Industrial processes discharge fine particulates containing organic as well as inorganic compounds into the atmosphere which are known to induce damage to cell and DNA, both in vitro and in vivo. Source and area speci...
详细信息
Industrial processes discharge fine particulates containing organic as well as inorganic compounds into the atmosphere which are known to induce damage to cell and DNA, both in vitro and in vivo. Source and area specific studies with respect to the chemical composition, size and shape of the particles, and toxicity evaluations are very much limited. This study aims to investigate the trace elements associated with the aerosol particles distributed near to a coal burning thermal power plant and to evaluate their toxicity through Comet assay. PM10 (particles determined by mass passing an inlet with a 50% cut-off efficiency having a 10-mu m aerodynamic diameter) samples were collected using respirable dust samplers. Twelve elements (Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb, Se, Hg, and As) were analyzed using ICP-AES. Comet assay was done with the extracts of aerosols in phosphate buffered saline (PBS). Results show that Fe and Zn were found to be the predominant elements along with traces of other analyzed elements. Spherical shaped ultrafine particles of <1 mu m aerodynamic diameter were detected through scanning electron microscope. PM10 particles near to the coal burning power plant produced comets indicating their potential to induce DNA damage. DNA damage property is found to be depending upon the chemical characteristics of the components associated with the particles besides the physical properties such as size and shape. (C) 2009 Elsevier Ltd. All rights reserved.
Turbulence is the key process transporting material and energy in the atmosphere. Furthermore, turbulence causes concentration fluctuations, influencing different atmospheric processes such as deposition, chemical rea...
详细信息
Turbulence is the key process transporting material and energy in the atmosphere. Furthermore, turbulence causes concentration fluctuations, influencing different atmospheric processes such as deposition, chemical reactions, formation of low-volatile vapours, formation of new aerosol particles and their growth in the atmosphere, and the effect of aerosol particles on boundary-layer meteorology. In order to analyse the connections, interactions and feedbacks relating those different processes require a deep understanding of atmospheric turbulence mechanisms, atmospheric chemistry and aerosol dynamics. All these processes will further influence air pollution and climate. The better we understand these processes and their interactions and associated feedback, the more effectively we can mitigate air pollution as well as mitigate climate forcers and adapt to climate change. We present several aspects on the importance of turbulence including how turbulence is crucial for atmospheric phenomena and feedbacks in different environments. Furthermore, we discuss how boundary-layer dynamics links to aerosols and air pollution. Here, we present also a roadmap from deep understanding to practical solutions.
The Weather Research and Forecasting (WRF) model coupled with chemistry (WRF-Chem) is used to simulate rainfall pattern over the Indian landmass during a normal monsoon year (June-September 2010). Sensitivity analysis...
详细信息
The Weather Research and Forecasting (WRF) model coupled with chemistry (WRF-Chem) is used to simulate rainfall pattern over the Indian landmass during a normal monsoon year (June-September 2010). Sensitivity analysis is performed using three different microphysical (MP) schemes (Thompson, Morrison, and Lin) to simulate the rainfall pattern and distribution over India. A significant difference in the rainfall amount, as well as distribution, is observed among the MP schemes, despite using the same model configuration and the meteorological and chemical initial and boundary condition. Lin MP scheme performed better than other schemes in simulating the rainfall over the Indian domain. Heavy rainfall along the foothills of the Himalayas, the mountainous coastal region of western India, and the northeastern part of India and sparse rainfall over northwest India are captured realistically in the model, which agrees well with the observed rainfall pattern over India. The spatial distribution of aerosol optical depths retrieved from the MODIS satellites is broadly well simulated by the model. The model simulated convective and non-convective rainfall characteristics over the Indian landmass are found to be consistent with the monsoon precipitation climatology. It is shown that the change in both convective and non-convective rainfall due to aerosols and chemistry is non-negligible over India during monsoon season. The total rainfall is found to increase significantly over the entire Western Ghats and some part of northeast India, while it is diminished over the northwest, north and east India when aerosol chemistry effects are considered in the model simulation. Additional analysis is performed to simulate the perturbations in convective and non-convective rainfall due to aerosols (e.g., dust, sea salt, black carbon etc.). Results show that the effect of aerosols on convective and non-convective rainfall distribution over India is non-linear. Depending on the meteorologica
The Mediterranean basin is one of the most sensitive regions in the world regarding climate change and air quality. Deserts and marine aerosols combine with combustion aerosols from maritime traffic, large urban cente...
