Resuspension Of Dust Particles Research Articles

Using a Gaussian model to estimate the level of particle matter concentration on paved and unpaved roads in urban environment: A case study

Introduction: In both developed and developing countries, re-suspension of dust particles along the road owing to tire and brake wear is the most common source of Particulate Matters (PM) pollution in metropolitan areas. This study in Douala analyses the effects of paved and unpaved roads on particle matters concentration thresholds in urban environments.
 Materials and methods: The United States Environmental Protection Agency (US EPA)'s model AP-42 equations were used to calculate the amount of particle matter emissions on the roads. Between 6 am and 8 pm, a traffic analysis using information from the city of Douala was conducted. The busiest times for traffic were from 8 to 9 a.m. and 6 to 7 p.m. We applied a two-dimensional Gaussian model to determine the particle concentration. Two different scenarios were taken into account: Compared to Scenario 2 (S2), Scenario 1 (S1) represents an unpaved road. The PM10 and PM2.5 types of particles were the main topics of interest.
 Results: We obtained for S , around 917.70 µg/m3 and 559.00 µg/m3 respectively for PM and PM . We got roughly 170.00 µg/m3 and 103.90 10 2.5 µg/m3 for S , respectively for the two particles. The amount of silt deposited on the road, the kind of road (paved or unpaved), the number, and the types of vehicles moving all influence the emission of road dust re-suspension. Regardless of particle size, these pollution levels are beyond World Health Organization (WHO) recommended norms.
 Conclusion: This study offers important information on Douala's pollution levels, which can be a significant cause of disease in the area and should be considered.

Case Study of the Evidence of PM1& PM2.5 Contribution on PM10 from Podul De Piatra– Iasi City

Abstract The importance of air quality monitoring has been strongly demonstrated in numerous scientific studies. This study, carried out in an intense circular intersection, brings additional arguments that the monitoring of the fine particles like PM1 and PM2.5 that influence in more than 80% the concentration of PM10 particles must be measured at several points. Few were the cases [approx. 20%] in which the increase of PM10 concentrations is given by particles with diameters from 2.5 to 10 μm, most likely caused by the re-suspension of dust particles. Grimm Aerosol Technik Germany and SC INOESY SRL conducted a campaign for monitoring the air quality [PM1, PM2.5, PM10] in Iasi, Stone Bridge area, from 8 to 22 February 2018. The monitoring point was located close (150 m) to the APMIS-01 station of the National Environmental Protection Agency.

Analysis and Sources Identification of Atmospheric PM10 and Its Cation and Anion Contents in Makkah, Saudi Arabia

In this paper, atmospheric water-soluble cation and anion contents of PM10 are analysed in Makkah, Saudi Arabia. PM10 samples were collected at five sites for a whole year. PM10 concentrations (µg/m3) ranged from 82.11 to 739.61 at Aziziyah, 65.37 to 421.71 at Sanaiyah, 25.20 to 466.60 at Misfalah, 52.56 to 507.23 at Abdeyah, and 40.91 to 471.99 at Askan. Both daily and annual averaged PM10 concentrations exceeded WHO and Saudi Arabia national air quality limits. Daily averaged PM10 concentration exceeded the national air quality limits of 340 µg/m3, 32% of the time at Aziziyah, 8% of the time at Sanaiyah, and 6% of the time at the other three sites. On average, the cations and anions made a 37.81% contribution to the PM10 concentrations. SO42−, NO3−, Ca2+, Na+, and Cl− contributed 50.25%, 16.43%, 12.11%, 11.12%, and 8.70% to the total ion concentrations, respectively. The minor ions (F−, Br−, Mg2+, NO2−, and PO43−) contributed just over 1% to the ion mass. Four principal components explained 89% variations in PM10 concentrations. Four major emission sources were identified: (a) Road traffic, including emission from the exhaust, wear-and-tear, and the resuspension of dust particles (F−, SO42−, NO3−, Ca2+, Na+, Mg+, Br−, Cl−, NO2−, PO43−); (b) Mineral dust (Cl−, F−, Na+, Ca2+, Mg2+, PO43−); (c) Industries and construction–demolition work (F−, SO42−, Ca2+, Mg2+); and (d) Seaspray and marine aerosols (Cl−, Br−, Mg2+, Na+). Future work would include an analysis of the metal contents of PM10 and their spatiotemporal variability in Makkah.

