Total Suspended Particulate Concentrations Research Articles

Spatiotemporal Variations of Particulate and Gaseous Pollutants and Their Relations to Meteorological Parameters: The Case of Xiangyang, China.

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.

Vertical Distribution of Particulates within the Near-Surface Layer of Dry Bulk Port and Influence Mechanism: A Case Study in China

Knowing the vertical distribution of ambient particulate matter (PM) will help port authorities choose the optimal dust-suppression measures to reduce PM concentrations. In this study, we used an unmanned aerial vehicle (UAV) to assess the vertical distribution (0–120 m altitude) of PM in a dry bulk port along the Yangtze River, China. Total suspended particulates (TSP), PM10, and PM2.5 concentrations at different altitudes were measured at seven sites representing different cargo-handling sites and a background site. Variations in results across sites make it not suitable to characterize the vertical distribution of PM concentration at this port using simple representative distributions. Bulk cargo particle size, fog cannon use, and porous fence all affected the vertical distribution of TSP concentrations but had only minor impacts on PM10 and PM2.5 concentrations. Optimizing porous fence layout according to weather conditions and cargo demand at port have the most potential for mitigating PM pollution related to port operation. As ground-based stations cannot fully measure vertical PM distributions, our methods and results represent an advance in assessing the impact of port activities on air quality and can be used to determine optimal dust-suppression measures for dry bulk ports.

Spatial and temporal variability in concentration and characteristics of aerosols at Visakhapatnam (east) and Goa (west) coasts of India.

Knowledge on the variability in quantity and compositions of various size groups of aerosols is important to understand their sources and their role in biogeochemical and climate processes. Here, we studied total suspended particles (TSP), PM10 and PM2.5 for their quantitative and water soluble compositional (F-, Cl-, SO42-, NO3-, NH4+, Na+, K+, Ca2+, and Mg2+) distributions, and to understand their nature and potential sources at Goa and Visakhapatnam on the west and east coasts, respectively, of India. While the mean concentrations of TSP were found to be 117 ± 44 and 85 ± 51 μg/m3 its maximal levels occurred in spring intermonsoon (SIM; 141 ± 52) and winter monsoon (WM; 155 ± 145 μg/m3) seasons at Goa and Visakhapatnam, respectively. PM10 and PM2.5 exhibited higher ranges at Visakhapatnam than Goa. The increase in PM2.5 abundance from WM to SIM at Visakhapatnam seems to occur in coincidence with decrease in TSP favored by topography and ambient meteorological conditions. Locally released and seasonally transported (from land and sea) constituents contributed to the observed variability in aerosol compositions. Sulphate dominated the aerosol composition at both Goa (57-64%) and Visakhapatnam (43-55%) followed by NO3- (5-16% and 6-18%, respectively) where the former component was higher in PM10 and PM2.5. The NO3- was more in TSP. Relations between SO42- and NH4+ suggested possible presence of NH4HSO4. Examination of ionic ratios and balance suggested near neutrality in PM10 and PM2.5 while TSP was acidic at the both locations. Notable relations between Ca2+ and NO3-, particularly in PM10 at Goa, indicated their release from mining related activities.

Characterising the levels and sources of the historical metal contamination in the atmosphere of Montreal (Canada) from 1973 to 2013 by coupling chemistry and Lead and Osmium isotope ratios

Abstract Since 1969 the city of Montreal monitors the air quality on its island through a network of sampling stations. Some of these stations collect aerosols, including total suspended particles (TSP), at various locations, representative of specific environments: downtown, harbour, road traffic… Between 1973 and 2013 the implementation of mitigation measures by the government resulted in successive decreases in the TSP concentrations. Here, the study of the Pb atmospheric concentrations suggests three distinct periods: 1) 1973, with expected high atmospheric Pb concentrations, 2) between 1978 and 1988, a period corresponding to the phasing out of lead in gasoline in Canada (officially from 1974 to 1990), where Pb concentrations decreased at an approximate rate of 0.05 μg/m3/year, and 3) 1993 to 2013, a period during which atmospheric Pb concentrations still decreased but at a slower rate. The Pb and Os stable isotope analysis allows us to identify the major sources of metal contamination during these periods as well as to characterise the evolution of their respective contributions. The combustion of leaded gasoline mainly explains the Pb isotope ratios of the first period, followed by contributions corresponding to emissions from the US industries between 1988 and 2002. After 2002, Pb isotopes identify a higher contribution from local Pb emitters. In contrast, Os atmospheric concentrations remained low over the same period, although Os isotopes suggest an anthropogenic contribution from automobile catalytic converters and/or waste industries for the highest concentrations.

