Ryegrass uptake behavior and forage risk assessment after exposing to soil with combined polycyclic aromatic hydrocarbons and cadmium.

Internalization of chemicals and the forage risks of ryegrass under the combined exposure to PAHs and Cd at environmental concentrations were studied here. The effect of soil pH was also concerned due to the widely occurred soil acidification and general alkali remediation for acidification soil. Unexpectedly, as same as the acid-treated group (pH 6.77), the alkali-treatment (pH 8.83) increased Cd uptake compared with original soil pH group (pH 7.92) for the reason of CdOH+ and CdHCO3+ formed in alkali-treated group. Co-exposure to PAHs induced more oxidative stress than Cd exposure alone due to PAHs aggregated in young root regions, such as root tips, and consequently, affecting the expression of Cd-transporters, destroying the basic structure of plant cells, inhibiting the energy supply for the transporters, even triggering programmed cell death, and finally resulting in decreased Cd uptake. Even under environmental concentrations, combined exposure caused potential risks derived from both PAHs and Cd. Especially, ryegrass grown in alkali-treated soil experienced an increased forage risks despite the soil meeting the national standards for Cd at safe levels. These comprehensive results reveal the mechanism of PAHs inhibiting Cd uptake, improve the understanding of bioavailability of Cd based on different forms, provide a theoretical basis to formulate the safety criteria, and guide the application of actual soil management.

Dose-Dependent Effect on Plant Growth of Exposure to Metal-Organic Framework MIL-101(Cr).

With the increasing use of metal-organic frameworks (MOFs), they will inevitably enter the environment intentionally or unintentionally. However, the effects of MOFs on plant growth are poorly understood. Here, we investigated the effects of exposure of the rhizosphere to MOFs on plant growth. MIL-101(Cr) was selected as a research model due to its commercial availability and wide use. Soybean plants at the two-leaf stage were subjected to various durations (1-7 days) and concentrations (0-1000 mg/L) of exposure in hydroculture with a control group treated with ultrapure water. We found that MIL-101(Cr) had a positive effect on soybean growth at a lower dose (i.e., 200 mg/L); however, at higher doses (i.e., 500 and 1000 mg/L), it exhibited significant toxicity to plant growth, which is evidenced by leaf damage. To investigate the mechanism of this effect, we used Cr as an indicator to quantify, track, and image MIL-101(Cr) in the plant with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Results indicated that MIL-101(Cr) primarily accumulated in the cortex of roots (up to 40 times higher than that in stems), with limited translocation to stems and negligible presence in leaves and cotyledons. In addition, metabolomic analysis of soybeans indicated that low-dose MIL-101(Cr) could increase the sucrose content of soybean roots to promote plant growth, while a high dose could induce lipid oxidation in roots. This study provides valuable insights into the ecological toxicology of MOFs and underscores the importance of assessing their environmental impact for sustainable agricultural practices.

Simultaneous determination of 19 bromophenols by gas chromatography-mass spectrometry (GC-MS) after derivatization.

Bromophenols (BPs) are a class of ubiquitous emerging halogenated pollutants. Their 19 congeners are problematically separated and detected. This work described the separation and detection of 19 BP congeners by gas chromatography-mass spectrometry (GC-MS). Investigations into the derivatization of bromophenols were carried out using two silylation reagents (N,O-bis(trimethylsilyl)trifluoroacetamide and N-methyl-N-(trimethylsily)trifluoroacetamide), two alkylation reagents (methyl iodide and trimethylsilyldiazomethane) and acetic anhydride prior to GC-MS analysis. Optimal chromatographic separation, sensitivity, and linearity were achieved after BP derivatization using acetic anhydride, featuring the equipment detection limits of 0.39-1.26 pg and correlation coefficients of 0.9948-0.9999 (linear range: 0.5-250 ng mL-1) for all 19 BP congeners. Furthermore, the simultaneous determination of 19 bromophenols and 19 bromoanisoles, common environmental transformation products of BPs, is also demonstrated. The improved analytical performance on GC-MS after derivatization would benefit investigations on the environmental origins, behaviors and fates of BPs and their environmental metabolites.

