High Log Kow Research Articles

Different effects of polyethylene microplastics on bioaccumulation of three fungicides in maize (Zea mays L.)

Despite the ubiquity of microplastics (MPs) and pesticides in agricultural soils, the effects of MPs on the behavior and bioavailability of pesticides in soil–plant systems remain largely unknown. This study comparatively investigated the adsorption and dissipation of three commonly used fungicides (metalaxyl, azoxystrobin and tebuconazole) in soil as well as their accumulation and distribution in maize Zea mays L. with and without the amendment of polyethylene MPs (PE-MPs). The results showed that the adsorption of the fungicides to both MPs and soil was strongly dependent on their octanol/water partition coefficients (logKow). The addition of 5% PE-MPs significantly increased the adsorption of the hydrophobic fungicides azoxystrobin and tebuconazole to soil due to their greater adsorption affinity to PE-MPs than to soil, while the effect was negligible in the case of the hydrophilic fungicide metalaxyl. The enhanced adsorption of azoxystrobin and tebuconazole to soil with the amendment of PE-MPs decreased their bioavailable fractions in soil, especially the concentration in in situ pore water, resulting in prolonged persistence in soil and reduced accumulation in maize plants. PE-MPs caused a greater reduction in the dissipation and bioaccumulation of tebuconazole than azoxystrobin, presumably because PE-MPs were more effective in promoting the adsorption of tebuconazole (with a higher logKow) in soil. Comparatively, PE-MPs had little effect on the dissipation and bioaccumulation of metalaxyl since its bioavailability was almost unaffected. Our work provides effective information for the risk assessment of co-contamination of MPs and pesticides.

Drivers distinguishing of PAHs heterogeneity in surface soil of China using deep learning coupled with geo-statistical approach

Although numerous studies have reported the influencing factors of polycyclic aromatic hydrocarbons (PAHs) in surface soil from source, process or soil perspectives, the mechanism of PAHs heterogeneity in surface soil are still not well understood. In this study, the effects of 16 PAHs in surface soil of China sampled between 2003 and 2020 with their 17 “source-process-sink” factors at 1 km resolution (N = 660)) were explored using deep learning (eXtreme Gradient Boosting) to mine key information from complex dataset under the optimized parameters (i.e., learning rate = 0.05, maximum depth = 5, sub-sample = 0.8). It was observed that top five factors of 16 PAH had the largest cumulative contribution (i.e., from 84.8% to 98.1%) on their soil concentrations. PAH emission was the predominant driver, and its effect on soil PAH increases with increasing logKow. Soil was the second driver, in which clay can promote the partition of PAHs with low or middle logKow. However, sand can accumulate those congeners with high logKow. Moreover, the deep learning plus geo-statistical models (with low deviation for testing dataset (N = 283)) were capable of predicting soil PAH concentrations using their drivers with high accuracy. This study improved the understanding of the environmental fate and spatial variability of soil PAHs, as well as provided a novel technique (i.e., deep learning coupled with geo-statistics) for accurate prediction of soil pollutants.

Effect of log Kow on the degradation of pharmaceutically active compounds in a heterogeneous catalytic persulfate activation system

In heterogeneous catalytic advanced oxidation processes (HC-AOP), enhancing the reaction rate is the biggest challenge. To enhance the reaction rate, it is necessary to increase the mass transfer rate of reactants toward the catalyst surface and the number of active sites that will provide better contact with the reactants and higher mass transfer. The hydrophobicity of the reactant is an important parameter that affects the transport of molecules toward solid surfaces. In this study, the effect of log Kow, an indicator of hydrophobicity, on enhancing the catalytic activity in persulfate (PS) activation for pharmaceutic compounds (PCs) degradation was investigated. For this purpose, some PCs with different log Kow were selected and their adsorption and degradation behaviors were investigated depending on the PS concentration, catalyst dosage, contact time, pH, and temperature in HC-AOP. Adsorption percentages increased significantly with increasing log Kow value. PCs with higher log Kow were completely degraded at the end of the shorter contact times in the presence of lower catalyst and PS. PCs were significantly degraded by the triple catalytic effect of AC, Fe, and temperature. The pseudo-first-order kinetic model was the best fit for the degradation reaction for all PCs. The higher apparent rate constants and lower activation energy values of the PCs belonging to high log Kow confirmed that log Kow is an effective parameter in enhancing the catalytic activity.