The effect of atmospheric particulates on the rainwater chemistry in the Yangtze River Delta, China

ABSTRACTTo investigate the effect of atmospheric particulates on the chemistry and acidity of rainwater during the washout process in areas with highly acidic rainfall, rainwater and particulates (before, during and after rain) were sampled and analyzed from June 2008 to June 2009 in the Yangtze River Delta region, China. The volume-weighted mean pH of the rainwater was only 4.44 in Hangzhou, and the average concentrations of TSP (total-suspended particulates) and PM10 (particulates with aerodynamic equivalent diameters of less than 10 μm) during the study period were 191 μg/m3 and 155 μg/m3, respectively. The measured acid buffering capacities of PM10 and TSP were 1.31 ± 0.45 and 1.61 ± 0.84 ml/mg, on average, respectively, indicating that both had a certain acid buffering capacity. Rain appeared to have a pronounced scouring effect on particulates, except for F− and Cl− in PM10. Upon combining the correlation analysis between ions in particulates and rainwater with Enrichment Factor and Principal Component Analysis of the rainwater chemistry, the results suggested that the components of rainwater were mainly derived from washout processes acting on particulates from crustal dust and building industry sources (Ca2+), marine sources (Na+, K+ (in spring), Mg2+ and Cl−) and anthropogenic sources, especially secondary aerosols emitted from agricultural land, motor vehicles and industrial plants (NO3−, SO42-, and NH4+). The F− in rainwater was mainly contributed by gaseous pollutants, such as HF from cooling systems, coal burning and surrounding factories.Implications: The interaction between particulates and rain in areas with highly acidic rainfall include the following: rain appears to have a pronounced scouring effect on most components in the particulates; the components of the rainwater are mainly derived from washout processes acting on PM contributed by crustal dust, sea salt and secondary aerosol subcloud; and the acid buffering capacities of PM10 and TSP in Hangzhou are 1.31 ± 0.45 and 1.61 ± 0.84 ml/mg, respectively, and had a certain acid buffering capacity toward rainwater.

Assessment of Factors Contributing to Indoor Air Pollutants Exposure and Prevalence of Respiratory Health Problems in Seka Town

Objective : The main objective this study is to assess factors contributing to combustion and non-combustion related indoor air pollutants exposure and related prevalence of respiratory health problem among women and young children in Seka town. Methods: The study used a household-based cross-sectional study design from May 1-30, 2017. A systematic random sampling technique was used to select the 341 households included in the survey. The survey instrument was specific structured questionnaire that was adapted from WHO guidelines for survey of household fuel use indoor spray and acute respiratory infections. Concentration of total suspended particles(TSP) was measured in small subset of 34(10%) sampled households during the cooking and non-cooking hours using SKC 52 model air sampling pump .The survey data was analyzed by using a software package SPSS version 20.Logistic regression analysis was used to determine the association of household fuel using characteristics to ARI and descriptive statistics such as frequency distributions and measure of central tendencies were used to describe concentrations of total suspended particulates. Results: The finding from the survey analysis shows that 332 (97.4%) of mothers were exposed to indoor air pollution during cooking. Majority of the respondents 271 (79.5%) had poor ventilation and 149 (43.7%) were reported that they used indoor spray unsafely. However, 67.2% of them reported as they do not know how to apply indoor spray. As a result 66% of the respondents did not close food items during the spray and 73.3% of them close windows and doors during spray. The study found an indoor total suspended particulate matter (TSP) concentration7881.6 µg/m 3 during cooking. This was about 1.4 times when compared to non-cooking time. The study found statistically strong significant association with mother’s education status 1.58 times more to develop respiratory health problems and also small kitchen size, kitchen ventilation, have strong significances 1.57 and 1.62 times respectively the occurrence of respiratory health problems. The Type of fuel for cooking, Time of spent on cooking and mothers’ level of knowledge on effect of indoor air pollution also strong significances 1.71,1.80 and 2.0 times respectively association with respiratory health problems development. Conclusion : Housing and kitchen characteristics, type of fuels and stoves are the main factors contributing to increased indoor air pollutant concentration and to increased prevalence of respiratory health problems. Keywords : Household biomass fuel; Indoor spray; Indoor air Pollution; Respiratory health problems; AFI; factors contributing; exposures; Seka DOI : 10.7176/JMPB/61-03 Publication date: November 30 th 2019

Relationship of Asian Dust Events with Atmospheric Endotoxin and Protein Levels in Sasebo and Kyoto, Japan, in Spring.