Screening Allergenic Potencies of Skin-Contact Products Using the Human-Derived THP-1 Cell Activation Test.

With the prevalence of allergic contact dermatitis (ACD) from the usage of skin-contact products, like wearable, skin care, and hair care products, screening their skin sensitizing potential is necessary, for the sake of alleviating the consequent public health impact. In the present study, a total of 77 skin-contact products classified by four categories, watch bands (WBs), skin care products (SCPs), hair care products (HCPs), and rubber gloves (RGs), were investigated, using an optimized in vitro assay of human cell line activation test (h-CLAT). Extracting the products using neutral artificial sweat simulated well the practical usage scenarios, and testing the extracts showed that 26 of them were allergy test positive, including nine WBs, six SCPs, two HCPs, and nine RGs. The allergenic response was mainly characterized by the induction of CD54 expression, and diverse paradigms of CD54 and CD86 levels were observed by analyzing dose-response curves, which could also be influenced by the compromised viability of the THP-1 cells. The data implicated the intricate regulation by different contributors to suspicious ingredients in the test samples. Altogether, a promising methodology for testing skin allergy potential was well established for commonly used commodities by neutral artificial sweat extraction coupled with h-CLAT screening. The findings would be of great help in tracing the potential allergens in practical products and improving their qualities.

Rice Seedlings and Microorganisms Mediate Biotransformation of Se in CdSe/ZnS Quantum Dots to Volatile Alkyl Selenides.

Quantum dots (QDs) are widely applied and inevitably released into the environment. The biotransformation of Se in typical CdSe/ZnS QDs coated with glutathione (CdSe/ZnS-GSH) to volatile alkyl selenides and the fate of alkyl selenides in the hydroponically grown rice system were investigated herein. After a 10-day exposure to CdSe/ZnS-GSH (100 nmol L-1), seven alkyl selenides, dimethyl selenide (DMSe), dimethyl diselenide (DMDSe), methyl selenol (MSeH), ethylmethyl selenide (EMSe), ethylmethyl diselenide (EMDSe), dimethyl selenenyl sulfide (DMSeS), and ethylmethyl selenenyl sulfide (EMSeS), were detected in the exposure system using the suspect screening strategy. CdSe/ZnS-GSH was first biotransformed to DMSe and DMDSe by plant and microorganisms. The generated DMSe was volatilized to the gas phase, adsorbed and absorbed by leaves and stems, downward transported, and released into the hydroponic solution, whereas DMDSe tended to be adsorbed/absorbed by roots and upward transported to stems. The airborne DMSe and DMDSe also partitioned from the gas phase to the hydroponic solution. DMSe and DMDSe in the exposure system were further transformed to DMSeS, EMSeS, EMSe, EMDSe, and MSeH. This study gives a comprehensive understanding on the behaviors of Se in CdSe/ZnS-GSH in a rice plant system and provides new insights into the environmental fate of CdSe/ZnS QDs.

Migration of polycyclic aromatic hydrocarbons in the rhizosphere micro-interface of soil-ryegrass (Lolium perenne L.) system.