Uptake, accumulation and translocation of traditional and novel organophosphate esters by rice seedlings in the presence of micro(nano)-polystyrene plastics: Effects of concentration and size of particles

Micro(nano)plastics (MNPs) and organophosphate esters (OPEs) are becoming ubiquitous as emerging pollutants. To data, the effects of MNPs on the uptake, accumulation and translocation of OPEs by rice plant are still unclear, especially for novel OPE species. In this study, the impacts of polystyrene MNPs of different sizes and concentrations on the uptake of eight OPEs (six traditional organophosphate triesters and two novel discovered aryl organophosphate triesters) by rice seedlings were investigated in hydroponic exposure experiments. The results showed that OPEs accumulated in a concentration-dependent manner in both the roots and shoots of rice seedlings. The impacts of MNPs on uptake by rice seedlings were concentration- and size-dependent by influencing the transpiration rate or activities of antioxidant enzymes. Especially, significant effects were usually found in exposure group of medium-size and high-concentration MNPs. MNPs had more obvious effects on OPE species with lower logKow in roots, whereas, more obvious effects on OPE species with higher logKow in shoots were observed. There was a significantly positive linear relationship between logTF and logKow (p < 0.001), and a significantly negative linear relationship between logRCF and logKow (p < 0.001), indicating that OPEs with higher hydrophobicity seemed to be more liable to be absorbed from solutions to roots, but difficult to further translocate to shoots. Without novel OPEs (bis-(2-ethylhexyl)-phenyl phosphate and tris(2,4-di-tert-butylphenyl)phosphate), better fits for a linear model for logKow and logRCF (or logTF) were exhibited, indicating differences between novel and traditional OPEs. This work highlights that the presence of MNPs could altered the characteristics of uptake, translocation and accumulation of OPEs in rice seedlings, and provides an important evidence for comprehensive control strategy of new pollutants.

Exploring sorption of pesticides and PAHs in microplastics derived from plastic mulch films used in modern agriculture

The sorption and vector effect of microplastics on the transfer of pesticides and polycyclic aromatic hydrocarbons (PAHs), as well as its impact on agriculture remain largely unexplored. This comparative study is first to investigate the sorption behavior of different pesticides and PAHs at environmentally realistic concentrations by model microplastics and microplastics derived from polyethylene mulch films. Sorption was found to be up to 90% higher in the case of microplastics derived from mulch films as opposed to pure polyethylene microspheres. For microplastics from mulch films, the sorption percentages for pesticides in media containing CaCl2 were reported to be: pyridate (75.68% and 52.44%), fenazaquin (48.54% and 32.02%), pyridaben (45.04% and 56.70%), bifenthrin (74.27% and 25.88%), etofenprox (82.16% and 54.16%) and pyridalyl (97.00% and 29.74%) at 5 μg/L and 200 μg/L pesticide concentration levels respectively. For PAHs, the sorption amounts were: naphthalene (22.03% and 48.00%), fluorene (38.99% and 39.00%), anthracene (64.62% and 68.02%) and pyrene (75.65% and 86.38%) at 5 μg/L and 200 μg/L PAH concentration levels respectively. Sorption was influenced by the octanol-water partition coefficient (log Kow) and ionic strength. Kinetics of the process in the case of sorption of pesticides were best explained by pseudo-first order kinetic model (R2 between 0.90 and 0.98) while the best fitting isotherm model was Dubinin-Radushkevich (R2 between 0.92 and 0.99). Results suggest the presence of surface level physi-sorption through a micropore volume filling mechanism and the role of hydrophobic and electrostatic forces. Pesticide desorption data in polyethylene mulch films indicate that pesticides with high log Kow were almost completely retained in mulch films, while those with lower log Kow were desorbed rapidly into the surrounding media. Our study highlights the role of microplastics from plastic mulch films as vectors for pesticide and PAH transport at environmentally realistic concentrations and the factors that influence it.

