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1
Naresh, R., e S. Sundar. "A Nonlinear Dynamical Model to Study the Removal of Gaseous and Particulate Pollutants in a Rain System". Nonlinear Analysis: Modelling and Control 12, n. 2 (25 aprile 2007): 227–43. http://dx.doi.org/10.15388/na.2007.12.2.14713.
Abstract (sommario):
An ecological type nonlinear mathematical model is proposed to study the removal of gaseous pollutants and two distinct particulate matters by precipitation scavenging in the atmosphere. The atmosphere during precipitation consists of five interacting phases namely the raindrops phase, the gaseous pollutants phase, the smaller particulate matters phase, the larger particulate matters phase and the absorbed phase of gaseous pollutants. We assume that gaseous pollutants are removed from the atmosphere by the processes of impaction as well as by absorption while particulate matters are assumed to be removed by impaction process. The model is analyzed using stability theory of nonlinear differential equations. It is shown that, under appropriate conditions, the pollutants can be removed from the atmosphere and their removal rates would depend mainly upon the rates of emission of pollutants, rate of rain drops formation and the rate of raindrops falling on the ground. If the rate of precipitation is very high, all the pollutants (gaseous as well as particulate matters) would be removed completely from the atmosphere. A numerical study is also performed to study the dynamics of the model system. The results are found to be in line with the experimental observations published in the literature.
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Boussouara, Karima, e Mahfoud Kadja. "Empirical soot formation and oxidation model". Thermal Science 13, n. 3 (2009): 35–46. http://dx.doi.org/10.2298/tsci0903035b.
Abstract (sommario):
Modelling internal combustion engines can be made following different approaches, depending on the type of problem to be simulated. A diesel combustion model has been developed and implemented in a full cycle simulation of a combustion, model accounts for transient fuel spray evolution, fuel-air mixing, ignition, combustion, and soot pollutant formation. The models of turbulent combustion of diffusion flame, apply to diffusion flames, which one meets in industry, typically in the diesel engines particulate emission represents one of the most deleterious pollutants generated during diesel combustion. Stringent standards on particulate emission along with specific emphasis on size of emitted particulates have resulted in increased interest in fundamental understanding of the mechanisms of soot particulate formation and oxidation in internal combustion engines. A phenomenological numerical model which can predict the particle size distribution of the soot emitted will be very useful in explaining the above observed results and will also be of use to develop better particulate control techniques. A diesel engine chosen for simulation is a version of the Caterpillar 3406. We are interested in employing a standard finite-volume computational fluid dynamics code, KIVA3V-RELEASE2.
3
Xue, Wei, Qingming Zhan, Qi Zhang e Zhonghua Wu. "Spatiotemporal Variations of Particulate and Gaseous Pollutants and Their Relations to Meteorological Parameters: The Case of Xiangyang, China". International Journal of Environmental Research and Public Health 17, n. 1 (24 dicembre 2019): 136. http://dx.doi.org/10.3390/ijerph17010136.
Abstract (sommario):
High air pollution levels have become a nationwide problem in China, but limited attention has been paid to prefecture-level cities. Furthermore, different time resolutions between air pollutant level data and meteorological parameters used in many previous studies can lead to biased results. Supported by synchronous measurements of air pollutants and meteorological parameters, including PM2.5, PM10, total suspended particles (TSP), CO, NO2, O3, SO2, temperature, relative humidity, wind speed and direction, at 16 urban sites in Xiangyang, China, from 1 March 2018 to 28 February 2019, this paper: (1) analyzes the overall air quality using an air quality index (AQI); (2) captures spatial dynamics of air pollutants with pollution point source data; (3) characterizes pollution variations at seasonal, day-of-week and diurnal timescales; (4) detects weekend effects and holiday (Chinese New Year and National Day holidays) effects from a statistical point of view; (5) establishes relationships between air pollutants and meteorological parameters. The principal results are as follows: (1) PM2.5 and PM10 act as primary pollutants all year round and O3 loses its primary pollutant position after November; (2) automobile manufacture contributes to more particulate pollutants while chemical plants produce more gaseous pollutants. TSP concentration is related to on-going construction and road sprinkler operations help alleviate it; (3) an unclear weekend effect for all air pollutants is confirmed; (4) celebration activities for the Chinese New Year bring distinctly increased concentrations of SO2 and thereby enhance secondary particulate pollutants; (5) relative humidity and wind speed, respectively, have strong negative correlations with coarse particles and fine particles. Temperature positively correlates with O3.
4
Campanale, Claudia, Daniela Losacco, Mariangela Triozzi, Carmine Massarelli e Vito Felice Uricchio. "An Overall Perspective for the Study of Emerging Contaminants in Karst Aquifers". Resources 11, n. 11 (17 novembre 2022): 105. http://dx.doi.org/10.3390/resources11110105.
Abstract (sommario):
Karst aquifers are essential drinking water sources, representing about 25% of the total available sources globally. Groundwater ecosystems consist of fissured carbonate rocks commonly covered with canopy collapse sinkholes. The open nature of karst aquifers makes them susceptible to rapidly transporting contaminants from the surface in dissolved and particulate forms. The principal aim of this review is to contribute to filling the gap in knowledge regarding major concerns affecting karst aquifers and understanding their vulnerabilities and dynamics. The principal groundwater pollutants of relevance are detailed in the present work, including well-known issues, such as the input of agriculture and its role in water quality. Emerging pollutants such as microplastics, still poorly studied in the groundwater systems, were also considered. Case studies for each typology of pollutant were highlighted, as their relative concerns for karst environments. Final considerations underlined an approach for studying karst environments more focused on understanding dynamics and links among different pollutants inputs and their drivers than on individual sources and impacts.
5
Liu, Liyang, Hui Liu e Yiming Ma. "Surrogate-Assisted Fine Particulate Matter Exposure Assessment in an Underground Subway Station". International Journal of Environmental Research and Public Health 19, n. 4 (17 febbraio 2022): 2295. http://dx.doi.org/10.3390/ijerph19042295.
Abstract (sommario):
With the increase in subway travelers, the air quality of underground enclosed spaces at subway stations has attracted much more attention. The study of pollutants exposure assessment, especially fine particulate matter, is important in both pollutant control and metro station design. In this paper, combining pedestrian flow analysis (PFA) and computational fluid dynamics (CFD) simulations, a novel surrogate-assisted particulate matter exposure assessment method is proposed, in which PFA is used to analyze the spatial-temporal movement characteristics of pedestrians to simultaneously consider the location and value of the pedestrian particulate generation source and their exposure streamline to particulate matter; the CFD model is used to analyze the airflow field and particulate matter concentration field in detail. To comprehensively consider the differences in the spatial concentration distribution of particulate matter caused by the time-varying characteristics of the airflow organization state in subway stations, surrogate models reflecting the nonlinear relationship between simulated and measured data are trained to perform accurate pedestrian exposure calculations. The actual measurement data proves the validity of the simulation and calculation methods, and the difference between the calculated and experimental values of the exposure is only about 5%.
6
Gianquintieri, Lorenzo, Daniele Oxoli, Enrico Gianluca Caiani e Maria Antonia Brovelli. "Land use influence on ambient PM2.5 and ammonia concentrations: Correlation analyses in the Lombardy region, Italy". AGILE: GIScience Series 4 (6 giugno 2023): 1–7. http://dx.doi.org/10.5194/agile-giss-4-26-2023.
Abstract (sommario):
Abstract. Air pollution is identified as the primary environmental risk to health worldwide. Although most of the anthropic emissions are due to combustion processes, intensive farming activities may also contribute significantly, especially as a source of particulate matter 2.5 and ammonia. Investigations on particulate matter and precursors dynamics, identifying the most relevant environmental factors influencing their emissions, are critical to improving local and regional air quality policies. This work presents an analysis of the correlation between particulate matter 2.5 and ammonia concentrations, obtained from the Copernicus Atmosphere Monitoring Service, and local land use characteristics, to investigate the influence of agricultural activities on the space-time pollutant concentration patterns. The selected study area is the Lombardy region, northern Italy. Correlation is evaluated through Spearman’s coefficient. Agricultural areas resulted in a significant factor for high ammonia concentrations, while particulate matter 2.5 was strongly correlated with built-up areas. Natural areas resulted instead a protective factor for both pollutants. Results provide data-driven evidence of the land use effect on air quality, also quantifying such effects in terms of correlation coefficients magnitude.
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Qi, Wang, Yoo Sung-Jun, Wang Xin e Ito Kazuhide. "Exploratory computational fluid and particle dynamics analyses in multi-layered vertical duct-type ventilation system for heat exchange and air purification". E3S Web of Conferences 396 (2023): 03006. http://dx.doi.org/10.1051/e3sconf/202339603006.
Abstract (sommario):
This study aims to develop a vertical air duct which is embedded inside the building envelop. It is also designed as a counter-flow heat recovery ventilator (HRV). The vertical air duct model in this study adopted baffle structure considering two methods to suppress the inflow of the particulate matters from outdoor: 1) trapping by wall surface and airflow structure and 2) gravitational sedimentation in the air duct. Design parametric analyses are conducted using computational fluid dynamics to determine optimal design of vertical air duct. Three types of analytical case with various set-up of baffles inside air passages are prepared, and heat exchange efficiency is estimated by heat transfer analysis inside ventilator. In addition, particulate pollutants’ behaviour inside air passages is predicted based on Euler-Lagrange particle transport analysis. Through the series of numerical analysis, differences in heat exchange efficiency and effectiveness of particulate pollutant removal corresponding to different baffle design are quantitatively discussed, and finally optimal design for air passages in HRV is determined. The building-integrated HRV introduced in this study could contribute to sustainable design of building environment.