The unclear multi-media and multi-interface processes of polycyclic aromatic hydrocarbons (PAHs) in environments have drawn great concern. Here, 16 controlled PAHs were selected to reveal the differences in the bioavailability and migration of congeners in soil-ryegrass exposure system. The presence of ryegrass in the exposure groups (with newly introduced PAHs) resulted in a decrease in PAHs dissipation (31.3 %) from soil compared to the unplanted groups (43.2 %). The presence of ryegrass inhibited the soil-air exchange process, which has not been widely reported. PAH congeners with less benzene rings (molecular weight < B[a]A) had consistent bioavailability before and after long-term aging, the competition between adsorption/absorption to plants and soil was not strong (RCFs < 3.5), and their migration in the rhizosphere rapidly reached equilibrium. PAH congeners with more benzene rings (molecular weight ≥ B[a]A) adsorbed to soil particles and significantly decreased their bioavailability after long-term aging. Their concentrations in the rhizosphere were stable and lower than bulk soil, revealing their slow equilibrium process in soil. In addition, PAHs with larger molecular weight and KOW showed less migration at the rhizosphere micro-interface. The migration behavior of congeners with close KOW depended on their molecular structure. Congeners with non-symmetric K-region or L-region showed greater migration ability in the rhizosphere. These findings revealed the fate of PAHs, especially different PAH congeners, in the rhizosphere interfaces for the first time, and explored the molecular mechanisms that affect their rhizosphere behaviors, improving the understanding and knowledge of PAHs in the microenvironment, providing new data on evaluating and controlling the environmental risks of PAHs.

Sensitive method for simultaneous determination of TBBPA and its ten derivatives.

Tetrabromobisphenol A (TBBPA) and its derivatives are regarded as new contaminants, raising much attention on their environmental occurrence and fates. However, the sensitive detection of TBBPA and its main derivatives is still a great challenge. This study investigated a sensitive method for simultaneous detection of TBBPA and its ten derivatives using high-performance liquid chromatography coupled with triple quadrupole mass spectrometry (HPLC-MS/MS) with atmospheric pressure chemical ionization (APCI) source. The method exhibited much better performance than previously reported methods. Furthermore, it was successfully applied in determining complicated environmental samples, including sewage sludge, river water and vegetable samples with concentration range from undetected (n.d.) to 25.8 ng g-1 dry weight (dw). For sewage sludge, river water and vegetable samples, the spiking recoveries of TBBPA and its derivatives ranged from 69.6 ± 7.0% to 86.1 ± 12.9%, 69.5 ± 13.9% to 87.5 ± 6.6%, and 68.2 ± 5.6% to 80.2 ± 8.3%, respectively; the accuracy ranged from 94.9 ± 4.6% to 113 ± 5%, 91.9 ± 10.9% to 112 ± 7%, and 92.1 ± 5.1% to 106 ± 6%, and the method quantitative limits ranged from 0.00801 to 0.224 ng g-1 dw, 0.0104-0.253 ng L-1, and 0.00524-0.152 ng g-1 dw, respectively. Moreover, the present manuscript describes for the first time the simultaneous detection of TBBPA and ten derivatives from various environmental samples, providing fundamental work for further research on their environmental occurrences, behaviors and fates.

Mollusks reveal the temporal-spatial variations and trophic transferring of ongoing bromophenols in the Bohai Sea, China.

Bromophenols (BrPs) are artificial precursors of some flame retardants and important substances with natural marine- or ocean-like flavors. This study studied the temporal variations and spatial distributions of BrPs in 150 mollusk samples (12 species) collected from 9 cities around the Bohai Sea from 2009 to 2019. Only 3 B.P. among the tested 19 congeners, 4-monobromophenol (4-mBrP), 2,4-dibromophenol (2,4-diBrP), and 2,4,6-tribromophenol (2,4,6-triBrP), were extensively detected with the detection frequency of 98.7 %, 86.7 %, and 98.0 %. The median concentration of 2,4,6-triBrP was 4.27 ng/g dw, followed by 4-mBrP (1.89 ng/g dw) and 2,4-diBrP (0.625 ng/g dw). The concentration of 3 detectable congeners, ∑3BrPs' ranged from 0.152 to 703 ng/g dw with a median value of 8.08 ng/g dw. The highest concentrations of ∑3BrPs and 2,4,6-triBrP all occurred in Rapana venosa (49.2 and 45.1 ng/g dw) which belongs to Muricidae (2009 to 2019) that was at a relatively higher trophic level among the tested mollusks. The concentration of BrPs in Gastropoda is much higher than that in Bivalvia. The median concentrations of 2,4-diBrP, 2,4,6-triBrP, and ∑3BrPs in Gastropoda and Bivalvia from Shandong Province were higher than those in other administrative divisions at the provincial level because of the large volume of BrP production and brominated flame retardants. Temporal variations in Gastropoda and Bivalvia from Weihai showed that concentrations of ∑3BrPs, 2,4,6-triBrP, 4-mBrP, and 2,4-diBrP declined slowly from 2009 to 2019. Our results provide a systematic insight into the environmental occurrence and fate of BrPs in the Bohai Sea.