Percutaneous Penetration of Liquid Crystal Monomers (LCMs) by In Vitro Three-Dimensional Human Skin Equivalents: Possible Mechanisms and Implications for Human Dermal Exposure Risks.

Liquid crystal monomers (LCMs) are indispensable materials in liquid crystal displays, which have been recognized as emerging persistent, bioaccumulative, and toxic organic pollutants. Occupational and nonoccupational exposure risk assessment suggested that dermal exposure is the primary exposure route for LCMs. However, the bioavailability and possible mechanisms of dermal exposure to LCMs via skin absorption and penetration remain unclear. Herein, we used EpiKutis 3D-Human Skin Equivalents (3D-HSE) to quantitatively assess the percutaneous penetration of nine LCMs, which were detected in e-waste dismantling workers' hand wipes with high detection frequencies. LCMs with higher log Kow and greater molecular weight (MW) were more difficult to penetrate through the skin. Molecular docking results showed that ABCG2 (an efflux transporter) may be responsible for percutaneous penetration of LCMs. These results suggest that passive diffusion and active efflux transport may be involved in the penetration of LCMs across the skin barrier. Furthermore, the occupational dermal exposure risks evaluated based on the dermal absorption factor suggested the underestimation of the continuous LCMs' health risks via dermal previously.

Understanding impacts of organic contaminants from aquaculture on the marine environment using a chemical fate model.

As demand for sustainable marine aquaculture (mariculture) and marine food supply surges worldwide, there is a growing need for new tools to assess mariculture impacts on local ecosystems, including the cycling of toxic organic contaminants. With this in mind, we developed the Contaminant Fate in Aquaculture-Modified Ecosystems (CFAME) model. The current model was designed to explore the fate of mariculture-derived organic contaminants in the Marlborough Sounds, New Zealand, known for its Chinook salmon farming industry. Model evaluation indicated robust model design, with 80% of modeled concentrations falling within a factor of ten of measured ones for native biota. Model results showed that mariculture was a source of organic contaminants in the sediment even at the Marlborough Sounds regional level and in wild marine fishes with high trophic levels near the farm area. Future research attention should be directed toward measuring chemicals with low log KAW (<0) and high log KOW values (e.g., >3) in sediment, and chemicals with log KOW values of 3-9 in wild fish.

The Acute and Chronic Effects of a Sediment-Bound Synthetic Musk, Galaxolide, on Hyalella azteca, Chironomus dilutus, and Lumbriculus variegatus

Galaxolide is one of the most frequently used synthetic polycyclic musks on the market and is commonly detected in aquatic waterways. Previous studies have mainly evaluated the toxicity of this emerging contaminant using water-only exposures; however, its high Log Kow (5.9) suggests that this compound is likely to partition to sediments. Three benthic invertebrates, Chironomus dilutus, Hyalella azteca, and Lumbriculus variegatus, were exposed to sediment-bound Galaxolide using both acute (10d; survival) and chronic (28d; survival and growth) bioassays. The acute and chronic LC50s for Galaxolide ranged from 238 to 736mg/kg sediment (2400-7430µg/g organic carbon [OC]) for all three species, which were above concentrations commonly detected in the environment (< 2.5mg/kg). Growth effects (i.e., weight and/or length) were noted in two of the three organisms (with C. dilutus being the exception); however, these effects were also noted at concentrations above those that are environmentally relevant. Molecular level evaluations were conducted with surviving L. variegatus and C. dilutus collected from treatments near the LC50 value. Markers of oxidative stress (glutathione-s-transferase) and endocrine disruption (estrogen-related receptor) in C. dilutus were significantly decreased in the treatment group compared to controls by 0.7-fold and 1.9-fold, respectively. Although acute and chronic effects were largely absent at environmentally relevant concentrations, changes in endocrine response suggest that more sensitive endocrine-based endpoints, such as emergence (for C. dilutus) and molting (for H. azteca), are needed to ensure that the risk of this emerging contaminant is low at environmentally relevant concentrations.

