خيارات البحث
النتائج 1941 - 1950 من 7,921
Heterogeneous photochemical uptake of NO2 on the soil surface as an important ground-level HONO source
2021
Yang, Wangjin | Han, Chŏng | Zhang, Tingting | Tang, Ning | Yang, He | Xue, Xiangxin
Nitrous acid (HONO) production from the heterogeneous photochemical reaction of NO₂ on several Chinese soils was performed in a cylindrical reactor at atmospheric pressure. The NO₂ uptake coefficient (γ) and HONO yield (YHONO) on different soils were (0.42–5.16) × 10⁻⁵ and 6.3%–69.6%, respectively. Although the photo-enhanced uptake of NO₂ on different soils was observed, light could either enhance or inhibit the conversion efficiency of NO₂ to HONO, depending on the properties of the soils. Soils with lower pH generally had larger γ and YHONO. Soil organics played a key role in HONO formation through the photochemical uptake of NO₂ on soil surfaces. The γ showed a positive correlation with irradiation and temperature, while it exhibited a negative relationship with relative humidity (RH). YHONO inversely depended on the soil mass (0.32–3.25 mg cm⁻²), and it positively relied on the irradiance and RH (7%–22%). There was a maximum value for YHONO at 298 K. Based on the experimental results, HONO source strengths from heterogeneous photochemical reaction of NO₂ on the soil surfaces were estimated to be 0.2–2.7 ppb h⁻¹ for a mixing layer height of 100 m, which could account for the missing daytime HONO sources in most areas.
اظهر المزيد [+] اقل [-]Bisphenol A exposure induces apoptosis and impairs early embryonic development in Xenopus laevis
2021
Ge, Yaming | Ren, Fei | Chen, Lingli | Hu, Dongfang | Wang, Xinrui | Cui, Yunli | Suo, Yu | Zhang, Hongli | He, Junping | Yin, Zhihong | Ning, Hongmei
Bisphenol A (BPA), an endocrine-disrupting chemical that is largely produced and used in the plastics industry, causes environmental pollution and is absorbed by humans through consumption of food and liquids in polycarbonate containers. BPA exerts developmental and genetic toxicities to embryos and offsprings, but the embryotoxicity mechanism of this chemical is unclear. This study aimed to explore the toxic effect of BPA on embryonic development and elucidate its toxicity mechanism. Embryos of Xenopus laevis as a model were treated with different concentrations (0.1, 1, 10, and 20 μM) of BPA at the two-cell stage to investigate the developmental toxicity of BPA. Embryonic development and behaviors were monitored 24 h–96 h of BPA exposure. BPA concentrations greater than 1 μM exerted significant teratogenic effects on the Xenopus embryos, which showed short tail axis, miscoiled guts, and bent notochord as the main malformations. The 20 μM BPA-treated embryos were seriously damaged in all aspects and exhibited deformity, impaired behavioral ability, and tissue damage. The DNA integrity and apoptosis of the Xenopus embryos were also investigated. Exposure to BPA concentrations higher than 0.1 μM significantly induced DNA damage (p < 0.05). The 10 and 20 μM BPA-treated embryos exhibited higher levels of cleaved caspase-3 protein than the control. The ratios of bax/bcl-2 mRNA were significantly higher in the 10 μM and 20 μM-treated embryos than the ratio in the control group. Overall, data indicated that BPA can delay the early development, induce DNA damage and apoptosis, and eventually cause multiple malformations in Xenopus embryos.
