Mono-(2-ethylhexyl) phthalate (MEHP) is the primary monoester transformation product of the commonly used plasticizer, di-2-ethylhexyl phthalate (DEHP), and has been frequently detected in various environmental compartments (e.g., soil, biosolids, plants). Plants growing in contaminated soils can take up MEHP, and consumption of the contaminated plants may result in unintended exposure for humans and other organisms. The metabolism of MEHP in plants is poorly understood, but critical for evaluating the potential human and environmental health risks. The present study represents the first attempt to explore the metabolic fate of MEHP in plants. We used Arabidopsis thaliana cells as a plant model and explored metabolic pathways of MEHP using deuterium stable isotope labelling (SIL) coupled with time-of-flight high resolution mass spectrometer (TOF-HRMS). A. thaliana rapidly took up MEHP from the culture medium and mediated extensive metabolism of MEHP. Combining SIL with TOF-HRMS analysis was proved as a powerful method for identification of unknown MEHP metabolites. Four phase Ⅰ and three phase Ⅱ metabolites were confirmed or tentatively identified. Based on the detected transformation products, hydroxylation, oxidation, and malonylation are proposed as the potential MEHP metabolism pathways. In cells, the maximum fraction of each transformation product accounted for 2.8–56.5% of the total amount of metabolites during the incubation. For individual metabolites, up to 2.9–100% was found in the culture medium, suggesting plant excretion. The results in the cell culture experiments were further confirmed in cabbage and A. thaliana seedlings. The findings suggest active metabolism of MEHP in plants and highlight the need to include metabolites in refining environmental risk assessment of plasticizers in the agro-food systems.

Cyanobacterial blooms and their secondary metabolites, microcystins (MCs), are not only toxic to aquatic organisms, but also to humans. MCs exert reproductive toxicity in female fish by affecting the oocyte development. However, the mechanism behind MC-LR interference in oocyte development remains largely unknown. In our study, adult female zebrafish were exposed to MC-LR (0, 1, 5, 20 μg/L) for 30 d. After exposure to MC-LR for 30 d, fertilized eggs from the treated females and healthy males were collected and cultured in water without MC-LR. Histomorphological observations showed pathological damage in the ovary after MC-LR exposure, which was mainly characterized by enlarged intercellular spaces, detachment of follicular cells from oocytes, and vacuolation of parenchymal tissues. The 20 μg/L MC-LR treatment caused a remarkable increase in the rate of the zebrafish oocytes germinal vesicle breakdown (GVBD) and a significant decrease in the levels of cyclic adenosine monophosphate (cAMP) and vitellogenin (VTG). In addition, the phosphorylation levels of the extracellular signal-regulated kinases (ERK) were elevated in ovaries from zebrafish exposed to 5 and 20 μg/L MC-LR, and cyclinB phosphorylation levels were also upregulated notably in the 20 μg/L MC-LR group. However, MC-LR exposure did not cause any change in the levels of cAMP-dependent protein kinase (PKA) protein and cdc2 phosphorylation in all the treatments. All the doses of MC-LR reduced the number of eggs, prematurely hatched the fertilized eggs and increased the abnormal rate of offspring generation. In summary, the present study demonstrates that MC-LR promotes oocyte maturation by activating the ERK1/2 and MPF signaling pathways, and cAMP is involved in this process.

The emission of mercury (Hg) from cropland soil greatly affects the global Hg cycle. Combinations of different crop cultivars and planting densities will result in different light transmittance under canopies, which directly affects the solar and heat radiation flux received by the soil surface below crops. In turn, this might lead to differences in the soil–air total gaseous mercury (TGM) exchange under different cropping patterns. However, soil–air TGM exchange fluxes in croplands under differing canopies have been poorly investigated. Here, a one-year observation of TGM exchange flux was conducted for cropland soils covering five different crop cultivars and three planting densities in North China Plain using the dynamic flux chamber method. The results showed that light transmittance under the canopies was the key control on soil–air TGM exchange fluxes. High light transmittance can enhance soil TGM emission rates and increase the magnitude of diurnal variations in soil–air TGM exchange fluxes. Furthermore, we found that there were piecewise–function relationships (Peak function–constant equation) between light transmittance under the different canopies and the numbers of days after crop sowing. The soil–air TGM exchange fluxes showed a parabolic response to changes in light transmittance under the different canopies. A second-order model was established for the response relationship between soil–air TGM exchange flux and soil Hg concentration, total solar radiation above the canopy, and numbers of days after sowing. The estimated annual average soil–air TGM exchange flux was 5.46 ± 21.69 ng m⁻² h⁻¹ at corn–wheat rotation cropland with 30 cm row spacing using this second-order model. Our results might a data reference and a promising foundation for future model development of soil–air TGM exchange in croplands under different crop cultivars and planting densities.