Distinct biomagnification of chlorinated persistent organic pollutants in adjacent aquatic and terrestrial food webs

Biomagnification of persistent organic pollutants (POPs) in food webs has been studied for many years. However, the different processes and influencing factors in biomagnification of POPs in aquatic and terrestrial food webs still need clarification. Polychlorinated biphenyls (PCBs) and short-chain chlorinated paraffins (SCCPs) were measured in organisms from adjacent terrestrial and aquatic environment in this study. The median levels of PCBs in terrestrial and aquatic organisms were 21.7–138 ng/g lw and 37.1–149 ng/g lw, respectively. SCCP concentrations were 18.6–87.3 μg/g lw and 21.4–93.9 μg/g lw in terrestrial and aquatic organisms, respectively. Biomagnification factors (BMFs) of PCBs increased with higher log KOW in all food chains. BMFs of SCCPs were negatively correlated with log KOW in aquatic food chains, but positively correlated with log KOW in terrestrial food chains. The terrestrial food web had similar trophic magnification factors (TMFs) of PCBs, and higher TMFs of SCCPs than the aquatic food web. Biomagnification of PCBs was consistent in aquatic and terrestrial food webs, while SCCPs had higher biomagnification potential in terrestrial than aquatic organisms. The distinct biomagnification of SCCPs was affected by the respiratory elimination for terrestrial organisms, the different metabolism rates in various species, and more homotherms in terrestrial food webs. Fugacity model can well predict levels of less hydrophobic chemicals, and warrants more precise toxicokinetic data of SCCPs.

The accumulation of organic contaminants in hair with different biological characteristics

Human hair has increasingly been used as a noninvasive biomonitoring matrix for assessment of human exposure to various organic contaminants (OCs). However, the accumulation processes of OCs in hair remains unclear thus far, which raised concerns on the reliability of hair analysis results for OCs. Herein, Chinese population was selected as the study subject, the effects of changes in hair biological characteristics, including length and color, on the accumulation of OCs in hair was investigated. With the growing of hair shaft and the increased distance from the scalp, a significant increasing trend was found for levels of polychlorinated biphenyls (PCBs) and organophosphate flame retardants (PFRs) along the hair shafts (p < 0.05). Source identification using Chemical Mass Balance model indicated that PCBs in hair were mainly from exogenous sources (air and dust). The accumulation rates of PCB and PFR individuals in the hair shaft decreased with increasing of log Kow values. Additionally, the levels of OCs in hair decreased with the change in color from black to white, probably because of the loss of melanin in white hair. The ratios (R) of Cblack/Cwhite were significantly correlated with the log Kow values for individual chemicals (p < 0.05), implying that OCs with high log Kow values tend to accumulate more readily in black hair. The results of this study demonstrated the growth and change in colors of hair, as well as the physicochemical properties of chemicals, play vital roles in the accumulation of OCs in hair. The present study provides fundamental basis for the precise assessment of human exposure to OCs using hair as a biomonitoring matrix in future studies.

Metabolic Disorder Enhances Oxidative Stress after Exposure to Aromatic Components of Fine Particulate Matter

Metabolic disorder can exacerbate oxidative damage following exposure to fine particulate matter (PM2.5), but the role of chemical composition in this process remains unclear. This study comprehensively assessed the oxidative stress effect from the synergy of metabolic disorder and the organic components in PM2.5 as well as their molecular features. We high-throughput characterized 942 PM2.5 chemicals from an elderly urban population exposure and found the association between oxidative stress markers of exhaled nitric oxide (eNO) and urinary malondialdehyde (MDA) and 330 and 32 compounds, respectively, was enhanced by metabolic disorder. Most of these compounds were aromatics, including PAHs and their functionalized and oxidized products. The integrated explanatory random forest approach incorporating source tracers showed that primary aromatics arising from combustion with a high unsaturation degree, high logKOW, and low volatility were responsible for the increased eNO levels in participants with metabolic disorder, while compounds formed through atmospheric oxidation reactions with high numbers of carbonyl groups and oxygen atoms and relatively low logKOW were associated with elevated MDA in disordered individuals. This study provides the first evidence that metabolic disorder exacerbates oxidative stress after exposure to specific PM2.5 components, which could in turn exacerbate chronic diseases in the elderly population.

