细化搜索
结果 4441-4450 的 8,010
Interaction of environmental eukaryotic microorganisms and fungi in the pond-cultured carps: new insights into the potential pathogenic fungi in the freshwater aquaculture 全文
2021
Zhou, Aiguo | Xie, Shaolin | Zhang, Yue | Chuan, Jiacheng | Tang, Huijuan | Li, Xiang | Zhang, Li | Xu, Guohuan | Zou, Jixing
The quality and safety of the aquatic products have gradually become the focus of global attention. In this study, the environmental eukaryotic and fungi communities in pond-cultured grass carp (Ctenopharyngodon idellus) and the koi carp (Cyprinus carpio L.) were investigated. For comparative analysis, the alpha diversity shows that the environmental microbial abundance in the koi carp groups were higher than that in the grass carp groups, while beta diversity reveals that the differences of the microbial community composition and structures in the grass carp groups were significantly higher than those in the koi carp groups. Meanwhile, the environmental microbial diversity of grass carp groups was higher than that of koi carp groups at phylum level, but showed no significant difference at genus level. Additionally, the dominant total phyla were Opisthokonta, Stramenopiles plusAlveolates plusRhizaria, Archaeplastida, Cryptophyceae, and Centrohelida for the 18S rRNA gene and Ciliophora, Chlorophyta, and Ascomycota for the ITS2 rRNA gene in both of the two carp groups. Additionally, annotation analysis showed that the biomarkers in the grass carp groups are significantly higher than those of the koi carp groups. Furthermore, the functional prediction of Funguild showed significant difference in outputs, while similarity in trophic modes and guild types between the two carp groups. Meanwhile, the total relative abundances of animal pathogen, fungal parasite, and plant pathogen were extremely similar between the two carp groups. Surprisingly, one pathogenic fungus of genus Fusarium was identified in both the environments of two carp groups based on filtered operational taxonomic unit tables. Overall, this is the first robust report to understand the characteristics of environmental eukaryotic microorganisms and fungi in the edible and ornamental carps. Our results also provide the basic data for the prevention of fungal diseases and the healthy culture of the carps.
显示更多 [+] 显示较少 [-]Source apportionment and deposition of dustfall-bound trace elements around Tabriz, Iran 全文
2021
Eivazzadeh, Mehran | Hassanvand, Mohammad Sadegh | Faridi, Sasan | Gholampour, Akbar
The monthly and spatial variations of atmospheric dustfall (DF) and their elemental components were determined. The DF sampling was performed using the ASTM method D-1739 from April 2017 to March 2018 in four urban and suburb sampling sites around Tabriz, Iran. The ICP-OES was utilized for the determination of the elemental components of DF.The results showed that the level of DF varied from 1.3 to 27.6 (8.0 ± 3.4) g/m².month during the sampling period, and the level of DF was higher in warm seasons than cold seasons. Also, it was revealed that the mean DF has a direct and significant relationship with temperature, wind speed, and relative humidity.The elements of Fe (11,997–17,093 mg/Kg and 71–81%) and Al (2903–6852 mg/Kg and 14–25%), which are the main elements of the Earth crust, were the dominant metals of DF among the analyzed elements. The lowest average value of the enrichment factor (EF) was for Al and was < 1, while the highest EF belonged to Hg, Pb, Cu, Sr, Mn, Co, Ni, and Cr, which were > 10 in all the sites, indicating that anthropogenic emission sources spread a considerable amount of trace elements in DF compared to the Lake Urmia bed or soil. The EF values for various elements (except than Cu and Hg) in cold seasons considerably increased compared to warm seasons.In all the study sites, Fe (540–1307 mg/m².yr) had the highest deposition rates among the metals. This study revealed that the Earth crust is the main source of DF in the region.
