Dissipation and dietary risk assessment of tristyrylphenol ethoxylate homologues in cucumber after field application

The potential for tristyrylphenol ethoxylates (TSPEOs) residues to contaminate crops or be released into the environment is of increasing concern, as they are toxic to living organisms. This study determined the dissipation of TSPEO homologues in cucumber under field conditions. TSPEOn (n = 6-29) dissipated more rapidly in cucumber than in soil samples, with half-lives of 1.80-4.30 d and 3.73-6.52 d, respectively. Short-chain TSPEOn (n = 6-11) persisted for longer than other oligomers in soil. Concentrations of the final residues (∑TSPEOs) in cucumber and soil were 24.3-1349 μg/kg and 47.3-1337 μg/kg, respectively. TSP15EO or TSP16EO was the dominant oligomer, with concentrations of 2.30-150 μg/kg. The risk assessment showed that the acute and chronic dietary exposure risks of ∑TSPEOs in cucumber were 0.03-0.57% and 0.05-0.39%, respectively, suggesting little or no health risk to Chinese consumers.

Imidacloprid dissipation, metabolism and accumulation in Agaricus bisporus fruits, casing soil and compost and dietary risk assessment

An improved understanding of imidacloprid (IMI) metabolism and accumulation in casing soil or compost-mushroom systems will help to optimise the safe use of IMI for agricultural pest control in Agaricus bisporus cultivation. In this study, the dissipation, metabolites and accumulation of IMI in casing soil or compost-A. bisporus systems were investigated. The results show that the IMI dissipation half-lives at doses of 10 and 50 mg kg^-1 were 65 d and 59 d in casing soil and 6.6 d and 6.2 d in compost, respectively during the cultivation period. Three IMI metabolites were observed in casing soil during cultivation of mushrooms. Urea-imidacloprid (IMI-urea) was a major metabolite, accounting for more than 59%. In compost, the main metabolite in the first 5 days was IMI-urea, from 5 to 10 days olefin-imidacloprid (IMI-ole) and 6-chloronicotinic acid (6-CNA) were both the most prominent compounds, and after 10 days 6-CNA alone. At 50 mg kg^-1 dose, IMI and the metabolites (IMI-urea, IMI-ole) were detected in the fruiting body with IMI applied to casing soil and only the metabolite 6-CNA was detected in fruiting body with IMI applied to compost. The bio concentration factors (BCFs) of IMI-ole and IMI-urea were higher than of IMI and 6-CNA, and the BCFs had no obvious relationship with log K_ow. Furthermore, the potential dietary risk of IMI in A. bisporus was acceptable when application rates in casing soil or compost was up to 50 mg kg^-1. Our study supports a safe use of IMI as agricultural pest control in A. bisporus cultivation.

Dissipation Kinetics and Environmental Risk Assessment of Thiamethoxam in the Sandy Clay Loam Soil of Tropical Sugarcane Crop Ecosystem

Thiamethoxam 75 SG has recently got registered for use against shoot borer and termites of sugarcane. It is the only neonicotinoid having label claim against both the major pests of sugarcane. The dissipation kinetics and environmental risk assessment of thiamethoxam 75 SG were studied in a typical tropical sugarcane crop ecosystem as detailed reports are lacking. Rapid and sensitive method adopted to determine the residues of thiamethoxam in the soil employing HPLC could provide more than 95.5% recoveries. The insecticide was observed to persist in the sandy clay loam soil for 60 days and reached below the detectable level of less than 0.01 mg/kg (LOQ = 0.01 mg/kg) on 75th day when applied @ 120 g a.i./ha. The half-life was worked out to be 16.50 days. At double the recommended dose (240 g a.i./ha), the insecticide persisted up to 75 days with the half-life of 16.91 days. The risk quotient values indicated medium to low level of risk to earthworms during the course of degradation of thiamethoxam in the soil.

Vegetation alleviate the negative effects of graphene oxide on benzo[a]pyrene dissipation and the associated soil bacterial community