Pond mitigation in dissolved and particulate pesticide transfers: Influence of storm events and seasonality (Auradé agricultural catchment, SW-France)

In agricultural headwater catchments, wetlands such as ponds are numerous and well known to partly dissipate contamination. Most of the pesticides are transferred from soils to the aquatic environment during flood events. This study reports the annual/seasonal behaviour of 6 pesticides (metolachlor, boscalid, epoxiconazole, tebuconazole, aclonifen and pendimethalin) in such an environment. Because it is rarely considered, the study focussed on the high frequency of the distribution of pesticides between dissolved and particulate phases, as well as the main controlling factors of their upstream-downstream transfer. The pond removal rate was calculated to evaluate the wetland efficiency in pesticide mitigation. We conducted a one-year high frequency hydrochemical survey, with particular emphasis on flood events, in the upper Auradé catchment (SW-France), an area of long-term conventional agriculture on highly erosive carbonated soils. The inlet and outlet of the pond were instrumented for water level measurements and water sampling.The highest concentrations were observed for tebuconazole and, in general, the presence of the molecules during the year depended on the season. The pond showed satisfactory efficiency in pesticide attenuation for the six molecules considered, although the removal rate depended on the molecule and the bearing phase (from 28.4% for boscalid to 89.4% for aclonifen in the dissolved phase and from 22.1% for pendimethalin to 96.8% for metolachlor in the particulate fraction). Interestingly, the more hydrophilic the molecule (low LogKOW), the more efficient the pesticide removal rate was for its particulate fraction, and the opposite for hydrophobic molecules (high LogKOW).Flood events carried a large amount of Total Suspended Solid (TSS) bearing hydrophobic molecules from a major legacy of upper catchment soils, although 52% of the pesticides were transported by the dissolved fraction. Significant resuspension of TSS from the pond was evidenced by the annual mass balance with four tons of TSS released, while the positive rate of pesticide removal involved other effective mechanisms such as exchange and complexation. Although these constructed wetlands may be beneficial for pesticide mitigation, the results highlighted the need for improved land management in the upstream catchment during the different seasons to avoid bare soils that pose a risk of high surface water contamination, especially due to the presence of hydrophobic molecules in combination with a high erosive context.

Effects of decabromodiphenyl ether (BDE-209) on a mangrove plant, Kandelia obovata and the uptake, translocation and accumulation of BDE-209

Due to close proximity to urban development, mangroves exposed to the contamination of polybrominated diphenyl ethers (PBDEs). Decabromodiphenyl ether (BDE-209) is one of the most predominant PBDE congener. The present study aimed to investigate the toxic effects of BDE-209 on the antioxidative and non-antioxidative responses of Kandelia obovata, a very common mangrove species, under different concentrations of BDE-209, 0.1, 1, 5 and 10 mg l-1. BDE-209 did not exhibit any negative effects on the growth of K. obovata seedlings. The stimulatory effects of BDE-209 on the enzymes including superoxide dismutase, peroxidase and catalase only occurred in weeks 1 and 4 and diminished in week 8. The concentrations of total polyphenols (TP) and extractable condensed tannins (ECT) were not affected by BDE-209. The production of O2·- was induced only at the very high level of BDE-209 (10 mg l-1). H2O2 was induced only in weeks 1 and 4 under BDE-209 treatment. BDE-209 was taken up by the roots of K. obovata, translocated to above-ground tissues, and accumulated in plant tissues with the concentrations declined in the order of root &amp;gt; propagule &amp;gt; stem &amp;gt; leaf. Although BDE-209 has higher molecular weight and higher log Kow than other PBDE congeners, the K. obovata seedlings could absorb, translocate and accumulate BDE-209. These findings suggested that mangrove plants could take up, accumulate PBDEs, and BDE-209 are less toxic than other congeners but more difficult to be removed by mangrove systems.