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Samaké, Abdoulaye, Amadou Mahamane, Mahamadou Alassane e Ouaténi Diallo. "A Mathematical and Numerical Framework for Traffic-Induced Air Pollution Simulation in Bamako". Computation 10, n. 5 (17 maggio 2022): 76. http://dx.doi.org/10.3390/computation10050076.
Abstract (sommario):
We present a mathematical and numerical framework for the simulation of traffic-induced air pollution in Bamako. We consider a deterministic modeling approach where the spatio-temporal dynamics of the concentrations of air pollutants are governed by a so-called chemical transport model. The time integration and spatial discretization of the model are achieved using the forward Euler algorithm and the finite-element method, respectively. The traffic emissions are estimated using a road traffic simulation package called SUMO. The numerical results for two road traffic-induced air pollutants, namely the carbon monoxide (CO) and the fine particulate matter (PM2.5), support that the proposed framework is suited for reproducing the dynamics of the pollutants specified.
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Lapere, Rémy, Laurent Menut, Sylvain Mailler e Nicolás Huneeus. "Seasonal variation in atmospheric pollutants transport in central Chile: dynamics and consequences". Atmospheric Chemistry and Physics 21, n. 8 (28 aprile 2021): 6431–54. http://dx.doi.org/10.5194/acp-21-6431-2021.
Abstract (sommario):
Abstract. Central Chile faces atmospheric pollution issues all year long as a result of elevated concentrations of fine particulate matter during the cold months and tropospheric ozone during the warm season. In addition to public health issues, environmental problems regarding vegetation growth and water supply, as well as meteorological feedback, are at stake. Sharp spatial gradients in regional emissions, along with a complex geographical situation, make for variable and heterogeneous dynamics in the localization and long-range transport of pollutants, with seasonal differences. Based on chemistry–transport modeling with Weather Research Forecasting (WRF)–CHIMERE, this work studies the following for one winter period and one summer period: (i) the contribution of emissions from the city of Santiago to air pollution in central Chile, and (ii) the reciprocal contribution of regional pollutants transported into the Santiago basin. The underlying 3-dimensional advection patterns are investigated. We find that, on average for the winter period, 5 to 10 µg m−3 of fine particulate matter in Santiago come from regional transport, corresponding to between 13 % and 15 % of average concentrations. In turn, emissions from Santiago contribute between 5 % and 10 % of fine particulate matter pollution as far as 500 km to the north and 500 km to the south. Wintertime transport occurs mostly close to the surface. In summertime, exported precursors from Santiago, in combination with mountain–valley circulation dynamics, are found to account for most of the ozone formation in the adjacent Andes cordillera and to create a persistent plume of ozone of more than 50 ppb (parts per billion), extending along 80 km horizontally and 1.5 km vertically, and located slightly north of Santiago, several hundred meters above the ground. This work constitutes the first description of the mechanism underlying the latter phenomenon. Emissions of precursors from the capital city also affect daily maxima of surface ozone hundreds of kilometers away. In parallel, cutting emissions of precursors in the Santiago basin results in an increase in surface ozone mixing ratios in its western area.
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Aiswarya, R., A. R. Resmi, C. T. Rahsha, Sona Dharman, S. Adarsh e M. Mamatha. "Analyzing the Effect of Air Pollutants on Particulate Matter Concentrations of the Tropical coastal city of Thiruvananthapuram, India by Wavelet Coherence". IOP Conference Series: Earth and Environmental Science 1237, n. 1 (1 settembre 2023): 012017. http://dx.doi.org/10.1088/1755-1315/1237/1/012017.
Abstract (sommario):
Abstract The main environmental risk factor that need regular monitoring and analysis for efficient air quality management is particulate matter (PM). This paper analyzes the effect of gaseous air pollutants (SO2, CO, Ozone, NOx) on PM concentration in the coastal city of Thiruvananthapuram, India using Wavelet coherence (WTC). The study was conducted using the data from Plammoodu station of the city for the period of 2018 to 2021. The teleconnections of air pollutants with PMs are analysed using WTC for the data of different time spells of 2018-2021, 2018 and 2020. Results showed that among the air pollutants, Ozone (AWC of 0.4713 & PoSC of 23.0234 for PM10, AWC of 0.4814 & PoSC of 26.2261 for PM2.5) have most dominant influence on irrespective of the particulate matter type and time spells. The secondary influencing factors were found to be different with respect to the time spells chosen, indicating the dynamics of local variables on PM concentrations of the city.
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Zhang, J. J., e X. Y. Li. "Coagulation and sedimentation of particulate pollutants in marine waters after wastewater outfall discharge". Water Supply 6, n. 1 (1 gennaio 2006): 79–86. http://dx.doi.org/10.2166/ws.2006.009.
Abstract (sommario):
Outfall discharge to seawater is generally used as a practical means of wastewater disposal in many coastal cities. However, deposition of solid pollutants from the wastewater on the seabed would affect the benthic communities. In the present study, both laboratory experiments and numerical simulations were carried out on the role of particle coagulation in the transport and sedimentation of sewage solid materials in marine waters after outfall discharge. Actual sewage samples were collected from two treatment plants in Hong Kong for the experimental study. A flocculator-imaging system was developed for characterization of the particle size distribution (PSD) dynamics during flocculation and dilution of sewage particles in seawater. The system consisted of an external flow-through cell, a microscopic CCD video recorder and an image analyzer. The laboratory results demonstrated that coagulation played an important role in regulating the transport of solid pollutants in marine waters. Flocculation of 30–45 min could shift the PSD considerably, transforming small particles to larger, fast-settling particle aggregates. With a growth in particle size by flocculation, the average settling velocity of the sewage particulates increased by a factor of 2 or more. In addition to the laboratory study, a mathematical model was developed to simulate the transport dynamic of wastewater particles in seawater after outfall discharge. The results of numerical simulations compared well with the experimental observations. Both laboratory and simulation results suggest the important role of coagulation in the transport and sedimentation dynamics of sewage particles in marine waters, especially in the early phase of outfall discharge. As a result, suspended solids from the wastewater discharge would deposit more closely in the vicinity of the outfall sites.
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Zubiaga, Asier, Synne Madsen, Hassan Khawaja e Gernot Boiger. "Atmospheric Contamination of Coastal Cities by the Exhaust Emissions of Docked Marine Vessels: The Case of Tromsø". Environments 8, n. 9 (3 settembre 2021): 88. http://dx.doi.org/10.3390/environments8090088.
Abstract (sommario):
Docked ships are a source of contamination for the city while they keep their engine working. Plume emissions from large boats can carry a number of pollutants to nearby cities causing a detrimental effect on the life quality and health of local citizens and ecosystems. A computational fluid dynamics model of the harbour area of Tromsø has been built in order to model the deposition of CO2 gas emitted by docked vessels within the city. The ground level distribution of the emitted gas has been obtained and the influence of the wind speed and direction, vessel chimney height, ambient temperature and exhaust gas temperature have been studied. The deposition range is found to be the largest when the wind speed is low. At high wind speeds, the deposition of pollutants along the wind direction is enhanced and spots of high pollutant concentration can be created. The simulation model is intended for the detailed study of the contamination in cities near the coast or an industrial pollutant source of any type of gas pollutant and can easily be extended for the study of particulate matter.
13
Kim, Donghyun, Heechan Han, Wonjoon Wang, Yujin Kang, Hoyong Lee e Hung Soo Kim. "Application of Deep Learning Models and Network Method for Comprehensive Air-Quality Index Prediction". Applied Sciences 12, n. 13 (1 luglio 2022): 6699. http://dx.doi.org/10.3390/app12136699.
Abstract (sommario):
Accurate pollutant prediction is essential in fields such as meteorology, meteorological disasters, and climate change studies. In this study, long short-term memory (LSTM) and deep neural network (DNN) models were applied to six pollutants and comprehensive air-quality index (CAI) predictions from 2015 to 2020 in Korea. In addition, we used the network method to find the best data sources that provide factors affecting comprehensive air-quality index behaviors. This study had two steps: (1) predicting the six pollutants, including fine dust (PM10), fine particulate matter (PM2.5), ozone (O3), sulfurous acid gas (SO2), nitrogen dioxide (NO2), and carbon monoxide (CO) using the LSTM model; (2) forecasting the CAI using the six predicted pollutants in the first step as predictors of DNNs. The predictive ability of each model for the six pollutants and CAI prediction was evaluated by comparing it with the observed air-quality data. This study showed that combining a DNN model with the network method provided a high predictive power, and this combination could be a remarkable strength in CAI prediction. As the need for disaster management increases, it is anticipated that the LSTM and DNN models with the network method have ample potential to track the dynamics of air pollution behaviors.
14
Ren, Lulu, Farun An, Meng Su e Jiying Liu. "Exposure Assessment of Traffic-Related Air Pollution Based on CFD and BP Neural Network and Artificial Intelligence Prediction of Optimal Route in an Urban Area". Buildings 12, n. 8 (12 agosto 2022): 1227. http://dx.doi.org/10.3390/buildings12081227.