Graphene oxide (GO) will enter the soil environment in increasing amounts. The effects of GO on the dissipation of benzo[a]pyrene (B[a]P) from contaminated soil and their phytoremediation system have been explored in this study. B[a]P is a ubiquitous soil pollutant used as a representative indicator of polycyclic aromatic hydrocarbons. A pot experiment was performed to investigate the effects of GO or/and vegetation (Tagetes patula) on B[a]P dissipation and the associated bacterial communities in soil. The bacterial communities in soil were investigated by Illumina sequencing analysis. The presence of vegetation significantly enhanced the dissipation of B[a]P from soil. The addition of GO (100 mg/kg) significantly decreased the B[a]P dissipation. When vegetation and GO coexisted, the inhibition effects of GO on B[a]P dissipation were alleviated by vegetation. Compared with the control treatment, the presence of GO or vegetation had no significant effects on the richness and diversity of bacterial communities in B[a]P-contaminated soil. Compared with the presence of only vegetation, the richness and diversity all significantly decreased when vegetation and GO coexisted. And, vegetation had a greater influence on the bacterial community composition than GO. Vegetation alleviated the inhibition effects of GO on B[a]P dissipation and had a greater influence on the associated bacterial communities than GO. This work helps to understand the interactive effects of GO and vegetation on B[a]P dissipation and the associated bacterial communities in contaminated soil.

Rice root exudates enhance desorption and bioavailability of phthalic acid esters (PAEs) in soil associating with cultivar variation in PAE accumulation

Phthalic acid esters (PAEs) is a class of prevalent pollutants in agricultural soil, threating food safety through crop uptake and accumulation of PAEs. Accumulation of PAEs varies largely among crop species and cultivars. Nevertheless, how root exudates affect PAE bioavailability, dissipation, uptake and accumulation is still not well understood. In the present study, desorption and pot experiments were designed to investigate how root exudates from high-(Peizataifeng) and low-(Fengyousimiao) PAE accumulating rice cultivars affect soil PAE bioavailability, dissipation, and accumulation variation. Rice root exudates including low molecular weight organic acids (LMWOAs) of Peizataifeng and Fengyousimiao could enhance desorption of two typical PAE compounds, di-n-butyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP), from aged soil to their available fractions by increasing soil dissolved organic carbon (DOC), thus improving their bioavailability in soil. Peizataifeng produced twice higher amounts of oxalic acid, critic acid and malonic acid in root exudates, and exhibited stronger effects on enhancing desorption and bioavailability of DBP and DEHP than Fengyousimiao. Higher (by about 50%) total organic carbon contents of root exudates from Peizataifeng led to higher (by 10-30%) soil microbial biomass carbon and nitrogen than Fengyousimiao, and thus promoted more PAE dissipation from soil than Fengyousimiao. Nevertheless, higher (by 20-50%) soil DOC and significantly higher PAE bioavailability in the soils planted Peizataifeng resulted in greater (by 53-93%) PAE accumulation in roots and shoots of Peizataifeng than Fengyousimiao, confirming by higher (by 1.82-3.48 folds) shoot and root bioconcentration factors of Peizataifeng than Fengyousimiao. This study reveals that the difference in root exudate extent and LMWOAs between Peizataifeng and Fengyousimiao differentiates PAE accumulation.

Dissipation kinetics, dietary and ecological risk assessment of chlorantraniliprole residue in/on tomato and soil using GC-MS

An alternate single quadrupole gas chromatography coupled with electron ionization mass spectrometry (GC-EI-MS) method was developed and validated for the determination chlorantraniliprole residue in tomato and soil. The target analyte was extracted from selected matrices with acetonitrile followed by dispersive solid-phase extraction clean up with primary secondary amine and graphitized carbon black sorbent to remove co-extractives prior to analysis. Limit of quantification of the method was 0.01 μg/g and the recovery of chlorantraniliprole was in the range of 92-99% with RSD of less than 3%. The dissipation kinetics of chlorantraniliprole in tomato and soil followed first-order kinetics with the half-life of 1.26 and 1.77 days, respectively. A safe waiting period of 1 day suggested for safe consumption of tomato fruits considering the FSSAI maximum residue limit of 0.6 μg/g. The residue concentrations were reduced in the range of 13 to 64% from tomato fruit using simple household approaches. The present study suggested that the use of chlorantraniliprole in tomato does not seem to pose any dietary risk to consumers. The ecological risk quotient (RQ) values indicated that the chlorantraniliprole residues in the soil may pose a medium level of risk to earthworms and arthropods during this period.