Risk Assessment of the Insecticide/Acaricide Milbeknock with the Active Substance Milbemectin

Milbeknock is a new insecticide/acaricide containing the new active substance milbemectin, which is a microbial fermentation product of Streptomyces. It is applied for control of mites and leafminers. The intended use is as a foliar spray in fruits (apples/pears), strawberries (only after harvest) and in ornamental plants growing in greenhouse and outdoors. The risk assessment was finalized at a meeting November 24, 2011, by VKM’s Scientific Panel on plant protection products (Panel 2). Panel 2 is in particular asked by the Norwegian Food Safety Authority to look at the following: 1) The human health risk for operators related to the properties of the active substance and the product. 2) The degree of oral absorption. 3) Acute toxicity. 4) The reproduction and developmental toxicity. 5) Establishment of reference values (ADI, AOEL and ARfD). 6) The fate and behaviour in the environment and environmental risk with regard to the properties of Milbeknock and milbemectin. 7) Bioavailability of milbemectin. 8) The microcosm study. &#x0D; VKM Panel 2’s conclusion is as follows: &#x0D; Health: Panel 2 proposes to set the absorption to 50%, which is in agreement with the EU DAR report (propose 47%). For acute toxicicity, Panel 2 concludes that milbemectin probably has a LD50 for dogs between 100 and 200 mg/kg body weight (bw)/day. Dogs seem to be the most sensitive experimental species and should be considered for hazard classification purposes. With respect to reproduction and developmental toxicity, Panel 2 concludes that the documentation of the role of the P-glycoprotein transporter is not convincing, and that the CF1 mice study cannot be used to support the argumentation of no developmental toxicity put forward by the applicant. The following reference values have been estimated: ADI of 0.03 mg/kg bw/day; AOEL of 0.015 mg/kg bw/day and ARfD of 0.067 mg/kg bw/day for milbemectin. Provided that personal protection equipment is used, the AOEL for operators is not exceeded. &#x0D; Environment: With respect to environmental fate, the opinion of the Panel is that the relatively rapid degradation in soil indicates a significant bioavailability in both soil and water-sediment systems. Further it concludes that 0.058µg/L should be regarded as NOECpopulation for the microcosm study. Panel 2 concludes that there is a medium risk of toxic effects on aquatic organisms due to exposure of milbemectin sprayed in fruits with the proposed application regime, provided that a buffer zone of 30 meters to surface water is applied. There are minimal risks of toxic effects on aquatic organisms with sufficient buffer zones in other applied crops. Panel 2 further considers the risk for foliage dwelling non-target predators and parasitoids to be high, and the risk to earthworms to be medium. &#x0D; The strong sorption to soil suggests that the bioavailability in soil may be limited. However, the opinion of the Panel is that the relatively rapid degradation in soil indicates a significant bioavailability. Also, for a substance with such a high log Kow the reported water solubility is relatively high, which will contribute to the availability for biological uptake. The toxicity observed in the microcosm study indicates high bioavailability also in a water/sediment system.

Dissipative behavior, residual pattern, and risk assessment of four pesticides and their metabolites during tea cultivation, processing and infusion.

In recent years, metabolic products of pesticides have gained much attention due to their substantial characteristics as organic pollutants. So far, the behavior and metabolite levels of pesticide metabolites in crops have not been characterized well. In the present study, four registered pesticides (imidacloprid, diafenthiuron, malathion and chlorothalonil) were applied on tea plants in Fujian and Sichuan to characterize their metabolites residue pattern and dietary risk. Four pesticides dissipated first-order kinetics in the fresh tea leaves with the half-lives of 1.4-3.8 days. Nine metabolites were detected in the fresh tea leaves and green tea after processing. The metabolites residues showed an increasing trend first and then declined after treatment, and reached the maximum near the half-lives of pesticide. Compared with the parent pesticide, the total residue and acute risk (included the metabolites) increased by 1.7-105.2 times. Some metabolites, especially those whose parent pesticides have high water solubility and low Log Kow, will be more easily transferred to tea infusion. Pesticides were metabolized rapidly on tea plants after application, but the production of metabolites increased the health risk of tea consumption. These results could provide insights to use the pesticides in tea gardens and risk monitoring after application. © 2022 Society of Chemical Industry.

Profiles of Sterigmatocystin and Its Metabolites during Traditional Chinese Rice Wine Processing.

