خيارات البحث
النتائج 2961 - 2970 من 4,937
Distribution characteristics and noncarcinogenic risk assessment of culturable airborne bacteria and fungi during winter in Xinxiang, China النص الكامل
2019
Yan, Xu | Qiu, Dezhi | Zheng, Shikan | Yang, Jie | Sun, Hongyan | Wei, Yue | Han, Jingru | Sun, Jianhui | Su, Xianfa
Bioaerosols are an important component of particulate matter in the atmosphere and are harmful to human health. In this study, the concentration, size distribution, and factors influencing culturable airborne bacteria and fungi in the atmosphere were investigated using a six-stage impactor device in the city of Xinxiang, China, during the winter season. The results revealed that the concentration of culturable airborne bacteria and fungi varied significantly during the sampling period: 4595 ± 3410 and 6358 ± 5032 CFU/m³, respectively. The particle sizes of the bioaerosols were mainly within stage V (1.1–2.1 μm), and fine particulate matter accounted for 45.9% ± 18.9% of airborne bacteria and 52.0% ± 18.5% of airborne fungi, respectively. With the deterioration of air quality, the concentration of airborne fungi gradually increased, and that of airborne bacteria increased when the air quality index was lower than 200 and decreased when it was higher than 200. With respect to the diurnal variation pattern of bioaerosol concentration, the highest and lowest concentrations were registered at night and noon, respectively, probably because of changes in ultraviolet radiation intensity. Bioaerosol concentration positively correlated with humidity, concentration of PM₂.₅, PM₁₀, SO₂, and NO₂ and negatively correlated with O₃ concentration. The risk of exposure of humans to the airborne bacteria was primarily associated with the respiratory inhalation pathway, and the risk of skin exposure was negligible. These results should improve our understanding of the threat of bioaerosols to public health.
اظهر المزيد [+] اقل [-]Identification of photoproducts of florasulam in water using UPLC-QTOF-MS النص الكامل
2019
Qiao, Yuxin | Chen, Guofeng | Ma, Chengyi | Tao, Bo | Ma, Hong | Zhang, Xiaobo | Liu, Feng
Here, we aimed to investigate florasulam photodegradation in aquatic environments under UV-visible irradiation. LC-MS/MS was used to explore the photolysis kinetics of florasulam degradation with respect to different light source types, florasulam concentrations, water sources, and pH. We also tested whether the addition of the nitrate ions, Fe³⁺, or I⁻ to the reaction solution influences florasulam photolysis kinetics. NO₃⁻ accelerates florasulam degradation at low concentrations (0.01–1 mg L⁻¹), but decreases the process at higher concentrations. At low concentrations (≤ 0.1 mg L⁻¹), Fe³⁺ enhanced florasulam photodegradation obviously. However, the addition of 0.01–10 mg L⁻¹ I⁻ decreased the degradation rate linearly. The florasulam photolysis rates in alkaline and neutral solutions were higher than that in acidic solutions. The florasulam degradation rate under mercury light irradiation was greater than that under xenon light. The rate of florasulam degradation in distilled water was greater than in tap water, lake water, and rice paddy water. As the concentration of florasulam increased, the photodegradation rate decreased. Six kinds of transformation products (TPs) were isolated and identified using UPLC/Q-TOF-MS. Based on these TPs and their evolutionary processes, we inferred the florasulam degradation mechanisms, identifying four possible florasulam degradation pathways. Cleavage of the florasulam sulfonamide bond yielded TPs2. TPs2 was intermolecularly rearranged to form a SO₂ extrusion compound, TPs3. Cleavage of the [C-F] bonds led to the formation of TPsl, TPs4, and TPs5, while hydroxylation led to the formation of TPs6. We then predicted the stability of each of the florasulam TPs in water. TPs2 and TPs3 rapidly degraded after reaching maximum concentration due to poor light stability. TPs4 and TPs6 were more photostable than florasulam (the parent compound) and may be important contributors to water pollution.