Accounting for the dissipation of abiotic resources in LCA: Status, key challenges and potential way forward

The concept of resources or materials dissipation after their use in the technosphere has been increasingly considered in life-cycle based studies, applying Substance and Material Flow Analysis (SFA and MFA), Input-Output Analysis, and Life Cycle Assessment (LCA). However, there is currently no common understanding of what a dissipative flow is. This article first reviews 45 publications to describe the status of resource dissipation in life-cycle based studies, discussing how resource dissipation is usually defined, which temporal perspective is considered, which compartments of dissipation are distinguished, and which approaches (including the implementation of parameters) are considered to assess resource dissipation in a system. Moreover, this article proposes a comprehensive definition of resource dissipation, building from the literature review and focusing on abiotic resources. It then discusses this definition with respect to its potential implementation in LCA considering today's existing Life Cycle Inventory (LCI) datasets and best practices. Overall it shows that the LCA framework may be well suited to assess abiotic resource dissipation. In particular i) the compartments of dissipation usually considered in the literature are covered in LCA, and ii) LCI databases could be a source of information to be further used to quantify a set of flows defined as "dissipative", as commonly considered in SFA/MFA studies. However, major challenges are still faced before any potential routine implementation in LCA. The article accordingly discusses the potential way forward in the short-term (development and test of possible approaches), mid-term (towards satisfactory robustness, and consensus) and long-term (large-scale changes of LCI databases).

Impact of organic manures on the persistence of imidacloprid in the sandy clay loam soil of tropical sugarcane crop ecosystem

Impact of organic manures, viz., composted coir pith, press mud, sugarcane trash, and farmyard manure (FYM) on the persistence of imidacloprid in the sandy clay loam soil of tropical sugarcane crop ecosystem, was studied by employing rapid sample preparation method and reversed phase HPLC. The recoveries of the method employed to determine the residues of imidacloprid in the soil were in the range of 94.5 ± 7.02-97.3 ± 2.94% across the five levels of fortification ranged between 0.005 and 0.5 μg/g. Imidacloprid was observed to persist in the soil manured with FYM and composted coir pith for 30 days with the half-life of 7.62 and 7.0 days, respectively as against 21 days with the half-life of 6.66 days in the non-manurial soil. The comparatively longer persistence of imidacloprid in the FYM and composted coir pith-applied soils was attributed to reduced leaching from the plow layer due to the adsorption of insecticide molecules by the added organic manures.

Persistence, dietary and ecological risk assessment of indoxacarb residue in/on tomato and soil using GC-MS

An efficient single quadrupole gas chromatography with mass spectrometry method was developed and validated for the determination of indoxacarb residues in tomato and soil. Residues were extracted from the samples using acetonitrile as extracting solvent and the extracts were purified through primary secondary amine and graphitized carbon black. Recoveries were obtained in the range of 92.12-110.51% with the relative standard deviation of 1.32-4.32%. Indoxacarb dissipated with half-life of 3.12-3.21 and 1.24-1.35d for tomato and soil, respectively following doses of indoxacarb 14.5% SC at 60, 90 and 120 g.a.i./ha. Safe waiting periods were found to be 1-3d. The residues were removed from tomato fruit was in the range of 16.73 to 54.32% using simple decontamination approaches. The present study suggest that the use of indoxacarb in tomato at recommended dose, does not seem to pose any dietary risk to the consumers. The soil RQ values indicated low level of risk to earthworms and arthropods.

Analytical method validation, dissipation and safety evaluation of combination fungicides fenamidone + mancozeb and iprovalicarb + propineb in/on tomato

Dissipation behavior and degradation kinetics of fenamidone + mancozeb (Sectin 60 WG) and iprovalicarb + propineb (Melody Duo 66.75 WP) in tomato were studied at recommended dose (RD) and double dose (DD) of application. The analysis of the field samples were carried out by employing liquid chromatography tandem mass spectrometry (LC-MS/MS) for fenamidone and iprovalicarb residues and gas chromatography mass spectrometry for mancozeb and propineb residues after thorough validation of the extraction methods. The dissipation of residues best followed 1st + 1st order for all the test fungicides. The half-life period for fenamidone, mancozeb, iprovalicarb and propineb were 2, 2, 1.5 and 2 days for RD and 3, 2.5, 2 and 3 days for DD, respectively. The pre-harvest intervals were not applicable for iprovalicarb, fenamidone and mancozeb (at RD) as the residues at 0 day were below maximum residue limit set by European Union, and it was 1 day for DD of iprovalicarb, 3.5 days for DD of fenamidone, 3 days for DD of mancozeb, 3 and 7 days for propineb at RD and DD, respectively. A PHI of 4 and 7 days are proposed for fenamidone + Mancozeb and iprovalicarb + propineb, respectively. Dietary exposure calculated for all the pesticides were safe on all the sampling days except for propineb residues for which it was safe after first day of the double dose application. The study will be useful for promoting effective residue management and safe use of these chemicals for controlling fungal diseases in tomato crop.

