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1.
J Agric Food Chem ; 68(11): 3362-3371, 2020 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-32105463

RESUMO

Carbamazepine (CBZ) is an anticonvulsant pharmaceutical compound of environmental concern due to its persistence, bioactive toxicity, and teratogenic effects. Studies on the kinetics and metabolic pathways of CBZ in plant tissues are still limited. In the present study, the phytotransformation of 14C-CBZ was explored. The 14C detected in bound residues was lower than in extractable residues (>85% of the uptaken 14C radioactivity) in plant tissues. CBZ underwent appreciable transformation in plants. A large portion of accumulated 14C radioactivity (80.3 ± 6.4%) in the cells was distributed in the cell water-soluble fraction. A total of nine radioactive transformation products of CBZ were identified, three of which were generated in vivo due to the contraction of the heterocycle ring. The proposed metabolic pathways revealed that conjugation with glutathione or phenylacetic acid was the major transformation pathway of CBZ in plants, with the contribution of epoxidation, hydroxylation, methoxylation, methylation, amination, and sulfonation.

2.
Sci Rep ; 10(1): 491, 2020 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-31949272

RESUMO

Understanding the bioavailability and phytotoxicity of Carbendazim (MBC) bound residues (BR) in soils incubated with different Superabsorbent polymer (SAP) amendment on succeeding crops is essential to assess their environmental fate and risks. In our research, we studied the morphological characteristics and 14C-accumulation of Chinese cabbage and released BR in three typical cultivated soils. The plant dry weight was in order of superabsorbent-hydrogels formulations (HMBC) > MBC > MBC and SAP (MBC-SAP) at 35 d in basic soil 3 (S3), with 675.40 ± 29.07 mg/plant.d.w, 575.93 ± 25.35 mg/plant.d.w and 427.86 ± 18.79 mg/plant.d.w. The whole plant accumulated 2-fold more BR when grew in neutral soil 2 (S2) treated with SAP than MBC at 7 d. The root accumulated a greater proportion of 14C-MBC residue than shoot, with order of MBC-SAP > MBC > HMBC at 21d. The results indicate MBC-BR could be released and accumulated in plant. HMBC promoted the Chinese cabbage growth with lowest 14C accumulation, while MBC-SAP inhibited plant growth with the highest 14C uptake. The released BR rate was 61.43 ± 3.75% of initial BR in MBC-SAP, with 2-fold higher than MBC and HMBC. It is assumed HMBC could be a potential environmentally friendly measure for rational use of pesticides in future.

3.
Environ Sci Pollut Res Int ; 27(8): 8323-8333, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31897987

RESUMO

Biosolids are regarded as a major source of pharmaceutically active compounds (PhACs) in soil and may lead to their accumulation in plants and potential human risks through dietary intake. Using 14C labeling, we explored the effect of biosolids on the uptake and tissue distribution of carbamazepine (CAB) by three ready-to-eat vegetables (i.e., carrot, celery, and pak choi) under greenhouse conditions. The 14C-CAB was consistently detected in vegetables and plant tissues with bioconcentration factors in a range of 1.28-37.69, and it was easily translocated from root to leaf and/or stem with translocation factors > 1. The inhibition on the uptake and accumulation of 14C-labeled carbamazepine from soil by the addition of biosolids was consistently observed, and such inhibitory effect was related to the biosolid amendment rates, the category of vegetable, and the plant growth stages. The influence of biosolids on behavior of CAB and other emerging pollutants in the soil-plant system should be considered in their environmental risk assessment.


Assuntos
Carbamazepina/química , Poluentes do Solo , Solo , Humanos , Verduras
4.
Sci Total Environ ; 704: 135398, 2020 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-31836228