Mycotoxin pollution is widespread in cereal, which greatly threatens food security and human health. In this study, the migration and transformation of sterigmatocystin (STG) mycotoxin during the contaminated rice wine processing was systematically assessed. QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) coupled with ultrahigh-performance liquid chromatography coupled with tandem mass spectrometry (UPLC−MS/MS) method was firstly established for STG analysis in rice wine. It was found that high levels of rice leaven caused a significant reduction in STG in the fermented rice and wine, which was mainly due to the adsorption of yeast cells and Rhizopus biological degradation. However, compared with rice, the levels of STG in separated fermented wine was significantly decreased by 88.6%, possibly attributed to its high log Kow (3.81) and low water solubility (1.44 mg/L). The metabolites of STG (i.e., monohydroxy STG) were identified in rice wine fermentation for the first time. Moreover, STG disturbed the metabolic profile rice wine composition mainly by glycine, serine and threonine metabolism, alanine, aspartate and glutamate metabolism, purine metabolism pathway, particularly with regard to eight amino acids and sixteen lipids. This study elucidated the STG migration and transformation mechanism during the rice wine processing. The finding provided new analytical method for mycotoxin exposure and pollutant in food production, which may support agricultural production and food security.

Transfer behavior of pesticides from honeysuckle into tea infusions: Establishment of an empirical model for transfer rate prediction

Affected by some external conditions and internal factors, pesticides can be transferred from tea into its infusion, causing subsequent damage to humans as tea infusion is generally consumed. This study aimed to explore the inherent regularity in transfer behavior of 23 pesticides belonging to different classes from honeysuckle to its tea infusion, and to understand the effects of external brewing conditions and internal physicochemical parameters of the pesticides on their transfer rates. Results indicated that the transfer rates (Rt) of pesticides from honeysuckle into tea solutions increased with prolonged brewing time, or adding a cover on a container, but decreased with increasing the times of infusion. In addition, the transfer potential of these pesticides greatly depended on their physicochemical properties but not their type. The pesticides with high water solubility and low water partition coefficient (LogKow, e.g., omethoate) were more easily transferred into tea infusions than those with low water solubility and high LogKow (e.g., chlorpyrifos). Compared the tea brewing in a covered container, the empirical models obtained in an uncovered cup predicted the transfer behavior and drinking risk of pesticides potentially introduced into honeysuckle and its tea infusion. The linear equation was as follow: Rt = 10.756 LogWS + 7.517, R = 0.8771. In practice, honeysuckle should be brewed in an uncovered cup within a short brewing time, and the first tea infusion should be abandoned to reduce the transfer percentage of pesticides. This study provided beneficial references for pesticide application in honeysuckle plantation to establish realistic maximum residue limits of multi-pesticides in honeysuckle tea and related products.

Triclosan biodegradation performance of adapted mixed cultures in batch and continuous operating systems at high-concentration levels

Pollutants like triclosan (TCS) of medium to high logKow value tend to be mainly adsorbed and poorly biodegraded during waste water treatment, complicating removal after release. Complete mineralization of TCS is crucial, since transformation products may be even more toxic, but has been proven only in a few cases. In this study, the performance of different batch (cultivation flask, TCSmix100) and continuous operating systems (submerged biotrickling filter, TCSmix100; biomembrane reactor, TCSmix200) was tested with two pre-adapted mixed cultures named TCSmix100 and TCSmix200, and compared to non-adapted cultures in a biotrickling filter and a sand filter as reference systems. Mineralization rates up to 172 mg TCS/L/d were observed during batch conditions for TCSmix100 at 1.45 g TCS/L as initial concentration. Triclosan was completely mineralized by both cultures, as shown by stoichiometric release of chloride at conversion rates of 5,7–11.4 mg TCS/L/d (biotrickling filter) and 0.72–1.45 mg TCS/L/d (biomembrane reactor) at 20 and 7.5–15 mg TCS/L as influent concentrations. In TCSmix100, Achromobacter sp. was identified as the relevant strain in TCS biodegradation. Community analysis of TCSmix200 revealed Nitrosomonas europaea, Nitrospira moscoviensis, Nitrosospira multiformis , and Rhodanobacter lindaniclasticus as the predominant strains. In contrast, chloride formation and triclosan elimination in the non-adapted biotrickling filter was less than 12% of the expected chloride concentration at hydraulic retention times up to 60 d. In the reference sand filter, TCS abatement was 42.8% in average with neither formation of chloride nor increase in biofilm density, indicating mostly sorptive or precipitative effects for elimination. With mineralization levels surpassing those of comparable references by a factor of 3–11, both adapted fixed-biomass reactor systems proved highly suitable for treatment of effluents containing high concentrations of TCS as they occur in industrial discharges or concentrates of membrane-based wastewater treatment plants. • Two aerobic mixed cultures were enriched able to completely mineralize triclosan (TCS) • Mixed cultures were dominated by Achromobacter sp. or nitrifying bacteria • Turnover rates were up to two orders higher than in literature (172 mg TCS L −1 d −1 ) • Fixed biomass systems showed stable performance during 110 d and 137 d of operation • TCS was solely eliminated by sorptive effects in a sand filter as reference system

