, which may cause some impacts on aquatic organisms. Here, to determine the developmental toxicity of PCM, embryonic and larval zebrafish were exposed to PCM at 0, 1, 10, 100 μg/L in dehydrogenated natural water containing 0.01% acetone for 7 days. The results showed that high concentration of PCM could cause the pericardial edema and increase the heart rates in larval zebrafish, suggesting that PCM had developmental toxicity to zebrafish. We also observed that PCM exposure not only changed the physiological parameters including TBA, GLU and pyruvic acid, but also changed the transcriptional levels of glycolipid metabolism related genes. In addition, after transcriptomics analysis, a total of 1065 differentially expressed genes, including 456 up-regulated genes and 609 down-regulated genes, changed significantly in 100 μg/L PCM treated larval zebrafish. Interestingly, after GO (Gene Ontology) analysis, the different expression genes (DEGs) were mainly enriched to the three different biology processes including GABA-nervous, lipid Metabolism and response to drug. We also observed that the levels of GABA receptor related genes including gabrg2, gabbr1α, gabbr1 and gabra6α were inhibited by PCM exposure. Interestingly, the swimming distance of larval zebrafish had the tendency to decrease after PCM exposure, indicating that the nervous system was affected by PCM. Taken together, the results confirmed that the fungicide PCM could cause developmental toxicity by influencing the lipid metabolism and GABA mediated nervous system and behavior in larval zebrafish. We believed that the results could provide an important data for the influence of PCM on aquatic animals.

Enhancement of dicarboximide fungicide degradation by two bacterial cocultures of Providencia stuartii JD and Brevundimonas naejangsanensis J3

Bioremediation is commonly conducted by microbial consortia rather than individual species in natural environments. Biodegradation of dicarboximide fungicides in brunisolic soil were significantly enhanced by two bacterial cocultures of Providencia stuartii JD and Brevundimonas naejangsanensis J3. The cocultures degraded 98.42 %, 95.44 %, and 96.81 % of 50 mg/L dimethachlon, iprodione, and procymidone in liquid culture within 6 d respectively, whose efficiency was 1.23 and 1.26, 1.25 and 1.23, and 1.24 and 1.24 times of strains JD and J3, respectively. The cocultures could effectively degrade dimethachlon, iprodione and procymidone to simple products. Moreover, the cocultures immobilized in a charcoal-alginate-chitosan carrier obviously surpassed free cocultures in terms of degradability, stability and reusability. In the field brunisolic soils treated by immobilized cocultures, 96.74 % of 20.25 kg a.i./ha dimethachlon, 95.02 % of 7.50 kg a.i./ha iprodione and 96.27 % of 7.50 kg a.i./ha procymidone were degraded after 7 d, respectively. Moreover, the lower half-lifes (1.53, 1.59 and 1.57 d) by immobilized cocultures were observed, as compared to free cocultures (3.60, 4.03 and 3.92 d) and natural dissipation (21.33, 20.51 and 20.09 d). This study highlights that strains JD and J3 have significant synergetic degradation advantages in rapid bioremediation of dicarboximide fungicide contamination sites.

Pesticide residues in soils planted with Panax notoginseng in south China, and their relationships in Panax notoginseng and soil

In this study, 73 samples from soils planted with Panax notoginseng and six P. notoginseng samples were collected in Yunnan Province to investigate the residual levels of six pesticides and their relationships with P. notoginseng and soil. All six pesticides were detected in the soils planted with P. notoginseng located in three regions of Shilin, Kaiyuan, and Yanshan. The detection frequencies of the pesticides in the soils followed the order: quintozene (100%) > iprodione (96%) > procymidone (69%) > chlorothalonil (51%) > pyrimethanil (49%) > pyraclostrobin (29%). The median concentrations of iprodione, pyraclostrobin, pyrimethanil, quintozene, procymidone, and chlorothalonil were 46.40, 6.4, 3.1, 2.86, 2.69, and 0.24 μg/kg, respectively. The mean concentrations of pesticides in the three regions followed the order: Kaiyuan > Shilin > Yanshan, except for iprodione. Furthermore, the concentrations of pesticide residues in soils in each region followed the order: soils never planted with P. notoginseng < soils previously planted with P. notoginseng < soils currently planted with P. notoginseng. The concentration of chlorothalonil in P. notoginseng followed the order: root > stem > leaf, whereas those of the other five pesticides followed the opposite order: root < stem < leaf. There were significant positive correlations between the mean concentrations of pesticides in P. notoginseng and those in the corresponding soils. These results indicate that the rational application of pesticides in P. notoginseng cultivation would be effective for reducing the accumulation of pesticides in P. notoginseng to protect people from the harmful effects of residual pesticides.