RESUMO

The differences of PBDE absorption, accumulation, and metabolism in different cultivars of the same crop are rarely explored. This study used 14C tracing to fully demonstrate the uptake and transformation of soil-borne BDE209 in three rice cultivars, including two indica (HHZ and YD1) and one japonica cultivars (NJ3). Results showed that about 6.9, 17.2, and 17.4% of the applied 14C-BDE209 were transformed to 14C-metabolites in soils planted with HHZ, YD1, and NJ3, respectively. The 14C-BDE209 and its 14C-metabolites in soil could be absorbed by the rice and gradually transported to its root, stem, leaf, and grain, with the total whole-plant uptake of 8.52, 4.55 and 3.43 nmol for HHZ, YD1, and NJ3, respectively. The cultivar of HHZ had the greatest whole-plant 14C absorption but the lowest ΣPBDEs residues in its grain, with the ΣPBDEs of 421.8, 454.2 and 967.0 ng g-1 for HHZ, YD1, and NJ3, respectively. BDE-209 accounted for 90%, 31% and 50% of the ΣPBDEs in the grain from HHZ, YD1, and NJ3, respectively. The estimated daily intake (EDI) amounts of ΣPBDEs were 928, 1056, and 2675 ng kg-1 bw d-1 via consuming rice grains from HHZ, YD1, and NJ3, respectively, which were below the safe threshold limits for human consumption. This study proved the different BDE-209 absorption, accumulation and transformation in different rice cultivars, which potentially suggests the need of considering cultivar differences in assessing the dietary risks of PBDEs.


Assuntos
Éteres Difenil Halogenados/metabolismo , Oryza/metabolismo , Poluentes do Solo/metabolismo , Transporte Biológico , Radioisótopos de Carbono , Grão Comestível , Humanos , Folhas de Planta , Solo
5.
Environ Pollut ; 252(Pt B): 1593-1598, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31279977

RESUMO

Exploring traditional neonicotinoid pesticides substitutes has become one of the global scientific attentions because of their hazardous environmental impacts. Cycloxaprid (CYC) is considered to be a promising candidate alternative. But the environmental behaviors and fate of CYC in different planting system remain poorly understood. The accumulation of 14C-labeled CYC stereoisomers within different parts of Chinese cabbage (Brassica chinensis L.) was investigated, with a particular focus on the foliar absorption, translocation and stereoselectivity of CYC, during a laboratory trial. In general, the stereoisomers 14C-5R,8S-CYC and 14C-5S,8R-CYC, their metabolites, as well as the breakdown and reaction products can be transferred in both acropetal and basipetal directions. Most of the two stereoisomers absorbed by plants remained in the treated leaves, whereas a small amount was distributed to the roots. The amount of 14C in the stalks varied among the experimental time points. At 192 h after treatment (HAT), the detected radioactivity of both 14C-5R,8S-CYC and 14C-5S,8R-CYC in the leaves above the treated leaf (LATL) was higher than that in the leaves below the treated leaf (LBTL). However, the stereoisomers of CYC underwent nonstereoselective absorption and translocation in this trial. This information implies that racemic CYC and its metabolites should be a main research focus. Thus, the obtained results provide implications for a more accurate prediction about the risk assessment of CYC, which will be helpful for guiding its rational use as well as securing the ecological environment safety and human health.


Assuntos
Brassica/metabolismo , Compostos Heterocíclicos com 3 Anéis/metabolismo , Inseticidas/metabolismo , Neonicotinoides/metabolismo , Folhas de Planta/metabolismo , Piridinas/metabolismo , Transporte Biológico , Compostos Heterocíclicos com 3 Anéis/química , Inseticidas/química , Modelos Teóricos , Neonicotinoides/química , Raízes de Plantas/metabolismo , Piridinas/química , Estereoisomerismo
6.
J Hazard Mater ; 375: 255-263, 2019 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-31078061

RESUMO

Macrolides are widely used antibiotics with ubiquitous occurrence in aquatic environments. Unlike many emerging contaminants, macrolides are positively charged on their amine groups and are likely to interact with negative charge groups of dissolved organic matters (DOMs), which may alter macrolide bioaccumulation but yet to be explored. Here we evaluated the effects of different DOM (LeHA, PPHA, SRHA and SRFA) on erythromycin (an important macrolide) bioaccumulation into aquatic biota with 14C tracing. Results showed that ERY uptake in organisms was significantly inhibited by DOM (P < 0.05). In the presence of DOM at 20 mg L-1, the averaged equilibrium concentration (Ce) decreased by 28.1-40.6% for zebrafish and 10.9-25.8% for duckweed, corresponding to reductions in the bioconcentration factor (BCF) by 15.9-32.8% and 10.9-18.5%, respectively. Likely due to their higher carboxyl group content, SRHA and SRFA exhibited stronger inhibitory effects than LeHA or PPHA. The possible interactions between ERY and DOM were explored and results suggested that DOM inhibited ERY bioavailability by forming DOM-ERY complexes via ionic bonding of -COO- and ERY+, hydrogen bonding and hydrophobic partitioning. This study was the first to report on inhibitory effects of DOM on erythromycin bioavailability and has important implications for better understanding risks of macrolides.

