scholarly journals Direct observations of the atmospheric processing of Asian mineral dust

2006 ◽  
Vol 6 (3) ◽  
pp. 4109-4170 ◽  
Author(s):  
R. C. Sullivan ◽  
S. A. Guazzotti ◽  
D. A. Sodeman ◽  
K. A. Prather
Keyword(s):  
Urban Areas ◽  
Mineral Dust ◽  
Field Studies ◽  
Dust Particles ◽  
Reaction Products ◽  
Mass Source ◽  
Atmospheric Processing ◽  
Acid Reaction ◽  
The Individual ◽  
High Degree

Abstract. The accumulation of secondary acid products and ammonium on individual mineral dust particles during ACE-Asia has been measured in real-time using ATOFMS. Changes in the amounts of sulphate, nitrate, and chloride mixed with dust particles corresponded to different air mass source regions. During volcanically influenced periods, dust mixed with sulphate dominated. This rapidly switched to dust predominantly mixed with chloride when the first Asian dust front reached the R/V Ronald Brown. We hypothesise that the high degree of mixing of dust with chloride was caused by the prior reaction of NOy(g) and volcanic SO2(g) with sea salt particles, reducing the availability of nitrate and sulphate precursors while releasing HCl(g), which then reacted with the incoming dust front. The segregation of sulphate from nitrate and chloride in individual dust particles is demonstrated for the first time. This is likely caused by the dust plume encountering elevated SO2(g) in the Chinese interior before reaching coastal urban areas polluted by both SO2(g) and NOx(g). This caused the fractions of dust mixed with nitrate and/or chloride to be strongly dependent on the total dust loadings, whereas dust mixed with sulphate did not show this same dust concentration dependence. Ammonium was also significantly mixed with dust and the amount correlated strongly with the total amount of secondary acid reaction products in the dust. Submicron dust and ammonium sulphate were internally mixed, contrary to frequent statements that they exist as an external mixture. The size distribution of the mixing state of dust with these secondary species validates previous models and mechanisms of the atmospheric processing of dust. The uptake of secondary acids was also dependent on the individual dust particle mineralogy; nitrate accumulated on calcium-rich dust while sulphate accumulated on aluminosilicate-rich dust. Oxidation of S(IV) to S(VI) by iron in the aluminosilicate-rich dust is a probable explanation for this result, with important consequences for dust as a vector for the fertilization of remote oceans by soluble iron. This series of novel results has important implications for improving the treatment of dust in global chemistry models and highlights several key processes requiring further investigation through laboratory and field studies.

scholarly journals Direct observations of the atmospheric processing of Asian mineral dust

2007 ◽  
Vol 7 (5) ◽  
pp. 1213-1236 ◽  
Author(s):  
R. C. Sullivan ◽  
S. A. Guazzotti ◽  
D. A. Sodeman ◽  
K. A. Prather
Keyword(s):  
Mineral Dust ◽  
Heterogeneous Reaction ◽  
Field Studies ◽  
Dust Particles ◽  
Reaction Products ◽  
Transport Pathway ◽  
Air Masses ◽  
Atmospheric Processing ◽  
Acid Reaction ◽  
The Individual

Abstract. The accumulation of secondary acids and ammonium on individual mineral dust particles during ACE-Asia has been measured with an online single-particle mass spectrometer, the ATOFMS. Changes in the amounts of sulphate, nitrate, and chloride mixed with dust particles correlate with air masses from different source regions. The uptake of secondary acids depended on the individual dust particle mineralogy; high amounts of nitrate accumulated on calcium-rich dust while high amounts of sulphate accumulated on aluminosilicate-rich dust. Oxidation of S(IV) to S(VI) by iron in the aluminosilicate dust is a possible explanation for this enrichment of sulphate, which has important consequences for the fertilization of remote oceans by soluble iron. This study shows the segregation of sulphate from nitrate and chloride in individual aged dust particles for the first time. A transport and aging timeline provides an explanation for the observed segregation. Our data suggests that sulphate became mixed with the dust first. This implies that the transport pathway is more important than the reaction kinetics in determining which species accumulate on mineral dust. Early in the study, dust particles in volcanically influenced air masses were mixed predominately with sulphate. Dust mixed with chloride then dominated over sulphate and nitrate when a major dust front reached the R. V. Ronald Brown. We hypothesize that the rapid increase in chloride on dust was due to mixing with HCl(g) released from acidified sea salt particles induced by heterogeneous reaction with volcanic SO2(g), prior to the arrival of the dust front. The amount of ammonium mixed with dust correlated strongly with the total amount of secondary acid reaction products in the dust. Submicron dust and ammonium sulphate were internally mixed, contrary to frequent reports that they exist as external mixtures. The size distribution of the mixing state of dust with these secondary species validates previous mechanisms of the atmospheric processing of dust and generally agrees with simulated aerosol chemistry from the STEM-2K3 model. This series of novel results has important implications for improving the treatment of dust in global chemistry models and highlights a number of key processes that merit further investigation through laboratory and field studies.