Abstract (sommario):
Due to rapid global economic development, the number of motor vehicles has increased sharply, causing significant traffic pollution and posing a threat to people’s health. People’s exposure to traffic-related particulate matter with an aerodynamic diameter less than 2.5 μm (PM2.5) primarily occurs during commuting. Many studies have used exposure risk assessment models to assess the possible adverse effects of PM2.5, but few have used them to plan low-risk pathways for commuters. This study simulated the pollutant concentration distribution in an idealized urban area in different scenarios. We then used a back propagation (BP) neural network to predict the pollutant concentration. The commuter respiratory deposition dose was calculated based on the BP prediction results, and the respiratory deposition dose was converted into obstacles on the commuting map. Finally, the rapidly exploring random tree star (RRT*) algorithm was used to plan low-risk paths for commuters. The results indicate that pollutants discharged by cars and tree planting can significantly affect the pollutant concentration. A 30.25 μg/m3 increase in the pollutant concentration discharged by cars resulted in a 7~13 μg/m3 increase in the traffic-related air pollution concentration on sidewalks. Combining a computational fluid dynamics simulation, a BP neural network model, and the RRT* algorithm provides a system to plan low-risk paths for commuters. This work proposes artificial-intelligence-based models for calculating the exposure risk to traffic-related pollutants (PM2.5) and choosing a low-risk commuting path to ensure healthy travel.
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Wu, Chi-Hua. "Seasonal adjustment of particulate matter pollution in coastal East Asia during the 2020 COVID lockdown". Environmental Research Letters 16, n. 12 (22 novembre 2021): 124023. http://dx.doi.org/10.1088/1748-9326/ac343c.
Abstract (sommario):
Abstract Seasonally, the East Asian particulate matter (PM) level is higher in the winter–spring period than in summer, at which time the level rapidly decreases due to the summer monsoon migration. Attempting to attribute East Asian PM pollution to a source without considering such natural factors is challenging. However, to what degree the effect of season on an attribution bias remains controversial; the bias may even be implicated in PM-related health effects. This study examined seasonal dynamics including the unusual precipitation evolution during 2020—a year in which coronavirus-related lockdowns occurred frequently worldwide—and suggested a large-scale effect from the removal of PM pollutants from most of the coastal cities in East Asia. In winter–spring 2020, compared with that of previous years, a deeper and farther southward intrusion of the East Asian coastal trough and a stronger surface monsoon flow acted jointly to transport air pollutants over the Korea–Japan region. In summer 2020, the strength and migration of the western North Pacific (WNP) high increased precipitation and removed air pollutants in mid-latitude East Asia, whereas it reduced precipitation in the subtropical WNP. Consequently, the reduced PM level in the subtropical region (including Taiwan) may be irrelevant to the anomalous seasonal pattern. Although an artificial effect is conceivable and may be primarily responsible for the marked decrease in 2020 East Asian PM pollutants in some subtropical cities, the modulation of a large-scale and precipitating effect also deserves consideration.
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Sekula, Piotr, Miroslaw Zimnoch, Jakub Bartyzel, Anita Bokwa, Michal Kud e Jaroslaw Necki. "Ultra-Light Airborne Measurement System for Investigation of Urban Boundary Layer Dynamics". Sensors 21, n. 9 (21 aprile 2021): 2920. http://dx.doi.org/10.3390/s21092920.
Abstract (sommario):
Winter smog episodes are a severe problem in many cities around the world. The following two mechanisms are responsible for influencing the level of pollutant concentrations: emission of pollutants from different sources and associated processes leading to formation of secondary aerosols in the atmosphere and meteorology, including advection, which is stimulated by horizontal wind, and convection, which depends on vertical air mass movements associated with boundary layer stability that are determined by vertical temperature and humidity gradients. The aim of the present study was to evaluate the performance of an unmanned aerial vehicle (UAV)-based measurement system developed for investigation of urban boundary layer dynamics. The evaluation was done by comparing the results of temperature, relative humidity, wind speed and particulate matter fraction with aerodynamic diameter below 10 μm (PM10) concentration vertical profiles obtained using this system with two reference meteorological stations: Jagiellonian University Campus (JUC) and radio transmission tower (RTCN), located in the urban area of Krakow city, Southern Poland. The secondary aim of the study was to optimize data processing algorithms improving the response time of UAV sensor measurements during the ascent and descent parts of the flight mission.
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Ferreira Gadelha, Antonio José, Tony Herbert Freire de Andrade, Severino Rodrigues de Farias Neto e Antonio Gilson Barbosa de Lima. "Numerical Simulation of Thermofluid Dynamics of Pollutants’ Dispersion by Thermal Electricity Production". Defect and Diffusion Forum 366 (aprile 2016): 135–43. http://dx.doi.org/10.4028/www.scientific.net/ddf.366.135.
Abstract (sommario):
The growing global demand for energy has led researchers to seek the improvement of technology in order to maximize the generation of electricity by different ways. Among the different methods of production is the energy produced by thermal power plants, which account for more than 60% of the energy produced in the world. This energy is generated through combustion of fuels such as coal, diesel oil, natural gas and others. The main problem caused by the production of thermal energy is the emission of gaseous pollutants into the atmosphere, such as carbon dioxide (CO2), sulfur dioxide (SO2), nitrogen oxides (NOx), and also particulate matter which causes environmental problems such as acid rain, greenhouse effect, and health problems, especially respiratory diseases. Computational fluid dynamics (CFD) is presented as an important tool in solving problems involving the dispersion of chemicals into the atmosphere. In this sense, this study aims to evaluate the thermofluid dynamics of pollutants’ dispersion emitted from the chimney of a thermal power plant, based on numerical simulations using the Ansys CFX 12.0 commercial code. Fields of velocity and mass concentration of the component involved in the process are presented and analyzed.
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Slomberg, Danielle L., Patrick Ollivier, Olivier Radakovitch, Nicole Baran, Nicole Sani-Kast, Auguste Bruchet, Martin Scheringer e Jérôme Labille. "Insights into natural organic matter and pesticide characterisation and distribution in the Rhone River". Environmental Chemistry 14, n. 1 (2017): 64. http://dx.doi.org/10.1071/en16038.
Abstract (sommario):
Environmental contextNatural organic matter in surface waters is a transport vector for environmental pollutants with both its concentration and composition influencing pollutant fate. Characterisation of organic matter in surface waters, crucial to understanding pollutant transport, should also account for spatial variation along the water source. The present work characterises the natural organic matter in the Rhone River and describes the distributions of various pesticides and metabolites along the river. AbstractThorough characterisation of natural organic matter (NOM) in natural surface waters remains vital for evaluating pollutant dynamics and interactions with NOM under realistic environmental conditions. Here, we present the characterisation of NOM and pesticide compositions for nine sampling sites over the length of the Rhone River, also evaluating the advantages and limitations of different analytical techniques to determine how they complement one another. Together with dissolved and particulate organic carbon analyses, the dissolved organic matter (DOM, <0.8μm) or NOM (unfiltered organic matter) was characterised with gel permeation chromatography, the polarity rapid-assessment method, excitation–emission matrix fluorescence, and pyrolysis–gas chromatography–mass spectrometry to evaluate both composition and distribution. An additional objective was the determination of the NOM degradation state (i.e. constantly produced autochthonous or weakly degraded allochthonous species), an important factor in assessing potential NOM–pollutant interactions. The NOM compositions (i.e. proteins, polyhydroxy aromatics, polysaccharides, amino sugars) and proportions were similar between sites, but variations were observed in the relative proportions of autochthonous and allochthonous material from north to south. Anionic proteins and polyhydroxy aromatics in a molecular weight range of ~1000–1200 Da comprised the majority of the DOM. As a pollutant case study, five pesticides (glyphosate, metalochlor, chlortoluron, isoproturon, propyzamide) and some of their metabolites (aminomethylphosphonic acid, metolachlor ethanesulfonic acid and metolachlor oxanilic acid) were measured. Several exhibited trends with the NOM, particulate organic carbon and suspended particulate matter distributions in the Rhone waters, suggesting a significant influence on pesticide fate and transport in the river.
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Rasche, Marius, Mario Walther, Rene Schiffner, Nasim Kroegel, Sven Rupprecht, Peter Schlattmann, P. Christian Schulze et al. "Rapid increases in nitrogen oxides are associated with acute myocardial infarction: A case-crossover study". European Journal of Preventive Cardiology 25, n. 16 (15 febbraio 2018): 1707–16. http://dx.doi.org/10.1177/2047487318755804.
Abstract (sommario):
Aims High concentrations of air pollutants are associated with increased risk for myocardial infarction. The European Union has defined statutory limits for air pollutants based on upper absolute concentrations. We evaluated the association between rapid changes in air pollutants and the risk of myocardial infarction independently of absolute concentrations. Methods and results Using a hospital-based case-crossover study, effects of 24h changes of nitrogen oxides (NOX/2), particulate matter (PM10), and ozone on the risk of myocardial infarction was assessed in 693 patients. In the overall population, increases of NOX of more than 20 µg/m3 within 24 h were associated with an increase in the risk of myocardial infarction by up to 121% (odds ratio (OR) 2.21, 95% confidence interval (CI) 1.19–4.08). Comparably, rapid increases of NO2 of more than 8 µg/m3 tended to increase myocardial infarction risk by 73% (OR 1.73, 95% CI 0.91–3.28) while myocardial infarction risk decreased by 60% after a decrease of NO2 concentration of more than 8 µg/m3 (OR 0.4, 95% CI 0.21–0.77), suggesting a close-to-linear association. While results for ozone concentrations were ambiguous, rapid change in PM10 was not associated with myocardial infarction risk. Conclusion Dynamics and extent of increase in nitrogen oxide concentrations may be an independent risk factor for myocardial infarction. As there are currently no European Union statutory limits reflecting this dynamic variation of air pollutants on a daily basis, the results urgently call for confirming studies in different geographical regions to verify the observations.