详细信息
The Mediterranean basin is one of the most sensitive regions in the world regarding climate change and air quality. Deserts and marine aerosols combine with combustion aerosols from maritime traffic, large urban centers, and at a larger scale from populated industrialized regions in Europe. From Tetouan city located in the North of Morocco, we attempted to better figure out the main aerosol transport pathways and their respective aerosol load and chemical profile by examining air mass back trajectory patterns and aerosol chemical compositions from May 2011 to April 2012. The back trajectory analysis throughout the sampling period led to four clusters, for which meteorological conditions and aerosol chemical characteristics have been investigated. The most frequent cluster (CL3: 39%) corresponds to polluted air masses coming from the Mediterranean Basin, characterized by urban and marine vessels emissions out of Spain and of Northern Africa. Two other polluted clusters were characterized. One is of local origin (CL1: 22%), with a marked contribution from urban aerosols (Rabat, Casablanca) and from biomass burning aerosols. The second (CL2: 32%) defines air masses from the near Atlantic Ocean, affected by pollutants emitted from the Iberian coast. A fourth cluster (CL4: 7%) is characterized by rather clean, fast and rainy oceanic air masses, influenced during their last 24 h before reaching Tetouan by similar sources with those affecting CL2, but to a lesser extent. The chemical data show that carbonaceous species are found in the fine aerosols fraction and are generally from local primary sources (low OC/EC) rather than long-range transported. In addition to fresh traffic and maritime vessel aerosols, our results suggest the contribution of local biomass burning.
This review article is an introduction to the range of specific aerosol effects arising when a strong laser beam interacts with aerosol particles. After a short overview of the aerosol processes in the laser beam, the...
详细信息
This review article is an introduction to the range of specific aerosol effects arising when a strong laser beam interacts with aerosol particles. After a short overview of the aerosol processes in the laser beam, the following effects are considered: (i) heating, evaporation and disintegration of aerosol particles in the strong laser beam;(ii) charging of aerosol particles, thermo-emission of electrons and semi-direct photoeffects;(iii) aerosol-induced breakdown of gases;(iv) clearing of channel in aerosol clouds;(v) nonlinear scattering of intense light by aerosol;and (vi) electromechanical effects: motion of aerosol particles in strong laser beams. The cited literature emphasizes works from the former U.S.S.R.
The behavior of a melt of a UO2-ZrO2-SiO2-Fe3O4-CaO-Al2O3 system that is formed in the case of the dilution of corium (a melt of a UO2-ZrO2-Zr system) with sacrificial materials (a mixture of aluminum and iron oxides ...
详细信息
The behavior of a melt of a UO2-ZrO2-SiO2-Fe3O4-CaO-Al2O3 system that is formed in the case of the dilution of corium (a melt of a UO2-ZrO2-Zr system) with sacrificial materials (a mixture of aluminum and iron oxides with Portland cement) has been studied. It has been found that, as a result of the evaporation of oxides, spherical aerosol particles are formed, the sizes of which have a trimodal distribution (1, 5, and 11 mu m) and the composition of which depends on the nature of the atmosphere over the melt: 90.8UO(2) center dot 5.2SiO(2) center dot 4.0Fe(3)O(4) in the atmosphere of nitrogen and 68.9U(3)O(8) center dot 6Al(2)O(3) center dot 2.5Fe(3)O(4) center dot 22.5Na(2)O in air.
Given the uncertainties associated with GCM modelling of aerosol effects on regional precipitation, a simple model is used to make a preliminary assessment of the influence of aerosols on rainfall in the Lake Tanganyi...