Ejection of Dust From the Ocean as a Potential Source of Marine Ice Nucleating Particles

AbstractOceans are, generally, relatively weak sources of ice nucleating particles (INPs). Thus, dust transported from terrestrial regions can dominate atmospheric INP concentrations even in remote marine regions. Studies of ocean‐emitted INPs have focused upon sea spray aerosols containing biogenic species. Even though large concentrations of dust are transported over marine regions, resuspended dust has never been explicitly considered as another possible source of ocean‐emitted INPs. Current models assume that deposited dust is not re‐emitted from surface waters. Our laboratory studies of aerosol particles produced from coastal seawater and synthetic seawater doped with dust show that dust can indeed be ejected from water during bubble bursting. INP concentration measurements show these ejected dust particles retain ice nucleating activity. Doping synthetic seawater to simulate a strong dust deposition event produced INPs active at temperatures colder than −13°C and INP concentrations 1 to 2 orders of magnitude greater than either lab sea spray or marine boundary layer measurements. The relevance of these laboratory findings is highlighted by single‐particle composition measurements along the Californian coast where at least 9% of dust particles were mixed with sea salt. Additionally, global modeling studies show that resuspension of dust from the ocean could exert the most impact over the Southern Ocean, where ocean‐emitted INPs are thought to dominate atmospheric INP populations. More work characterizing the factors governing the resuspension of dust particles is required to understand the potential impact upon clouds.

Study of particle resuspension from dusty surfaces using a centrifugal method.

Particle resuspension has been recognized as a secondary source of indoor air pollution by many field studies. However, some laboratory studies showed that the air velocities or force fields required to resuspend aerosol particles are very high that rarely occurred in indoor environments. In fact, the surfaces used in these studies were treated to ensure cleanliness, but in reality, dusty surfaces are ubiquitous in our daily life. This work aims to investigate the effect of dust on a surface on resuspension of a coarse particle (polyethylene) by a centrifugal method. Dusty surfaces with different loadings were made by gravitational settling of Arizona test dust on a clean poly(methyl methacrylate) substrate inside a deposition chamber. The resuspension of dust particles was first investigated, and it was found that dust particles were resuspended by two stages with different rates of resuspension. For the resuspension of the particles on the dusty surface, the remaining fraction of the polyethylene particles decreased with increasing force field and dust loading. Dust could greatly reduce the adhesion of the particles from one to two orders of magnitude depending on loadings. This gives an explanation to the discrepancy between the field and the laboratory studies.

Assessment of Air Pollution by PM10 and PM2.5 in Nawabshah City, Sindh, Pakistan

Increased traffic density due to urbanization is a major cause of air quality deterioration. Atmospheric particulate matter (PM) constitutes one of the most challenging issues in environmental research. This study was designed to assess PM10 and PM2.5 pollution at ten main locations in Nawabshah. Analysis of PM10 and PM2.5 pollution was carried randomly at different selected locations of the city. The highest concentration of PM10 was found at Mohini bazar (MB) and the highest concentration for PM2.5 was found at New Naka (NN). The mean concentration of PM10 was 78.3% higher than world health organization (WHO) standards and 35% than Pakistan’s National Environmental Quality Standards (NEQS). The mean concentration of PM2.5 was 47.3% and 26.3% higher respectively. Mean concentrations of PM2.5 on day-2 and day-10 were found lower than those set by NEQS, while mean concentrations of PM10 on all days exceeded the WHO and NEQS standards indicating that the city was heavily polluted more with PM10 than with PM2.5. Re-suspension of dust particles due to traffic flow, open burning of unmanaged solid waste on the sides of the road and in the street, and improper handling of construction and demolition waste were identified as the main sources for PM pollution in the city. Exposure to higher levels of PM10 and PM2.5 can cause health problems. High levels of PM10 and PM2.5 are a call for the implementation of strict measures to control PM pollution at Nawabshah in order to protect public health and the environment.

Heavy metals in road deposited sediments and road dusts of Colombo Capital, Sri Lanka

Road deposited sediment (RDS) and road dust analyses are useful techniques to understand the heavy metal (HM) pollution in an urban area. Therefore, this study focused on the chemical characteristics of RDS and road dust in order to evaluate the pollution conditions in the Colombo Metropolitan Region (CMR) in terms of HMs. Forty six (46) RDS samples and forty eight (48) road dust samples were collected, and elemental concentrations of Zn, Cu, Pb, Fe, Mn and Cr were determined. Out of these measured elements, the most abundant element in all the samples was Fe, which is a common element in the basement lateritic soil in the area. Cu, Pb, Fe and Cr concentrations in RDS are high in industrial areas, while Zn and Mn are high in commercial areas. Except Fe, all the other element levels were higher in road dust than in RDS. Data analysis revealed that vehicle-related activities are the dominant source for the metals in the city. Zn, Cu, Mn and Fe contents were significantly higher than the background levels of the area. Statistical analysis reconfirms that road dust is more polluted than RDS in terms of Zn and Cu. According to the geoaccumulation index, road dust is moderate to strongly polluted and RDS are moderately polluted. Higher pollution conditions of road dust may be due to the resuspension of dust particles. Spatial distribution patterns show that HMs of anthropogenic origin were accumulated towards the North and Northwestern parts where the transportation related activities are centered in the CMR. However, the prevailing natural conditions such as wind direction, geomorphology and basement soil also control the level of contamination in the area.

