Transformation of bisphenol compounds during nitrogen removal processes in wastewater treatment plants, along with the key microbial taxa associated with this transformation, remains poorly understood. In this study, we examined the transformation of a series of alkylbisphenols (ABPs; bisphenol A, bisphenol E, and bisphenol F) and sulfonylbisphenol (bisphenol S) in an enriched nitrifying activated sludge (NAS). While bisphenol S was persistent in the NAS, the ABPs were effectively transformed; however, 14C-isotope tracing revealed that the majority of BPA (presumably also other ABPs) was retained in the NAS as transformable intermediates and potentially toxic nitroaromatic compounds, with minor mineralization (< 1 %). In total, nine transformation products were identified, including nitrated aromatic compounds and single-ring phenolic compounds. Ammonia‑oxidizing bacteria (AOB), primarily Nitrosomonas, drove abiotic ABP transformation to persistent nitroaromatic products. Heterotrophic bacteria, such as Sphingomonas, Methyloterena, and Comamonas, initiated ABP transformation via type II ipso-hydroxylation and oxidative cleavage, and also mineralized the intermediates formed through the AOB-mediated dealkylative nitration. By integrating batch experiments, HPLC-QTOF-MS/MS, 14C-tracing, and 16S rRNA gene sequencing, we provide a comprehensive understanding of these complementary transformation pathways and the key microbial taxa involved. Our findings highlight the significant role of AOB-mediated abiotic reactions in ABP transformation, and alarmingly revealed that the traditional nitrogen removal processes using NAS may produce toxic persistent nitroaromatic compounds, thereby leading to unexpected environmental risks.

Plant associated microbes play pivotal role in promoting host fitness and health. However, modern agricultural practices, such as agrochemicals use and domestication are eroding plant-microbe partnership. Here, we show that nanoenabled seed priming strengthens plant-microbe interactions, enhancing the plant holobiont performance. We found that SiO2@CuO nanozymes (NZs) with peroxidase (POD)-like activities, as seed priming agent, initiate earlier and stronger seed respiration and boost exudates release (sugars, amino acids, and fatty acids), creating a nutrient-rich and transiently hypoxic spermosphere microenvironment. Field trials revealed that by day 40, rhizosphere microbiome diversity increased, with enrichment of functional taxa involved in carbon and nitrogen metabolism, as determined by 16S rRNA and metagenomic sequencing. Throughout the growing season, above-ground tissues in the nanopriming group consistently outperformed the hydropriming control in photosynthetic pigment content and plant height. At harvest, without additional fertilizers or other inputs, nanopriming increased maize yield by 8.1% and improved kernel nutritional quality: starch (21.0%), protein (24.5%), and iron (24.2%). Soil nutrient availability (N, P, K, Ca) and cation exchange capacity also increased, indicating the improved soil quality. Notably, the soil from nanopriming group confers the subsequent maize crop with better drought tolerance and enhanced P uptake capacity, compared to the soil from hydropriming group, indicating beneficial legacy effect. This study demonstrates that a simple seed nanopriming can steer a positive feedback loop between plant and microbe, cascading into multifaceted holobiont benefits. This offers a sustainable strategy to harness plant microbiomes and promote sustainable and climate resilient agriculture.

The widespread presence of antibiotics in aquatic environments raises concerns about their ecological impacts. However, the molecular-level effects of antibiotics and the underlying mechanisms, particularly the responses across aquatic species, remain unclear. We established a freshwater microcosm including duckweeds (Salvinia natans), snails (Cipangopaludina cathayensis), and fish (Danio rerio) to investigate their uniform and specific responses to antibiotics (sulfamethoxazole, ciprofloxacin, oxytetracycline, and azithromycin), each at 1, 10, and 100 μg/L for 45 days. Antibiotic exposure diminished chlorophyll content in duckweeds, increased soluble sugar levels, elevated triglyceride levels in snails, and raised total bile acid concentrations in fish. Metabolomic analysis revealed that both duckweeds and fish tended to store energy to defend against antibiotic-induced stress, but through different pathways. Duckweeds accumulated sugar metabolites and downregulated antioxidants, while fish consumed primary sugars and converted them into lipid metabolites. Microbiome analysis indicated a self-coordination of gut bacteria in both snails and fish exposed to 1 and 10 μg/L of antibiotics, while dysbiosis occurred in snails at 100 μg/L, marked by increased pernicious bacteria abundance. In contrast, the abundance of probiotic bacteria increased in the fish gut due to microbial resistance to antibiotics, which played a crucial role in bile acid metabolism and positively influenced hepatic lipid metabolism via the gut-liver axis. This study uncovered the uniform and specific defense and dysregulation behaviors of multilevel aquatic organisms in response to antibiotic exposure, providing valuable insights into the selection of molecular-level endpoints for water quality benchmark development to safeguard aquatic life from antibiotic pollution.