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Bisetti, Fabrizio, Antonio Attili e Heinz Pitsch. "Advancing predictive models for particulate formation in turbulent flames via massively parallel direct numerical simulations". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 372, n. 2022 (13 agosto 2014): 20130324. http://dx.doi.org/10.1098/rsta.2013.0324.
Abstract (sommario):
Combustion of fossil fuels is likely to continue for the near future due to the growing trends in energy consumption worldwide. The increase in efficiency and the reduction of pollutant emissions from combustion devices are pivotal to achieving meaningful levels of carbon abatement as part of the ongoing climate change efforts. Computational fluid dynamics featuring adequate combustion models will play an increasingly important role in the design of more efficient and cleaner industrial burners, internal combustion engines, and combustors for stationary power generation and aircraft propulsion. Today, turbulent combustion modelling is hindered severely by the lack of data that are accurate and sufficiently complete to assess and remedy model deficiencies effectively. In particular, the formation of pollutants is a complex, nonlinear and multi-scale process characterized by the interaction of molecular and turbulent mixing with a multitude of chemical reactions with disparate time scales. The use of direct numerical simulation (DNS) featuring a state of the art description of the underlying chemistry and physical processes has contributed greatly to combustion model development in recent years. In this paper, the analysis of the intricate evolution of soot formation in turbulent flames demonstrates how DNS databases are used to illuminate relevant physico-chemical mechanisms and to identify modelling needs.
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Ige, Oluwafemi E., Kevin J. Duffy, Oludolapo A. Olanrewaju e Obiora C. Collins. "An Integrated System Dynamics Model and Life Cycle Assessment for Cement Production in South Africa". Atmosphere 13, n. 11 (29 ottobre 2022): 1788. http://dx.doi.org/10.3390/atmos13111788.
Abstract (sommario):
Cement is one of the most produced materials globally. Population growth and urbanization cause an increased demand for the cement needed for expanding infrastructures. As a result of this circumstance, the cement industry must find the optimum compromise between increasing cement production and reducing the negative environmental impact of that production. Since cement production uses a lot of energy, resources and raw materials, it is essential to assess its environmental impact and determine methods for the sector to move forward in sustainable ways. This paper uses an integrated life cycle assessment (LCA) and a system dynamics (SDs) model to predict the long-term environmental impact and future dynamics of cement production in South Africa. The first step used the LCA midpoint method to investigate the environmental impact of 1 kg of Portland cement produced in South Africa. In the cement production process, carbon dioxide (CO2), nitrogen oxides (NOx), sulphur dioxide (SO2), methane (CH4) and particulate matter (PM) were the major gases emitted. Therefore, the LCA concentrated on the impact of these pollutants on global warming potential (GWP), ozone formation, human health, fine particulate matter formation and terrestrial acidification. The system dynamics model is used to predict the dynamics of cement production in South Africa. The LCA translates its results into input variables into a system dynamics model to predict the long-term environmental impact of cement production in South Africa. From our projections, the pollutant outputs of cement production in South Africa will each approximately double by the year 2040 with the associated long-term impact of an increase in global warming. These results are an important guide for South Africa’s future cement production and environmental impact because it is essential that regulations for cement production are maintained to achieve long-term environmental impact goals. The proposed LCA–SD model methodology used here enables us to predict the future dynamics of cement production and its long-term environmental impact, which is the primary research objective. Using these results, a number of policy changes are suggested for reducing emissions, such as introducing more eco-blended cement productions, carbon budgets and carbon tax.
22
Piemjaiswang, R., e B. Chalermsinsuwan. "Statistical Study of the Effect of Particle Properties on the Particle Penetration in the Idealized Trachea". International Journal of Environmental Science and Development 11, n. 10 (2020): 477–82. http://dx.doi.org/10.18178/ijesd.2020.11.10.1293.
Abstract (sommario):
The particulate matter (PM) is one of the harmful pollutants that causing an impact on human health. To study the significance of those small particle properties, the research had been conducted using three-dimensional computational fluid dynamics with the Eulerian-Lagrangian approach. The trajectories of the particles were tracked and recorded. The effect of particle diameter, particle density, and particle sphericity on the escaped particle percentage was investigated and characterized using the statistical analysis of variance. The results showed that the particle diameter, particle density, their interaction, and the quadratic effect of the particle diameter played important roles in the penetration of those injected particles.
23
Fronza, Raffaele, Marina Lusic, Manfred Schmidt e Bojana Lucic. "Spatial–Temporal Variations in Atmospheric Factors Contribute to SARS-CoV-2 Outbreak". Viruses 12, n. 6 (27 maggio 2020): 588. http://dx.doi.org/10.3390/v12060588.
Abstract (sommario):
The global outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection causing coronavirus disease 2019 (COVID-19) has reached over five million confirmed cases worldwide, and numbers are still growing at a fast rate. Despite the wide outbreak of the infection, a remarkable asymmetry is observed in the number of cases and in the distribution of the severity of the COVID-19 symptoms in patients with respect to the countries/regions. In the early stages of a new pathogen outbreak, it is critical to understand the dynamics of the infection transmission, in order to follow contagion over time and project the epidemiological situation in the near future. While it is possible to reason that observed variation in the number and severity of cases stems from the initial number of infected individuals, the difference in the testing policies and social aspects of community transmissions, the factors that could explain high discrepancy in areas with a similar level of healthcare still remain unknown. Here, we introduce a binary classifier based on an artificial neural network that can help in explaining those differences and that can be used to support the design of containment policies. We found that SARS-CoV-2 infection frequency positively correlates with particulate air pollutants, and specifically with particulate matter 2.5 (PM2.5), while ozone gas is oppositely related with the number of infected individuals. We propose that atmospheric air pollutants could thus serve as surrogate markers to complement the infection outbreak anticipation.
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Hassan, Muhammad Azher, Tariq Mehmood, Ehtisham Lodhi, Muhammad Bilal, Afzal Ahmed Dar e Junjie Liu. "Lockdown Amid COVID-19 Ascendancy over Ambient Particulate Matter Pollution Anomaly". International Journal of Environmental Research and Public Health 19, n. 20 (19 ottobre 2022): 13540. http://dx.doi.org/10.3390/ijerph192013540.
Abstract (sommario):
Air is a diverse mixture of gaseous and suspended solid particles. Several new substances are being added to the air daily, polluting it and causing human health effects. Particulate matter (PM) is the primary health concern among these air toxins. The World Health Organization (WHO) addressed the fact that particulate pollution affects human health more severely than other air pollutants. The spread of air pollution and viruses, two of our millennium’s most serious concerns, have been linked closely. Coronavirus disease 2019 (COVID-19) can spread through the air, and PM could act as a host to spread the virus beyond those in close contact. Studies on COVID-19 cover diverse environmental segments and become complicated with time. As PM pollution is related to everyday life, an essential awareness regarding PM-impacted COVID-19 among the masses is required, which can help researchers understand the various features of ambient particulate pollution, particularly in the era of COVID-19. Given this, the present work provides an overview of the recent developments in COVID-19 research linked to ambient particulate studies. This review summarizes the effect of the lockdown on the characteristics of ambient particulate matter pollution, the transmission mechanism of COVID-19, and the combined health repercussions of PM pollution. In addition to a comprehensive evaluation of the implementation of the lockdown, its rationales—based on topographic and socioeconomic dynamics—are also discussed in detail. The current review is expected to encourage and motivate academics to concentrate on improving air quality management and COVID-19 control.
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Wang, Y. X., X. Y. Li e J. H. W. Lee. "Modelling of sediment oxygen demand and organic flux for a pulsed sediment organic load". Water Science and Technology 54, n. 11-12 (1 dicembre 2006): 85–92. http://dx.doi.org/10.2166/wst.2006.838.
Abstract (sommario):
Biodegradation of organic matter in the sediment affects both the level of dissolved oxygen (DO) in the overlaying water and material flux into the water body. In the present study, a mathematical model was developed to describe the DO dynamics and related organic transformation in the sediment after a pulsed load of rich organic, sediment. The model includes DO diffusion at the sediment–water interface and inside the sediment, diagenetic reactions of particulate organic to soluble organic, substances, biodegradation of soluble organic, and related DO consumption. The model can simulate sediment oxygen demand (SOD) in a dynamic system after a sudden organic load on the sediment and the flux of both biodegradable and non-biodegradable organic can be predicted. In addition, laboratory experiments were conducted using SOD chambers to investigate the SOD dynamics and sediment material fluxes. The sediment of the batch SOD tests was loaded with fish food at various rates for the sudden organic input. Numerical simulations for SOD and organic fluxes compared well with the experimental measurements. The results demonstrate that the model can be used to predict the effect of sediment pollutants on the water quality of surface waters.
26
Hallberg, Lukas, Faruk Djodjic e Magdalena Bieroza. "Phosphorus supply and floodplain design govern phosphorus reduction capacity in remediated agricultural streams". Hydrology and Earth System Sciences 28, n. 2 (26 gennaio 2024): 341–55. http://dx.doi.org/10.5194/hess-28-341-2024.