7.
Appl Microbiol Biotechnol ; 103(10): 4217-4227, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30911786

RESUMO

The planting of transgenic rice has aroused ongoing controversy, due to the public anxiety surrounding the potential risk of transgenic rice to health and the environment. The soil microbial community plays an important environmental role in the plant-soil-microbe system; however, few studies have focused on the effect of transgenic rice on the soil rhizospheric microbiome. We labeled transgenic gene rice (TT51, transformed with Cry1Ab/1Ac gene), able to produce the Bt (Bacillus thuringiensis) toxin, its parental variety (Minghui 63), and a non-parental variety (9931) with 13CO2. The DNA of the associated soil rhizospheric microbes was extracted, subjected to density gradient centrifugation, followed by high-throughput sequencing of bacterial 16S rRNA gene. Unweighted unifrac analysis of the sequencing showed that transgenic rice did not significantly change the soil bacterial community structure compared with its parental variety. The order Opitutales, affiliated to phylum Verrucomicrobia and order Sphingobacteriales, was the main group of labeled bacteria in soil planted with the transgenic and parental varieties, while the orders Pedosphaerales, Chthoniobacteraceae, also affiliated to Verrucomicrobia, and the genus Geobacter, affiliated to class Deltaproteobacteria, dominated in the soil of the non-parental rice variety. The non-significant difference in soil bacterial community structure of labeled microbes between the transgenic and parental varieties, but the comparatively large difference with the non-parental variety, suggests a limited effect of planting transgenic Bt rice on the soil microbiome.


Assuntos
Proteínas de Bactérias/metabolismo , Endotoxinas/metabolismo , Proteínas Hemolisinas/metabolismo , Microbiota , Oryza/crescimento & desenvolvimento , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Rizosfera , Microbiologia do Solo , Dióxido de Carbono/metabolismo , Isótopos de Carbono/metabolismo , Análise por Conglomerados , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Sequenciamento de Nucleotídeos em Larga Escala , Marcação por Isótopo , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
8.
Environ Pollut ; 243(Pt B): 1352-1359, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30273861

RESUMO

Carbamazepine (CBZ) is an antiepileptic drug that is frequently detected in wastewater treatment plants, soil and plants after irrigation with treated wastewater or application of biosolids. However, little information is available on the fate and uptake of CBZ in edible vegetables. In this study, radioautographic visualization of the 14C distribution revealed that 14C-CBZ can be taken up by all three ready-to-eat vegetables. Furthermore, a mass-balance study was conducted to evaluate the dynamic processes of the uptake and translocation of CBZ by 14C labeling. 14C-CBZ was gradually taken up with the growth of vegetables, with maximum uptake ratios of 2.19 ±â€¯0.15, 2.86 ±â€¯0.24 and 0.25 ±â€¯0.05% of applied 14C in celery, carrot and pak choi, respectively. The bioconcentration factors (BCFs) based on 14C measurements ranged from 7.6 to 26.1 for celery, 3.6-12.9 for carrot, and 4.4-44 for pak choi. 14C-CBZ was easily translocated from the roots to the leaves and/or stems. The amendment of biosolids had a significant inhibitory effect on the uptake and translocation of 14C-CBZ from soil.


Assuntos
Carbamazepina/análise , Raízes de Plantas/química , Poluentes do Solo/análise , Radioisótopos de Carbono/análise , Folhas de Planta/química , Solo , Verduras , Águas Residuárias
9.
J Labelled Comp Radiopharm ; 61(11): 812-819, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29896796

RESUMO

ZJ0712, a broad-spectrum fungicidal ingredient of strobilurin, exhibits a high protective and curative activity against plant pathogenic fungi. To support the study on its metabolism, residue, environmental behavior, and fate for safety evaluation, two versions of carbon-14 labeled ZJ0712, methyl (E)-2-(2-((2,5-dimethylphenoxy)methyl)phenyl)-3-methoxy[2-14 C]acrylate (2) and methyl (E)-2-(2-((2,5-dimethyl[phenyl-U-14 C6 ]phenoxy)methyl)phenyl)-3-methoxyacrylate (3), were synthesized from barium [14 C]carbonate in 6-step yield of 47% and from 2,5-dimethyl[phenyl-U-14 C6 ]phenol in the yield of 91%, respectively.