اظهر المزيد [+] اقل [-]Static decontamination of oil-based drill cuttings with pressurized hot water using response surface methodology النص الكامل
2019
Chen, Zhong | Li, Dongyuan | Tong, Kun | Chen, Zeliang | Chen, Hongzhen | Chen, Qiao | Xu, Yuanjian
Separating organic pollutants from oil-based drill cuttings (OBDC) is the current trend for its safe disposal. In this study, pressurized hot water extraction (PHWE) was adapted to decontaminate OBDC for the first time. Two typical OBDC samples, i.e., diesel-based drill cuttings (OBDC-A) and white oil-based drill cuttings (OBDC-B), were statically extracted in a homemade batch autoclave. Response surface methodology (RSM) with a central composite design (CCD) was applied to investigate the effects and interactive effects of three independent operating parameters (temperature, extraction time, and water volume) and to ultimately optimize the PHWE process. The results suggested that temperature is the dominant parameter, followed by water volume and extraction time. Interactive effects among the three parameters are present in the PHWE of OBDC-A but absent in the PHWE of OBDC-B. The suitable conditions for the effective PHWE of OBDC-A were found to be a temperature of 284–300 °C, water volume of 15–35 ml, and extraction time of 20–60 min. The corresponding conditions were 237–300 °C, 15–35 ml, and 20–60 min for the PHWE of OBDC-B. These different phenomena are caused by the different characteristics of the two OBDC samples. All of the polynomial models obtained from the RSM experiments are very valid and can adequately describe the relationship among the three independent operating parameters and responses. The experimental results also confirmed that PHWE is a more efficient separation technique for decontaminating OBDC than single organic solvent extraction or low-temperature thermal desorption because PHWE integrates the advantages of both these processes.
اظهر المزيد [+] اقل [-]Towards integrating toxicity characterization into environmental studies: case study of bromine in soils النص الكامل
2019
Bratec, Tatiana | Kirchhübel, Nienke | Baranovskaya, Natalia | Laratte, Bertrand | Jolliet, Olivier | Rikhvanov, Leonid | Fantke, Peter
Towards integrating toxicity characterization into environmental studies: case study of bromine in soils النص الكامل
2019
Bratec, Tatiana | Kirchhübel, Nienke | Baranovskaya, Natalia | Laratte, Bertrand | Jolliet, Olivier | Rikhvanov, Leonid | Fantke, Peter
Pollution from bromine and some of its related compounds is currently unregulated in soil from Russia and other countries, and tools for sound assessment of environmental impacts of bromine contamination are largely missing. Hence, assessing potential implications for humans and ecosystems of bromine soil contamination is urgently needed, which requires the combination of measured soil concentrations from environmental studies and quantified potential toxicity impacts. To address this need, we used data from an experimental study assessing bromine in soils (384 samples) of Tomsk oblast, Russia, starting from measured concentrations obtained by Instrumental Neutron Activation Analysis in an earlier study. From these data, we calculated the bromine mass in soils and used these as starting point to characterize related cumulative impacts on human health and ecosystems in the Tomsk region, using a global scientific consensus model for screening-level comparative toxicity characterization of chemical emissions. Results show that the combination of sampling methodology with toxicity characterization techniques presents a new approach to be used in environmental studies aimed at environmental assessment and analysis of a territory. Our results indicate that it is important to account for substance-specific chemical reaction pathways and transfer processes, as well as to consider region-specific environmental characteristics. Our approach will help complement environmental assessment results with environmental sustainability elements, to consider potential tradeoffs in impacts, related to soil pollution, in support of improved emission and pollution reduction strategies.