Abstract (sommario):
Abstract. Agricultural headwater streams are important pathways for diffuse sediment and nutrient losses, requiring mitigation strategies beyond in-field measures to intercept the transport of pollutants to downstream freshwater resources. As such, floodplains can be constructed along existing agricultural streams and ditches to improve fluvial stability and promote deposition of sediments and particulate phosphorus. In this study, we evaluated 10 remediated agricultural streams in Sweden for their capacity to reduce sediment and particulate phosphorus export and investigated the interplay between fluvial processes and phosphorus dynamics. Remediated streams with different floodplain designs (either on one side or both sides of the channel, with different width and elevation) were paired with upstream trapezoidal channels as controls. We used sedimentation plates to determine seasonal patterns in sediment deposition on channel beds and floodplains and monthly water quality monitoring. This was combined with continuous flow discharge measurements to examine suspended sediment and particulate phosphorus dynamics and reduction along reaches. Remediated streams with floodplains on both sides of the channel reduced particulate phosphorus concentrations and loads (−54 µg L−1, −0.21 kg ha−1 yr−1) along reaches, whereas increases occurred along streams with one-sided floodplains (27 µg L−1, 0.09 kg ha−1 yr−1) and control streams (46.6 µg L−1). Sediment deposition in remediated streams was five times higher on channel beds than on floodplains and there was no evident lateral distribution of sediments from channel to floodplains. There was no effect from sediment deposition on particulate phosphorus reduction, suggesting that bank stabilization was the key determinant for phosphorus mitigation in remediated streams, which can be realized with two-sided but not one-sided floodplains. Further, the overall narrow floodplain widths likely restricted reach-scale sediment deposition and its impact on P reductions. To fully understand remediated streams' potential for reductions in both nitrogen and different phosphorus species and to avoid pollution swapping effects, there is a need to further investigate how floodplain design can be optimized to achieve a holistic solution towards improved stream water quality.
27
Jovanovic, Luka, Gordana Jovanovic, Mirjana Perisic, Filip Alimpic, Svetlana Stanisic, Nebojsa Bacanin, Miodrag Zivkovic e Andreja Stojic. "The Explainable Potential of Coupling Metaheuristics-Optimized-XGBoost and SHAP in Revealing VOCs’ Environmental Fate". Atmosphere 14, n. 1 (4 gennaio 2023): 109. http://dx.doi.org/10.3390/atmos14010109.
Abstract (sommario):
In this paper, we explore the computational capabilities of advanced modeling tools to reveal the factors that shape the observed benzene levels and behavior under different environmental conditions. The research was based on two-year hourly data concentrations of inorganic gaseous pollutants, particulate matter, benzene, toluene, m, p-xylenes, total nonmethane hydrocarbons, and meteorological parameters obtained from the Global Data Assimilation System. In order to determine the model that will be capable of achieving a superior level of performance, eight metaheuristics algorithms were tested for eXtreme Gradient Boosting optimization, while the relative SHapley Additive exPlanations values were used to estimate the relative importance of each pollutant level and meteorological parameter for the prediction of benzene concentrations. According to the results, benzene levels are mostly shaped by toluene and the finest aerosol fraction concentrations, in the environment governed by temperature, volumetric soil moisture content, and momentum flux direction, as well as by levels of total nonmethane hydrocarbons and total nitrogen oxide. The types of conditions which provided the environment for the impact of toluene, the finest aerosol, and temperature on benzene dynamics are distinguished and described.
28
Khan, Sarah, Quamrul Hassan, Kaushal Kumar, Saurav Dixit, Kshama Sharma, Vivek Kumar C., Navdeep Dhaliwal e Bhukya Madhu. "Modelling the Impact of Road Dust on Air Pollution: A Sustainable System Dynamics Approach". E3S Web of Conferences 430 (2023): 01176. http://dx.doi.org/10.1051/e3sconf/202343001176.
Abstract (sommario):
Road dust contributes significantly to air pollution by releasing fine particulate matter (PM) and other pollutants into the air, which can cause respiratory and cardiovascular problems and premature death. This dust is generated through the wear and tear of vehicle tires and road surfaces, as well as the accumulation of dirt and debris on the road, primarily from construction activities and cargo trucks carrying building materials. Wind, weather conditions, and vehicle movement play crucial roles in the distribution and concentration of these particles in the air. To address this issue, this paper focuses on identifying various variables that are connected to road dust operations and their interrelationships with air pollution variables, representing the dynamic pattern of the entire system. The paper proposes the establishment of a sustainable causal-loop model using system dynamics (SD) modeling in Vensim, connecting feedback mechanisms to effectively control the road dust concentration. Additionally, the paper suggests different policy interventions applied to the whole system to achieve optimized results. In the future, this research aims to convert and simulate the causal-loop model to a stock-flow model and compare the effectiveness of different policy interventions to further reduce road dust contributing to air pollution.
29
Savastru, Dan, Maria A. Zoran, Roxana Savastru, Marina N. Tautan e Daniel V. Tenciu. "Time Series Satellite and Observational Data for Assessment of Urban Air Pollution and Climate Dynamics Impacts on COVID-19 transmission in Bucharest". WSEAS TRANSACTIONS ON ENVIRONMENT AND DEVELOPMENT 20 (26 ottobre 2023): 8–15. http://dx.doi.org/10.37394/232015.2024.20.2.
Abstract (sommario):
This study conducts a complex analysis to evaluate urban air pollution and climate dynamics impacts on COVID-19 viral infection incidence and mortality in Bucharest metropolitan city in Romania. It is motivated by the COVID-19 pandemic occurrence and environmental/health challenges caused by increasing urbanization in Bucharest. This paper presents the temporal patterns characteristics of the main air pollutants PM2.5 and PM10 (inhalable particulate matter with aerodynamic size less than or equal to 2.5 µm and 10 µm, respectively) as well as nitrogen dioxide-NO2, ozone-O3, sulfur dioxide-SO2, and carbon monoxide-CO during the period March 2020–March 2022 through the integration of time-series surface observation and satellite data. Through the employing of descriptive statistics and regression models for multiple datasets of air pollutants and climate-related parameters such as air temperature at 2m height (T), relative humidity (RH), wind speed intensity (w), and direction, Planetary Boundary Layer height-PBL, and surface solar irradiance-SI, this study found that seasonal variation of aerosol loading parameters (PM2.5 and PM10) over the investigated metropolitan city have a direct impact on COVID-19 spreading. Nevertheless, additional environmental and epidemiological investigations are required to test the causality of air pollution and climate seasonality impacts on COVID-19 seasonality and its severity.
30
Zhang, Weiji, Han Zhao, Ang Zhao, Jiaqiao Lin e Rui Zhou. "Current Status, Challenges and Resilient Response to Air Pollution in Urban Subway". Atmosphere 10, n. 8 (16 agosto 2019): 472. http://dx.doi.org/10.3390/atmos10080472.
Abstract (sommario):
Subway air pollution mainly refers to inhalable particulate matter (PM) pollution, organic pollution, and microbial pollution. Based on the investigation and calculation of the existing researches, this paper summarizes the sources of air pollutants, chemical compositions, and driving factors of PM variations in subway. It evaluates the toxicity and health risks of pollutants. In this paper, the problems and challenges during the deployment of air pollution governance are discussed. Results show that the global PM compliance rate of subway is about 30%. Subway air pollution is endogenous, which means that pollutants mainly come from mechanical wear and building materials erosions. Particles are mainly metal particles, black carbon, and floating dust. The health risks of some chemical elements in the subway have reached critical levels. The variations of PM concentrations show spatial-temporal characteristics, which are mainly controlled by train age, brakes types, and environmental control systems. The authors then analyze the dynamics of interactions among government, companies and public during the air pollution governance by adding the following questions: (a) who pays the bill; (b) how to evaluate the cost-effectiveness of policies; (c) how the public moves from risk perception to actions; (d) how to develop clean air technology better so as to ultimately incentivize stakeholders and to facilitate the implementation of subway clean air programme in a resilient mode.
31
Letaïef, Sarah, Pierre Camps, Thierry Poidras, Patrick Nicol, Delphine Bosch e Romane Pradeau. "Biomagnetic Monitoring vs. CFD Modeling: A Real Case Study of Near-Source Depositions of Traffic-Related Particulate Matter along a Motorway". Atmosphere 11, n. 12 (28 novembre 2020): 1285. http://dx.doi.org/10.3390/atmos11121285.
Abstract (sommario):
A test site located along a 12-lane motorway east of Montpellier, France, is used to evaluate the potential of biomagnetic monitoring on traffic-related particulate matter (PM) to parametrize a computational fluid dynamics (CFD) simulation of the local airflow. Two configurations were established on the site with three vegetated flat-top earth berms of a basic design, and a fourth one was located windward to the traffic roofed with a 4-m-high precast concrete wall. As a first step, PM deposition simultaneously on plant leaves, on low-cost passive artificial filters, and on soils was estimated from proxies supplied by magnetic and X-ray fluorescence measurements on both sides of the motorway. These latter revealed that traffic-related pollutants are present on soils samples highlighted with a clear fingerprint of combustion residues, and wears of breaks, vehicles, and highway equipment. Maximum PM accumulations were detected in the lee of the berm–wall combination, while no significant deposition was observed on both sides of the flat-top earth berms. These results are in line with measurements from PM µ-sensors operated by the regional state-approved air quality agency. Finally, we compared the experimental measurements with the outcomes of a computational fluid dynamics (CFD) modeling based on the Reynolds-Averaged Navier–Stokes (RANS) equations that consider the traffic-induced momentum and turbulence. The CFD modeling matches the experimental results by predicting a recirculated flow in the near wake of the berm–wall combination that enhances the PM concentration, whereas the flat-top berm geometry does not alter the pollutants’ transport and indeed contributes to their atmospheric dispersion.