Asian dust events are caused by dust storms originating from deserts in Mongolia and northern China, and these events are observed in Japan, mainly in spring. To explore the effect of Asian dust events on atmospheric endotoxin and protein levels, we collected the total suspended particles (TSP) in the spring months (March, April, and May) of 2015 in Sasebo and Kyoto, Japan, and assessed the levels of biological elements at both locations. At both locations, the daily concentrations of TSP, water-soluble Ca2+ (an indicator mineral of soil in dust), endotoxins, and proteins were found to be high during and after Asian dust events recorded by the Japan Meteorological Agency. The concentration of Ca2+ showed a strong positive correlation with the concentrations of TSP and endotoxin, while the concentration of protein was moderately positively correlated with Ca2+ in both Sasebo and Kyoto. There were large concentrations of endotoxins, and the fluctuation ranges were higher in Sasebo than in Kyoto. In contrast, protein concentrations showed low levels of fluctuation, and no major differences were found in the concentration at each location.

Determination of phthalate esters in total suspended particulates in Central Taiwan

Phthalate esters (PAEs) are ubiquitous contaminants from plasticizers of polyvinyl chloride and other polymers. The investigation of the PAEs in the environment, especially ambient air particulates, is very important. In this study, the determination of PAEs in total suspended particulates (TSP) by using gas chromatography/mass spectrometry (GC/MS) was evaluated. The results indicated that the concentrations of TSP at Luliao sampling site ranged from 40.23 to 94.9 μg m−3. In addition, Di(2-ethylhexyl) phthalate was the most abundant PAEs accounting for 89.7–98.9% of TSP. Total PAEs concentrations in central Taiwan ranged from 20.89 to 86.50 ng m−3. Moreover, the GC/MS method enabling simple, rapid, sensitive and reliable results was adopted in this study. The method is recommended for the analysis of PAEs in TSP samples from the ambient air.

Variation in the mercury concentration and stable isotope composition of atmospheric total suspended particles in Beijing, China

We investigated the effect of the temporary ban of local industrial activities during the Asia-Pacific Economic Cooperation (APEC) summit (4th–14th Nov 2014) in Beijing, China on total suspended particulate mercury (HgTSP) concentrations and isotope compositions. We measured Hg concentrations and isotope ratios in 33 TSP samples from central Beijing, including 21 samples collected from Jun 2012 to Apr 2014, and 12 samples collected from 14th Oct–19th Nov 2014. Volumetric concentrations of both TSP and HgTSP during the APEC summit were a factor of 2 lower than during the pre-APEC period, indicating substantial reductions in total particulate matter and HgTSP as a result of emissions controls. However, mass-normalized concentrations and mercury isotope ratios of HgTSP did not vary significantly between samples collected before, during, or after the APEC summit. These results show that local emissions are important sources of particle bound mercury (PBM) in Beijing and that their control can be used to immediately lower the volumetric concentration of HgTSP. They also indicate that a similarly complex mixture of sources contributed to PBM in Beijing before and during emissions controls were put in place and that PBM concentrations in Beijing are primarily controlled by emissions and secondarily by photoreduction.

Analysis of Potential Risks Associated with Urban Stormwater Quality for Managed Aquifer Recharge.