اظهر المزيد [+] اقل [-]Towards integrating toxicity characterization into environmental studies: case study of bromine in soils النص الكامل
2019
Bratec, Tatiana | Kirchhübel, Nienke | Baranovskaya, Natalia | Laratte, Bertrand | Jolliet, Olivier | Rikhvanov, Leonid | Fantke, Peter | Centre de Recherches et d'Etudes Interdisciplinaires sur le Développement Durable (CREIDD) ; Institut Charles Delaunay (ICD) ; Université de Technologie de Troyes (UTT)-Centre National de la Recherche Scientifique (CNRS)-Université de Technologie de Troyes (UTT)-Centre National de la Recherche Scientifique (CNRS) | Tomsk Polytechnic University [Russie] (UPT) | Danmarks Tekniske Universitet = Technical University of Denmark (DTU) | Institut de Mécanique et d'Ingénierie de Bordeaux (I2M) ; Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Arts et Métiers Sciences et Technologies | University of Michigan [Ann Arbor] ; University of Michigan System
International audience | Pollution from bromine and some of its related compounds is currently unregulated in soil from Russia and other countries,and tools for sound assessment of environmental impacts of bromine contamination are largely missing. Hence, assessingpotential implications for humans and ecosystems of bromine soil contamination is urgently needed, which requires the combi-nation of measured soil concentrations from environmental studies and quantified potential toxicity impacts. To address this need,we used data from an experimental study assessing bromine in soils (384 samples) of Tomsk oblast, Russia, starting frommeasured concentrations obtained by Instrumental Neutron Activation Analysis in an earlier study. From these data, we calcu-lated the bromine mass in soils and used these as starting point to characterize related cumulative impacts on human health andecosystems in the Tomsk region, using a global scientific consensus model for screening-level comparative toxicity character-ization of chemical emissions. Results show that the combination of sampling methodology with toxicity characterizationtechniques presents a new approach to be used in environmental studies aimed at environmental assessment and analysis of aterritory. Our results indicate that it is important to account for substance-specific chemical reaction pathways and transferprocesses, as well as to consider region-specific environmental characteristics. Our approach will help complement environmen-tal assessment results with environmental sustainability elements, to consider potential tradeoffs in impacts, related to soilpollution, in support of improved emission and pollution reduction strategies.
اظهر المزيد [+] اقل [-]Synthesis and application of ion-imprinted polymer for the determination of mercury II in water samples النص الكامل
2019
Francisco, Janaina E. | Feiteira, Fernanda N. | da Silva, Wanderson A. | Pacheco, Wagner F.
In this study, an innovative analytical methodology capable of selectively identifying and quantifying mercury contamination by the association of solid-phase extraction using ion-imprinted polymers as a sorbent phase and differential pulse anodic stripping voltammetry is proposed. To this end, the ion-imprinted polymers were synthesized and characterized by infrared spectroscopy and atomic force microscopy. The sorption capacities and the selectivity of the ion-imprinted polymers were compared to the ones related to the non-imprinted ones. Next, the experimental parameters of this solid-phase extraction method (IIP-SPE) were evaluated univariately. The selectivity of this polymeric matrix against other cations (Cd II, Pb II, and Cu II) was also evaluated. Limits of detection (LOD) and quantification (LOQ) obtained for the here proposed methodology were 0.322 μg L⁻¹ and 1.08 μg L⁻¹, respectively. Also, the precision of 4.0% was achieved. The method was finally applied to three water samples from different sources: for the Piratininga and Itaipu Lagoon waters, Hg II concentrations were below the LOQ and for Vargem River waters a concentration equal to 1.35 ± 0.07 mg L⁻¹ was determined. These results were confirmed by recovery tests, resulting in a recovery of 96.2 ± 4.0%, and by comparison with flame atomic absorption spectrometry, resulting in statistical conformity between the two methods at 95% confidence level.