32
Guigue, Catherine, Lionel Bigot, Jean Turquet, Marc Tedetti, Nicolas Ferretto, Madeleine Goutx e Pascale Cuet. "Hydrocarbons in a coral reef ecosystem subjected to anthropogenic pressures (La Réunion Island, Indian Ocean)". Environmental Chemistry 12, n. 3 (2015): 350. http://dx.doi.org/10.1071/en14194.
Abstract (sommario):
Environmental context Hydrocarbons are among the most widespread and harmful pollutants found in the aquatic media. Although they have been investigated in various temperate coastal environments, their dynamics in coral reef tropical ecosystems, which are under increasing human pressure, remain poorly understood. It was found that hydrocarbons had moderate to high concentrations, multiple origins (biogenic and anthropogenic) and could be used to track inland intrusions in fore reef waters of the eutrophicated La Saline reef ecosystem (La Réunion Island, Indian Ocean). Abstract The La Saline fringing reef, which is the most important coral reef complex of La Réunion Island, (south-western Indian Ocean), is subjected to anthropogenic pressures through river and groundwater inputs. Salinity and biogeochemical parameters (silicates, nitrates, dissolved organic carbon, chlorophyll-a), as well as aliphatic hydrocarbons (AHs) and polycyclic aromatic hydrocarbons (PAHs) were analysed in particulate and dissolved material from groundwaters, rivers, harbour, back reef, fore reef and oceanic waters in the La Saline reef area during the rainy season (February–March 2012). Particulate and dissolved AH concentration ranges were 0.07–144 and 0.06–0.58µgL–1 respectively. Particulate and dissolved PAH concentrations ranges were 4.3–326 and 28–350ng L–1 respectively. AHs, dominated by nC15, nC17, nC18 compounds or nC26, nC27, nC29, nC31 compounds, were mainly of biogenic origin (phytoplankton, bacteria, higher-plant debris) although some anthropogenic (petroleum inputs) signatures were recorded in the dissolved phase from the harbour and fore reef areas. PAHs, dominated by two- to three-ring compounds and their alkylated homologues, reflected unburned petroleum inputs, but probably also biogenic sources. From the distribution of salinity, biogeochemical parameters and hydrocarbons, we found that inland waters flowed mainly in the surface and in the southern part of reef waters and that particulate PAHs allowed tracking these inland water intrusions in fore reef waters. Finally, this pilot study highlights the uncoupling between the dynamics of AHs and PAHs in tropical environments.
33
Crawford, Ben, David H. Hagan, Ilene Grossman, Elizabeth Cole, Lacey Holland, Colette L. Heald e Jesse H. Kroll. "Mapping pollution exposure and chemistry during an extreme air quality event (the 2018 Kīlauea eruption) using a low-cost sensor network". Proceedings of the National Academy of Sciences 118, n. 27 (21 giugno 2021): e2025540118. http://dx.doi.org/10.1073/pnas.2025540118.
Abstract (sommario):
Extreme air quality episodes represent a major threat to human health worldwide but are highly dynamic and exceedingly challenging to monitor. The 2018 Kīlauea Lower East Rift Zone eruption (May to August 2018) blanketed much of Hawai‘i Island in “vog” (volcanic smog), a mixture of primary volcanic sulfur dioxide (SO2) gas and secondary particulate matter (PM). This episode was captured by several monitoring platforms, including a low-cost sensor (LCS) network consisting of 30 nodes designed and deployed specifically to monitor PM and SO2 during the event. Downwind of the eruption, network stations measured peak hourly PM2.5 and SO2 concentrations that exceeded 75 μg m−3 and 1,200 parts per billion (ppb), respectively. The LCS network’s high spatial density enabled highly granular estimates of human exposure to both pollutants during the eruption, which was not possible using preexisting air quality measurements. Because of overlaps in population distribution and plume dynamics, a much larger proportion of the island’s population was exposed to elevated levels of fine PM than to SO2. Additionally, the spatially distributed network was able to resolve the volcanic plume’s chemical evolution downwind of the eruption. Measurements find a mean SO2 conversion time of ∼36 h, demonstrating the ability of distributed LCS networks to observe reaction kinetics and quantify chemical transformations of air pollutants in a real-world setting. This work also highlights the utility of LCS networks for emergency response during extreme episodes to complement existing air quality monitoring approaches.
34
Arvin, E., e P. Harremoës. "Concepts and Models for Biofilm Reactor Performance". Water Science and Technology 22, n. 1-2 (1 gennaio 1990): 171–92. http://dx.doi.org/10.2166/wst.1990.0145.
Abstract (sommario):
This paper reviews the state of knowledge of the basic mechanisms governing transformation of pollutants and the present approaches with which to predict the performance of biofilm reactors. The design of biofilm reactors is based mainly on empirical loading criteria or empirical design formulae. Introduction of more stringent effluent requirements, new types of biofilm reactors, as well as application of biofilm reactors to more untraditional types of waste materials, calls for new design procedures with higher degrees of confidence. Most new attempts to model biofilm reactors are based on fundamental principles for mass transport to and through biofilms coupled with kinetic expressions for pollutant transformations in the biofilms. A simple simulation model based on half order kinetics is able to describe the removal of soluble substrates, mineralisation of organic matter, nitrification and denitrification. A simple first order kinetics is able to predict degradation of some xenobiotics. Advanced simulation models appearing in the past few years show a strong promise for detailed analysis of the effect of variation in influent waste characteristics, population dynamics, reactor configuration, etc. However, none of the models are able to predict properly the removal of particulate matter and mixtures of several groups of industrial organic chemicals. Again, insight in the basic removal mechanisms is required.
35
Figueroa, Juan, Hugo Valdes, Juan Vilches, Walter Schmidt, Felipe Valencia, Viviana Torres, Luis Diaz-Robles et al. "Comparative Analysis of Gas Emissions from Ecokiln and Artisanal Brick Kiln during the Artisanal Firing of Bricks". Sustainability 16, n. 3 (3 febbraio 2024): 1302. http://dx.doi.org/10.3390/su16031302.
Abstract (sommario):
This article focuses on the research of gas emissions in two types of brick kilns located in the Maule Region, Chile. One of them is an artisanal brick kiln known as a “chonchón” (AKC), while the other is a semi-artisanal brick kiln with an improved design. The latter is referred to as the Ecokiln. This study focuses on the assessment of the emission profiles of key pollutants such as particulate matter (PM), CO, CO2, SO2, and NOx. The emission measurements of gasses, temperature, and flow were conducted during the operation of the kilns. These measurements were carried out following the protocol established by Chilean standards. The Ecokiln’s design facilitates optimal fluid dynamics. In direct comparison to the AKC, it exhibits reduced fuel consumption, shorter operation periods, an increased brick processing capacity, decreased burnt brick losses, and notably lower emissions, with a concentration of SO2 that is 83% less than that of the AKC, NOx emissions, 58% lower than the AKC, and a remarkable 74.3% reduction in PM10 emissions. Moreover, the Ecokiln reduces pollutant emissions, improving the well-being of brickmakers and their communities. These results offer insights into the environmental impact of local brick production and support sustainable manufacturing practices.
36
Deroubaix, Adrien, Cyrille Flamant, Laurent Menut, Guillaume Siour, Sylvain Mailler, Solène Turquety, Régis Briant, Dmitry Khvorostyanov e Suzanne Crumeyrolle. "Interactions of atmospheric gases and aerosols with the monsoon dynamics over the Sudano-Guinean region during AMMA". Atmospheric Chemistry and Physics 18, n. 1 (16 gennaio 2018): 445–65. http://dx.doi.org/10.5194/acp-18-445-2018.
Abstract (sommario):
Abstract. Carbon monoxide, CO, and fine atmospheric particulate matter, PM2.5, are analyzed over the Guinean Gulf coastal region using the WRF-CHIMERE modeling system and observations during the beginning of the monsoon 2006 (from May to July), corresponding to the Africa Multidisciplinary Monsoon Analysis (AMMA) campaign period. Along the Guinean Gulf coast, the contribution of long-range pollution transport to CO or PM2.5 concentrations is important. The contribution of desert dust PM2.5 concentration decreases from ∼ 38 % in May to ∼ 5 % in July. The contribution of biomass burning PM2.5 concentration from Central Africa increases from ∼ 10 % in May to ∼ 52 % in July. The anthropogenic contribution is ∼ 30 % for CO and ∼ 10 % for PM2.5 during the whole period. When focusing only on anthropogenic pollution, frequent northward transport events from the coast to the Sahel are associated with periods of low wind and no precipitation. In June, anthropogenic PM2.5 and CO concentrations are higher than in May or July over the Guinean coastal region. Air mass dynamics concentrate pollutants emitted in the Sahel due to a meridional atmospheric cell. Moreover, a part of the pollution emitted remotely at the coast is transported and accumulated over the Sahel. Focusing the analysis on the period 8–15 June, anthropogenic pollutants emitted along the coastline are exported toward the north especially at the beginning of the night (18:00 to 00:00 UTC) with the establishment of the nocturnal low level jet. Plumes originating from different cities are mixed for some hours at the coast, leading to high pollution concentration, because of specific disturbed meteorological conditions.
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Islam, Nazrul. "Income-Environment Relationship: How Different is Asia?" Asian Development Review 15, n. 01 (gennaio 1997): 18–51. http://dx.doi.org/10.1142/s011611059700002x.