Modulation of electromagnetic wave absorption via porosity in Pechini-derived carbon guided by a random network model.

It is well established that porosity in carbon materials can benefit electromagnetic wave absorption by providing stronger interfacial polarization, better impedance matching, multiple reflections, and lower density, but an in-depth assessment is still lacking on this issue. The random network model describes the dielectric behavior of a conduction-loss absorber-matrix mixture with two parameters related to the volume fraction and conductivity, respectively. In this work, the porosity in carbon materials was tuned by a simple, green, and low-cost Pechini method, and the mechanism of how porosity affects EM wave absorption was investigated quantitatively based on the model. It was discovered that porosity was crucial for the formation of a random network, and a higher specific pore volume led to a larger volume fraction parameter and a lower conductivity parameter. Guided by the high throughput parameter sweeping based on the model, the Pechini-derived porous carbon could achieve an effective absorption bandwidth of 6.2 GHz at 2.2 mm. This study further verifies the random network model, unveiling the implication and influencing factors of the parameters, and opens a new path to optimize the electromagnetic wave absorption performance of conduction-loss materials.

Accumulation, translocation, and transformation of two CdSe/ZnS quantum dots in rice and pumpkin plants.

As a widely applied semiconductor nanomaterial, quantum dots (QDs) have drawn considerable interest. In this study, pumpkin and rice seedlings were hydroponically exposed to two core/shell CdSe/ZnS QDs coated with cysteamine (CdSe/ZnS-CA) and polyethylene glycol-carboxy (CdSe/ZnS-PEG-COOH) for 10 days to analyze their time-varying uptake, translocation, and transformation behaviors in plants. Both QDs were mainly adsorbed/absorbed by the roots in the particulate state, and more CdSe/ZnS-CA accumulated than CdSe/ZnS-PEG-COOH. For CdSe/ZnS-CA-treated plants, the Se and Cd concentrations (CSe and CCd) associated with the roots were 561 ± 75 and 580 ± 73 µg/g (dw) for rice and 474 ± 49 and 546 ± 53 µg/g (dw) for pumpkin, respectively, on day 10. For CdSe/ZnS-PEG-COOH-treated plants, the concentrations of Se and Cd associated with roots were 392 ± 56 and 453 ± 56 µg/g (dw) for rice and 363 ± 52 and 417 ± 52 µg/g (dw) for pumpkin, respectively. The surface charges and coatings significantly affected the accumulation of QDs at the beginning of exposure; however, the impaction decreased with time. The ratios between the Cd and Se concentrations (CCd/CSe) in the stems and leaves varied from those of the QD standards, indicating the transformation of the QDs in the exposure system. Se and Cd were more likely to translocate in CdSe/ZnS-PEG-COOH-treated plants than in CdSe/ZnS-CA-treated plants. The vertical translocation of Se was greater than that of Cd. Rice showed greater abilities of accumulation and translocation of Se and Cd from both QDs than pumpkin. These findings improve our understanding of the interference of QDs with plants and their environmental fate.

Bromophenol Induced Multiple Stress Responses in Rice Plants: Impact of Doses and Congener Structures.