Biodegradation plays a crucial role in the removal of sulfonamides (SAs) from soils; however, the biodegradation pathways in soils and the impacts of soil organic matter (SOM) on SA biodegradation remain unclear. Here, we used [phenyl-U-14 C]-labeled SAs to investigate the degradation of sulfadiazine (SDZ), sulfamonomethoxine (SMM), and sulfamethoxazole (SMX) in a soil-free enrichment culture derived from an SDZ-degrading soil microbial community in the absence or presence of soil humic acids and artificial root exudates. The culture utilized the individual SAs as the sole carbon source and mineralized 60.4%-65.4% of the phenyl ring within 156 h, which was not inhibited by the antifungal actidione, suggesting a predominant bacterial contribution to the degradation. Several typical SA-degrading genera, including Achromobacter, Brevundimonas, Leucobacter, Micro-bacterium, Pseudomonas, and Rhodococcus, were enriched, and 16, 14, and 10 metabolites of SDZ, SMM, and SMX were identified, respectively. Twelve primary transformation pathways were proposed, including sulfonamide bond cleavage, desulfonylation, para-amino group modification, and heterocyclic moiety modification. Notably, the downstream transformation pathways of two desulfonylation products were elucidated, revealing their contributions to SA mineralization. The presence of additional organic matter, especially humic acids, significantly promoted the degradation and mineralization via covalent binding or co-metabolism, and substantially altered the dynamics and amounts of SA metabolites. Though biodegradation of SAs in soil can be much lower than in bacterial enrichment culture, our results provide insights into the complex SA transformation by soil microbial communities and the regulatory effects of SOM, with new implications for managing SA-contaminated environments.

Diatoms play a central role in marine CO2-fixation and the marine food web, yet their survival is increasingly threatened by intensifying marine heatwaves. Here, we demonstrate that engineered nanoparticles (ENPs) can significantly enhance diatom thermotolerance. The diatom Skeletonema costatum pre-exposed to 0.1 mg/L SiO2 NPs exhibited significantly higher survival rates (from 43 to 64-71%), increased biomass, enhanced photosynthetic pigment content, and a bolstered antioxidant system compared to untreated, heat-stressed controls. Multiomics analyses revealed that SiO2 NPs precondition the cells by reprogramming the transcriptome and metabolome, thereby sustaining healthy carbon metabolism, reinforcing cytoskeletal integrity and proteostasis, and activating a coordinated antioxidant response. Mechanistically, SiO2 NPs catalyze mild reactive oxygen species (ROS) generation, which acts as a mild, preconditioning oxidative stress to establish a cellular memory and prepare diatoms for subsequent heat stress. Importantly, preliminary experiments with other ENPs with ROS-generating (Fe2O3 and CuO) or ROS-scavenging (Se and CeO2) properties also improved the thermotolerance of the diatom Skeletonema costatum. This phenomenon was further observed in other diatoms (Thalassiosira weissflogii, Phaeodactylum tricornutum, Cyclotella) and cyanobacteria (Nostoc), suggesting a universal thermal tolerance mechanism. These findings uncover a previously unrecognized role of engineered nanoparticles, highlighting their potential as a tunable strategy to sustain carbon fixation and marine ecosystem stability under global warming.