Mesenchymal stem cells-derived cartilage micropellets: A relevant in vitro model for biomechanical and mechanobiological studies of cartilage growth

The prevalence of diseases that affect the articular cartilage is increasing due to population ageing, but the current treatments are only palliative. One innovative approach to repair cartilage defects is tissue engineering and the use of mesenchymal stem/stromal cells (MSCs). Although the combination of MSCs with biocompatible scaffolds has been extensively investigated, no product is commercially available yet. This could be explained by the lack of mechanical stimulation during in vitro culture and the absence of proper and stable cartilage matrix formation, leading to poor integration after implantation. The objective of the present study was to investigate the biomechanical behaviour of MSC differentiation in micropellets, a well-defined 3D in vitro model of cartilage differentiation and growth, in view of tissue engineering applications. MSC micropellet chondrogenic differentiation was induced by exposure to TGFβ3. At different time points during differentiation (35 days of culture), their global mechanical properties were assessed using a very sensitive compression device coupled to an identification procedure based on a finite element parametric model. Micropellets displayed both a non-linear strain-induced stiffening behaviour and a dissipative behaviour that increased from day 14 to day 29, with a maximum instantaneous Young's modulus of 179.9 ± 18.8 kPa. Moreover, chondrocyte gene expression levels were strongly correlated with the observed mechanical properties. This study indicates that cartilage micropellets display the biochemical and biomechanical characteristics required for investigating and recapitulating the different stages of cartilage development.

Dissipation and distribution of difenoconazole in bananas and a risk assessment of dietary intake

The dissipation and terminal residues of difenoconazole in whole bananas and pulp were investigated under field conditions. The residual levels of difenoconazole in various parts of bananas grown in Guangdong, Hainan and Yunnan were determined by a GC-ECD detection method after simple, rapid pretreatment. The mean recovery was 80.66~107.40%, and the relative standard deviation was 3.36~9.84%. The results showed that the half-lives of difenoconazole in whole bananas and in the pulp were 12.16~13.33 days and 17.77~20.38 days, respectively. At harvest intervals of 28 and 35 days after the last application, the terminal residues of difenoconazole in whole bananas and pulp were 0.45~0.84 mg/kg and 0.19~0.37 mg/kg, respectively, which were lower than the maximum residue level established in China. The distribution of difenoconazole in banana pulp and peels was studied. The results showed that until harvesting, the residue in the peels was always 2.19~12.30 times larger than that in the pulp. Difenoconazole was mainly absorbed by the banana peels but did not easily penetrate into the pulp. Based on dietary risk assessment results, the residual levels of difenoconazole at the sampling interval of 28 days after the last application were within acceptable limits for chronic and acute dietary risks in different populations in China. This study can provide a reference for the safe and rational use of difenoconazole as a fungicide and for the future research and application of banana pulp and peels.

Dissipation behavior, residue distribution, and risk assessment of triflumizole and FM-6-1 in greenhouse strawberries and soil

This study aimed to develop a reliable method for the simultaneous analysis of triflumizole (TRIF) and its primary metabolite FM-6-1 (N-4-chloro-2-trifluoromethylphenyl-2-propoxy-acetamidine) in the soil and treated strawberries using solid phase extraction (SPE) coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS). Using this method, TRIF and FM-6-1 degradation in strawberries and the soil under greenhouse conditions were investigated. The field trials showed that t_1/2 of TRIF and total residues (the sum of TRIF and FM-6-1) were 1.6-2.2 days and 2.4-2.9 days in strawberry and 4.3-6.1 days and 5.5-6.9 days in soil, respectively. Terminal total residues were ≤ 0.39 mg/kg in strawberry and ≤ 0.42 mg/kg in soil from 5 to 10 days of harvest. The risk quotient (RQ) of TRIF was below 1.89%, showing that the dietary risk of TRIF in strawberry was low. These findings provide guidance for the use of TRIF on crops and provide reference to establish the maximum residue level (MRL) of TRIF in strawberry.

Homeostatic disturbance of thermoregulatory functions in rats with chronic fatigue

Chronic fatigue syndrome (CFS) is characterized by long-lasting fatigue, and a range of symptoms, and is involved in homeostasis disruption. CFS patients frequently complain of low grade fever or chill even under normal body temperature indicating that thermosensory or thermoregulatory functions might be disturbed in CFS. However, little is known about the detailed mechanisms. To elucidate whether and how thermoregulatory function was altered during the development of chronic fatigue, we investigated temporal changes in body temperature with advance of fatigue accumulation in a chronic fatigue rat model using a wireless transponder. Our findings demonstrated that the body temperature was adaptively increased in response to fatigue loading in the early phase, but unable to retain in the late phase. The tail heat dissipation was often observed and the frequency of tail heat dissipation gradually increased initially, then decreased. In the late phase of fatigue loading, the body temperature for the tail heat dissipation phase decreased to a value lower than that for the non-dissipation phase. These results suggest that adaptive changes in thermoregulatory function occurred with fatigue progression, but this system might be disrupted by long-lasting fatigue, which may underlie the mechanism of fatigue chronification.