scholarly journals Simulation of heterogeneous photooxidation of SO<sub>2</sub> and NO<sub><i>x</i></sub> in the presence of Gobi Desert dust particles under ambient sunlight

2018 ◽  
Vol 18 (19) ◽  
pp. 14609-14622 ◽  
Author(s):  
Zechen Yu ◽  
Myoseon Jang
Keyword(s):  
Urban Areas ◽  
Mineral Dust ◽  
Buffering Capacity ◽  
Dust Particles ◽  
Gobi Desert ◽  
Heterogeneous Chemistry ◽  
Desert Dust ◽  
Malachite Green Dye ◽  
Photodegradation Rate ◽  
Nitrate Salts

Abstract. To improve the simulation of the heterogeneous oxidation of SO2 and NOx in the presence of authentic mineral dust particles under ambient environmental conditions, the explicit kinetic mechanisms were constructed in the Atmospheric Mineral Aerosol Reaction (AMAR) model. The formation of sulfate and nitrate was divided into three phases: the gas phase, the non-dust aqueous phase, and the dust phase. In particular, AMAR established the mechanistic role of dust chemical characteristics (e.g., photoactivation, hygroscopicity, and buffering capacity) in heterogeneous chemistry. The photoactivation kinetic process of different dust particles was built into the model by measuring the photodegradation rate constant of an impregnated surrogate (malachite green dye) on a dust filter sample (e.g., Arizona test dust – ATD – and Gobi Desert dust – GDD) using an online reflective UV–visible spectrometer. The photoactivation parameters were integrated with the heterogeneous chemistry to predict the formation of reactive oxygen species on dust surfaces. A mathematical equation for the hygroscopicity of dust particles was also included in the AMAR model to process the multiphase partitioning of trace gases and in-particle chemistry. The buffering capacity of dust, which is related to the neutralization of dust alkaline carbonates with inorganic acids, was included in the model to dynamically predict the hygroscopicity of aged dust. The AMAR model simulated the formation of sulfate and nitrate using experimental data obtained in the presence of authentic mineral dust under ambient sunlight using a large outdoor smog chamber (University of Florida Atmospheric Photochemical Outdoor Reactor, UF-APHOR). Overall, the influence of GDD on the heterogeneous chemistry was much greater than that of ATD. Based on the model analysis, GDD enhanced the sulfate formation mainly via its high photoactivation capability. In the case of NO2 oxidation, dust-phase nitrate formation is mainly regulated by the buffering capacity of dust. The measured buffering capacity of GDD was 2 times greater than that of ATD, and consequently, the maximum nitrate concentration with GDD was nearly 2 times higher than that with ATD. The model also highlights that in urban areas with high NOx concentrations, hygroscopic nitrate salts quickly form via titration of the carbonates in the dust particles, but in the presence of SO2, the nitrate salts are gradually depleted by the formation of sulfate.

scholarly journals Saharan dust levels in Greece and received inhalation doses

2008 ◽  
Vol 8 (3) ◽  
pp. 11967-11996 ◽  
Author(s):  
C. Mitsakou ◽  
G. Kallos ◽  
N. Papantoniou ◽  
C. Spyrou ◽  
S. Solomos ◽  
...  
Keyword(s):  
Urban Areas ◽  
Particle Deposition ◽  
Mineral Dust ◽  
Weather Conditions ◽  
Pm10 Concentration ◽  
Saharan Dust ◽  
Dust Particles ◽  
Annual Number ◽  
Human Respiratory Tract ◽  
Dust Transport