Comparative catalytic degradation of a metabolite 3,5-dichloroaniline derived from dicarboximide fungicide by laccase and MnO2 mediators

A ternary catalysis system was investigated to evaluate the comparative degradation of toxic fungicide metabolite 3,5-dichloroaniline (3,5-DCA) by laccase and MnO₂ with mediators. In this study, copper based fungal enzyme laccase (Trametes versicolor origin) and metal catalyst MnO₂ with various combinations of phenolic mediators (catechol, syringaldehyde, syringic acid, caffeic acid and gallic acid) were monitored to optimize and screen the better one for 3,5-DCA degradation assay. Catechol showed better potentiality in reduction of 3,5-DCA among the studied mediators. Catechol (2mM) showed the highest reduction rate (99-100%) followed by syringaldehyde (40.51%) with 2U/mL of laccase at 25 °C within 24 h reaction time. Similarly, complete degradation of 3,5-DCA was obtained by catechol (2mM) with 2 mg/mL of MnO₂ in MnO₂-mediator assay. The notable finding of current study indicated the triggering of catechol for better 3,5-DCA degradation at higher pH condition but inertness in laccase-mediator assay due to laccase destabilization. The reaction pathways of optimized mediator-based catalysis for laccase and MnO₂ were proposed. Finally, the optimized laccase-catechol based degradation was considered as a pioneer green catalysis approach to reduce the toxic metabolite 3,5-DCA concentrations in aqueous medium as compared to MnO₂-catechol catalysis.

Bioaugmentation and rhizosphere-assisted biodegradation as strategies for optimization of the dissipation capacity of biobeds

Biobeds are on-farm biodepuration systems whose efficiency rely on their high pesticide biodegradation capacity. We evaluated two optimization strategies, bioaugmentation and/or rhizosphere-assisted biodegradation, to maximize the dissipation capacity of biobeds. Iprodione was used as a model pesticide. Its dissipation and metabolism was determined in a biobed packing material inoculated with an iprodione-degrading Arthrobacter strain C1 (bioaugmentation, treatments B+C1) and/or seeded with ryegrass (rhizosphere-assisted biodegradation, treatments B+P). The impact of those strategies on the activity and composition of the microbial community was determined. Bioaugmentation accelerated the dissipation of iprodione which was further enhanced in the bioaugmented, rhizosphere-assisted treatment (treatment B+P+C1, Half-life (DT₅₀) = 3.4 d), compared to the non-bioaugmented, non rhizosphere-assisted control (DT₅₀ = 9.5 d, treatment B). Bioaugmentation resulted in the earlier formation of intermediate formation of metabolites I (3,5-dichlorophenyl-carboxamide), II (3,5-dichlorophenylurea acetate) and 3,5-dichloroaniline (3,5-DCA). The latter was further dissipated by the indigenous microbial community. Acid phosphatase (AP) and β-glucosidase (GLU) were temporarily stimulated in rhizosphere-assisted treatments, whereas a stimulation of the fluorescein diacetate (FDA) hydrolytic activity in the bioaugmented treatments coincided with the hydrolysis of iprodione. q-PCR showed that changes in the abundance of alpha-proteobacteria and firmicutes was driven by the presence of rhizosphere while bioaugmentation had no significant effect.