اظهر المزيد [+] اقل [-]Lycopene prevents DEHP-induced hepatic oxidative stress damage by crosstalk between AHR–Nrf2 pathway
2021
Zhao, Yi | Bao, Rong-Kun | Zhu, Shi-Yong | Talukder, Milton | Cui, Jia-Gen | Zhang, Hao | Li, Xue-Nan | Li, Jin-Long
Di (2-ethylhexyl) phthalate (DEHP) is a widespread plasticizer that persists in the environment and can significantly contribute to serious health hazards of liver especially oxidative stress injury. Lycopene (LYC) as a carotenoid has recently gained widespread attention because of antioxidant activity. However, the potential mechanism of DEHP-induced hepatotoxicity and antagonism effect of LYC on it are still unclear. To explore the underlying mechanisms of this hypothesis, the mice were given by gavage with LYC (5 mg/kg) and DEHP (500 or 1000 mg/kg). The data suggested that DEHP caused liver enlargement, reduction of antioxidant activity markers, increase of oxidative stress indicators and disorder of cytochrome P450 enzymes system (CYP450s) homeostasis. DEHP-induced reactive oxygen species (ROS) activated the NF-E2-relatedfactor2 (Nrf2) and nuclear xenobiotic receptors (NXRs) system including Aryl hydrocarbon receptor (AHR), Pregnane X receptor (PXR) and Constitutive androstane receptor (CAR). Interestingly, these disorders and injuries were prevented after LYC treatment. Taken together, DEHP administration resulted in hepatotoxicity including oxidative stress injury and disordered CYP450 system, but these alterations might be ameliorated by LYC via crosstalk between AHR–Nrf2 pathway.
اظهر المزيد [+] اقل [-]Accumulation of phthalates under high versus low nitrogen addition in a soil-plant system with sludge organic fertilizers instead of chemical fertilizers
2021
Hui, Kunlong | Tang, Jun | Cui, Yini | Xi, Beidou | Tan, Wenbing
Nitrogen is the main nutrient in soil. The long-term addition of N leads to changes in the soil dissolved organic matter (DOM) and other quality indicators, which affects the adsorption and accumulation of organic pollutants. The use of organic fertilizer is important for the development of green agriculture. However, organic fertilizers (especially sludge organic fertilizers (SOFs) contain phthalates (PAEs) that may accumulate in the soil and result in environmental contamination. How this accumulation response varies with the magnitude of long-term N addition, especially in different soil layer profiles, remains unclear. Here, changes in the content of PAEs in the soil–plant system without and after SOFs application were studied through field experiments in soils with different N addition backgrounds (CK, N1, N3 (0, 100, 300 kg N ha⁻¹ yr⁻¹ respectively)). Our results showed that the application of SOFs increase the accumulation of PAEs in soil profiles and plant systems, increasing human health risks. The content of Σ₅PAEs in the topsoil increased from 0.96 ± 0.10 to 1.86 ± 0.09 mg kg⁻¹. Moreover, under a high N addition background and SOFs application, the characteristics of soil DOM change, and the accumulation of PAEs in soil was nearly 30% higher compared with the low N group. Some suggestions such as removing PAEs from SOFs during preparation, conducting soil surveys before applying PAEs, and using soil amendments, which are provided for optimizing the trialability and environmental safety of SOFs application.
اظهر المزيد [+] اقل [-]Size effects of polystyrene microplastics on the accumulation and toxicity of (semi-)metals in earthworms
2021
Xu, Guanghui | Yang, Yang | Yu, Yong
Microplastics (MPs) are plastic fragments less than 5 mm, which may have adverse impacts on organisms. In this study, we investigated the impacts and mechanisms of polystyrene MPs (10 μm and 100 μm) and nanoplastics (NPs, 100 nm) with different concentrations (10 mg/kg and 100 mg/kg) in soil on the uptake of metal Cd and semi-metal As in earthworms, Eisenia fetida. MPs facilitated the accumulation of (semi-)metals via damaging the integrity of earthworm intestine, and earthworms accumulated more (semi-)metals in MP treatment groups than NP treatment groups, especially in group of 100 mg/kg of 10 μm MP with concentrations of 1.13 mg/kg and 32.7 mg/kg of Cd and As, respectively. Higher genotoxicity to earthworms was observed for MPs than NPs. Antioxidant enzymes activity and their mRNA gene relative expression levels indicated that MPs with high concentration induced severer damage to earthworms, thus resulting in the increased accumulation of (semi-)metals by earthworms. In addition, proteomic and metabolomic analysis revealed that MPs (100 ppm of 10 μm) disturbed the earthworm immune and metabolic systems, resulting in the highest accumulation of (semi-)metals in earthworms. This study clarifies the influence mechanisms of MPs with different sizes and levels on the accumulation of (semi-)metals by terrestrial invertebrates.