Assuntos
Acrilatos/química , Radioisótopos de Carbono/química , Fungicidas Industriais/química , Fungicidas Industriais/síntese química , Estrobilurinas/química , Estrobilurinas/síntese química , Técnicas de Química Sintética , Marcação por Isótopo
10.
Sci Total Environ ; 637-638: 1221-1229, 2018 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-29801215

RESUMO

Benzene kresoxim-methyl (BKM) is an effective strobilurin fungicide for controlling fungal pathogens but limited information is available on its degradation and metabolism. This study explored the degradation and metabolic profiling for BKM in soils by carbon-14 tracing and HPLC-TOF-MS2 analyzing. Results indicated that 88%-98% of 14C-BKM remained as parent or incomplete intermediates after 100 days. Three main radioactive metabolites (M1 to M3, ≥90%) and three subordinate radioactive metabolites (Ma to Mc, ≤2%) were observed, along with a non-radioactive metabolite M4. The main intermediates were further confirmed by self-synthesizing their authentic standards, and BKM was proposed to degrade via pathways including: 1) the oxidative cleavage of the acrylate double bond to give BKM-enol (M1); 2) the hydrolysis of the methyl ester to give BKM acid (M2); 3) the cleavage of M1 and M2 to yield Mc, which could be decarboxylated to give M3; and 4) the ether cleavage between aromatic rings to form M4. This study builds a solid metabolic profiling method for strobilurins and gives a deeper insight into the eventual fate of BKM by demonstrating its transformation pathways for the first time, which may also be beneficial for understanding the risks of other analogous strobilurins.


Assuntos
Benzeno/análise , Fungicidas Industriais/análise , Estrobilurinas/análise , Radioisótopos de Carbono , Monitoramento Ambiental , Metabolômica
11.
Sci Total Environ ; 630: 1133-1142, 2018 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-29554735

RESUMO

The intensive use of pesticides has caused serious environmental pollution and ecological issues. Thus, it is imperative to explore an efficient way to minimize the pesticide residues and pollution. In the present study, we employed the superabsorbent hydrogels (SHs)-coated pesticide 14C-carbendazim (H-14C-MBC) to investigate the fate of MBC in aerobic soils and to assess the soil microbial state during incubation. The results showed that after coating with SHs, MBC dissipation was improved significantly by 34.2-54.1% compared with that in the control (p<0.05), reducing the persistence of MBC in soil matrix. At 100d, the release of 14C-CO2 was enhanced by 68.0% and 46.6% in neutral loamy soil and basic saline soil, respectively, with respect to the control, resulting in more complete degradation and detoxification of MBC. Additionally, the bound residue in soils, which was associated with potential environmental risk and pollution, was reduced by 15.2% and 14.2%, respectively, compared with that in control soils. The microbial diversity of post-H-14C-MBC soil varied, and microbial composition and abundance remained different from the control, even with the refreshment of soil stability and fertility compared with the blank soil. These results demonstrate the environmental behavior of SHs-coated MBC in soils, and illustrate that SHs-encapsulated formulations would be a promising measure for reducing the soil-residue pollution and environmental risk of pesticides.

12.
J Environ Qual ; 46(3): 546-552, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28724104

RESUMO

Benzene kresoxim-methyl (BKM) is a promising broad-spectrum strobilurin fungicide widely used to control fungal pathogens in crops. However, information on its environmental fate is limited. To broaden our understanding of this fungicide's kinetic fate in aerobic soils, we labeled BKM with C on its benzoate ring and used ultralow-level liquid scintillation counting coupled with high-performance liquid chromatography analysis. Results show that degradation, mineralization, and bound residue (BR) formation of BKM was controlled by soil type and microbial community composition. Degradation of BKM followed first-order dynamics, and the half-lives () were 51.7, 30.8, and 26.8 d for clay, loamy, and saline soils, respectively. After 100 d, about 0.13, 4.35, and 5.94% of the initial C-BKM was mineralized, and 14.43, 19.90, and 28.81% was formed as BRs in the clay, loamy, and saline soils, respectively. About 60 to 85% of the C-BKM residue in soil was extractable; of this fraction, 30 to 50% was composed of incomplete degradation intermediates. Up to 40% of extractable C-BKM in soil was readily available. Our results suggest that BKM and its incomplete intermediates had a relatively long persistence in soil, which may lead to exposure for nontarget organisms. Soil microbes may play a dominant role in controlling the fate of BKM in soil as sterilization sharply decreased its mineralization rate from 4.35 to 0.03%, increased from 30.8 to 85.6 d, and decreased the BR fraction from 19.90 to 3.25%.