While biochar (BC) is proposed to mitigate estrogen-associated ecological risks in soil, its effects on estrogen fate remain obscure. We studied mineralization, transformation, and non-extractable residue (NER) formation of 17β-estradiol (E2) in sterilized soil and active soil with 0 %, 0.1 %, and 1 % BC amendment under oxic conditions for 42 days. E2 dissipated rapidly in the active soil (half-life = 1.5 days), mainly forming NERs (65 ± 1 % at the end of experiments) or mineralized (11.1 ± 0.4 %), with generation of minor extractable residues containing estrone (2.0 ± 0.2 %) and one unknown biotransformation product TP (2.5 ± 0.2 %). E2-derived NERs were formed mainly via physico-chemical entrapment (59 ± 3 % of the total NERs) and were associated with humin fraction (66 ± 3 % of the total NERs). BC application had no significant effect on E2 mineralization, transformation into estrone and TP, and NERs quantity, but significantly promoted the formation of physico-chemical entrapped NERs and fulvic acids-bound NERs at 0.1 % level, while increasing BC level might increase the formation of humic acids-bound NERs. Our findings highlight a critical role of NERs in determining environmental risk of E2 and suggest that BC application may not be effective strategy for mitigating estrogen contamination in soil.

Bisphenol AF (BPAF), a polyfluorinated compound and widely used substitute for bisphenol A, is ubiquitous in the environment. However, the fate of BPAF in soil is still obscure. Here, we used [ring-U-14C]-labeled BPAF to investigate its fate in three agricultural soils for 240 days, based on a four-compartment fate model. BPAF dissipated in the soils with a half-life of 35-110 days, accompanied by low mineralization (8.5-11.3% of the initial radioactivity). The main fate of BPAF in the soils was formation of nonextractable residues (NERs) (44.2-65.3%), mostly (>90%) via physicochemical sequestration (31.2-42.7%) and ester bonds (10.0-22.6%). Notably, the sequestered free BPAF in the NERs increased the half-life by 1.4-2.5 times. Six transformation products (TPs) were identified, including BPAF mono- and dimethyl ethers, monosulfate ester, and three single-ring monophenolic compounds. BPAF monomethyl ether was the predominant extractable TP, while the polar TPs were the predominant physico-chemically sequestered and ester-linked TPs in the NERs. Three transformation pathways for BPAF in the soils are proposed, including type II ipso-substitution, O-methylation, and sulfate conjugation. Our study provides the first quantitative information on the fate of BPAF in soil, and highlights the importance of NERs in determining the persistence of BPAF.

Under a changing climate, enhancing the drought resilience of crops is critical to maintaining agricultural production and reducing food insecurity. Here, we demonstrate that seed priming with amorphous silica (SiO2) nanoparticles (NPs) (20 mg/L) accelerated seed germination speed, increased seedlings vigor, and promoted seedling growth of rice under polyethylene glycol (PEG)-mimicking drought conditions. An orthogonal approach was used to uncover the mechanisms of accelerated seed germination and enhanced drought tolerance, including electron paramagnetic resonance, Fourier transform infrared spectroscopy (FTIR), metabolomics, and transcriptomics. It was revealed that the unique surface chemistry of amorphous silica, characterized by an enrichment of silanol and siloxane groups, can catalyze the production of reactive oxygen species. This, in turn, initiates redox signaling and activates downstream drought-responsive genes. In addition, silica-primed seeds exhibited a significant enrichment of 18 amino acids and 6 sugars compared to those undergoing hydropriming, suggesting the accelerated mobilization of stored energy reserves. The drought-tolerance trait was observed in vegetative tissues of 35 day-old plants, where this tolerance was associated with an accelerated catabolism of amino acids and an enhanced anabolism of antioxidants. A separated field trial showed that SiO2NPs seed priming not only increased rice grain yield by 7.77% (p = 0.051) and 6.48% (p = 0.066), respectively, under normal and drought conditions but also increased the grain amino acid content. These results demonstrate that a simple and cost-effective nanoseed-priming approach can convey life cycle-long drought tolerance while simultaneously increasing rice grain yield and nutrition quality, providing an effective and sustainable strategy to cultivate climate-resilient crops.