Bromophenols (BPs) have both natural and artificial sources in the environment and are frequently detected in plants. Herein, the ubiquitous 2,4,6-TriBP was hydroponically exposed to rice seedlings at two concentrations (0.2 and 2.0 mg/L) to characterize the dose-dependent abiotic stress responses of rice plants to BPs. The 2,4,6-TriBP induced oxidative damage to rice roots and subsequently inhibited plant transpiration and growth at the end of exposure in both concentrations. Moreover, the gene expression of OsUGT72B1 and the activity of glycosyltransferases of exposed rice roots were 2.36-to-4.41-fold and 1.23-to-1.72-fold higher than that of the blank controls after 24 h, following the formation of glycoconjugates in response to 2,4,6-TriBP exposure. It was notable that the glycosylation rates also showed a dose-effect relationship in rice roots. One and six glycoconjugates of 2,4,6-TriBP were detected in 0.2 and 2.0 mg/L exposure groups, respectively. Considering the detected species of glycoconjugates for four other types of BPs, the numbers of bromine atoms were found to dramatically affect their glycosylation process in rice plants. These results improve our fundamental understanding of the impact of congener structures and exposure concentrations of organic contaminants on the glycosylation process in response to phytotoxicity.

Ultra-thin graphene cube framework@TiO2 heterojunction as high-performance anode materials for lithium ion batteries.

Here, we proposed a new strategy to build the integrated graphene cube (Gr) framework@TiO2 composite to improve the ion transport kinetics and electrical conductivity of TiO2 as a long-life and high-capacity anode for lithium ion batteries. Combined with the salt template method for ultra-thin framework, the distinct structure of Gr@TiO2 shows an excellent electrochemical performance, e.g., initial coulombic efficiency (ICE), rate performance and specific capacity, due to the increased kinetics of lithium ions. Through this method, the integrity is dramatically improved and the pulverization and agglomeration of the anode after long-term cycles are restrained. The optimized Gr@TiO2 displays a high stable reversible capacity of 179.5 mAh g-1 after 4000 cycles at 1 A g-1, excellent rate performance (125.5 mAh g-1 at 5 A g-1). Kinetic studies through Electrochemical Impedance Spectra, Galvanostatic Intermittent Titration Technique and Linear Sweep Voltammetry confirm that the electrical conductivity and ion transport kinetics are dramatically improved through the ultra-thin graphene cube framework as a heterojunction structure of Gr@TiO2.

Biotic and Abiotic Transformation Pathways of a Short-Chain Chlorinated Paraffin Congener, 1,2,5,6,9,10-C10H16Cl6, in a Rice Seedling Hydroponic Exposure System.

In this work, a typical congener of short-chain chlorinated paraffins (SCCPs) with six chlorine atoms (CP-4, 1,2,5,6,9,10-C10H16Cl6, 250 ng/mL) was selected to elaborate the comprehensive environmental transformation of SCCPs in rice seedling exposure system. CP-4 was quickly absorbed, translocated, and phytovolatilized by seedlings with a small quality of CP-4 (5.81-36.5 ng) being detected in the gas phase. Only 21.4 ± 1.6% of an initial amount (10,000 ng) of CP-4 remained in the exposure system at the end of exposure. Among the transformed CP-4, some were attributed to the degradation of the rhizosphere microorganism (9.1 ± 5.8%), root exudates (2.2 ± 4.2%), and abiotic transformation (3.0 ± 2.8%) that were proved by several transformation products found in the root exudate exposure groups and unplanted controls, and a majority was phytotransformed by rice seedlings. Here, 61 products were determined through complex transformation pathways, including multihydroxylation, -HCl elimination, dechlorination, acetylation, sulfation, glycosylation, and amide acid conjugation. The acetylated and amide acid conjugates of CPs were first observed. Phase I and Phase II phytometabolic reactions of CPs were found intertwining. These findings demonstrate that multiactive transformation reactions contribute to the overlook of CPs accumulated in plants and are helpful for the environmental and health risk assessments of SCCPs in agricultural plants.

Metal Oxide/Nitrogen-Doped Carbon Nanosheet Heteronanostructures as Highly Efficient Electromagnetic Wave Absorbing Materials.