Managed aquifer recharge (MAR) can be used to increase storage and availability of groundwater resources, but water resources available for recharge are constrained due to a surface water shortage. Alternative resources, like stormwater, are receiving increasing attention as sustainable resources for reuse in MAR. However, pollutants in stormwater can impact groundwater quality, and cause clogging of the infiltration system. Based on the stormwater data in the literature, the physicochemical stormwater properties of data were analyzed. The results showed that concentrations of pollutants from different underlying surfaces varied widely. The main pollutants of stormwater were as follows: Total suspended particles (TSSs), organic matter represented by the chemical oxygen demand (COD), nutrients (total nitrogen, TN; total phosphorus, TP; and NH3-N), and metals (Zn, Pb, Cu, Cd, Fe, and Mn). Based on the simulation of TOUGHREACT, the contamination risk of pollutants for each type of stormwater was assessed. The risk of contamination was divided into four categories due to the different migration times of ions through the sand column. The iron ion has the highest risk of contamination, followed by Zn and Mn, and the contamination risk of nutrients and other metals (Pb, Cu, and Cd) are relatively low. Besides, the physical, biological, and chemical clogging risk were evaluated. The physical clogging potential of all types of stormwater is very high because of the high concentration of TSS. According to the concentration of TN that can spur the growth of bacteria and algae, the relative risk of biological clogging for stormwater is greenbelt stormwater < road stormwater < roof stormwater. However, only road stormwater has high chemical clogging due to the existence of iron, which can generate precipitation that blocks the pore volume.

Comparative mutagenic activity of atmospheric particulate matter from limeira, stockholm, and kyoto.

Atmospheric particulate matter (PM) organic fractions from urban centers are frequently mutagenic for the Salmonella/microsome assay. This mutagenicity is related to both primary and secondary pollutants, and meteorological conditions have great influence on the secondary pollutant's formation. Our objective was to compare the mutagenicity of atmospheric total suspended particulates (TSP) from three cities with marked different meteorological conditions and TSP concentrations: Limeira (Brazil) with 99.0 μg/m3 , Stockholm (Sweden) with 6.2 μg/m3 , and Kyoto (Japan) with 28.0 μg/m3 . For comparison, we used the same batch of filters, sample extraction method, and Salmonella/microsome testing protocol with 11 strains of Salmonella with and without metabolic activation. Samples were collected during winter and pooled into one single extract representing each city. All samples were mutagenic for all tested strains, except for TA102. Based on the strain's selectivity, nitroarenes, polycyclic aromatic hydrocarbons, and aromatic amines play a predominant role in the mutagenicity of these samples. The mutagenic potencies expressed by mass of extracted organic material (EOM; revertants/μg EOM) were similar (~twofold difference) among the cities, despite differences in meteorological conditions and pollution sources. In contrast, the mutagenic potencies expressed by air volume (rev/m3 ) varied ~20-fold, with Limeira > Kyoto ≈ Stockholm. These results are the first systematic assessment of air mutagenicity from cities on three continents using the same protocols. The results confirm that the mutagenic potency expressed by EOM mass is similar regardless of continent of origin, whereas the mutagenic potency expressed by air volume can vary by orders of magnitude. Environ. Mol. Mutagen. 2019. © 2019 Wiley Periodicals, Inc.

CFD Modeling of Near-Roadway Air Pollution

Currently, there is an increasing interest in modeling the dispersion of atmospheric pollutants using computational fluid dynamics (CFD), to characterize the influence of the traffic-generated emissions on the temporal and spatial variability in air pollutant concentrations in the near-roadway environment. To advance in this task, we modeled the dispersion of total suspended particles (TSP), over a flat terrain, within a neutrally stratified and fully developed atmospheric boundary layer. We included the effect of turbulence and deposition on particle size distribution downstream. We found that TSP concentration downwind exhibits a single profile when expressed in terms of three dimensionless numbers: normalized concentration, normalized distance, and emission speed ratio. Using this generic character of the results, we determined the average short- and long-term TSP concentration, modeling successive short-term intervals in which it could be assumed a pseudo-steady-state behavior. Results exhibited correlation levels of R2 > 0.85 for daily and R2 > 0.94 for monthly averages when compared with measured TSP concentrations downwind two unpaved roadways. Results also showed that the implemented CFD model resolved the two main issues with Gaussian models (currently the most used air quality model): over-prediction of pollutant concentrations near the roadway and problems dealing with wind speeds < 1 ms−1.