اظهر المزيد [+] اقل [-]ESSIMAGE: a tool for the assessment of the agroecological performance of agricultural production systems النص الكامل
2019
Trabelsi, Meriam | Mandart, Elisabeth | Le Grusse, Philippe | Bord, Jean-Paul
Over the last few years, intensive agriculture has often been denounced as a source of negative effects, particularly at the environmental and health level (overexploitation of natural resources, degradation of their quality, appearance and development of several diseases, etc.). Reducing the excessive use of agricultural inputs for the protection of the environment and the preservation of human and animal health is a social requirement nowadays. Investing in more sustainable agricultural models which make it possible to reduce, or even eliminate the risks, has become urgent. A possible solution may be to resort to agroecological systems. In order to be sustainable, these new systems must be performant at the agronomic, economic, social, and environmental levels. There is a multitude of tools for assessing the sustainability of agricultural systems. These tools are inappropriate for organic and agroecological systems, and do not make it possible to measure the agroecological transition performance of farms (Trabelsi et al. Environ Sci Pollut Res 23:139–156, 2016; Trabelsi 2017). This research project aims to design a decision support tool in order to help farms throughout the agroecological transition process, to assess the performance of this transition, and to put forward improvement scenarios. Contrary to other assessment methods, ESSIMAGE (Evaluation and Simulation of Agroecological Systems) is based on both pressure and impact indicators, and takes the specificities of agricultural production systems into account. It is a dynamic tool which not only makes it possible to assess farm performance at the present moment but also to consider the future by putting forward possible alternative improvement scenarios and by simulating their consequences at a later stage. ESSIMAGE is based on the interaction of two elements: agro-environmental, social, and economic indicators, and the GIS (Geographic Information System) software. This tool has been tested as part of a CASDAR “Post-MAET Gimone” (agriculture.gouv.fr/ministere/mobilisation-collective-pour-lagroecologie.) project on the subject of “Collective mobilization for agroecology” by using farm data, most of the farms having been involved in an agro-environmental measure for the progressive reduction of phytosanitary treatments since 2008. It has made it possible to compare the agroecological performances of these farms with an optimal situation, as well as with each other. Considering the research objectives and the approaches discussed, this study is an original step in the development of agricultural management strategies in favor of agroecology.
اظهر المزيد [+] اقل [-]Urbanization impact on residential energy consumption in China: the roles of income, urbanization level, and urban density النص الكامل
2019
Wang, Qiaoran | Yang, Xianming
This paper investigated the impact of urbanization on residential energy consumption (REC) in China by taking cognizance of the levels of income, urbanization and urban density. Threshold analyses were employed to investigate the nonlinear relationships based on the STIRPAT (Stochastic Impacts by Regression on Population, Affluence, and Technology) framework using a balanced panel dataset of 29 provinces of China over the period of 1998–2014. The common correlated effects mean group estimator (CCEMG) was used to address time-series cross-section (TSCS) issues. The results confirmed the existence of the nonlinear relationship between urbanization and REC in China. The impact of urbanization on REC varied at different economic development levels and urbanization levels. Specifically, urbanization decreased REC at the stage that per capita disposable income of urban residents (PDI) less than 2615 USD, while it increased REC at the stage that PDI higher than 2615 USD. Similarly, urbanization decreased REC at the stage that urbanization rate lower than 55.31% and increased REC after urbanization rate exceeded 55.31%. This study did not find evidence to support the urban environmental transition theory, indicating there was still no region in China had stepped into the win-win stage of urbanization and energy consumption. Furthermore, the nonlinear impact of urban density on REC was estimated and the results indicated that urban density exerted a positive effect on REC when urban density was lower than 808 inhabitants per square kilometer, while it was no longer relevant to REC after that threshold point. Based on these results, the corresponding countermeasures and suggestions to achieve low-carbon urbanization were put forward.
اظهر المزيد [+] اقل [-]Bisphenol S exposure affects gene expression related to intestinal glucose absorption and glucose metabolism in mice النص الكامل
2019
Rezg, Raja | Abot, Anne | Mornagui, Bessem | Knauf, Claude
Bisphenol S, an industrial chemical, has raised concerns for both human and ecosystem health. Yet, health hazards posed by bisphenol S (BPS) exposure remain poorly studied. Compared to all tissues, the intestine and the liver are among the most affected by environmental endocrine disruptors. The aim of this study was to investigate the molecular effect of BPS on gene expression implicated in the control of glucose metabolism in the intestine (apelin and its receptor APJ, SGLT1, GLUT2) and in the liver (glycogenolysis and/or gluconeogenesis key enzymes (glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK)) and pro-inflammatory cytokine expression (TNF-α and IL-1β)). BPS at 25, 50, and 100 μg/kg was administered to mice in water drink for 10 weeks. In the duodenum, BPS exposure reduces significantly mRNA expression of sodium glucose transporter 1 (SGLT1), glucose transporter 2 (GLUT2), apelin, and APJ mRNA. In the liver, BPS exposure increases the expression of G6Pase and PEPCK, but does not affect pro-inflammatory markers. These data suggest that alteration of apelinergic system and glucose transporters expression could contribute to a disruption of intestinal glucose absorption, and that BPS stimulates glycogenolysis and/or gluconeogenesis in the liver. Collectively, we reveal that BPS heightens the risk of metabolic syndrome.