اظهر المزيد [+] اقل [-]Urinary antibiotic level of school children in Shanghai, East China, 2017–2020
2021
Wang, Hexing | Tang, Chuanxi | Wang, Yuanping | Han, Minghui | Jiang, Feng | Jiang, Lufang | Wu, Jingui | Fu, Chaowei | Chen, Yue | Jiang, Qingwu
In recent years, an extensive exposure to antibiotics from various sources has been demonstrated in China by the biomonitoring method, but the temporal trend remains little known. The study aim was to explore the temporal trend of exposure to antibiotics and associated health risk in children. A dynamic child cohort was established in Shanghai, East China between 2017 and 2020. A total of 684 school children aged 7-11 years were included, and 280 in 2017, 279 in 2018, 288 in 2019, and 287 in 2020 participated in annual surveys. Twenty-three typical antibiotics and three metabolites from five categories (four tetracyclines, five qinolones, six macrolides, eight sulfonamides, and three phenicols), bisphenol A (BPA), and monobutyl phthalate (MBP) were determined in urine. Logistic regression analysis with generalized estimating equations was conducted to investigate the associations between various variables and the detection frequency of antibiotics in urine. Seventeen antibiotics and three metabolites were found in 51.9% of all urine samples. Compared to 2017, the detection frequency in urine reduced 31.8% in 2020 for all antibiotics (58.2% vs 39.7%) and reduced 36.8%–55.8% for tetracyclines (11.4% vs 7.0%), qinolones (34.3% vs 21.3%), macrolides (8.6% vs 3.8%), sulfonamides (16.4% vs 8.7%), and phenicols (19.3% vs 12.2%). After accounting for personal characteristics, food consumption, and urinary BPA and MBP, a decreasing temporal trend of detection frequencies was observed from 2017 to 2020 for most antibiotics. Urinary concentration, estimated daily intake, and acceptable daily intake-based health risk of antibiotics showed a temporal trend similar to detection frequency. There was an extensive exposure to antibiotics in children. However, a decreasing temporal trend occurred for the exposure during the period from 2017 to 2020. The trend was likely to be caused by decreased antibiotic use and/or decreased residues in food and/or drinking water.
اظهر المزيد [+] اقل [-]Effect of soil amendments on molybdenum availability in mine affected agricultural soils
2021
Wang, Xiaoqing | Brunetti, Gianluca | Tian, Wenjie | Owens, Gary | Qu, Yang | Jin, Chaoxi | Lombi, Enzo
Molybdenum (Mo) contamination of agricultural soils around Mo-mining areas is of emerging environmental concern. This study evaluated potential practical techniques for chemical immobilization of three Mo contaminated agricultural soils via application of up to six amendments from four different types of materials including biosolids, biochar supported nanoscale zero-valent iron (BC-nZVI), drinking water treatment residues (WTR) and ferrous minerals (magnetite and ferrihydrite). The efficacy of the different amendments on soil Mo bioaccessibility and bioavailability was evaluated by monitoring Mo uptake in both monocotyledon (ryegrass) and dicotyledon (alfalfa) plants, soil extractable Mo, and Mo bioavailability as measured by Diffusive Gradient in Thin Films (DGT®). All amendments exhibited no immobilization effect and increased Mo extractability in the severely contaminated soil (264 mg Mo kg⁻¹). In contrast, in lightly and moderately contaminated soils (22 and 98 mg Mo kg⁻¹), biosolids, WTR and magnetite all reduced soil extractable Mo and decreased Mo uptake in both alfalfa and ryegrass shoots relative to controls (CK). Moreover, DGT showed that during incubation experiments while biosolids amendments increased Mo bioavailability from 115 to 378% compared to the CK treatments, all other amendments decreased Mo bioavailability insignificantly.