Bisphenol AF (BPAF) contamination in soil from plastic and rubber use is widespread, yet its bioaccumulation and biotransformation in terrestrial invertebrates and its effects on the fate of BPAF in soil remain unknown. Here, we used 14C-radiotracer to study the accumulation, distribution, metabolism, and excretion of BPAF in the geophagous earthworm Metaphire guillelmi. Earthworms significantly promoted the formation of nonextractable BPAF residues in soil, accelerating BPAF dissipation. After 21 days of exposure, bioaccumulation of total BPAF-derived residues was 6.3-fold higher than that of extractable parent BPAF in earthworms, primarily located in the gut (73.6%), followed by skin (14.7%), body fluid (7.0%), and organs (4.7%), with 47.4% overall existing as tissue-bound residues (TBRs). TBRs showed limited elimination from earthworms but might release BPAF and its transformation products (TPs), predominantly BPAF, into the soil upon earthworm death, increasing BPAF persistence. The dominant TP in earthworms was the monosulfate conjugate of BPAF, the first such conjugate reported in soil animals. Both the TBR formation and excretion of BPAF monosulfate could contribute to the detoxification of BPAF in M. guillelmi. The results underscore a dual role of earthworms in the fate of BPAF in soil (accelerating dissipation vs. increasing persistence) and highlight risks associated with BPAF conjugation and TBR formation.

The fate of sulfonamide antibiotics in farmlands is crucial for food and ecological safety, yet it remains unclear. We used [phenyl-U-14C]-labeled sulfamethoxazole (14C-SMX) to quantitatively investigate the fate of SMX in a soil-maize system for 60 days, based on a six-pool fate model. Formation of nonextractable residues (NERs) was the predominant fate for SMX in unplanted soil, accompanied by minor mineralization. Notably, maize plants significantly increased SMX dissipation (kinetic constant kd = 0.30 day-1 vs 0.17 day-1), while substantially reducing the NER formation (92% vs 58% of initially applied SMX) and accumulating SMX (40%, mostly bound to roots). Significant NERs (maximal 29-42%) were formed via physicochemical entrapment (determined using silylation), which could partially be released and taken up by maize plants. The NERs consisted of a considerable amount of SMX formed via entrapment (1-8%) and alkali-hydrolyzable covalent bonds (2-12%, possibly amide linkage). Six and 10 transformation products were quantified in soil extracts and NERs, respectively, including products of hydroxyl substitution, deamination, and N-acylation, among which N-lactylated SMX was found for the first time. Our findings reveal the composition and instability of SMX-derived NERs in the soil-plant system and underscore the need to study the long-term impacts of reversible NERs.

Background As a kind of widely used antibiotics, sulfonamide antibiotics (SAs) has become ubiquitous environmental contaminants that caused public concerns. The behavior of SAs in complex environmental system need to be elucidated, which is hampered by unavailability or high cost of isotope-labelled SAs. Results Using commercially available uniformly [ l4 C]- and [ l3 C]-labelled aniline as starting material, we synthesized [phenyl-ring- 14 C]- and [phenyl-ring- l3 C]-labelled sulfamethoxazole (SMX), sulfamonomethoxine (SMM), and sulfadiazine (SDZ) using four-step (via condensation of labelled N -acetylsulfanilyl chloride and aminoheterocycles) or five-step (via condensation of labelled N -acetylsulfonamide and chloroheterocycles) reactions in good yields (5.0−22.5% and 28.1−54.1% for [ 14 C]- and [ 13 C]-labelled SAs, respectively) and high purities (> 98.0%). Conclusion The synthesis of [ l4 C]-labelled SAs could be completed on milligram-level, being feasible for preparation of labelled SAs with high specific radioactivity. This study provides efficient and maneuverable methods to obtain a variety of [ 14 C]- or [ 13 C]-labelled SAs for studies on their environmental behavior, such as fate, transformation, and bioaccumulation.