In this paper, we will discuss the excellent broadband microwave absorption behaviors of Cu/CuO/carbon nanosheet composites: traces of copper and oxide embedded in a carbon nano-sheet not only cut down the high permittivity of adsorbs but also induce more interfacial polarization centers. The results showed that at a cracking temperature of 900 °C, the fabricated material has a unique ripple-like structure, which promotes the hierarchical interfacial polarization. The prepared material has a maximum absorption bandwidth of 4.48 GHz at an exceedingly thin thickness of 1.7 mm and a maximum reflection loss of -25.3 dB at a thickness of 2 mm. It is a relatively ideal material for electromagnetic wave absorption.

Two Typical Glycosylated Metabolites of Tetrabromobisphenol A Formed in Plants: Excretion and Deglycosylation in Plant Root Zones.

The glycosylation process was investigated for the common brominated flame retardant tetrabromobisphenol A (TBBPA) in hydroponic exposure systems with pumpkin seedlings. Two typical glycosylation metabolites of TBBPA formed in pumpkin seedlings, TBBPA mono-ß-d-glucopyranoside (TBBPA MG) and TBBPA di-ß-d-glucopyranoside (TBBPA DG), increasing their mass early in the exposure (reaching maximum masses of 608 ± 53 and 3806 ± 1570 pmol at 12 h, respectively) and then falling throughout exposure. These two metabolites were released from roots to rhizosphere solutions, where they also exhibited initial increases followed by decreasing trends (reaching maximum masses of 595 ± 272 pmol at 3 h and 77.1 ± 36.0 pmol at 6 h, respectively). However, a (pseudo)zero-order deglycosylation of TBBPA MG and TBBPA DG (during the first 1.5 h) back to TBBPA was unexpectedly detected in the hydroponic solutions containing pumpkin exudates and microorganisms. The function of microorganisms in the solutions was further investigated, revealing that the microorganisms were main contributors to deglycosylation. Plant detoxification through glycosylation and excretion, followed by deglycosylation of metabolites back to the toxic parent compound (TBBPA) in hydroponic solutions, provides new insight into the uptake, transformation, and environmental fate of TBBPA and its glycosylated metabolites in plant/microbial systems.

Simultaneous determination of tetra-, penta- and hexachlorobutadienes in shellfish by gas chromatography-triple quadrupole mass spectrometry.

Polychloro-1,3-butadienes (polyCBDs) are attracting increasing concern due to their high toxicity. However, research on multiple polyCBDs in aquatic biota is still extremely limited. In this study, a sensitive method for simultaneous determination of nine polyCBD (Cl4-Cl6) congeners, including six tetrachlorobutadiene (TeCBD) isomers, two pentachlorobutadiene (PeCBD) isomers, and hexachlorobutadiene (HCBD), in shellfish was developed based on accelerated solvent extraction (ASE), solid-phase extraction (SPE) clean-up and gas chromatography-triple quadrupole mass spectrometry (GC-QqQ-MS/MS). Low method limits of detection (MDLs) in the range 0.03-0.21 ng/g dry weight for target analytes with satisfactory recoveries (47.7 %-70.6 %) were achieved. The valid method was then applied to analyze nine polyCBDs congeners in 42 shellfish and 11 fish samples collected from markets in eight coastal cities, China. Trace HCBD was detected in 14 samples, while TeCBDs and PeCBDs were under the MDLs in all the samples, indicating little contamination of these pollutants in the marketed shellfish and fish in China. Multiple polyCBDs especially TeCBDs and PeCBDs were firstly involved in the proposed method and investigation here, which lay the groundwork for future research on the environmental behavior and exposure risks of polyCBDs in aquatic biotas.

Medium- and Short-Chain Chlorinated Paraffins in Mature Maize Plants and Corresponding Agricultural Soils.