Distribution and physicochemical properties of particulate matter in swine confinement barns

Air pollutants accumulated in confined livestock barns could impact the health of animals and staff. Particulate matter (PM) and ammonia (NH3) concentrations are typically high in enclosed livestock houses with weak ventilation. The objective of this study was to investigate the distribution of PM in different size fractions and the levels of NH3 in a high-rise nursery (HN) barn and a high-rise fattening (HF) barn on a swine farm and to analyse the physicochemical properties of fine PM (PM2.5, PM with aerodynamic diameter ≤ 2.5 μm). The concentrations of total suspended particles (TSP, PM with aerodynamic diameter ≤ 100 μm), inhalable PM (PM10, PM with aerodynamic diameter ≤ 10 μm), PM2.5 and NH3 were monitored continuously for 6 d in each barn. The results showed that the concentrations of PM and NH3 varied with position, they were significantly higher inside the barns than outside (P < 0.01) and significantly higher in the forepart than at the rear of the two barns (P < 0.05). In the HF barn, the values of the two parameters were 0.777 ± 0.2 mg m−3 and 26.7 ± 7 mg m−3, respectively, significantly higher than the values observed in the HN barn at all monitored sites (P < 0.05). The PM concentrations increased markedly during feeding time in the two barns. Chemical characteristics analysis revealed that the main sources of PM2.5 in the two barns may have consisted of blowing dust, feed, mineral particles and smoke. In conclusion, the air quality at the forepart was worse than that at the rear of the barns. Activities such as feeding could increase the PM concentrations. The components of PM2.5 in the two barns were probably blowing dust, feed, mineral particles and smoke from outside.

Comparisons of ambient air particulates concentrations (TSP, PM2.5) and dry depositions during smog and non-smog periods at Luliao, Shalu District sampling site

The concentrations of ambient total suspended particulates (TSP) and PM2.5, and the dry depositions at a sample site at Luliao Junior High School (Luliao) in central Taiwan were measured during smog and non-smog days between December 2017 and July 2018. The results are compared to those obtained during non-smog periods in the years 2015–2017. The mean TSP and PM2.5 concentrations and dry deposition flux were 72.41 ± 26.40, 41.88 ± 23.51 μg/m3, and 797.57 ± 731.46 μg/m2 min, respectively, on the smog days. The mean TSP and PM2.5 concentrations and dry deposition flux on the non-smog days were 56.39 ± 18.08, 34.81 ± 12.59 μg/m3 and 468.93 ± 600.57 μg/m2 min, respectively. The mean TSP concentration in the smog period was 28% greater than that in the non-smog period, and the mean PM2.5 concentration was 20% higher. The mean dry deposition flux in the smog period was 70% higher than that in the non-smog period at Luliao. The PM2.5 concentrations exceeded the standards set by the Taiwan EPA (35 μg/m3 daily, and 15 μg/m3 annually). Therefore, the TSP and PM2.5 concentrations and dry deposition must be reduced in central Taiwan on smog days. In addition, atmospheric TSP and PM2.5 concentrations at various sampling sites were compared, and those herein were not higher than those measured in other countries. Finally, apart from the local traffic emissions, during smog periods, the other pollution source originated from the transportation process of traffic pollutants emitted in the northwest side of Taiwan.

Field Evaluation of the Dust Impacts from Construction Sites on Surrounding Areas: A City Case Study in China

Construction activities generate a large amount of dust and cause significant impacts on air quality of surrounding areas. Thus, revealing the characteristics of construction dust is crucial for finding the way of reducing its effects. To fully uncover the characteristics of construction dust affecting surrounding areas, this study selected seven representative construction sites in Qingyuan city, China as empirical cases for field evaluation. In the experiment, the up-downwind method was adopted to monitor and collect TSP (total suspended particulate), PM10 and PM2.5 (particulate matter ≤10 µm and 2.5 µm in aerodynamic diameter, respectively) concentrations, meteorological data and construction activities of each site for 2 to 3 days and 18 h in a day. The results show that the average daily construction site makes the surrounding areas’ concentration of TSP, PM10 and PM2.5 increase by 42.24%, 19.76% and 16.27%, respectively. The proportion of TSP, PM10 and PM2.5 in building construction dust is 1, 0.239 and 0.116, respectively. The large diameter particulate matter was the major constituent and the distance of its influence was limited. In addition, construction vehicles were one of the main influencing factors for building construction dust. However, building construction dust was not significantly correlated with any single meteorological factor when it did not change too much. Findings of this research can provide a valuable basis for reducing the impact of building construction dust on surrounding areas.