显示更多 [+] 显示较少 [-]State of the art in the analysis of brominated flame retardants in biota and sediment: insights from the characterisation of two new certified reference materials 全文
2021
Ricci, Marina | Shegunova, Penka | Vorkamp, Katrin
The Joint Research Centre (JRC) of the European Commission has recently released two new Certified Reference Materials (CRMs) for the analysis of brominated flame retardants (BFRs): the freshwater sediment ERM-CC537a and the fish tissue ERM-CE102. The production of these CRMs responds to the need of expanding the offer of quality assurance/quality control tools for the analysis of BFRs in the fields of environmental analysis and food control, especially for compliance purposes. The sediment ERM-CC537a carries certified values for polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDD) diastereoisomers in the μg/kg range (dry mass), while the fish tissue ERM-CE102 is certified for PBDEs in the ng/kg range (wet weight). ERM-CC537a is the first reference material ever available with certified values for α-, β- and γ-HBCDD. The assignment of the certified values was performed via an intercomparison of expert laboratories. The evaluation of the data confirms the improving trend, observed in recent years, regarding the comparability of PBDE measurement results. The relative standard deviation (RSD) among laboratories is slightly better for the fish material (8–11%) compared to the sediment (9–15%), despite lower mass fractions in the biota matrix. The RSD of HBCDD data (17%) reveals that they are more challenging analytes. The average measurement uncertainty declared by the participants is about 30%, but an in-depth analysis of their performance reveals that it should be feasible to reduce the uncertainty budget.
显示更多 [+] 显示较少 [-]Diatomite-enhanced coagulation for algal removal in polluted raw water: performance optimization and pilot-scale study 全文
2021
Jiang, Chao | Ding, Wei | Zhu, Weitang | Zhu, Liang | Xu, Xiangyang
Algae blooms have seriously threatened the health of aquatic ecosystems and the safety of drinking water. In this study, diatomite-enhanced coagulation technology was developed to improve the removal of algae and other pollutants. The dosage and ratio of diatomite and aluminum salts were optimized to 40mg/L and 1:1 which achieved algal removal efficiency of 98.8±0.65%. The effect of environmental factors was studied and it shows that cell density, pH, and temperature had a significant impact on algal removal. The mechanism of diatomite-enhanced coagulation was speculated to be adsorption bridging and sweep flocculation. Pilot-scale equipment was set up to verify the performance of diatomite-enhanced coagulation in engineering applications on algae polluted raw water. Results showed a better removal efficiency of algae, NH₄⁺-N, NO₂⁻-N, and CODMₙ and lower operation cost than the actual operation in the Waterwork Corporation were achieved with good application prospects and promotion value.
显示更多 [+] 显示较少 [-]Pulmonary toxicity of actual alveolar deposition concentrations of ultrafine particulate matters in human normal bronchial epithelial cell 全文
2021
Lin, Chia-Hua | Lung, Shih-Chun Candice | Chen, Yi-Chun | Wang, Lung-Chun
Air pollution is a major worldwide concern, and exposure to particulate matter (PM) can increase the risks of pulmonary diseases. Normal human bronchial epithelial cells were applied to clarify the role of ultrafine PM (UFPM) in the pathogenesis of pulmonary toxic effects with realistic alveolar deposition doses. The UFPM used in this research originated from vehicular emissions and coal combustion. UFPM exposure of up to 72 h was found to induce significant time- and concentration-dependent decreases in cell viability. Exposure to UFPM increased reactive oxygen species (ROS) accumulation through heme oxygenase-1 (HO-1) inhibition and induced massive oxidative stress that increased the interleukin-8 (IL-8) expression. UFPM also reduced the pulmonary trans-epithelial electrical resistance through the depletion of zonula occludens (ZO) proteins. Finally, UFPM decreased the α1-antitrypsin (A1AT) expression, which implies high risk of chronic obstructive pulmonary disease (COPD). The evidence demonstrates that exposure to UFPM, even at very low concentrations, may affect the functions of the respiratory system.