Large-Eddy Simulations of Flow in the FDA Benchmark Nozzle Geometry to Predict Hemolysis

PURPOSE

Modeling of hemolysis due to fluid stresses faces significant methodological challenges, particularly in geometries with turbulence or complex flow patterns. It is currently unclear how existing phenomenological blood-damage models based on laminar viscous stresses can be implemented into turbulent computational fluid dynamics simulations. The aim of this work is to generalize the existing laminar models to turbulent flows based on first principles, and validate this generalization with existing experimental data.

METHODS

A novel analytical and numerical framework for the simulation of flow-induced hemolysis based on the intermittency-corrected turbulent viscous shear stress (ICTVSS) is introduced. The proposed large-eddy simulation framework is able to seamlessly transition from laminar to turbulent conditions in a single flow domain by linking laminar shear stresses to dissipation of mechanical energy, accounting for intermittency in turbulent dissipation, and relying on existing power-law hemolysis models. Simulations are run to reproduce previously published hemolysis data with bovine blood in a benchmark geometry. Two sets of experimental data are relied upon to tune power-law parameters and justify that tuning. The first presents hemolysis measurements in a simple laminar flow, and the second is hemolysis in turbulent flow through the FDA benchmark nozzle. Validation is performed by simulation of blood injected into a turbulent jet of phosphate-buffered saline, with modifications made to account for the local concentration of blood.

RESULTS

Hemolysis predictions are found to be very sensitive to power-law parameters in the turbulent case, though a set of parameters is presented that both matches the turbulent data and is well-justified by the laminar data. The model is shown to be able to predict the general behavior of hemolysis in a second turbulent case. Results suggest that wall shear may play a dominant role in most cases.

CONCLUSION

The ICTVSS framework of generalizing laminar power-law models to turbulent flows shows promise, but would benefit from further numerical validation and carefully designed experiments.

Dissipation, transformation and accumulation of triclosan in soil-earthworm system and effects of biosolids application

Triclosan (TCS), widely used as an antimicrobial ingredient, is usually introduced into soil by biosolids application, and has presented potential risk in agro-ecosystem. The dissipation pathways of TCS in soil were analyzed in the presence and absence of earthworms (including Metaphire guillelmi and Eisenia fetida). Meanwhile the accumulation and transformation potentials of TCS in the two earthworms were evaluated. Results indicated that about 44% of initial TCS amount dissipated in sterile soil after 56-day incubation, which may mainly result from the bound-residues formation. In contrast, TCS in non-sterile soil dissipated more quickly with a t_1/2 of 12 days, suggesting that microbial degradation was responsible for TCS dissipation. Triclosan was methylated to methyl triclosan (MTCS) in soil, which however contributed little for TCS dissipation. The presence of M. guillelmi accelerated TCS dissipation with the reduced t_1/2 to 8 days, and inhibited MTCS formation in soil, while E. fetida had no significant (P > 0.05) effects on the fate of TCS. E. fetida accumulated more TCS than M. guillelmi, with bioaccumulation factors up to 11 vs. 0.6. It was also proved that methylation metabolism occurred in earthworms (including gut microorganisms), and M. guillelmi had higher metabolic efficiency compared to E. fetida. Even though eliminations of TCS and MTCS were rapid (except for TCS in M. guillelmi), the residues of the two compounds in both earthworms remained at high levels, having the potential to transfer in the terrestrial food web. In addition, results showed that biosolids application changed TCS persistence, as well as bioavailability dependent on earthworm species. When biosolids at 1% added, more residual TCS and MTCS in soil were observed, while TCS accumulation in E. fetida decreased, however, methylation metabolism in both earthworm species was not affected. The findings provide important information for a more precise risk assessment of biosolids land-application. CAPSULE: Triclosan dissipation, methylation and bioavailability in soils were affected by biosolids amendment and dependent on earthworm species with different accumulation and metabolic potentials.