Nitrated nonylphenols (NNPs) are main metabolites of the endocrine-disrupting nonylphenols in soil, yet their fate is unknown. Here, using four NNP isomers (NNP111, NNP112, NNP65, and NNP38), the degradation pattern of NNPs was investigated in an oxic soil for 266 days. Specifically, NNP111 was 14C-labeled to facilitate investigating its degradation, transformation, and non-extractable residue (NER) formation. NNPs degradation was isomer-specific with the decreasing order of half-life: NNP111 (126 days) > NNP112 (76 days) > NNP65 (14 days) > NNP38 (8.4 days), providing direct evidence of the greater persistence of NNPs in soil than their parent NPs. At the end of the incubation, 8.5 %, 7.3 %, and 39.9 % of 14C-NNP111 was mineralized, transformed to 2-amino-NP111, and formed NERs in active soil, respectively. In contrast, NERs in sterilized soils were significantly lower, amounting to 15.1 % and 17.3 % in autoclaved and γ-irradiated soil, respectively. The majority of the NERs (>70 %) were in humin fraction, in which type I NER was the predominant (>90 %) mode for NER formation. Our results provide comprehensive knowledge on the fate of NNPs in soil, demonstrating that isomer-specific behavior, transformation products of NNPs, and NER formation should be considered when evaluating environmental fate and risks of NNPs.

In this study, the performance of AgNPs-priming (20, 40, and 80 mg/L) on the seed germination, yield, and nutritional quality of Chinese cabbage were evaluated. We found that AgNPs-priming at 20 and 40 mg/L for 15 h significantly accelerated seed germination speed and seedling development. Cabbage seeds primed with different concentrations of AgNPs (0, 20, 40, and 80 mg/L) were then planted in a real soil and allowed to grow for 1 month in greenhouse. Results showed that AgNPs-priming at 40 mg/L significantly increased cabbage yield by 44.3%. Gas chromatography-mass spectrometry (GC-MS) combining with sparse partial least squares-discriminant analysis (sPLS-DA) reveals that AgNPs priming altered the metabolite profile of cabbage leaves in a dose-dependent manner, decreasing carbohydrates and increasing nitrogen related compounds. This indicates that the metabolic stimulation during germination stage can influence the entire life cycle of cabbage. The nutritional quality of cabbage edible leaves was evaluated by liquid chromatography with tandem mass spectrometry (LC-MS/MS) and inductively coupled plasma-mass spectrometry (ICP-MS). Results showed that AgNPs-priming at all tested concentrations significantly increased the content of essential amino acids for several folds in cabbage leaves, including alanine, aspartic acid, glutamine, glutamic acid, histidine, isoleucine, leucine, lysine, phenylalanine, proline, serine, threonine, tyrosine, and valine. Meanwhile, AgNPspriming (40 mg/L) significantly increased iron (Fe) content by 23.8% in cabbage leaves. Ag did not bioaccumulate in edible tissues, indicating the bio-safety of AgNPs-priming. These results suggest that AgNPs-priming is a low-cost and eco-friendly approach to increase crop yield and nutritional quality.

The environmental fate and persistence of bisphenol S (BPS), a substitute for bisphenol A (BPA), are unclear. This study used 14C-labeled BPS to examine the fate, biodegradation, and residue properties of BPS incubated in an oxic soil for 28 days. BPS dissipated quickly, with a half-life of 2.8 days. Most of the BPS was mineralized (53.6 ± 0.2% of initial amount by day 28) or transformed into non-extractable residues (NERs) (45.1 ± 0.3%), with generation of minor extractable residues (3.7 ± 0.2%) containing two metabolites. NERs were formed mainly via physico-chemical entrapment (51.1 ± 2.4% of the total NERs, consisting almost exclusively of BPS) and ester-linkages (31.5 ± 3.0% of the total NERs, consisting of both BPS and polar metabolites). When mixed with fresh soil, BPS-derived NERs became unstable and bioavailable. Subsequent mineralization was determined for 19.5 ± 1.1% of the total NERs and 35.5 ± 2.6% of the physico-chemically entrapped BPS. A fate model was used to describe the kinetics of NER formation, which indicated that microbial activity in soil could have strongly reduced the kinetic rate of the release of physico-chemically entrapped NERs into free form and therefore increased the stability of this type of NERs in soil. Our results provide unique insights into the fate of BPS in soil and suggest that while BPS is biodegradable, it includes the formation of large amounts of reversibly physico-chemically entrapped and covalently bound ester-linked NERs. The instability of these NERs should be considered in assessments on environmental persistence and risks of BPS. Our study also points out the environmental importance of NERs of agrochemicals.