Abstract. The desert of Sahara is one of the major sources of mineral dust on Earth, producing around 2×108 tons/yr. Under certain weather conditions, dust particles from Saharan desert get transported over the Mediterranean Sea and most of Europe. The limiting values set by the directive EC/30/1999 of European Union can easily be exceeded by the transport of desert dust particles in all south European areas and especially urban. In this study, the effects of dust transport on air quality in several Greek urban areas are quantified. PM10 concentration values from stationary monitoring stations are compared to dust concentrations for the 4-year period 2003–2006. The dust concentration values in the Greek areas were estimated by the SKIRON modelling system coupled with embedded algorithms describing the dust cycle. The mean annual dust contribution to daily-averaged PM10 concentration values was found to be around or even greater than 10% in the urban areas throughout the years examined. Natural dust transport may contribute by much more than 20% to the annual number of exceedances – PM10 values greater than EU limits – depending on the specific monitoring location. In a second stage of the study, the inhaled lung dose received by the residents in various Greek locations is calculated. The particle deposition efficiency of mineral dust at the different parts of the human respiratory tract is determined by applying a lung dosimetry numerical model, which incorporates inhalation dynamics and aerosol physical processes. The inhalation dose from mineral dust particles was greater in the upper respiratory system (extrathoracic region) and less significant in the lungs, especially in the sensitive alveolar region. However, in cases of dust episodes, the amounts of mineral dust deposited along the human lung are comparable to those received during exposure in heavily polluted urban or smoking areas.

scholarly journals Assessing the mineral dust indirect effects and radiation impacts on a simulated idealized nocturnal squall line

2012 ◽  
Vol 12 (11) ◽  
pp. 29607-29655 ◽  
Author(s):  
R. B. Seigel ◽  
S. C. van den Heever ◽  
S. M. Saleeby
Keyword(s):  
Indirect Effects ◽  
Mineral Dust ◽  
Synergistic Effects ◽  
Atmospheric Modeling ◽  
Dust Particles ◽  
Squall Line ◽  
Cold Pool ◽  
Freezing Level ◽  
Warm Rain Process ◽  
The Individual

Abstract. Mineral dust is arguably the most abundant aerosol species in the world and it plays a large role in aerosol indirect effects (AIEs). This study assesses and isolates the individual responses in a squall line that arise (1) from radiation, (2) from dust altering the microphysics, as well as (3) from the synergistic effects between (1) and (2). To accomplish these tasks, we use the Regional Atmospheric Modeling System (RAMS) set up as a cloud-resolving model (CRM). The CRM contains aerosol and microphysical schemes that allow mineral dust particles to nucleate as cloud drops and ice crystals, replenish upon evaporation and sublimation, be tracked throughout hydrometeor transition, and scavenge by precipitation and dry sedimentation. Factor separation is used on four simulations of the squall line in order to isolate the individual roles of radiation (RADIATION), microphysically active dust (DUST MICRO), and the nonlinear interactions of those factors (SYNERGY). Results indicate that RADIATION acts to increase precipitation, intensify the cold pool, and enhance the mesoscale organization of the squall line due to changes in microphysics beginning from cloud top cooling. Conversely, DUST MICRO decreases precipitation, weakens the cold pool, and weakens the mesoscale organization of the squall line due to an enhancement of the warm rain process. SYNERGY shows little impact on the squall line, except near the freezing level, where an increase in mesoscale organization takes place. The combined effect of the mineral dust AIE due to both DUST MICRO and SYNERGY is to weaken the squall line.

scholarly journals Saharan dust levels in Greece and received inhalation doses

2008 ◽  
Vol 8 (23) ◽  
pp. 7181-7192 ◽  
Author(s):  
C. Mitsakou ◽  
G. Kallos ◽  
N. Papantoniou ◽  
C. Spyrou ◽  
S. Solomos ◽  
...  
Keyword(s):  
Urban Areas ◽  
Particle Deposition ◽  
Mineral Dust ◽  
Pm10 Concentration ◽  
Saharan Dust ◽  
Anthropogenic Sources ◽  
Dust Particles ◽  
Annual Number ◽  
Human Respiratory Tract ◽  
Dust Transport