اظهر المزيد [+] اقل [-]Effects of hydrothermal treatments on destruction of per- and polyfluoroalkyl substances in sewage sludge
2021
Zhang, Weilan | Liang, Yanna
Sewage sludge has become a sink of per- and polyfluoroalkyl substances (PFAS) due to the ineffectiveness of PFAS removal during conventional activated sludge treatment process. In this study, we evaluated the performance of an enhanced method for PFAS extraction from sewage sludge. Significant matrix effect was observed for samples derived from untreated and hydrothermally treated sludge. Extra steps for removing potential interferences were thus needed to reduce these matrix effects and improve the accuracy of PFAS quantification. Hydrothermal treatment at 165 °C for 0.5/2 h and 250 °C for 0.5 h increased the concentration of extractable PFAAs in treated sludge. Increasing the temperature to 300 °C resulted in complete degradation of PFCAs after hydrothermal processing, but still increased the concentrations of PFSAs and PFAA precursors. The concentration increase could be due to the conversion of PFAA precursors to PFAAs and the release of PFAAs from sewage sludge during thermal treatment. Ca(OH)₂ addition to hydrothermal treatment completely removed PFAA precursors but significantly increased the extractable PFAAs, except PFHpA and PFHxS, at 165 °C and all PFSAs at 300 °C. This study revealed the difficulties in extracting and quantifying PFAS in sludge and demonstrated the need for further research on finding suitable solutions for complete removal or destruction of PFAS in highly heterogeneous sewage sludge.
اظهر المزيد [+] اقل [-]Prenatal exposure to propylparaben at human-relevant doses accelerates ovarian aging in adult mice
2021
Li, Milu | Zhou, Su | Wu, Yaling | Li, Yan | Yan, Wei | Guo, Qingchun | Xi, Yueyue | Chen, Yingying | Li, Yuanyuan | Wu, Meng | Zhang, Jinjin | Wei, Jia | Wang, Shixuan
Embryonic exposure to environmental chemicals may result in specific chronic diseases in adulthood. Parabens, a type of environmental endocrine disruptors widely used in pharmaceuticals and cosmetics, have been shown to cause a decline in women's reproductive function. However, whether exposure to parabens during pregnancy also negatively affect the ovarian function of the female offspring in adulthood remains unclear. This study aims to investigate the effects of prenatal propylparaben (PrP) exposure on the ovarian function of adult mice aged 46 weeks, which is equivalent to the age of 40 years in women. Pregnant ICR mice were intraperitoneally injected with human-relevant doses of PrP (i.e., 0, 7.5, 90, and 450 mg/kg/day) during the fetal sex determination period—from embryonic day E7.5 to E13.5. Our results revealed that ovarian aging was accelerated in PrP-exposed mice at 46 weeks, with altered regularity of the estrous cycle, decreased serum estrogen (E2) and progesterone (P4) levels, reduced size of the primordial follicle pool, and increased number of atretic follicles. It was found that prenatal exposure to human-relevant doses of PrP exacerbated ovarian oxidative stress, inflammation, and fibrosis, which promoted follicular atresia by activating the mitochondrial apoptosis pathway. To compensate, the depletion of primordial follicles was also accelerated by activating the PI3K/AKT/mTOR signaling pathway in PrP-exposed mice. Moreover, PrP induced hypermethylation of CpG sites in the promoter region of Cyp11a1 (a 17.16–64.28% increase) partly led to the disrupted steroidogenesis, and the altered methylation levels of imprinted genes H19 and Peg3 may also contribute to the phenotypes observed. These remarkable findings highlight the embryonic origin of ovarian aging and suggest that a reduced use of PrP during pregnancy should be advocated.
اظهر المزيد [+] اقل [-]The life of a plastic butter tub in riverine environments
2021
Delorme, Astrid E. | Koumba, Gaelle B. | Roussel, Erwan | Delor-Jestin, Florence | Peiry, Jean-Luc | Voldoire, Olivier | Garreau, Alexandre | Askanian, Haroutioun | Verney, Vincent
Plastic pollution in the world's ocean is one of the major environmental challenges that affects the society today, due to their persistence at sea, adverse consequences to marine life and being potentially harmful to human health. Rivers are now widely recognized as being the major input source of land-based plastic waste into the seas. Despite their key role in plastic transportation, riverine plastic pollution research is still in its infancy and plastic sources, hot-spots and degradation processes in riverine systems are to date poorly understood. In this contribution, we introduce a novel concept of following the aging of polypropylene based post-consumer goods placed in known trapping and mobility zones of macroplastics on a fluvial point bar, which was determined through repeated field surveys of macroplastic densities on this bar. As a proof-of-concept, we followed the degradation of 5 identical plastic butter tubs in 5 different locations on a riverbank and significant differences in the aging of the tubs were observed. The degree of aging of the tubs can to some extent be correlated to their proximity to the main river channel, exposure to natural conditions, such as solar radiation, and its storage time on land.
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