Kinetic-Monte-Carlo-Based Parallel Evolution Simulation Algorithm of Dust Particles

The evolution simulation of dust particles provides an important way to analyze the impact of dust on the environment. KMC-based parallel algorithm is proposed to simulate the evolution of dust particles. In the parallel evolution simulation algorithm of dust particles, data distribution way and communication optimizing strategy are raised to balance the load of every process and reduce the communication expense among processes. The experimental results show that the simulation of diffusion, sediment, and resuspension of dust particles in virtual campus is realized and the simulation time is shortened by parallel algorithm, which makes up for the shortage of serial computing and makes the simulation of large-scale virtual environment possible.

Wind tunnel study and numerical simulation of dust particle resuspension from indoor surfaces in turbulent flows

Particle resuspension from flooring is an important source of air pollution in the indoor environment. In this work, resuspension of monolayer, polydisperse, irregularly shaped dust particles from various types of floorings was studied via a series of wind tunnel experiments. The range of free-stream velocity needed for resuspension of dust particles was evaluated as a function of particle size and material of particles and surfaces. In addition, a Monte Carlo simulation for predicting the resuspension of dust particles was developed. The resuspension model took into account the effects of particle irregularity, particle surface roughness, and flow characteristics. The dust particle resuspension from different floorings for several particle sizes was evaluated. The model predictions for resuspension fractions were compared with the experimental data and good agreement was observed. The study provided information on the role of airflow velocity on irregular dust particle resuspension from common floorings.

Air Quality Study in Urban Centers: Case Study of Ouagadougou, Burkina Faso

In this work, a study on air quality in the city of Ouagadougou (Burkina Faso) was carried out. The concentration levels of NO2, SO2, BTEX and PM10 in the city have been quantified. The results show that NO2 concentrations (range from 22 to 27 μg m-3 on average) in the city remain below the limit set by the WHO standard, except for downtown where values often exceed this standard. The average concentrations of SO2 (range from 0.5 to 10.5 μg m-3) remain low in general throughout the city. The concentrations of BTEX (e.g. benzene: 27.9 μg m-3) are high in the city. PM10 concentrations are very high in the city in general; they exceed the limit set by the WHO standard by a factor of 3 to 4. These PM10 are mostly composed of dust from the desert and the re-suspension of dust particles related to vehicles traffic on unpaved roads. Two daily peaks for PM10 are observed at heavy traffic hours. Finally, the study showed that the values of PM10 concentrations observed are in the same order of magnitude of those generally observed in the Sahelian region (range from 119 to 227μg m-3).

Black carbon aerosols variation in Kathmandu valley, Nepal

Black carbon (BC) aerosols were measured using an aethalometer (AE-31) at Pulchowk Campus, an urban location of Kathmandu valley, Nepal from May 2009 to April 2010. The amount of BC in the total mass of the suspended particulate matter (TSP) were estimated by comparing the average BC with mass of particulate matter simultaneously measured with frm Omni Ambient Air Sampler for the last two months (March–April, 2010). BC concentration shows significant temporal variation with monthly mean concentration varying between 14.9 μg m−3 and 3.0 μg m−3. The highest daily mean concentration was recorded as high as 39.9 μg m−3. The highest concentration of BC occurred during winter and pre-monsoon seasons. The lowest concentration of BC was found during monsoon and post-monsoon seasons. A distinct diurnal variation of BC with two high peaks occurred; one in around 09:00 morning and another late evening around 20:00 local time. Minimum BC concentration was also observed in the afternoon. The annual average of BC for observation period was 8.6 ± 4.4 μg m−3. The seasonal, monthly and diurnal variation of BC were found to be significantly influenced by the local traffic movements, the domestic and industrial fuel consuming activities, wind speed, wind direction and rain. The amount of BC in the total mass of particulate matters during the observed period varied between 11.6 and 56.2 percent. This variation is attributed to the high amount of re-suspension of dust particles in the atmosphere of the valley.