Per- and polyfluoroalkyl substances (PFAS) are widely used in stain-resistant carpets, rugs, and upholstery, as well as in waxes and cleaners, and are potential contaminants in the childcare environment. However, limited knowledge exists on the occurrence of PFAS in indoor environments, apart from residential homes. Here, we determined the occurrence and distribution of 37 neutral and ionic PFAS, including perfluoroalkyl carboxylates (PFCAs) perfluoroalkyl sulfonates (PFSAs), fluorotelomer alcohols (FTOHs), fluorotelomer sulfonates (FTSs), perfluorooctane sulfonamides and perfluorooctane sulfonamidoethanols (FOSAs/FOSEs), and fluorotelomer acrylates and fluorotelomer methacrylates (FTACs/FTMACs) in the childcare environment and estimated children’s exposure through dust ingestion and dermal absorption. We analyzed dust and nap mats, a commonly used item in many childcares, from eight facilities located in the United States. Twenty-eight PFAS were detected in dust with total PFAS concentrations (ΣPFAS) ranging from 8.1 to 3,700 ng/g and were dominated by the two neutral PFAS groups: ΣFTOH (n.d. – 3,100 ng/g) and ΣFOSA/FOSE (n.d. – 380 ng/g). The ionic PFAS were detected at lower concentrations and were dominated by 6:2 FTS and 8:2 FTS (median 12 and 5.8 ng/g, respectively). ΣPFAS concentrations in mats (1.6–600 ng/g) were generally an order of magnitude lower than in dust and were dominated by ΣFOSA/FOSE concentrations (n.d. – 220 ng/g). Daily intake of neutral PFAS in the childcare environment via dust ingestion was estimated at 0.20 ng/kg bw/day and accounted for 75% of the ΣPFAS intake. This higher exposure to neutral PFAS is concerning considering that many neutral PFAS are the precursors of toxic ionic PFAS, such as PFOA.

Polychlorinated biphenyls (PCBs) are notorious environmental pollutants. For their hydrophobic and lipophilic capability, they are wildly spread to environment to threat human health thus attracts more attention. In this study, we observed increasing numbers of CD163 positive (CD163⁺) macrophages in aortic valve of ApoE⁻/⁻ mice after 2,3,5-trichloro-6-phenyl-[1,4]-benzoquinone (PCB29-pQ) treatment, the metabolite of polychlorinated biphenyl. In addition, in vitro studies identified that PCB29-pQ exposure significantly provoked the shifting of RAW264.7 macrophages and bone marrow derived monocytes (BMDMs) to CD163⁺ macrophages. Upon PCB29-pQ administration, CD163 and CD206 levels were enhanced in RAW264.7 cells as well as in BMDMs. However, the concentration of iron and total cholesterol (TC) were reduced due to the boosting of ferroportin (Fpn) and ATP binding cassette transporter, subfamily A, member 1 (ABCA1) which are efflux transporters of iron and cholesterol individually. Further investigation on mechanism indicated that PCB29-pQ exposure induced reactive oxygen species (ROS), which may result in activation of nuclear factor erythroid 2-related factor 2 (Nrf2), a protein responsible for macrophage polarization. After that, we blocked Nrf2 through Nrf2 shRNA and ROS scavenger NAC, which significantly reversed the shifting of macrophage to CD163⁺ sub-population. These results confirmed the importance of Nrf2 in inducing macrophage polarization. In short, our study uncovered that PCB29-pQ could promote macrophage/monocyte polarization to CD163⁺ macrophage which would be a potential incentive to accelerate atherosclerosis through Nrf2 signaling pathway.

The ammonium sulphate ((NH₄)₂SO₄) in-situ leaching process is the most widely used extraction technology for weathered crust elution-deposited rare earth ores (WCED-REOs). Highly concentrated (NH₄)₂SO₄, a representative leaching agent, is often used in the leaching process of WCED-REOs. However, this in-situ leaching process causes nitrogen pollution in the soil, surrounding surface and ground water due to the high concentrations of (NH₄)₂SO₄ solutions used as a long term leaching agent. To date, the mechanism behind the variations in ammonia nitrogen (AN) in deep soil profiles is unclear. We conducted vertical and lateral soil sampling and analyzed the collected samples for soil moisture, pH, ammonia forms, and AN contents in soil profiles deeper than 500 cm in an in-situ leaching mining area of Ganzhou, Jiangxi Province, southern China. The results show that primary chemical pollutants in the soil are derived from residual leaching agents with high acidities and concentrations of AN. Twelve years after the mining process was completed, the mean pH values of the tailings in the mining area were 3.90 and 4.87 in its lower reaches. Due to the presence of chemical residues, the AN concentration was 12–40 times higher than that of the raw ore soil before it was mined. The percentages of different ammonium forms in the rare earth tailing soil were 65%, 30%, and 5% for the water-soluble, exchangeable, and fixed ammonium forms, respectively. The results of this study support effective prevention and remediation treatment of environmental problems caused by AN pollution of the soil in WCED-REOs.