显示更多 [+] 显示较少 [-]Urinary benzophenones and synthetic progestin in Chinese adults and children: concentration, source and exposure 全文
2021
Wang, Siqi | Huo, Zhuhao | Shi, Wenyan | Wang, Hongyong | Xu, Gang
The endocrine-disrupting activities of UV filters and synthetic progestin have raised concerns about their adverse risks. In this study, 208 urine samples were collected from Shanghai residents for the determination of seven benzophenones (BPs) and six synthetic progestins. The highest median concentration (6.21ng g⁻¹ Cr) was observed in young adults (21–50 years), followed by a concentration of 3.86 ng g⁻¹ Cr in elderly adults (over 50 years old), and the lowest median concentration (1.32 ng g⁻¹ Cr) was found in children (8–11 years old). The detection rates of BP-3 and EE2 in adults were 97% and 82%, and in children were 31% and 24%, respectively. Synthetic progestin levels in Shanghai, China, were relatively low compared to other countries. And the urinary BPs level showed an increasing trend in Chinese in the past 5 years. The principal component analysis suggested that adults’ exposure to BP-1 and BP-3 was related, which occurs through food or dermal absorption of these chemicals present in cosmetic products and coatings. And diet was an important exposure pathway for children exposed to BPs. Despite relatively high levels of synthetic progestin for female and obese, the total estimated daily intake (EDI) was still lower than acceptable daily intake adopted by America. In the Monte-Carlo analysis, the 95th percentile of hazard quotients (HQs) was 0.83, which indicated that potential health risks were appreciated in the studied population.
显示更多 [+] 显示较少 [-]Assessing the risk of coal-burning arsenic-induced liver damage: a population-based study on hair arsenic and cumulative arsenic 全文
2021
Yao, Maolin | Zeng, Qibing | Luo, Peng | Sun, Baofei | Liang, Bing | Wei, Shaofeng | Xu, Yuyan | Wang, Qingling | Liu, Qizhan | Zhang, Aihua
Exposure to arsenic-contaminated air and food caused by the burning of coal in unventilated indoor stoves is a major environmental public health concern in Guizhou Province, China. The liver is one of the main target organs for coal-fired arsenic exposure; however, there is little information about the risk assessment between cumulative arsenic exposure and the prevalence of liver damage. This study first evaluated the chronic daily intake (CDI) for two exposure pathways (inhalation and ingestion) and five environmental media (i.e., indoor and outdoor air, drinking water, rice, corn, and chili peppers) in 1998, 2006, 2014, and 2017. Then, the dose-effect and dose-response relationship between hair arsenic (HA) and cumulative arsenic (CA) levels and liver damage was analyzed. The results clearly show that the CDI in 1998 was 34.9 μg·kg⁻¹·d⁻¹, 22.9 μg·kg⁻¹·d⁻¹ in 2006, 11.7 μg·kg⁻¹·d⁻¹ in 2014, and 6.7 μg·kg⁻¹·d⁻¹ in 2017 in the arsenic exposure area. All of these values were higher than the daily baseline level of 3.0 μg·kg⁻¹·d⁻¹ as recommended by the Joint FAO/WHO Expert Committee on Food Additives (JECFA), and the increased HA and CA can increase the risk of coal-fired arsenic-induced liver damage. In addition, we analyzed the possible maximum acceptable CA exposure level for coal-fired arsenic-induced liver damage using the Bayesian benchmark dose. The recommended maximum acceptable CA exposure level for liver damage caused by coal-burning arsenic is 7120 mg. This study provides scientific insight into understanding the dose-response relationship of liver damage caused by coal-burning arsenic exposure and the monitoring and prevention of arsenic poisoning.