Assuntos
Fungicidas Industriais/química , Poluentes do Solo/química , Estrobilurinas/química , Benzeno , Solo
13.
J Hazard Mater ; 328: 70-79, 2017 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-28103488

RESUMO

Superabsorbent polymers (SAPs) have been extensively used as soil amendments to retain water, and they often coexist with pesticides in agricultural fields. However, effects of SAPs on the fate of pesticides in soil remain poorly understood. In this study, a laboratory experiment was conducted to evaluate the effects of SAPs on the transformation of 14C-carbendazim in soils. The results showed that compared to the SAPs-free control, 11.4% relative reduction of 14C-carbendazim extractable residue was observed in red clayey soil with SAPs amendment after 100days of incubation (p<0.05). Carbendazim dissipation was enhanced by 34.7%, while no obvious difference was found in loamy soil and saline soil (p>0.05). SAPs changed the profiles of major metabolites (2-aminobenzimidazole and 2-hydroxybenzimidazole) to some extent. After 100days of SAPs treatment, the mineralization of 14C-carbendazim was significantly reduced by 37.6% and 41.2% in loamy soil and saline soil, respectively, relative to the SAPs-free treatment (p<0.05). SAPs increased the bound residue of carbendazim by 11.1-19.1% in comparison with SAPs-free controls. These findings suggest SAPs amendments significantly affected the fate of carbendazim and attention should be given to the assessment of environmental and ecological safety of pesticides in SAPs-amended soils.

14.
Environ Pollut ; 220(Pt A): 400-406, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27692886

RESUMO

The increasing discharge of pharmaceuticals and personal care products (PPCPs) into the environment has generated serious public concern. The recent awareness of the environmental impact of this emerging class of pollutants and their potential adverse effects on human health have been documented in many reports. However, information regarding uptake and intracellular distribution of PPCPs in hydrophytes under hydroponic conditions, and potential human exposure is very limited. A laboratory experiment was conducted using 14C-labeled triclosan (TCS) to investigate uptake and distribution of TCS in six aquatic plants (water spinach, purple perilla, cress, penny grass, cane shoot, and rice), and the subcellular distribution of 14C-TCS was determined in these plants. The results showed that the uptake and removal rate of TCS from nutrient solution by hydrophytes followed the order of cress (96%) > water spinach (94%) > penny grass (87%) > cane shoot (84%) > purple perilla (78%) > rice (63%) at the end of incubation period (192 h). The range of 14C-TCS content in the roots was 94.3%-99.0% of the added 14C-TCS, and the concentrations in roots were 2-3 orders of magnitude greater than those in shoots. Furthermore, the subcellular fraction-concentration factor (3.6 × 102-2.6 × 103 mL g-1), concentration (0.58-4.47 µg g-1), and percentage (30%-61%) of 14C-TCS in organelles were found predominantly greater than those in cell walls and/or cytoplasm. These results indicate that for these plants, the roots are the primary storage for TCS, and within plant cells organelles are the major domains for TCS accumulation. These findings provide a better understanding of translocation and accumulation of TCS in aquatic plants at the cellular level, which is valuable for environmental and human health assessments of TCS.


Assuntos
Anti-Infecciosos Locais/análise , Hidroponia , Plantas/química , Triclosan/análise , Poluentes Químicos da Água/análise , Humanos
15.
J Hazard Mater ; 321: 591-599, 2017 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-27694023