اظهر المزيد [+] اقل [-]Simultaneous removal of nitrogen oxides and sulfur dioxide using ultrasonically atomized hydrogen peroxide النص الكامل
2019
Wei, Jiaqi | Gu, Junjie | Guo, Junheng | Li, Wei | Wang, Chenglong | Zhang, Jinli
A new method was developed for denitrification and desulfurization using hydrogen peroxide with the aid of an ultrasonic nebulizer to obtain high removal efficiency of NOx and SO₂. Comparing with the atomizing nozzles having the aperture size of 0.01~0.02 mm, the droplets generated using the ultrasonic nebulizer show the smallest d₅₀ value of 7.2 μm, with 72% possessing the size less than 10 μm. Based on the numerical simulation of the vaporization rate of droplets, it is indicated that the droplets with the size of 7.2 μm can be vaporized totally at very short residence time (0.11 s) under 130 °C. Effects of influence factors including the reaction temperature, the initial H₂O₂ concentration, pH value, and the flue gas flow rate were studied on the removal efficiencies of NO and SO₂. Using the in-series double-oxidation subsystems with H₂O₂ concentration of 6 wt%, pH 5.0, and the reaction temperature of 130 °C, the removal efficiencies of SO₂ and NO are respectively 100% and 89.3% at the short residence time of 1.8 s, and the removal efficiency of NO can be increased to 100% as the residence time is longer than 3.7 s. It is confirmed that the ultrasonically atomized H₂O₂ can indeed enhance the removal efficiencies of NO and SO₂ at the optimal temperature, owing to the fast vaporization rate of fine droplets as well as the formation of more active radicals to be captured by NO and SO₂ simultaneously. The results here provide a promising route to remove effectively the emissions of NO and SO₂ simultaneously. Graphical abstract
اظهر المزيد [+] اقل [-]The agro-enabled urban revolution, pesticides, politics, and popular culture: a case study of land use, birds, and insecticides in the USA النص الكامل
2019
Brain, Richard A. | Anderson, Julie C.
Urbanization is an inevitable process in human civilization. When populations expand, socio-economic and political dynamics typically shift from agricultural predominance to one of industry and services. Accordingly, agrarian societies transform from diffuse rural communities to dense urban centers. By 2050, the world’s population is projected to reach 9.1 billion, with the urban population growing from 50 to 70%. Inevitably, this ever-expanding urban frontier encroaches along the human-ecological interface, creating a challenge for conservation and biodiversity. For the past 30 years, agricultural cropland area in the USA has remained fairly constant, despite significant population growth over the same time period. Thus, agricultural production in America has more than kept pace with rapid population growth and global export demand without increasing the farmland footprint at the expense of wildlife habitat. This is primarily due to considerable advances made in pesticide development, safety, and regulation, coupled with soil conservation and genetically modified crops. Still, the potential contribution of agriculture to ecosystem impairment remains contentious, particularly with regard to current use of pesticides. Recently, significant focus has been placed on the state of bird populations in the USA. Many species are considered imperiled, and this is often attributed in the popular media to pesticide use. However, focusing solely on the agricultural/chemical story as a significant driver of species viability and ecological risk within the broader biodiversity and conservation narrative lacks context and perspective. Moreover, the hypothesis that pesticides are indirectly affecting bird population status via reductions in food resources should be considered with caution and within the context of other likely causes. This work explores the dynamics between historical land use, human-controlled activity, and bird population trends from a holistic perspective within the USA. The aim is to provide context, developed from a relative comparison of potential contributing factors, in order to help inform discussion and foster dialogue between industry, academia, government, non-governmental organizations, and the public.
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