Abstract. The desert of Sahara is one of the major sources of mineral dust on Earth, producing around 2×108 tons/yr. Under certain weather conditions, dust particles from Saharan desert get transported over the Mediterranean Sea and most of Europe. The limiting values set by the directive EC/30/1999 of European Union can easily be exceeded by the transport of desert dust particles in the south European Region and especially in urban areas, where there is also significant contribution from anthropogenic sources. In this study, the effects of dust transport on air quality in several Greek urban areas are quantified. PM10 concentration values from stationary monitoring stations are compared to dust concentrations for the 4-year period 2003–2006. The dust concentration values in the Greek areas were estimated by the SKIRON modelling system coupled with embedded algorithms describing the dust cycle. The mean annual dust contribution to daily-averaged PM10 concentration values was found to be around or even greater than 10% in the urban areas throughout the years examined. Natural dust transport may contribute by more than 20% to the annual number of exceedances – PM10 values greater than EU limits – depending on the specific monitoring location. In a second stage of the study, the inhaled lung dose received by the residents in various Greek locations is calculated. The particle deposition efficiency of mineral dust at the different parts of the human respiratory tract is determined by applying a lung dosimetry numerical model, which incorporates inhalation dynamics and aerosol physical processes. The inhalation dose from mineral dust particles was greater in the upper respiratory system (extrathoracic region) and less significant in the lungs, especially in the sensitive alveolar region. However, in cases of dust episodes, the amounts of mineral dust deposited along the human lung are comparable to those received during exposure in heavily polluted urban or smoking areas.

scholarly journals Simulation of Heterogeneous Photooxidation of SO<sub>2</sub> and NO<sub>x</sub> in the presence of Gobi Desert Dust Particles under Ambient Sunlight

2018 ◽  
Author(s):  
Zechen Yu ◽  
Myoseon Jang
Keyword(s):  
Urban Areas ◽  
Mineral Dust ◽  
Kinetic Mechanism ◽  
Buffering Capacity ◽  
Dust Particles ◽  
Gobi Desert ◽  
Heterogeneous Chemistry ◽  
Desert Dust ◽  
Photodegradation Rate ◽  
Nitrate Salts

Abstract. To improve the simulation of the heterogeneous oxidation of SO2 and NOx in the presence of authentic mineral dust particles under ambient environmental conditions, the explicit kinetic mechanism was constructed in Atmospheric Mineral Aerosol Reaction (AMAR) model. The formation of sulfate and nitrate was divided into three phases: gas phase, non-dust aqueous phase and dust phase. Specially, AMAR established the mechanistic role of dust chemical characteristics (e.g., photoactivation, hygroscopicity, and buffering capacity) on heterogeneous chemistry. The photo-activation kinetic process of different dust particles was built into the model by measuring the photodegradation rate constant of an impregnated surrogate (malachite green dye) on a dust filter sample (e.g., Arizona Test dust (ATD) and Gobi Desert dust (GDD)) using an online reflective UV-visible spectrometer. The photoactivation parameters were integrated with the heterogeneous chemistry to predict OH radical formation on dust surfaces. A mathematical equation for the hygroscopicity of dust particles was also included in the AMAR model to process the multiphase partitioning of tracers and in-particle chemistry. The buffering capacity of dust, which is related to the neutralization of dust alkaline carbonates with inorganic acids, was included in the model to dynamically predict the hygroscopicity of aged dust. The AMAR model simulated the formation of sulfate and nitrate using experimental data obtained in the presence of authentic mineral dust under ambient sunlight using a large outdoor smog chamber (UF-APHOR). Overall, both GDD and ATD significantly enhanced the formation of sulfate and nitrate, compared to that in the system without dust particles. However, the influence of GDD on the heterogeneous chemistry was much greater than that of ATD. Based on the model analysis, GDD enhanced the sulfate formation mainly via its high photoactivation capability. In the case of NO2 oxidation, dust-phase nitrate formation is mainly regulated by the buffering capacity of dust. The measured buffering capacity of GDD was two times greater than that of ATD, and consequently, the maximum nitrate concentration with GDD was nearly two times higher than that with ATD. The model also highlights that in urban areas with high NOx concentrations, hygroscopic nitrate salts quickly form via titration of the carbonates in the dust phase, but in the presence of SO2, the nitrate salts are gradually depleted by sulfate.