RESUMO

Decabromodiphenyl ether (DecaBDE) is one of the most frequently detected flame retardants in terrestrial environments. However, the fate of DecaBDE and its transport in an earthworm-soil system with and without a DecaBDE-degrading strain have rarely been evaluated. In this study, 14C-DecaBDE was self-synthesized, and a DBDE-degrading strain, Rhodococcus erythropolis, was used in an earthworm-soil system. DecaBDE showed limited degradation and mineralization after 35days of all treatments. The bound-residue (BR) formation in soil was <2.5% in the system containing earthworms, which was significantly higher (p<0.05) than that observed in the absence of earthworms (<0.45%). DecaBDE could be adsorbed by the earthworms with a BSAF of ≤0.31. The distribution of 14C-DecaBDE concentrations in the earthworm roughly followed the pattern of crop gizzard>digestive system>head>tail>body wall, suggesting that DecaBDE was mainly uptaken through ingestion. Up to 31% of the 14C-DecaBDE in the earthworms was not extractable, revealing that the total concentration of accumulated 14C-DecaBDE was underestimated. The results also showed that the presence of DecaBDE-degrading bacteria did not significantly affect the fate of DecaBDE and its accumulation in earthworms. The study indicates that the conventional assessment of the bioaccumulation and ecological effects of DecaBDE, which is based only on extractable concentrations, may underestimate the risks.


Assuntos
Retardadores de Chama , Éteres Difenil Halogenados/química , Oligoquetos/metabolismo , Animais , Biodegradação Ambiental , Éteres Difenil Halogenados/metabolismo , Rhodococcus/metabolismo , Solo , Microbiologia do Solo , Poluentes do Solo/análise , Distribuição Tecidual
16.
Sci Total Environ ; 579: 667-674, 2017 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-27847184

RESUMO

Cycloxaprid (CYC) is one of the most effective neonicotinoid insecticides and is proposed to be a replacement of imidacloprid that has caused concerns over non-targeted resistance and ecological toxicity worldwide. The present study was performed with the 14C-labeled racemic CYC and its two enantiomers in aerobic soil. Racemic CYC and the enantiomers 1S2R-CYC and 1R2S-CYC underwent non-stereoselective degradation in the three soils tested. During the incubation period, CYC was transformed into three achiral degradation products which displayed varying degradation kinetics dependent upon soil properties. The soil properties were found to significantly influence the CYC metabolite profiles. The fastest degradation occurred in loamy soil, whereas the slowest reactions occurred in acidic clay soil. The primary transformation of CYC included cleavage of the oxabridged seven-member ring and CN between chloropyridinylmethyl and imidazalidine ring, carboxylation of the alkene group, and hydroxylation of imidazolidine ring. The results shed light on understanding of CYC degradation and provided useful information for applications and environmental assessments of chiral pesticides.

17.
Environ Pollut ; 222: 383-392, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28012668

RESUMO

Pharmaceutical and personal care products (PPCPs) are continuously introduced into the soil-plant system, through practices such as agronomic use of reclaimed water and biosolids containing these trace contaminants. Plants may accumulate PPCPs from soil, serving as a conduit for human exposure. Metabolism likely controls the final accumulation of PPCPs in plants, but is in general poorly understood for emerging contaminants. In this study, we used diclofenac as a model compound, and employed 14C tracing, and time-of-flight (TOF) and triple quadruple (QqQ) mass spectrometers to unravel its metabolism pathways in Arabidopsis thaliana cells. We further validated the primary metabolites in Arabidopsis seedlings. Diclofenac was quickly taken up into A. thaliana cells. Phase I metabolism involved hydroxylation and successive oxidation and cyclization reactions. However, Phase I metabolites did not accumulate appreciably; they were instead rapidly conjugated with sulfate, glucose, and glutamic acid through Phase II metabolism. In particular, diclofenac parent was directly conjugated with glutamic acid, with acyl-glutamatyl-diclofenac accounting for >70% of the extractable metabolites after 120-h incubation. In addition, at the end of incubation, >40% of the spiked diclofenac was in the non-extractable form, suggesting extensive sequestration into cell matter. The rapid formation of non-extractable residue and dominance of diclofenac-glutamate conjugate uncover previously unknown metabolism pathways for diclofenac. In particular, the rapid conjugation of parent highlights the need to consider conjugates of emerging contaminants in higher plants, and their biological activity and human health implications.


Assuntos
Arabidopsis/citologia , Arabidopsis/metabolismo , Diclofenaco/metabolismo , Resíduos de Drogas/metabolismo , Desintoxicação Metabólica Fase II , Desentoxicação Metabólica Fase I , Células Vegetais/metabolismo , Diclofenaco/análise , Diclofenaco/química , Resíduos de Drogas/análise , Resíduos de Drogas/química , Plântula/metabolismo
18.
J Agric Food Chem ; 64(43): 8109-8117, 2016 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-27767310

RESUMO

In this study, the fate of paichongding was investigated in three soils with contrasting soil properties. In general, low soil pH has the potential to retard the mineralization and promote the dissipation of paichongding and the formation of its primary transformation product and to accelerate the formation of bound residue. The dissipation of paichongding stereoisomers was very fast and diastereoselective. This selectivity was found only between diastereomers and not between enantiomers and was observed to be soil dependent. In the acidic soil, the enantiomers (5R,7R)- and (5S,7S)-paichongding were degraded more quickly than (5R,7S)- and (5S,7R)-paichongding, whereas a contrary trend was observed in the neutral soil, and such selectivity did not occur in the alkaline soil. The OM and clay contents also played important roles in the fate of paichongding. This effect of soil properties should be considered in risk assessment of chiral pesticides and their application in the field.