Lower-brominated diphenyl ethers (LBDEs) occur ubiquitously in soil, however their fate there has not been well evaluated, mainly owing to that the unavailability of commercial radioactively labelled LBDE congeners hampers the investigation on fate of LBDEs in the environment with complex matrixes, such as soil and sediment. Here, we successfully synthesized three congeners of LBDEs, i.e., 4-bromodiphenyl ether (BDE3), 4,4'-dibromodiphenyl ether (BDE15), and 2,2',4,4'-tetrabromodiphenyl ether (BDE47), with 14C-labelling on one aromatic ring, starting from commercially available 14C-labelled phenol in two steps with high yields and high radiochemical purities. Using the 14C-labelled congeners, we studied the fate of LBDEs in a red soil under oxic conditions, where LBDEs have been frequently detected in high levels. The major fate of the LBDE congeners in the soil was formation of NERs, followed by mineralization to CO2, while no transformation product was detected in the soil after incubation for 105 days. The mineralization strongly decreased with increasing number of the bromine atom on the congener molecule, amounting to 10.4 ± 0.3%, 2.45 ± 0.04%, and 0.51 ± 0.05% for BDE3, BDE15, and BDE47, respectively, at the end of incubation, while mineralization rate constant was independent of the molecular structure, suggesting that solubility of LBDEs is the limit factor for their persistence in soil. The mineralization was positively linearly correlated with the formation of NERs (22.5 ± 1.9%, 11.0 ± 3.6%, and 6.7 ± 2.7% for BDE3, BDE15, and BDE47, respectively), which was mainly located in humin fraction and formed also in sterilized soil, suggesting a binding of transformation intermediates to soil humic substances and a physico-chemical entrapment of LBDEs in soil. The results provide new insights into fate of LBDE congeners in soil, and suggest a need to elucidate nature of the NERs of LBDEs, especially the stability of NERs in the environment.

The quantitative fate of polybrominated diphenyl ethers (PBDEs) in soil is unknown. Furthermore, the effects of co-contamination by toxic copper on the behavior of PBDEs have not been investigated. Using a C-14-tracer, we studied mineralization, metabolism, and formation of non-extractable residues (NERs) of one PBDE congener, i.e., the 4-bromodiphenyl ether (BDE3) in oxic soil for 50 days, without and with amendment of Cu (400 mg kg(-1) soil dw). BDE3 rapidly dissipated with a half-life of 5.5 days and large amounts of CO2 (38.8 +/- 0.3% of initial applied amount at the end of incubation) and NERs (42.5 +/- 0.4%) were rapidly produced. One hydroxylated metabolite (4'-HO-BDE3) was formed (8.1 +/- 0.6%) at the beginning of the incubation, but then decreased to 2.2 +/- 0.4%. Only BDE3 occurred in physico-chemically entrapped NERs, amounting to 9.2 +/- 0.7%, while only 4'-HO-BDE3 in ester-linked NERs (10.9 +/- 0.7%). The addition of Cu strongly reduced the kinetics constants of the transformations (including dissipation, mineralization, and NER-formation), the predicted maximal amounts of mineralization, as well as covalent binding of 4'-HO-BDE3 to soil. The results provide first quantitative insights into the fate of low-brominated congeners of PBDEs in soil and indicate that co-contamination by Cu may increase the environmental risks of biodegradable PBDEs in soil by increasing their persistence. (C) 2020 Elsevier Ltd. All rights reserved.

建立了扫描电镜-能谱法(SEM-EDS)测定生活饮用水中石棉(≥10 μm)的方法,使用场发射扫描电镜可对宽度大于0.050 ～0.124μm的石棉纤维进行定性和计数.若生活饮用水中存在以藻类为主的有机质干扰,使用紫外-过硫酸钾消解可消除相应干扰.配置低、中、高3个浓度的石棉悬浊液模拟水样交由国内不同地区的6家实验室进行方法学验证,结果表明,方法实验室内RSD为10％ ～37％,实验室间RSD为10％ ～ 39％,蓝藻干扰消除实验回收率平均值为98.1％,RSD为11％.方法 检出限为5.0×104～11.6×104个/L,低于GB 5749限量规定的700×104个/L.