Electrochemical decomposition of PPCPs on hydrophobic Ti/SnO2-Sb/La-PbO2 anodes: Relationship between surface hydrophobicity and decomposition performance

The global detection and potential harm of pharmaceuticals and personal care products (PPCPs) call for the effective decomposition technology. In this study, the modified β-PbO2 anodes with different hydrophobicity (Ti/SnO2-Sb/La-PbO2, Ti/SnO2-Sb/La-PbO2-PTFE and Ti/SnO2-Sb/La-PbO2-PVDF) were prepared to decompose aqueous PPCPs, i.e. isoniazid, methotrexate, carbamazepine, sulfamethoxazole and ibuprofen. PTFE and PVDF modification improved the physical property, electrochemical property, stability and safety of β-PbO2 electrode. Moreover, Ti/SnO2-Sb/La-PbO2-PVDF had the highest oxygen evolution potential (1.95 V vs. SCE), the largest electroactive area (88.85 cm2), the highest HO• production rate (10.44 mM min−1 m−2) and the best degradation performance for all the five PPCPs. The hydrophobic surface increased the proportion of free HO•, resulting in higher radical utilization rate and better degradation performance. The excessive hydrophobicity could decrease the degradation performance of PPCPs with high log Kow due to the relatively large hydrophobic force zone. Furthermore, the hydrophobicity enhanced the mineralization (current) efficiency of isoniazid, and its electrochemical degradation mechanism on Ti/SnO2-Sb/La-PbO2-PVDF was thoroughly proposed. These results demonstrated that Ti/SnO2-Sb/La-PbO2-PVDF anode exhibited a good application prospect in treating wastewater containing PPCPs.

Octanol-water partition coefficient (logKow) dependent movement and time lagging of polycyclic aromatic hydrocarbons (PAHs) from emission sources to lake sediments: A case study of Taihu Lake, China

Understanding the movement of polycyclic aromatic hydrocarbons (PAHs) from emission sources to sediments is important for achieving long-term pollution control of PAHs in sediments. In this study, by exploring the correlation of individual PAHs concentrations (CPAHs) in Taihu Lake sediments reported in the past twenty years with their annual emissions (EPAHs) in the lake region, it was observed that mean concentrations of PAHs with low logKow (i.e., logKow≤4.00) in Taihu Lake sediments were correlated best with their emissions without lagging between the sediment sampling time and the PAHs emitting time. However, for PAHs with middle logKow (i.e., 4.00<logKow≤4.57) or high logKow (i.e., logKow>4.57), their mean concentrations in sediments were correlated best with the emissions of PAHs emitted 1 or 2 years before the sediment sampling time. The longer lagging time of PAHs with middle or high logKow from emission sources to lake sediments could be attributed to their retardation in soils and river sediments around the lake. Moreover, the retardation in soils and river sediments is dependent on PAHs logKow and degradation half-life, indicating the dependence of PAHs concentration in sediments on their environmental behaviors, including sorption and degradation. Kow dependent movement and the time lagging observed in Taihu Lake for PAHs from emission sources to sediments could be valuable for developing measures to control PAHs, especially for congeners with high logKow.