Persistence and dissipation kinetics of tebuconazole in apple, tomato, chilli and onion crops of Himachal Pradesh, India

Tebuconazole is a broad-spectrum fungicide extensively used worldwide for the control of many diseases such as powdery mildew and scab in apple, early blight of tomato, anthracnose of chilli, white rot and purple blotch of onion etc. Maximum residue level of this compound has not been worked out on these crops in India; the persistence and dissipation kinetics of tebuconazole on apple, tomato, chilli and onion were studied following three foliar applications of the formulation Folicur 430 SC at a standard dose (X) 322, 268.75, 215 and 215 g a.i./ha and at double dose (2X) 645, 537.5, 430 and 430 g a.i./ha, respectively, to work out the safe waiting periods and half-life period of tebuconazole. Extraction was done using QuEChERS method and cleanup by using dispersive solid-phase method. Tebuconazole residues were estimated on gas chromatograph-mass spectrometry (GC-MS). The recovery of tebuconazole in fortified matrix was above 90% with a limit of quantification (LOQ) at 0.05 mg kg^-1. The initial deposits of tebuconazole on apple at two locations under study ranged from 1.986-2.011 mg kg^-1at X dose to 3.698-3.843 mg kg^-1 at 2X dose. The initial deposits in tomato, chilli and onion were 1.129, 1.760 and 1.169 mg kg^-1 at X dose and 2.213, 2.784 and 2.340 mg kg^-1, respectively at the 2X dose. Dissipation of the fungicide followed first-order of kinetics and the half life of degradation ranged from 1.30-2.25 days at X dose to 1.40-2.62 days at 2X days on different crops under study. Residues declined below the determination limit (LOQ) of 15 and 20 days after spraying, respectively, at X and 2X dose in apple; 7 and 10 days in tomato; 10 and 15 days in chilli and onion. Waiting periods of 5, 2, 7 and 12 days, respectively, are suggested for apple, tomato, chilli and onion at 2X dose.

In-vitro evaluation of rice straw biochars' effect on bispyribac-sodium dissipation and microbial activity in soil

Dissipation of bispyribac-sodium was estimated in an unamended sandy loam soil and soil amended with rice straw and its biochars in pot culture experiment. Effect of herbicide and amendments on abundance and activity of soil microbial parameters was also assessed by determining soil biological parameters. Amendment type, application rate and soil moisture had differential influence on bispyribac-sodium dissipation and soil's microbial parameters. Amendment of soil with rice straw and its biochars enhanced the dissipation of bispyribac-sodium (DT₅₀ = 7.55-18.44 days) as compared to unamended soil (DT₅₀ = 23.13-28.60 days) and dissipation decreased in this order: rice straw >350BC > 550BC > CBC amended soil > unamended soil. Dissipation of bispyribac-sodium decreased with increase in amendment level of rice straw and its biochars in soil. Irrespective of amendment type and application rate, bispyribac sodium was more persistent under submerged conditions than at field capacity and its DT₅₀ was 10.13 to 28.60 and 7.55-27.14 days, respectively. Dehydrogenase, alkaline phosphatase activity and bacterial population indicated that application of the organic amendment decreased negative effects of the herbicide on soil enzymatic activities. These findings prove that biostimulation using rice straw and its biochars has the potential to decrease the persistence of bispyribac-sodium and minimize its environmental hazards.

Do pyrene and Kandelia obovata improve removal of BDE-209 in mangrove soils?

Combined pollution caused by polybrominated diphenyl ethers (PBDEs) and polycyclic aromatic hydrocarbons (PAHs) in mangrove wetlands is serious, with their remediation to be been paid more and more attention. However, little is known about the combined impact of PAHs and mangrove species on removal of PBDEs in contaminated soils. In this study, BDE-209 and pyrene were selected and a 9 months experiment was conducted to explore how BDE-209 removal in contaminated soil varied with pyrene addition and Kandelia obovata planting, and to clarify corresponding microbial responses. Results showed that BDE-209 removals in soil induced by pyrene addition or K. obovata planting were significant and stable after 6 months, with the lowest levels of BDE-209 in combined pyrene addition with K. obovata planting. Unexpected, root uptake of BDE-209 in K. obovata was limited for BDE-209 removal in soil, which was verified by lower total amount of BDE-209 bioaccumulated in K. obovata's root. In soil without K. obovata planting, BDE-209 removal caused by pyrene addition coexisted with changed bacterial abundance at phylum Planctomycetes and Chloroflexi, class Planctomycetacia, and genus Blastopirellula. K. obovata-induced removal of BDE-209 in soil may be related to bacterial enrichment in phylum Proteobacteria, class Gammaproteobacteria and genus Ilumatobacter, Gaiella. Thus, in BDE-209 contaminated soil, microbial community responses induced by pyrene addition and K. obovata planting were different at phylum, class and genus levels. This is the first study demonstrating that pyrene addition and K. obovata planting could improve BDE-209 removal, and differently affected the corresponding responses of microbial communities.