scholarly journals Watershed of a small river as source of contaminants and biogenic elements

2021 ◽  
Vol 265 ◽  
pp. 05002
Author(s):  
Stepan Klubov ◽  
Iuliia Rozhkova ◽  
Victor Tretyakov ◽  
Vasiliy Dmitriev
Keyword(s):  
Data Processing ◽  
Urban Areas ◽  
Field Studies ◽  
Green Spaces ◽  
Biogenic Elements ◽  
Gis Technologies ◽  
Watershed Analysis ◽  
Monitoring Data Processing ◽  
Agricultural Areas ◽  
High Degree

There is considered methodology of estimation of contaminants and biogenic elements intake into water objects from urban watersheds by municipal non-point runoff. We used the Volkovka River in St. Petersburg and its watershed for the research because the watershed is characterized by high degree of variety and includes all possible types of urban areas: multi-storey residential constructions, industrial areas, green spaces, cemeteries, wastelands, and even agricultural areas. The research included the monitoring data processing, the watershed analysis by GIS-technologies, and field studies.

scholarly journals Mineral dust indirect effects and cloud radiative feedbacks of a simulated idealized nocturnal squall line

2013 ◽  
Vol 13 (8) ◽  
pp. 4467-4485 ◽  
Author(s):  
R. B. Seigel ◽  
S. C. van den Heever ◽  
S. M. Saleeby
Keyword(s):  
Indirect Effects ◽  
Mineral Dust ◽  
Synergistic Effects ◽  
Atmospheric Modeling ◽  
Dust Particles ◽  
Squall Line ◽  
Cold Pool ◽  
Freezing Level ◽  
Warm Rain Process ◽  
The Individual

Abstract. Mineral dust is arguably the most abundant aerosol species in the world and as such potentially plays a large role in aerosol indirect effects (AIEs). This study assesses and isolates the individual responses in a squall line that arise (1) from radiation, (2) from dust altering the microphysics, as well as (3) from the synergistic effects between (1) and (2). To accomplish these tasks, we use the Regional Atmospheric Modeling System (RAMS) set up as a cloud-resolving model (CRM). The CRM contains aerosol and microphysical schemes that allow mineral dust particles to nucleate as cloud drops and ice crystals, replenish upon evaporation and sublimation, be tracked throughout hydrometeor transition, and be scavenged by precipitation and dry sedimentation. Factor separation is used on four simulations of the squall line in order to isolate the individual roles of radiation (RADIATION), microphysically active dust (DUST MICRO), and the nonlinear interactions of those factors (SYNERGY). Results indicate that RADIATION acts to increase precipitation, intensify the cold pool, and enhance the mesoscale organization of the squall line due to changes in microphysics originating from cloud top cooling. Conversely, DUST MICRO decreases precipitation, weakens the cold pool, and weakens the mesoscale organization of the squall line due to an enhancement of the warm rain process. SYNERGY shows little impact on the squall line, except near the freezing level, where an increase in mesoscale organization takes place. The combined effect of the mineral dust AIE due to both DUST MICRO and SYNERGY is to weaken the squall line.

Semiology of the Pain Syndrome - Identifying the Ideal Methods of Locoregional Anesthesia Based on Their Rationale and Features

2017 ◽  
Vol 68 (10) ◽  
pp. 2373-2377
Author(s):  
Mihaela Monica Scutariu ◽  
Vlad Danila ◽  
Corina Ciupilan ◽  
Oana Elena Ciurcanu
Keyword(s):  
Maxillofacial Surgery ◽  
Essential Element ◽  
Pain Syndrome ◽  
Oral And Maxillofacial Surgery ◽  
Structuring Element ◽  
Technical Accuracy ◽  
Locoregional Anesthesia ◽  
Special Approach ◽  
The Individual ◽  
High Degree