详细信息
Given the uncertainties associated with GCM modelling of aerosol effects on regional precipitation, a simple model is used to make a preliminary assessment of the influence of aerosols on rainfall in the Lake Tanganyika region of tropical southern Africa. No attempt will be made to consider the effects of changing carbon dioxide and moisture contents of the atmosphere that might have occurred at the same time. Atmospheric transport and recirculation of air and aerosols are considered and shown to occur on a large scale. Size distributions, residence times and concentrations of aerosols are examined and air volume and aerosol mass transports are estimated. South African data from stations on the interior plateau are used to approximate present-day seasonal and interannual variations in transmissivity due to changing aerosol loading in the atmosphere. A lake-catchment hydrological model is used to determine rainfall over Lake Tanganyika and its environs and from this a sensitivity analysis of rainfall receipt to aerosol-induced changes in atmospheric transmissivity is carried out. It is shown that a decrease in transmissivity commensurate with the present-day interannual range of variability of 10 per cent produces, in the absence of other changes, about a 15 per cent diminution in rainfall. The analysis is extended to show that in the past, during the sixteenth-century Little Ice Age, the transmissivity induced rainfall decrease could have been about 25 per cent and that at 18000 years BP it would have been more. Aerosol loading is shown to have important consequences for the occurrence of droughts through its modification of the surface radiation balance. (C) 1997 Royal Meteorological Society,
The first data on the concentrations, fluxes, and mineral and chemical compositions of aerosols from the near-water surface layer of the Caspian Sea are presented. It is shown that the aerosol fluxes onto the sea surf...
详细信息
The first data on the concentrations, fluxes, and mineral and chemical compositions of aerosols from the near-water surface layer of the Caspian Sea are presented. It is shown that the aerosol fluxes onto the sea surface are comparable to the fluxes of a lithogenic substance in a water column. The mineral and chemical compositions of aerosols depend on the carrying air masses that pass through different regions. The coefficients of enrichment of aerosols with chemical elements relative to the upper lithosphere and their correlation relationships are studied.
An ongoing program to continuously collect time- and size-resolved aerosol samples from ambient air at Summit Station, Greenland (72.6 N, 38.5 W) is building a long-term data base to both record individual transport e...
详细信息
An ongoing program to continuously collect time- and size-resolved aerosol samples from ambient air at Summit Station, Greenland (72.6 N, 38.5 W) is building a long-term data base to both record individual transport events and provide long-term temporal context for past and future intensive studies at the site. As a "first look" at this data set, analysis of samples collected from summer 2005 to spring 2006 demonstrates the utility of continuous sampling to characterize air masses over the ice pack, document individual aerosol transport events, and develop a long-term record. Seven source-related aerosol types were identified in this analysis: Asian dust, Saharan dust, industrial combustion, marine with combustion tracers, fresh coarse volcanic tephra, and aged volcanic plume with fine tephra and sulfate, and the well-mixed background "Arctic haze". The Saharan dust is a new discovery;the other types are consistent with those reported from previous work using snow pits and intermittent ambient air sampling during intensive study campaigns. Continuous sampling complements the fundamental characterization of Greenland aerosols developed in intensive field programs by providing a year-round record of aerosol size and composition at all temporal scales relevant to ice core analysis, ranging from individual deposition events and seasonal cycles, to a record of inter-annual variability of aerosols from both natural and anthropogenic sources. (C) 2011 Elsevier Ltd. All rights reserved.
A method is proposed which can facilitate parallel cornputations of particle transport in complex environments, Such as urban landscapes. A two stage-approach is used, where in the first stage, physical simulations of...
详细信息
A method is proposed which can facilitate parallel cornputations of particle transport in complex environments, Such as urban landscapes. A two stage-approach is used, where in the first stage, physical simulations of various aerosol release scenarios are conducted on a high-performance distributed computing facility, such as a Beowulf cluster or a computing grid, and stored in a database as a set of transfer probabilities. In this stage, the method provides a partially decoupled parallel implementation of a tightly coupled physical system. In the second stage, various aerosol release scenarios can be analysed in a timely manner, using obtained probability distributions and a simpler stochastic simulator, which can be executed on a commodity computer, such as a workstation or a laptop. The method presents a possibility of solving the inverse problem of determining the release source from the available deposition data. Using the proposed approach and developed graphical tools, a case of aerosol dispersion in a typical urban landscape has been studied. A considerable speedup of analysis time for different aerosol dispersion scenarios has been demonstrated. The method is appropriate for the development of express risk analysis systems. Copyright (C) 2006 John Wiley & Sons, Ltd.
暂无评论