Metabolism of fungicide 2-allylphenol in Rhizoctonia cerealis

2-Allylphenol is a biomimetic synthetic fungicide that mimics the compound ginkgol found in gingko fruit (Gingko biloba L.). This systemic fungicide can effectively suppress a wide range of plant diseases, including wheat sharp eyespot (Rhizoctonia cerealis). However, its degradation in environment after application is still unknown. To understand this fungicide degradation, major metabolites of 2-allylphenol in R. cerealis were examined. The parent and metabolites of 2-allylphenol were detected and quantified in the mycelia and liquid medium. Results showed that 2-allylphenol was metabolized and bio-transformed by R. cerealis, and four metabolites were found, including 2-(2-hydroxyphenyl) acetic acid (M1), 2-(2, 3-dihydroxypropyl) phenol (M2), 2-(2-hydroxypropyl)-phenol (M3) and 2-(3-hydroxypropyl)-phenol (M4). Based on the results, we propose that the biodegradation pathway is that 2-allylphenol is rapidly oxidized into metabolite M2 and hydrolyzed into M3 and M4, which formed M2, and carboxylation of M2 to 2-hydroxy-3-(2׳-hydroxyphenyl) propionic acid which undergo hydrolyzation and decarboxylation to form M1. 2-Allylphenol can be bio-transformed to new compounds by R. cerealis, suggesting the existence of microbe metabolic pathways for 2-allylphenol.

Ultraviolet degradation of procymidone--structural characterization by gas chromatography coupled with mass spectrometry and potential toxicity of photoproducts using in silico tests

RATIONALE

Procymidone is a dicarboximide fungicide mainly used for vineyard protection but also for different crops. The structural elucidation of by-products arising from the UV-visible photodegradation of procymidone has been investigated by gas chromatography coupled with mass spectrometry. The potential toxicities of photoproducts were estimated by in silico tests.

METHODS

Aqueous solutions of procymidone were irradiated for up to 90 min in a self-made reactor equipped with a mercury lamp. Analyses were carried out on a gas chromatograph coupled with an ion trap mass spectrometer operated in electron ionization and methanol positive chemical ionization. Multistage collision-induced dissociation (CID) experiments were performed to establish dissociation pathways of ions. Toxicities of byproducts were estimated using the QSAR T.E.S.T. program.

RESULTS

Sixteen photoproducts were investigated. Chemical structures were proposed mainly based on the interpretation of multistage CID experiments, but also on their relative retention times and kinetics data. These structures enabled photodegradation pathways to be suggested. Only three photoproducts remain present after 90 min of irradiation. Among them, 3,5-dichloroaniline presents a predicted rat LD50 toxicity about ten times greater than that of procymidone.

CONCLUSIONS

3,5-Dichloroaniline is the only photoproduct reported in previous articles. Eight by-products among the sixteen characterized might be as toxic, if not more, than procymidone itself considering the QSAR-predicted rat LD50.

Genistein and dicarboximide fungicides in infant formulae from the EU market

A method based on ultrasonic extraction and purification by solid phase extraction followed by LC-MS/MS and GC-MS analysis was developed for the determination of genistein, genistin, iprodione, vinclozolin and procymidone in infant powdered formulas. The method was tested for different formulations: milk, soy and hypoallergenic, and was applied to European pooled samples. Spike recoveries ranged from 53.1% to 91.5% and the relative standard deviation values for repeatability ranged from 9.6% to 17.7%, except for iprodione in milk formula (22.3%). None of the fungicides were found in the European pooled formulae, while genistein was found at 9.7μg/g in soy formula and the concentration of genistin, its β-glycosylated form, was respectively 31.4ng/g and 476ng/g in milk and soy formula.

Co-composting of oil exhausted olive-cake, poultry manure and industrial residues of agro-food activity for soil amendment

The co-composting of exhausted olive-cake with poultry manure and sesame shells was investigated. These organic solid wastes were watered by the confectionary wastewater which is characterized by its high content of residual sugars raising its COD. Four aerated windrows were performed to establish the effects of confectionary by-products on the compost process. Different mixtures of the agro-industrial wastes were used. During the composting process, physico-chemical parameters (temperature, moisture, pH, electrical conductivity, total carbon and total nitrogen) were studied. The stability of the biological system was noticed after 70 days. The final products were characterized by their relatively high organic matter content, and low C/N ratio of 14-17. The humidification of the windrows with the wastewater seemed to have accelerated the composting process in comparison to a windrow humidified with water. In addition, the organic matter degradation was enhanced to reach 55-70%. The application of the obtained composts to soil appeared to significantly improve the soil fertility. Indeed, field experiments showed an increase in potato yield; the production was 30.5-37.5 tons ha(-1), compared to 30.5 tons ha(-1) with farm manure.