Azoxystrobin dissipation and its effect on soil microbial community structure and function in the presence of chlorothalonil, chlortetracycline and ciprofloxacin

The residual characteristics and the adsorption-desorption behaviors of azoxystrobin (AZO) as well as the soil ecological effects in the individual repeated treatments of AZO and its combination with chlorothalonil (CTL), chlortetracycline (CTC) and ciprofloxacin (CIP) were systematically studied in organic manure (OM)-amended soil under laboratory conditions. The presence of CTL, CTC, and CIP, both individually and combined, decreased the sorption affinity of AZO with the Freundlich adsorption and desorption coefficient decreasing by 0.3-24.2%, and CTC and CIP exhibited greater adverse effects than CTL. AZO dissipated slowly and the residues significantly accumulated during ten repeated treatments. The dissipation of AZO was inhibited to different degrees in the combined treatments. Biolog analysis revealed that the soil microbial functional diversity in the OM-soil + AZO and OM-soil + AZO + CTL treatments was higher than that in the OM-soil treatment during the former three repeated treatments, but which was inhibited during the latter seven repeated treatments. The soil microbial functional diversity in the OM-soil + AZO + CTC, OM-soil + AZO + CIP and OM-soil + AZO + CTL + CTC + CIP treatments was inhibited during the ten repeated treatments compared with OM-soil treatment. Metagenomic results showed that all repeated treatments significantly increased the relative abundance of Actinobacteria, but significantly decreased that of Proteobacteria and Firmicutes during the ten repeated treatments. Furthermore, the relative abundance of soil dominant bacterial genera Rhodococcus, Mycobacterium and Arthrobacter in all the repeated treatments significantly increased by 1.5-1283.9% compared with the OM-soil treatment. It is concluded that coexistence of CTL, CTC and CIP, both individually and combined, with AZO can inhibit the dissipation of AZO, reduce the adsorption affinity of AZO on soil, and alter the soil microbial community structure and functional diversity.

Investigation of physical aspects of cubic autocatalytic chemically reactive flow of second grade nanomaterial with entropy optimization

BACKGROUND

Nanofluids have innovative characteristics that make them potentially beneficial in numerous applications in heat and mass transports like fuel cells, hybrid-powered engines, microelectronics, pharmaceutical processes, domestic refrigerator, engine cooling, heat exchanger, chiller and in boiler flue gas temperature decay. Nanomaterial increased the coefficient of heat transport and thermal performance compared to continuous phase liquid. Having such significance in mind, the nanofluid flow of second grade material over a convectively heated surface is examined here. Nano-fluid is electrically conducting. Energy expression is studied through Joule heating, heat source/sink and dissipation. In addition, thermophoresis and Brownian diffusion are investigated. Physical aspects of entropy optimization in nanomaterials with cubic autocatalysis chemical reaction are accounted. Through second law of thermodynamics the total entropy generation rate is computed.

METHODS

The nonlinear governing PDE's are transformed to ordinary ones through transformations. Total residual error is calculated for momentum, energy and concentration equations using optimal homotopy analysis method (OHAM).

RESULTS

Behaviors of different variables on velocity, Bejan number, concentration, temperature and entropy optimization are examined via graphs. Local skin friction coefficient (C_fx) and gradient of temperature (Nu_x)are examined graphically. Comparison between the recent and previous result is given. Temperature and velocity are enhanced significantly versus (λ₁). Entropy generation rate boosts up for magnetic parameter and Brinkman number.

CONCLUSIONS

The obtained outcomes show that velocity is higher via mixed convective variable. Temperature boosts up in presence of higher magnetic parameter, thermophoretic paraemter, Brinkman number and second grade parameter while Biot number decays. Concentration has increasing behavior via larger Brownian and homogeneous and heterogeneous parameters. Entropy rate and Bejan number have similar impact through diffusion parameters with respect to both homogeneous and heterogeneous reactions variables.