Abstract (sommario):
This paper shows that there is no rule that the environment has to first deteriorate with economic growth and improve only later. There is no absolute, invariant income-environment relationship (IER) to imply such a rule. This is shown by estimating IER for Asia and comparing it with the same for other regions of the world. It is found that IERs differ widely across regions and across pollutants, and do not usually conform to the shape implied by the Environmental Kuznets’s Curve hypothesis. This indicates that the role of income in explaining pollution dynamics is limited. With appropriate policies, pollution level can be kept low even during the initial stage of economic growth. In particular, policy measures are urgently needed in Asian countries to reduce solid particulate matter in air, and nitrate and arsenic in water.
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Platikanova, Magdalena, Borislava Chakrova, Lina Yordanova, Sergey Nikolaevich Lvov e Ivan Dimov. "A study of morbidity on the territory of the municipality of stara zagora in connection with air pollution aerosols lead". Pediatrician (St. Petersburg) 6, n. 4 (15 dicembre 2015): 32–38. http://dx.doi.org/10.17816/ped6432-38.
Abstract (sommario):
Within 5 years (2009-2013) surveyed the annual dynamics of the concentration of one of the major air pollutants in the municipality of Stara Zagora - lead aerosols and their impact on public health. In the process of monitoring parallel analyzed the average monthly levels of this pollutant. The problem of lead poisoning associated with heavy environmental pollution (primarily atmospheric air) is most relevant to large industrial cities. In the current environmental situation, the best indicator of the negative impact of lead pollution on the body is the level of morbidity of the population, which depends on the concentration of lead particulate pollutants in ambient air. When evaluating relationship pollution-morbidity on the outcome of hospitalization for different age groups the correlation dependences between the average annual concentration of lead aerosols and various diseases. For this purpose were formed correlation matrix for all types of registered diseases (associated with the impact of lead aerosols on the body), according 10 the International classification of diseases for 3 age groups: 0 to 17 years, 18 years and older and the total population. The analytical data show a significant dependence of the development of several classes of diseases as a result of exposure to toxic lead aerosols contained in the air. In the age group from 0 to 17 years the effect of pollution by lead compounds set the highest correlation dependence diseases of the skin and subcutaneous tissue, registered at the hospital, and for a group of 18 years and more with diseases of the blood and blood-forming organs. Lead aerosols and dust particles have an additive effect on the diseases of the circulatory system in the group of the total population in the municipality of Stara Zagora.
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O’Leary, Tim, Santosh Sapkota e Nabin Malakar. "Neighborhood-Level Air Pollution Monitoring and Analysis in Massachusetts". Journal of Nepal Physical Society 9, n. 3 (31 dicembre 2023): 37–45. http://dx.doi.org/10.3126/jnphyssoc.v9i3.62455.
Abstract (sommario):
Air pollution is a significant environmental issue with far-reaching consequences for both human health and the planet. It arises from the emission of harmful pollutants, such as particulate matter, ozone, and nitrogen dioxide, into the atmosphere. These pollutants originate from various sources, including vehicles, industrial facilities, and power plants. The impacts of air pollution are wide-ranging, encompassing respiratory infections, cardiovascular disease, cancer, harm to ecosystems, and contributions to climate change. The study of air pollution is a multidisciplinary field that draws upon knowledge from physics, chemistry, biology, and engineering. Understanding the causes and effects of air pollution is crucial for developing effective strategies to mitigate its harmful effects. Physics, in particular, plays a vital role in this field by providing the tools and techniques required to measure and comprehend the behavior of pollutants. By examining air pollution, we gain insights into the factors driving this problem and can devise measures to reduce pollution levels. Moreover, this knowledge empowers individuals and societies to make informed decisions about minimizing exposure to pollutants and formulating policies and regulations that safeguard both human well-being and the environment. In our study conducted in the central Massachusetts region, we investigated the status of air pollution using a combination of Environmental Protection Agency (EPA) monitoring sites and hand-held sensors. While the EPA sites offer longterm monitoring data, hand-held devices’ flexible and affordable nature allowed us to explore air quality at the local neighborhood and street levels. By utilizing these tools, we assessed the spatial and temporal variations in air pollution within the city, aiding in the identification of localized hotspots. Such information is valuable for targeting specific areas requiring interventions and further understanding the dynamics of pollution distribution.
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Varapongpisan, Ingsrisawang e Frank. "Taking drift-diffusion analysis from the study of turbulent flows to the study of particulate matter smog and air pollutants dynamics". Condensed Matter Physics 22, n. 2 (giugno 2019): 24001. http://dx.doi.org/10.5488/cmp.22.24001.
41
Archilla, Víctor, Dévora Hormigo, María Sánchez-García e David Raper. "AVIATOR - Assessing aViation emission Impact on local Air quality at airports: TOwards Regulation". MATEC Web of Conferences 304 (2019): 02023. http://dx.doi.org/10.1051/matecconf/201930402023.
Abstract (sommario):
Emissions from aircraft have adverse effects on the air quality in and around airports, contributing to public health concerns within neighbouring communities. AVIATOR will adopt a multi-level measurement, modelling and assessment approach to develop an improved description and quantification of the relevant aircraft engine emissions, and their impact on air quality under different climatic conditions. Particulate and gaseous emissions in a test cell and on-wing from an in-service aircraft will be measured to determine pollutant plume evolution from the engine and APU exhaust. This will provide an enhanced understanding of primary emitted pollutants, specifically the nvPM and vPM (down to 10nm), and the scalability between the regulatory test cell and real environments. AVIATOR will develop and deploy a proof-of-concept low cost sensor network for monitoring UFP, PM and gaseous species across multiple airports and surrounding communities. Campaigns will be complemented by high-fidelity modelling of aircraft exhaust dynamics, microphysical and chemical processes within the plume. CFD, box, and airport air quality models will be applied, providing validated parameterisations of the relevant processes, applicable to standard dispersion modelling on the local scale. Working with the regulatory community, AVIATOR will develop improved guidance on measuring and modelling the impact of aircraft emissions, and will provide airports and regulators with tools and guidance to improve the assessment of air quality in and around airports.
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Febri Juita Anggraini, Annisa Shalsabila e Zuli Rodhiyah. "Sebaran Particulate Matter (PM10, PM2,5, PM1, PM0,1) di SMP Negeri 1 Kota Jambi Menggunakan Model CFD (Computational Fluid Dynamics)". INSOLOGI: Jurnal Sains dan Teknologi 2, n. 4 (28 agosto 2023): 690–702. http://dx.doi.org/10.55123/insologi.v2i4.2269.
Abstract (sommario):
One source that contributes greatly to urban air quality is traffic. The proximity of schools to vehicles will put students at greater risk of exposure to high concentrations of particulate matter. SMP Negeri 1 Jambi City is an education center located in an urban area and adjacent to a busy road. CFD models are good at modeling the movement of pollutants in urban areas by taking into account the influence of buildings. The purpose of this study is to determine the concentration of PM10, PM2.5, PM1, and PM0.1 at SMPN 1 Jambi City based on direct measurement results and CFD modeling results and then see how accurate the modeled PM concentrations are when compared to the results of direct measurements. The results showed that the average concentrations of PM10, PM2.5, PM1, and PM0.1 from direct measurements were 20.66 µg/m3, 11.79 µg/m3, 8.74 µg/m3, and 1.96 µg/m3, respectively, while the modeling results showed lower average concentrations. The ratio of the difference between the measured and modeled PM concentrations is in the range of 11.67 - 233.45% and with the percentage of RMSPE obtained >30% (invalid), where the requirement for a modeling to be valid so that the results can be trusted in explaining the actual phenomenon is when the validity percentage is <30%.
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Mei, Xiong, e Guangcai Gong. "Characterizing transport and deposition of particulate pollutants in a two-zone chamber using a Markov chain model combined with computational fluid dynamics". Applied Mathematical Modelling 72 (agosto 2019): 650–62. http://dx.doi.org/10.1016/j.apm.2019.02.035.
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El Afandi, Gamal, e Hossam Ismael. "Spatiotemporal Variation of Summertime Urban Heat Island (UHI) and Its Correlation with Particulate Matter (PM2.5) over Metropolitan Cities in Alabama". Geographies 3, n. 4 (2 ottobre 2023): 622–53. http://dx.doi.org/10.3390/geographies3040033.
Abstract (sommario):
More than half of the global population lives in urban areas, which can cause the phenomenon known as Urban Heat Island (UHI). UHI is a phenomenon where urban areas experience higher temperatures compared to their rural surroundings. The occurrence of UHI in large cities is primarily due to urbanization and increased vehicular emissions. Factors such as wind speed and direction, solar flux, and the thermodynamic properties of surface materials determine the intensity of UHI. It can cause thermal air circulation, leading to high concentrations of urban air pollutants such as fine particulate matter (PM2.5). These pollutants can remain suspended in the air and cause asthma and allergies. It is essential to understand the characteristics of UHI intensity and its effect on air quality. This study aims to analyze the spatiotemporal variations of UHI and their correlation with PM2.5 concentration in three Alabama cities, namely Birmingham, Montgomery, and Mobile, during the summer seasons of 2002, 2012, and 2022. The study also compares UHI in these cities with nearby rural areas to determine the effect of urbanization by calculating the Normalized Difference Building Index (NDBI). To achieve these objectives, the Land Surface Temperature (LST), UHI intensity, and NDBI Datasets were analyzed. The results showed that PM2.5 concentrations in the cities have been decreasing annually since 2002, leading to an improvement in air quality. There was a negative linear correlation between UHI intensity and PM2.5 concentration. However, LST remained consistently high throughout the study period. The correlation between UHI intensity and NDBI was positive. The findings of this study can help us better understand the dynamics and driving mechanisms of the urban heat environment. Furthermore, they can assist urban metropolitan planners in developing more efficient mitigation strategies that reduce the negative impacts of UHI and PM2.5 concentrations on the environment.