As a group of emerging organic pollutants, chlorinated paraffins (CPs) have attracted rising global attention due to their persistence and toxicity. In this study, we have investigated the concentration levels and profiles of short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) in soils and sediments from Dongguan City, an industrial area in South China, and have also screened very short-chain chlorinated paraffins (vSCCPs) by means of ultra-high resolution liquid chromatograph coupled with an Orbitrap Fusion Tribrid mass spectrometer. The results indicated that total SCCP concentrations ranged from 6.75 to 993 ng/g (mean 172 ng/g) in soils and from 4.00 to 613 ng/g (mean 153 ng/g) in sediments, respectively. Higher MCCP levels were observed with a range of 23.9–2427 ng/g (mean 369 ng/g) in soils and 14.0–1581 ng/g (mean 493 ng/g) in sediments, respectively. The results indicated that MCCPs dominated over SCCPs in the studied region. The dominant homologues in soils and sediments were C₁₃Cl₆–₇ and C₁₄Cl₇–₈, C₁₃Cl₇, and C₁₄Cl₇–₈, respectively. Furthermore, six vSCCP homologues (C₈Cl₇–₈ and C₉Cl₅–₈) in soils and four vSCCPs (C₉Cl₅–₈) in sediments have been identified. Because of their higher detection frequencies, further studies should focus on the transformation mechanisms and toxicities of these vSCCPs in environmental media and biota.

Hydrophobic pollutants are still present in agricultural soil. The Cucurbitaceae family accumulates hydrophobic pollutants through roots, resulting in the contamination of aerial parts. Major latex-like proteins (MLPs), found in the Cucurbitaceae family, play an important role in the contamination by binding to these hydrophobic pollutants. Thus far, efficient cultivation methods for the production of safe crops with lower concentrations of hydrophobic pollutants have not been developed. Herein, we competitively inhibited the binding of MLPs to hydrophobic pollutants, pyrene and dieldrin, in roots by using MLP binding pesticides. By conducting a chemical array screening, we found that MLPs bound compounds with indole- and quinazoline-like structures. Commercially available pesticides amisulbrom and pyrifluquinazon, which possess such structures, successfully inhibited the binding of MLPs to pyrene and dieldrin in vitro. When zucchini plants were cultivated in the contaminated soil with 1.25 mmol/kg pyrene and 12.5 μmol/kg dieldrin, the concentration of pyrene and dieldrin in xylem sap was significantly decreased by 30% and 15%, respectively. Our results demonstrate that the pesticides binding to MLPs competitively inhibited the binding of MLPs to pyrene and dieldrin in roots, resulting in the reduction of overall contamination. This study proposes a novel approach to cultivate safer crops and advances the utilization of unknown functions of pesticides.

Tremendous efforts have been devoted by researchers on air particulate matter pollution for the increasing harm, however, the Air Pollution Index (API) from “good” to “excellent” is something hard to achieve. Here, halloysite nanotubes/polyvinyl alcohol (HNTs/PVA) hybrid membrane with surface micro-nano structure processing using a one-step method for efficient PM₂.₅ capture was prepared. The filtration efficiency is 45.35% and the pressure drop is 41.57 Pa of composite membrane with a 60 wt% halloysite dosage. Specially, it resulted in a relatively safer PM index value of about 16.54, which tends to be more stringent than the restriction by Government of China (PM₂.₅ < 35 μg/m³). The filtration performance was mainly attributed to the controllable microroughness surface as well as the hierarchical structure constructed by one-step method, which has a functional role in obstruction and adsorption for diluted PM₂.₅. The methodology can employ halloysite onto various polymers, like polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyacrylonitrile (PAN) and also polycaprolactone (PCL) to yield hybrid membranes with the similar modification of surface and structure. Such versatile membrane filters can be purposely designed and scaled up, which endows the existing hybrid membrane with great potentials in both residential and public areas pollution control to achieve a healthier living environment.

The Kızılırmak Delta is one of the most important agricultural production regions and it was included as part of the Ramsar Convention in 1998. The water used in agricultural irrigation is mostly supplied from drainage channels. In the present study, 120 water samples were collected from drainage channels and analyzed to characterize the groundwater chemistry and microbiological contamination. Sea water interface, discharge of sewage, wastewater from agricultural activities and livestock and uncontrolled solid waste landfills were identified as the most important pollutant sources in the delta. Serious microbiological pollution was detected in channel water samples. These results indicate that sewage waters mix with the channel waters in the delta. Also, the correlations of parameters such as EC, TDS, DO, Cl⁻ and SO₄²⁻ indicate that channel waters contain high dissolved minerals. It was concluded that especially agricultural pollution and waste water affects water resources negatively in the region.