For the most complex artificial chlorinated environmental contaminants, much less is known for medium-chain CPs than short-chain CPs. In this research, the spatial distributions of MCCPs and SCCPs in farmland soil and maize leaves near a CP production facility were found marginally influenced by seasonal winds. The levels of ∑MCCPs and ∑SCCPs were in the ranges of <1.51-188 and 5.41-381 ng/g dw for soils; and 77.6-52930 and 119-61999 ng/g dw for maize leaf, respectively. Bioaccumulation and tissue distributions of the CPs within maize plants were specifically analyzed. Most of the CPs were contained in the tissues directly exposed to airborne CPs. Though the estimated risk of CPs to humans through ingestion of kernels appears to be minimal, the edible safety of MCCPs in maize plants for cattle was nearly in the designated range of adverse effects. To our knowledge, this is the first report on bioaccumulation of CPs in mature maize plants, especially in the parts eaten by humans and domestic animals. It provides a baseline reference to the edible risks of CPs in agricultural food plants and alerts us to the problematic environmental behavior of MCCPs, a probable future replacement for SCCPs commercially.

Compartmentalization and Excretion of 2,4,6-Tribromophenol Sulfation and Glycosylation Conjugates in Rice Plants.

The most environmentally abundant bromophenol congener, 2,4,6-tribromophenol (2,4,6-TBP, 6.06 µmol/L), was exposed to rice for 5 d both in vivo (intact seedling) and in vitro (suspension cell) to systematically characterize the fate of its sulfation and glycosylation conjugates in rice. The 2,4,6-TBP was rapidly transformed to produce 6 [rice cells (3 h)] and 8 [rice seedlings (24 h)] sulfated and glycosylated conjugates. The predominant sulfation conjugate (TP408, 93.0-96.7%) and glycosylation conjugate (TP490, 77.1-90.2%) were excreted into the hydroponic solution after their formation in rice roots. However, the sulfation and glycosylation conjugates presented different translocation and compartmentalization behaviors during the subsequent Phase III metabolism. Specifically, the sulfated conjugate could be vertically transported into the leaf sheath and leaf, while the glycosylation conjugates were sequestered in cell vacuoles and walls, which resulted in exclusive compartmentalization within the rice roots. These results showed the micromechanisms of the different compartmentalization behaviors of 2,4,6-TBP conjugates in Phase III metabolism. Glycosylation and sulfation of the phenolic hydroxyl groups orchestrated by plant excretion and Phase III metabolism may reduce the accumulation of 2,4,6-TBP and its conjugates in rice plants.

Metabolism of SCCPs and MCCPs in Suspension Rice Cells Based on Paired Mass Distance (PMD) Analysis.

Short-chain and medium-chain chlorinated paraffins (SCCPs and MCCPs) are mixtures of complex chemical compounds with intensive usage. They are frequently detected in various environmental samples. However, the interaction between CPs and plants, especially the biotransformation behaviors of CPs within plants, is poorly understood. In this study, 1,2,5,6,9,10-hexachlorodecane (CP-4, a typical standard of individual SCCP congeners) and 52%-MCCP (a commercial mixture standard of MCCPs with 52% chlorine content by mass) were selected as representative chemicals to explore the metabolic behaviors of SCCPs and MCCPs using suspension rice cell culture exposure systems. Both 79.53% and 40.70% of CP-4 and 52%-MCCP were metabolized by suspension rice cells, respectively. A complementary suspected screening strategy based on the pair mass distances (PMD) analysis algorithm was used to study the metabolism of CPs mediated by the plant cells. Forty and 25 metabolic products for CP-4 and 52%-MCCP, respectively, were identified, including (multi-) hydroxylation, dechlorination, -HCl- elimination metabolites, (hydroxylation-) sulfation, and glycosylation conjugates. Here, we propose a comprehensive metabolic molecular network and provide insight on degradation pathways of SCCPs and MCCPs in plants for the first time, aiding in further understanding of the transformation behaviors of CPs.