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Lu, Jintao, Chong Zhang, Licheng Ren, Mengshang Liang, Wadim Strielkowski e Justas Streimikis. "Evolution of External Health Costs of Electricity Generation in the Baltic States". International Journal of Environmental Research and Public Health 17, n. 15 (22 luglio 2020): 5265. http://dx.doi.org/10.3390/ijerph17155265.
Abstract (sommario):
Implementation of strict policies for mitigating climate change has a direct impact on public health as far as the external health costs of electricity generation can be reduced, thanks to the reduction of emission of typical pollutants by switching to cleaner low carbon fuels and achieving energy efficiency improvements. Renewables have lower external health costs due to the lower life cycle emission of typical air pollutants linked to electricity generation, such as SO2, NOx, particulate matter, NH3, or NMVOC (Non-methane volatile organic compounds), which all appear to have serious negative effects on human health. Our case study performed in the Baltic States analyzed the dynamics of external health costs in parallel with the dynamics of the main health indicators in these countries: life expectancy at birth, mortality rates, healthy life years, self-perceived health, and illness indicators. We employed the data for external health costs retrieved from the CASES database, as well as the health statistics data compiled from the EUROSTAT database. The time range of the study was 2010–2018 due to the availability of consistent health indicators for the EU Member States. Our results show that the decrease of external health costs had a positive impact on the increase of the self-perceived good health and reduction of long-standing illness as well as the decrease of infant death rate. Our conclusions might be useful for other countries as well as for understanding the additional benefits of climate change mitigation policies and tracking their positive health impacts. The cooperation initiatives on clean energy and climate change mitigation between countries like One Belt One Road initiative by the Chinese government can also yield additional benefits linked to the public health improvements.
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Chan, T. W., e M. Mozurkewich. "Application of absolute principal component analysis to size distribution data: identification of particle origins". Atmospheric Chemistry and Physics Discussions 6, n. 5 (18 ottobre 2006): 10493–522. http://dx.doi.org/10.5194/acpd-6-10493-2006.
Abstract (sommario):
Abstract. Absolute principal component analysis can be applied, with suitable modifications, to atmospheric aerosol size distribution measurements. This method quickly and conveniently reduces the dimensionality of a data set. The resulting representation of the data is much simpler, but preserves virtually all the information present in the original measurements. Here we demonstrate how to combine the simplified size distribution data with trace gas measurements and meteorological data to determine the origins of the measured particulate matter using absolute principal component analysis. We have applied the analysis to four different sets of field measurements that were conducted at three sites in southern Ontario. Several common factors were observed at all the sites; these were identified as photochemically produced secondary aerosol particles, regional pollutants (including accumulation mode aerosol particles), and trace gas variations associated with boundary layer dynamics. Each site also exhibited a factor associated specifically with that site: local industrial emissions in Hamilton (urban site), processed nucleation mode particles at Simcoe (polluted rural site), and transported fine particles at Egbert (downwind from Toronto).
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Biddle, Trevor, Rajrupa Chakraborty, Qi Li, Mia Maltz, Jo Gerrard e David D. Lo. "The drying Salton Sea and asthma: A perspective on a “natural” disaster". California Agriculture 76, n. 1 (aprile 2022): 27–36. http://dx.doi.org/10.3733/ca.2022a0003.
Abstract (sommario):
The Salton Sea is a drying salt lake in an arid region with high aerosol particulate-matter concentrations. This region is plagued by a high incidence of asthma, attributed in part to the aerosols surrounding the Sea. But the connection between the Sea and asthma may be more than simple calculations of dust concentrations. While dusts might contain toxic substances that impact the lungs of residents, the complex dynamics related to the environmental degradation of the Salton Sea may be generating additional toxins relevant to public health, such as microcystins produced by algal blooms. This collection of pollutants may be driving inflammatory responses in the lungs of residents through multiple mechanisms. As such, examination of the full range of potential environmental triggers of lung inflammation promises to yield a better understanding of key mechanisms driving the high incidence of asthma in local residents. Our discussion provides a perspective aiming to re-frame the issue in the context of the historical theory of “miasma” and the linkages between environmental change and health impacts.
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Batur, Maryna, e Kateryna Babii. "Spatial assessment of air pollution due to mining and industrial activities: a case study of Kryvyi Rih, Ukraine". IOP Conference Series: Earth and Environmental Science 970, n. 1 (1 gennaio 2022): 012004. http://dx.doi.org/10.1088/1755-1315/970/1/012004.
Abstract (sommario):
Abstract Air pollution has remained a primary concern over the last decades. Respirable particulate matters (PM) PM2.5 and PM10 are the main atmospheric pollutants that have an adverse effect on human health. This study aimed to examine the air quality of Kryvyi Rih region through the spatial assessment by means of Ordinary Kriging. The study region has a major iron ore basin with several open cast mining operations and industrial activities, which are mainly contribute to the environmental issues. For the study, 10 monitoring stations were chosen located around the main residential and industrial areas of the city. The results showed that industrial plants were the largest sources of PM emissions. The average Air Quality Index (AQI) of PM2.5 and PM10 for the observed period obtained from the station located in close vicinity to the industrial plants were 170 and 89 respectively. Additionally, the 48 hours of PM dynamics were graphically analysed. It was found that PM reaches a peak primary between 12 AM and 12 PM before falling a little between 12 PM and 12 AM.
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Chan, T. W., e M. Mozurkewich. "Application of absolute principal component analysis to size distribution data: identification of particle origins". Atmospheric Chemistry and Physics 7, n. 3 (16 febbraio 2007): 887–97. http://dx.doi.org/10.5194/acp-7-887-2007.
Abstract (sommario):
Abstract. Absolute principal component analysis can be applied, with suitable modifications, to atmospheric aerosol size distribution measurements. This method quickly and conveniently reduces the dimensionality of a data set. The resulting representation of the data is much simpler, but preserves virtually all the information present in the original measurements. Here we demonstrate how to combine the simplified size distribution data with trace gas measurements and meteorological data to determine the origins of the measured particulate matter using absolute principal component analysis. We have applied the analysis to four different sets of field measurements that were conducted at three sites in southern Ontario. Several common factors were observed at all the sites; these were identified as photochemically produced secondary aerosol particles, regional pollutants (including accumulation mode aerosol particles), and trace gas variations associated with boundary layer dynamics. Each site also exhibited a factor associated specifically with that site: local industrial emissions in Hamilton (urban site), processed nucleation mode particles at Simcoe (polluted rural site), and transported fine particles at Egbert (downwind from Toronto).
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Pearson, C., R. Schumer, B. D. Trustman, K. Rittger, D. W. Johnson e D. Obrist. "Nutrient and mercury deposition and storage in an alpine snowpack of the Sierra Nevada, USA". Biogeosciences Discussions 12, n. 1 (12 gennaio 2015): 593–636. http://dx.doi.org/10.5194/bgd-12-593-2015.
Abstract (sommario):
Abstract. Bi-weekly snowpack core samples were collected at seven sites along two elevation gradients in the Tahoe Basin during two consecutive snow years to evaluate total wintertime snowpack accumulation of nutrients and pollutants in a high elevation watershed of the Sierra Nevada. Additional sampling of wet deposition and detailed snow pit profiles was conducted the following year to compare wet deposition to snowpack storage and assess the vertical dynamics of snowpack chemicals. Results show that on average organic N comprised 48% of all snowpack N, while nitrate (NO3--N) and TAN (total ammonia nitrogen) made up 25 and 27%, respectively. Snowpack NO3--N concentrations were relatively uniform across sampling sites over the sampling seasons and showed little difference between seasonal wet deposition and integrated snow pit concentrations in agreement with previous studies that identify wet deposition as the dominant source of wintertime NO3--N deposition. However, vertical snow pit profiles showed highly variable concentrations of NO3--N within the snowpack indicative of additional deposition and in snowpack dynamics. Unlike NO3--N, snowpack TAN doubled towards the end of winter and in addition to wet deposition, had a strong dry deposition component. Organic N concentrations in snowpack were highly variable (from 35 to 70%) and showed no clear temporal or spatial dependence throughout the season. Integrated snowpack organic N concentrations were up to 2.5 times higher than seasonal wet deposition, likely due to microbial immobilization of inorganic N as evident by coinciding increases of organic N and decreases of inorganic N, in deeper, aged snowpack. Spatial and temporal deposition patterns of snowpack P were consistent with particulate-bound dry deposition inputs and strong impacts from in-basin sources causing up to 6 times enrichment at urban locations compared to remote sites. Snowpack Hg showed little temporal variability and was dominated by particulate-bound forms (78% on average). Dissolved Hg concentrations were consistently lower in snowpack than in wet deposition which we attribute to photochemical-driven gaseous remission. In agreement with this pattern is a significant positive relationship between snowpack Hg and elevation, attributed to a combination of increased snow accumulation at higher elevations causing limited light penetration and lower photochemical re-emission losses in deeper, higher elevation snowpack. Finally, estimates of basin-wide loading based on spatially extrapolated concentrations and a satellite-based snow water equivalent reconstruction model identify snowpack chemical loading from atmospheric deposition as a substantial source of nutrients and pollutants to the Lake Tahoe basin, accounting for 113 t of N, 9.3 t of P, and 1.2 kg of Hg each year.