Method validation and dissipation kinetics of the new HPPD inhibitor QYR301 in rice, paddy water and paddy soil using a QuEChERS-based method and LC-MS/MS

A rapid and simple method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) of sample preparation using QuEChERS was developed for detecting residues of QYR301, a new HPPD-inhibiting herbicide, in rice plant (straw), water, soil, rice hull and brown rice (BR). To eliminate matrix interference, matrix-matched calibrations with satisfactory linearity (R² > 0.99) were used for accurate quantification. The method showed recoveries of 90.3-108.1% and relative standard deviations (RSDs) < 11%. The limits of quantification (LOQ) for QYR301 were 0.005 mg kg^-1 in all five matrixes. Furthermore, the dissipation kinetics and terminal residues of QYR301 were determined at two sites in 2018. The days for 50% dissipation (DT₅₀) of QYR301 in rice plants, water and soil were 3.6-4.4, 0.7-3.0 and 4.3-8.0 d, respectively, which indicated that QYR301 is a short-persistence herbicide. Moreover, no QYR301 residues were detected in BR, rice hull and straw collected at harvest following its application at 1.0 or 1.5 × of the recommended high rate. These results will help organizations and governments establish related principles/laws regarding the use of QYR301 in terms of environmental protection, food safety and other potential aspects.

Evaluation of the behaviour of propoxycarbazone herbicide in soils and water under different conditions. Post-targeted study

The aim of this study is to understand the levels and behaviour of the herbicide propoxycarbazone in environmental compartments, which are poorly characterized considering degradation products that might reach either surface water as groundwater or soil samples. To this end, an analytical method, based on ultra-high performance liquid chromatography (UHPLC) coupled with Orbitrap mass spectrometry (MS), has been developed to determine the parent compound and its transformation products in soils and water. In addition, a set of laboratory trials has been designed to address the dissipation process of propoxycarbazone formulation in both environmental substrates. The study revealed that the dissipation in water followed a first order kinetics and a non-linear "First Order Multi Compartment" model (FOMC) to soil. Relevant advances have been also achieved in terms of the analytical methodology, as far as the UHPLC-Orbitrap-MS technique allows the development of a retrospective screening of pesticide transformation products in water and soils. For this purpose, an accurate-mass database has been built and used for the post-run screening analysis with 9 transformation products. Photodegradation presumably plays an important role in the dissipation of propoxycarbazone. The results of UHPLC-Orbitrap-MS revealed that four transformation products were formed during the degradation process of the herbicide.

Analysis on safety assessment of Tephrosia vogelii Hook to Apis cerana cerana

Tephrosia vogelii Hook was excellent insecticidal plant, it was introduced into China and planted over a large area in Guangdong province. The main active components of T. vogelii was rotenone and it widely found in leaves and pods of T. vogelii. This paper study of the safety assessment of T. vogelii flowers to worker bees. In this paper, the content of rotenone in T. vogelii petal, nectar, pollen, pistil, and stamen samples were investigated by HPLC, and tested the toxicity of T. vogelii flowers for Apis cerana cerana during 24 h. The dissipation and dynamic of rotenone in A. c. cerana different biological compartments were investigated under indoor conditions during 24 h. The results showed, The LT₅₀ of T. vogelii flowers to worker bees were collected from the eastern, western, southern, northern and top were 13.95, 24.17, 12.55, 26.48, and 18.84 h, the haemolymph of worker bees have the highest content of rotenone, the least accumulation of rotenone in workers bee's thorax, and the rate of dissipation was slowly during the whole study. In conclusion, the results showed the T. vogelii create security risks to worker bees under some ecosystems.

Aerobic dissipation of avermectins and moxidectin in subtropical soils and dissipation of abamectin in a field study

Avermectins and moxidectin are antiparasitics widely used as active pharmaceutical ingredients in veterinary medicine, as well as in pesticide formulations for pest control in agriculture. Although the use of these compounds provides benefits to agribusiness, they can impact the environment, since a large part of these substances may reach the soil and water from the excreta of treated animals and following direct applications to crops. The present work had the objective of evaluating the dissipation behaviors of abamectin, doramectin, eprinomectin, ivermectin, and moxidectin in four native Brazilian soils of different textural classes (clay, sandy-clay, sandy, and sandy-clay-loam), following OECD Guideline 307. The studies were conducted in a climate chamber at 22 °C, 71% relative humidity, and protected from light. The dissipation studies were carried out with all drugs together, since no difference was verified when studies were done with each drug separately. The concentrations of the drugs in the soils were determined using an ultra-high performance liquid chromatograph coupled to a fluorescence detector or a tandem mass spectrometer. The dissipation half-life (DT₅₀) values ranged from 9 to 16 days and the calculated GUS index values were in the range from -1.10 to 0.08, indicating low mobility of the drugs in the soils evaluated and low tendency for leaching. In addition, a field study was carried out to evaluate the dissipation of abamectin after application of a foliar pesticide in an orange crop. A DT₅₀ of 9 days was determined, which was similar to that obtained under controlled conditions in the climate chamber (12 days), indicating that biotransformation was the primary process influencing the overall dissipation.