Resuspension of Dust Particles in a Chamber and Associated Environmental Factors

Experiments investigating particle resuspension from human activities were conducted in a full-scale experimental chamber. The experiments tested three types of flooring (vinyl tiles, new and old level-loop carpets) and two ventilation configurations (ceiling and side wall supply systems). The floorings were seeded with 0.1–10 μ m test particles. The airborne particle concentration was measured by an array of optical particle counters (OPCs) in the chamber. Resuspension rates were estimated in size ranges of 0.8–1, 1.0–2.0, 2.0–5.0, and 5.0–10 μm ranging from 10−5–10−2 hr−1, with higher resuspension rates associated with larger particles. Resuspension via walking activity varied from experiment to experiment. “Heavy and fast” walking was associated with higher resuspension rates than less active walking, most likely due to a combination of increased pace, increased air swirl velocity, and electrostatic field effects established by the walking. The type of floorings also influenced the particle resuspensio...

Size distribution of aerosols (PM10) and lead (Pb) near traffic intersections in Mumbai (India).

The size distribution of aerosols was measured near traffic intersections of Marol link road in air quality control region (AQCR1), which is a moderately industrial area and Dadar Khodad circle in AQCR2, which is a heavily commercial core of the Mumbai City. The reason behind selecting the two unidentical regions was to study the contribution from vehicles to the size separated PM10 and that of Pb. It is recognised that particulates in urban air are responsible for serious health effects. As very small particles are assumed to be important for the adverse health effects, the particle size distribution is thus an important factor that needs to be addressed whenever the particulates pollution is concerned. The size measurements were done with a cascade impactor of eight stages with a back-up filter. It effectively separates the particulate matter into nine-sizes ranging from 0.0-0.4 to 9.0-10.0 microm. Samples were analysed in nine-particle size fractions with special reference to a toxic metal - lead (Pb) by atomic absorption spectrophotometry (AAS). It was found that PM10 and Pb at both the intersections could easily be classified by the size distribution. The fractions of the PM10 and that of Pb showing a tendency of trimodal distributions with the first peak at coarse mode approximately 9.0-10.0 microm, second at approximately 5.8 microm and the third at coarse mode approximately1.1 microm. The significant percentage of Pb was found in the range below 2.5 microm at both the intersections. However, Pb in AQCR1 is found in the coarser range as well, which could probably be the influence of various industrial activities in the area. PM10 concentration values in the coarser range in AQCR2 are associated with the resuspension of dust particles and mechanical erosions.

Dust resuspension by the flow around an impacting sphere

A rigid body colliding with a layer of dust is capable of resuspending dust through two distinct mechanisms: a ballistic mechanism, where kinetic energy is transferred from the impacting body to dust particles through direct contact, and a hydrodynamic mechanism, where dust particles are resuspended by the flow disturbance generated by the body. In this paper, we study the hydrodynamic resuspension mechanism by considering the flow around a sphere moving either towards or away from a wall. Experiments were performed using a sphere translating at a constant velocity for Reynolds number, Re, in the range 300 to 3500, and at varying angles of approach and departure from a wall. A wider range of Re was investigated by releasing dense rigid spheres above the wall. The high Reynolds number flow past a steadily translating sphere is characterized by a recirculating wake region behind the sphere. When the sphere approaches the wall and stops on making contact with it, the wake vortex which is initially behind the sphere threads over the sphere's surface, generating a secondary vortex ring. The coherent structure, composed of the wake and secondary vortices, strikes the wall and pushes fluid or dust, initially adjacent to the wall, to one side. The resuspension of dust particles of diameter b which are initially at rest on the wall is governed by a particle Shields' parameter, θp, based on the sphere's impact velocity, U: θp = ρfU2/ (ρp−ρf)bg, where ρp and ρf are respectively the density of the dust particles and fluid. The resuspension criterion is a function of particle Reynolds number, Rep, based on the diameter and fall velocity of the dust particles and occurs when θp [ges ] θp,c where θp,c ≈ 3.0 for Rep [gsim ] 1, and θp,c ≈ 5.0/Re1/2p for Rep [lsim ] 1. The geometry of the region of dust resuspended by the sphere was studied as a function of the impact velocity, angle of impact and the properties of the dust particles. When the sphere impacts a thick layer of dust, the volume concentration of resuspended dust is sufficiently high to generate a particle-driven gravity current which transports the dust far from the point of impact. The dynamics of the gravity current were determined as a function of dust particle properties and size of the impacting sphere.A sphere moving impulsively from rest away from a wall is found not to play a significant role in the resuspension of dust; however trailing vorticity generated on the surface of the sphere advects a large volume of fluid away from the wall, which may contain dust already in suspension.