Influence of humic substances on the photolysis of aqueous pesticide residues

The present work investigated the direct and indirect photolysis of pesticide residues (atrazine, imazaquin, iprodione), in aqueous solutions and under UV-visible radiation (280-480nm). Different kinds of humic substances (HS) were added to samples in order to evaluate their behaviour as possible photocatalysts and their effect on the photolysis of pesticides. The fulvic acids were purchased from the International Humic Substances Society, and they were added to samples in concentrations ranging from 1 to 150 mgl(-1). Titanium dioxide was used as the photocatalyst, in concentration ranging from 10 to 150 mgl(-1). Pesticides photolysis were measured by UV-visible absorption spectroscopy and differential pulse polarography with all used pesticides, reaching total degradation after 2h of irradiation, thus indicating a fast direct photolysis. Photocatalysis by TiO(2) could increase the pesticides photolysis rate up to 40%. This effect, however, was not observed for imazaquin photolysis. Again, except for imazaquin, HS presence showed a positive effect in increasing pesticide degradation, but only within specific concentration ranges (below 10mg l(-1) for iprodione and about 30mgl(-1) for atrazine). Above these ranges HS induce a decrease in the pesticides photolysis rate. Spin-trapping measurements by electronic paramagnetic resonance spectroscopy, using the spin-trap DMPO, showed that HS are able to photogenerate hydroxyl radicals, increasing the pesticides molecule degradation. However, the HS also react with the photogenerated hydroxyl radical, influencing the pesticide photolysis, leading to a decrease in the photolysis rate and causing it to be strongly dependent on the nature and concentration of residues in the water to be treated.

Estrogenic effect of procymidone through activation of MAPK in MCF-7 breast carcinoma cell line

Procymidone modifies sexual differentiation in vitro and induces estrogenic activity in primary cultured rainbow trout hepatocytes, as shown by an increase in the contents of vitellogenin and heat shock proteins. Since this dicarboximide fungicide is found in human tissues, it was considered of interest to investigate its ability to induce endocrine damage in the MCF-7 human cell line. The mechanism of this estrogenic action was also evaluated. Procymidone 100 microM stimulated cell growth from day 3 up to day 12 and raised the level of pS2 on day 3. Although procymidone does not bind the estrogen receptor (ER), the antiestrogen ICI 182780 inhibited its effect on cell growth and pS2 content, suggesting that the ER is involved indirectly in these effects. In exploring the mechanism of ER indirect activation we found that the antibody against c-Neu receptor (9G6) did not modify procymidone's effects on cell growth and pS2 expression. Thus, procymidone does not bind the c-Neu membrane receptor, excluding this indirect ER activation pathway. We also found that procymidone induced mitogen-activated protein kinase (MAPK) at 15 and 30 min, and that PD 98059, a MAPK (Erk1/2) inhibitor, prevented procymidone's effects on cell growth and pS2, indicating that MAPK activation is responsible for procymidone ER activation. The production of reactive oxygen species (ROS) with these times and elimination of the phenomenon by alpha-tocopherol (alpha-T), a ROS scavenger, is proof that oxygen free-radical production is at the basis of the MAPK activation by procymidone.

Degradation of pyrimethanil in soil: influence of light, oxygen, and microbial activity

The research was carried out in order to verify the influence that light, oxygen, and microbial activity have on the degradability of pyrimethanil (PYR) in soil. The products of degradation were also identified and their evolution in time evaluated. The results indicate that the molecule is more persistent in the absence of light, oxygen, and microbial activity. The order of importance of these three factors is as follows: light < microbial activity < oxygen. The following products of degradation were identified: (1) benzoic acid, (2) cis,cis-muconic acid, (3) hydroxyl-4,6-dimethyl-2-pirimidinamine, (4) N'-ethyl-N-hydroxyformamidine, and (5) 4,6-dimethyl-2-piridinamine, which appeared different from those reported in literature for the degradation of PYR in abiotic conditions. This result suggests that the degradation in soil is mainly biotic.