Assuntos
Compostos Azabicíclicos/química , Inseticidas/química , Piridinas/química , Solo/química , Silicatos de Alumínio , Anaerobiose , Compostos Azabicíclicos/farmacocinética , Biodegradação Ambiental , Argila , Inundações , Concentração de Íons de Hidrogênio , Inseticidas/farmacocinética , Cinética , Resíduos de Praguicidas/química , Piridinas/farmacocinética , Estereoisomerismo
19.
J Agric Food Chem ; 64(40): 7423-7430, 2016 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-27660850

RESUMO

Paichongding is a chiral neonicotinoid insecticide currently marketed as racemate against sucking and biting insects. Under anaerobic condition, all paichongding stereoisomers underwent appreciable degradation in soil during 100 days of incubation, with estimated t1/2 values between 0.18 and 3.15 days. Diastereoselectivity in paichongding degradation was observed, with enantiomers (5S,7R)- and (5R,7S)-paichongding being more preferentially degraded in soils than enantiomers (5R,7R)- and (5S,7S)-paichongding. The half-lives of (5R,7R)- and (5S,7S)-paichongding were 3.05 and 3.15 days, respectively, as compared to 0.18 day for (5R,7S)- and (5S,7R)-paichongding. A total of nine intermediates were identified, of which depropylated paichongding was the predominant metabolite and appeared to be stable and recalcitrant to further degradation. Paichongding is degraded via denitration, depropylation, nitrosylation, demethylation, hydroxylation, and enol-keto tautomerism, producing chiral and biologically active products. These findings could have implications for environmental risk and food safety evaluations.


Assuntos
Compostos Azabicíclicos/química , Compostos Azabicíclicos/metabolismo , Inseticidas/metabolismo , Piridinas/química , Piridinas/metabolismo , Poluentes do Solo/metabolismo , Anaerobiose , Biodegradação Ambiental , Radioisótopos de Carbono , China , Cromatografia Líquida/métodos , Inundações , Meia-Vida , Inseticidas/química , Solo/química , Microbiologia do Solo , Poluentes do Solo/química , Estereoisomerismo , Espectrometria de Massas em Tandem/métodos
20.
Water Res ; 102: 117-124, 2016 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-27337347

RESUMO

Biosolids from wastewater treatment are primarily disposed of via land applications, where numerous pharmaceuticals and personal care products (PPCPs) may contaminate food crops and pose a human exposure risk. Biosolids are rich in organic carbon and addition of biosolids can increase the sorption of certain PPCPs in soil, decreasing their bioavailability. This study tested the hypothesis that the relative plant uptake of PPCPs decreases with increasing biosolids amendment. Accumulation of triclosan and triclocarban was measured in roots of radish and carrot grown in soils with or without biosolids. Addition of biosolids significantly prolonged the persistence of triclosan in soil. When expressed in bioaccumulation factor (BCF), accumulation of triclosan drastically decreased in biosolids-amended soils, while the effect was limited for triclocarban. Compared to the unamended soil, amending biosolids at 2% (w/w) decreased BCF of triclosan in the edible tissues of radish and carrot by 85.4 and 89.3%, respectively. Measurement using a thin-film passive sampler provided direct evidence showing that the availability of triclosan greatly decreased in biosolids-amended soils. Partial correlation analysis using data from this and published studies validated that biosolids decreased plant uptake primarily by increasing soil organic carbon content and subsequently sorption. Therefore, contamination of food crops by biosolids-borne contaminants does not linearly depend on biosolids use rates. This finding bears significant implications in the overall risk evaluation of biosolids-borne contaminants.


Assuntos
Disponibilidade Biológica , Triclosan , Produtos Agrícolas , Humanos , Solo , Poluentes do Solo
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