Anesthesia and the degree of control over the perception of pain depends on the personality of the individual, the socio-economic conditions, potential previous painful experiences and, last but not least, on fatigue and fear of the dentist. The perception of pain in patients is closely connected to their mental state. Pain is defined as a sensation of discomfort, with wide variations, both in quality and intensity, for different people in seemingly identical conditions; an unpleasant sensitive and emotional phenomena connected to the threat of a wound or caused in the tissues or described in the terms of this disease. The essential element of any type of anesthesia is analgesia, an effect which in some cases cannot be achived, due to the patient�s particularities or the physician�s lack of experience in anesthesia. Locoregional anesthesia (LRA) represents the blocking of the nociceptive sensitive and sympathetic autonomic afferents as well as that of motor efferents at the level of peripheral nerves� axons, by means of local anesthetic. To achieve the set purpose, we carried out a study on a representative human sample comprised of 10.123 patients treated in the Oral and Maxillofacial Surgery Clinic (Ambulatory) from the County Clinic Emergency Hospital St. Spiridon Iasi, between 01.01.2015-31.12.2016. The reason for the exclusion of certain categories of patients in the reseach was: the patients with a special conditions background require individual pre-anesthesia schemes, personalised for the nature of the pre-existing general condition, which must be further approved by the attending specialist physician : cardiologist, internist, diabetologist; children under 18 years old, with a high degree of anxiety; a high precentage of elderly patients, over 60 years old, possess a combination of general issues, thus requiring a special approach. The thoroughness lying at the core of the anesthetic practice, most especially the safegurading of a technical accuracy in the performance of anesthesia [12,], instead of improvisations, the lack of anatomical and stomatological training in general and the resulting inefficiency as such, is the underlying in-depth structuring element of this paper.

PHYTOMONITORING AS A METOD OF THE ASSESSMENT OF ATMOSPHERIC AIR POLLUTION BY URBAN ENVIRONMENT BY FINE DUST

2019 ◽  
pp. 42-53
Author(s):  
Irina Glinyanova ◽  
Valery Azarov ◽  
Valery Fomichev
Keyword(s):  
Urban Environment ◽  
Urban Areas ◽  
Fine Particles ◽  
Prunus Armeniaca ◽  
Dust Particles ◽  
Fine Dust ◽  
Control Zone ◽  
Atmospheric Air ◽  
Random Functions ◽  
The City

Fine dust: (PM2.5, PM10) is a priority pollutant that contributes to the development of numerous dis-eases in urban areas. The purpose of this scientific work is to study the dispersed composition of dust parti-cles on the leaves of apricot trees (Prúnus armeníaca) in the residential zone of Volgograd. The novelty of the work lies in the study of the dispersed composition of dust particles on the leaves of apricot trees (Prúnus armeníaca) in the residential zone in the city of Volgograd near the construction industry enterprise, me-chanical engineering, leather production and railway transport line in comparison with the conditionally clean (control) zone of the SNT “Orocenets” ”(Sovetsky District, Volgograd) from the standpoint of random functions expressed by integral distribution curves of the mass of particles over their equivalent diameters. As a result of the research, the dispersed composition of dust on the leaves of apricot trees (Prúnus ar-meníaca) in the residential area of Volgograd was revealed. Fine particles were found: PM2.5, PM10 in each of the studied points, which by their values, both in their number and mass fraction, significantly exceed the data on fine dust in a conditionally clean area (control) in the SNT “Oroshanets” (Sovetsky district Volgo-grad), which creates certain environmental risks for local residents. The dispersed analysis of particles from the standpoint of random functions in the future will allow with a sufficiently high degree of accuracy to pre-dict the dust content of urban atmospheric air in the range of monthly and / or seasonal average values compared to the traditional measurement of fine dust concentration in atmospheric air of the urban environ-ment as the maximum single or daily average. At the same time, further studies of dust on the leaves of plants in an urban environment, namely, the study of the density of its sedimentation, will also reveal a group of ur-ban plants that are best suited to retain PM2.5 and PM10 on leaf plates in this region, which can significantly increase the quality of the atmospheric air of the urban environment and be of a recommendatory nature for the state-owned landscaping services of the city of Volgograd when improving the green areas of a megacity.

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