显示更多 [+] 显示较少 [-]Heterogeneous Fenton degradation of ofloxacin catalyzed by magnetic nanostructured MnFe2O4 with different morphologies 全文
2021
Qin, Hangdao | Yang, Yingchang | Shi, Wei | She, Yuanbin
Magnetic nanostructured MnFe₂O₄ with different morphologies, synthesized via chemical co-precipitation and hydrothermal method, was assayed as heterogeneous Fenton catalysts. The as-prepared MnFe₂O₄ catalysts were thoroughly characterized by various characterization methods, such as X-ray diffraction (XRD), N₂ adsorption-desorption, transmission electron microscopy (TEM), magnetic hysteresis loops, temperature-programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS). The catalytic activity of MnFe₂O₄ catalysts was evaluated in the heterogeneous Fenton degradation of ofloxacin (OFX). In our study, the morphology exhibited a critical impact on the catalytic activity of MnFe₂O₄. For example, MnFe₂O₄ nanorods (MnFe₂O₄-NR) had a higher catalytic activity than MnFe₂O₄ nanospheres (MnFe₂O₄-NS) and MnFe₂O₄ nanocubes (MnFe₂O₄-NC) in OFX removal and H₂O₂ decomposition. Notably, the catalytic activity was remarkably enhanced with increasing the relative amount of Mn³⁺ and Fe²⁺ species on the surface. Based on the results from quenching experiments and quantitative determination of •OH radicals, a possible catalytic mechanism of MnFe₂O₄ was proposed. In addition, the stability and reusability of MnFe₂O₄-NR was ascertained, as the results suggested that MnFe₂O₄-NR was a stable and easily separated catalyst for heterogeneous Fenton process.
显示更多 [+] 显示较少 [-]Bacterial communities regulate temporal variations of the antibiotic resistome in soil following manure amendment 全文
2021
Cheng, Jianhua | Tang, Xiangyu | Liu, Chen
The increasing emergence of antibiotic-resistant genes (ARGs) represents a global threat to human health. Land application of animal manure is known to contribute considerably to the propagation and dispersal of antibiotic resistance in agro-ecosystems. Yet, the primary determinants of the fate of the soil resistome remain obscure. In this study, a pot experiment was conducted to examine temporal changes in ARGs, mobile genetic elements (MGEs), and bacterial communities in a weakly developed loamy soil (an entisol known as calcareous purple soil) upon addition of pig or chicken manure. On the day of manure application, substantial increases in the diversity and relative abundance of ARGs were observed in soil amended with raw pig manure. At the same time, no obvious changes were observed for soil amended with chicken manure. Antibiotic resistance in pig manure-amended soils rapidly decreased over time to a level that was still higher than that of unamended soil at 100 days after manure application. The results of the Mantel test and Procrustes analysis indicated that ARG profiles in soil were significantly correlated with the structure of the bacterial phylogeny. Variation partitioning analysis further revealed that the bacterial community played a major role in regulating the temporal changes in ARGs in soil following manure application. Increased numbers and relative abundances of MGEs and their significant positive correlations with ARGs were observed, which suggest that a potential contribution from lateral gene transfer to the persistence and spread of ARGs should not be overlooked. Overall, our findings provide a better understanding of the mechanisms underlying the dynamics of ARGs in entisols following manure application and have practical implications for managing manure applications in entisols of the study area and other areas.
显示更多 [+] 显示较少 [-]Does economic growth, international trade, and urbanization uphold environmental sustainability in sub-Saharan Africa? Insights from quantile and causality procedures 全文
2021
Iheonu, Chimere O. | Anyanwu, Ogochukwu C. | Odo, Obinna K. | Nathaniel, Solomon P.
International trade and urbanization are increasing at an unprecedented rate in sub-Saharan Africa (SSA). The region has also witnessed a fair share of economic growth, with minimal investment and consumption of renewables. Therefore, this study investigates the influence of economic growth, international trade, and urbanization on CO₂ emissions in SSA. The current study enriches the existing literature by employing the panel quantile regression analysis to account for existing levels of CO₂ emissions in the region. Empirical findings reveal that GDP increases CO₂ emissions across quantiles, especially in countries where the existing level of CO₂ emissions is low. International trade improves environmental sustainability in countries where the existing levels of CO₂ emissions are at their lowest and highest levels but exacts a reversed impact on CO₂ emissions at the median. Further findings suggest that urbanization increases CO₂ emissions across the observed quantiles with a more pronounced effect in countries where the existing levels of CO₂ emissions are at its lowest level. The study also reveals a bi-directional causality between economic growth, international trade, urbanization, and the emissions of CO₂. The limitations of the study and possible direction for future research have been highlighted. Policy directions are discussed.
显示更多 [+] 显示较少 [-]