The mechanisms underlying the bioaccumulation and detoxification of tetrabromobisphenol A (TBBPA) by terrestrial invertebrates are poorly understood. We used uniformly ring-14C-labelled TBBPA to investigate the bioaccumulation kinetics, metabolites distribution, and subsequent detoxification strategy of TBBPA in the geophagous earthworm Metaphire guillelmi in soil. The modeling of bioaccumulation kinetics showed a higher biota-soil-accumulation-factor of total 14C than that of the parent compound TBBPA, indicating that most of the ingested TBBPA was transformed into metabolites or sequestered as bound residues in the earthworms. Bound-residue formation in the digestive tract may hinder the accumulation of TBBPA in other parts of the body. Nonetheless, via the circulatory system, TBBPA was transferred to other tissues, especially the clitellum region, where sensitive organs are located. In the clitellum region, TBBPA was quickly transformed to less toxic dimethyl TBBPA ether and rapidly depurated through feces. We conclude that the detoxification of TBBPA in M. guillelmi occurred via bound-residue formation in the digestive tract as well as the generation and depuration of O-methylation metabolites. Our results provided direct evidence of TBBPA detoxification in earthworms. Further researches are needed to confirm whether O-methylation coupled with depuration is a common detoxification strategy for phenolic xenobiotics in other soil organisms needs to be determined.

Polychlorinated diphenyl sulfides (PCDPSs) are a group of dioxin-like compounds that have been widely used in agricultural and industrial productions. Here, we systematically investigated the photochemical behaviors of 2,2',3',4,5-pentachlorodiphenyl sulfide (2,2',3',4,5-PCDPS) on the surface of silica gel (SG) in an aqueous environment. Under the simulated sunlight irradiation, 2,2',3',4,5-PCDPS adsorbed on SG (0.11 mg/g) was found to be degraded with time, giving a removal rate of 68.5% within 16 h at pH 7.0. Environmental factors like pH and humic acid can also affect the removal rate. Results showed that the removal rate of 2,2',3',4,5-PCDPS in alkaline conditions (75.6% at pH 11) was higher than that in acidic conditions (46.7% at pH 3). Moreover, the addition of (1-5 mg/L) humic acid can promote the degradation rate compared to control group. In our study, it was found that SG can act as photocatalyst to generate reactive oxygen species (ROS) for the degradation of PCDPSs, and UV light contributed much more than visible light (> 420 nm). According to electron paramagnetic resonance (EPR) technology and radicals quenching experiments, hydroxyl radical (center dot OH), single oxygen (O-1(2)), and superoxide radical (center dot O-2(-)) participated in the removal of the contaminant. Based on the identified intermediate products via LC-MS, two main pathways, i.e., the hydroxyl-substituted reaction of the benzene ring and the oxidation of the sulfur atom, were proposed for the photodegradation of 2,2',3',4,5-PCDPS. Then, the density functional theory (DFT) was employed to confirm these reaction pathways. This study would enhance the understanding of the photochemical transformation and environmental fate of PCDPSs on the surface of solids in natural waters.

The worldwide environmental occurrence of natural steroid estrogens has drawn increasing concerns. However, the fate of the estrogens, especially the α-isomer of estradiol, in the environmental matrices is still obscure. Using 14C-radioactively labelled forms of these estrogens can facilitate and is sometimes a prerequisite for studying their transformation and residual distribution in the environment, but the availability of labelled compounds (owing to commercially high prices or unavailable) hampers such studies. Here we developed simple and stable methods to synthesize 14C-labelled estradiol isomers and estrone using relatively low-priced [carboxyl-14C]-labelled sodium acetate as a precursor. The radiochemical syntheses started from an enol lactone, which was prepared from nandrolone by oxidation to open the A-ring followed by recyclization. Inversion of the 17β-hydroxyl group into its 17α-form was achieved via the Walden inversion using the Mitsunobu reaction. [3-14C]-17β-estradiol, [3-14C]-17α-estradiol, and [3-14C]-estrone were synthesized in five, six, and seven steps with an overall radiochemical yield of 17.4%, 16.2%, and 13.9%, respectively. The synthesized 14C-labelled compounds provide materials for studying the fate and behavior of estrogens in complex environmental matrixes and for further synthesis of their 14C-labelled sulfate and glucuronide conjugates.