Organophosphate flame retardants in total suspended particulates from an urban area of zhengzhou, China: Temporal variations, potential affecting factors, and health risk assessment

Organophosphate esters (OPEs) are widely used as flame retardants and plasticizers in industry and daily life, but the partition of OPEs to particles is still unclear because of the wide range of their physicochemical properties. In this study, six target OPEs with different vapor pressures (log PL) were measured from 30 total suspended particulate (TSP) samples collected from an urban area of Zhengzhou from June to November in 2018. The total concentration of OPEs ranged from 0.30 to 3.46 ng/m3, with average concentration of 1.04 ng/m3. Tris (chloroethyl) phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCPP), and tributyl phosphate (TnBP) were most abundant in TSP, accounting for approximately 86.0% to the total OPEs. The temporal variations showed a specific trend that OPE concentrations in TSP were much higher in autumn than those of summer. Significant positive correlations were observed between TSP concentration in air and the total concentration of OPEs in TSP, with r up to 0.596. Particle concentrations caused major changes on OPE concentrations in TSP with octanol-air partition coefficient (log KOA) between 7.7 and 10 but had no significant influence on the OPEs with log KOA higher than 12. Temperature had significant influence on the total and individual OPEs with high vapor pressures (log PL > −4.0), indicating that log KOA and log PL had significant influence on the OPE concentrations in TSP and may be one of the key factors on their temporal variations. Temperature had significant influence on OPE concentrations in TSP due to the strong temperature dependency of log KOA and log PL. No significant relationships were found between the wind speed and OPE concentrations in TSP, suggesting that OPEs detected in TSP might be emitted from the local sources. The hazards quotient (HQ) values were 6–8 orders of magnitude lower than 1, indicating that there was a low risk to local residents from the exposure to OPEs in TSP. This study preliminarily illuminates the potential affecting factors on the temporal variations of OPEs in TSP. It would be helpful for investigating the gas-particle partitioning behaviors and human health risks of OPEs in air.

Characterization of TSP (Si, Pb and Ca) from tropical ambient air during building construction project

Apartment development in urban areas is often proposed as solution to meet the housing needs. However, building construction could contribute air pollutants that have a negative impact on health. This activity could generate Total Suspended Particulate (TSP). This study aimed to quantify the composition of TSP (Si, Pb and Ca) arising from building construction activities and comparing the measurement results with the air quality standard in Indonesia. The sampling method was undertaken according to SNI 19-7119.3-2005. Based on this research, the TSP concentration in samples has exceeded the permissible limit (the highest concentration of TSP was 786, 13 µg/m3). The result of characterization of TSP indicates that the highest Si concentration was found at the point of transportation path, while Pb and Ca.

An experimental and numerical study of air pollution near unpaved roads

Aiming to advance in the understanding of pollutant dispersion near roads, we measured, simultaneously, vehicle traffic, meteorological parameters, and 24-h average concentration of particulate matter (TSP, PM10, and PM2.5) at several locations downwind two unpaved roads, located on a flat region without any other relevant source of pollutants. We also implemented on a commercial software of computational fluids dynamics (CFD) an air quality model to simulate the dispersion of particles and gas-phase pollutants emitted from roads. Numerical results of monthly and daily averages of total suspended particles (TSP) concentrations showed high correlation with experimental measurements (R2 > 0.94). We found, numerically and experimentally, that the plots of pollutant concentrations vs distance to the road edge converge into a single curve when they are expressed in terms of dimensionless numbers. Profiles of vertical concentration sketch an exponential function at the road edge, an S shape downwind and a flat shape far from the road. Particle size distribution fits a Rosin-Rammler function with average diameter of ~ 7 μm. This distribution remains unaltered downwind the road, which implies that at any location within 1.5 km from the road, PM10 and PM2.5 concentrations are a constant fraction of TSP concentration. Experimental data confirmed this observation. Previous results can be used to determine the size of the area impacted by roads, identify mitigating and adaptive countermeasures, and to improve the accuracy of vehicular emission factors.

Threshold Friction Velocity Influenced by the Crust Cover of Soils in the Columbia Plateau

Core Ideas Particulate emissions from agricultural lands threaten air quality. Soil crusts reduce emissions by increasing threshold friction velocity. Threshold friction velocity was determined from temporal variations in particle concentrations inside a wind tunnel. Crust cover increased threshold friction velocity, particularly under 60 and 100% crust cover. Soil crusts provide stability and protection against wind erosion from semiarid and arid lands. Although erosion is initiated when the friction velocity (U*) exceeds the threshold friction velocity (U*t) of soils, there is little information available on the effect of soil crust cover on U*t. The objective of this study was therefore to evaluate the effect of soil crust cover on the U*t of five loessial soils of the Columbia Plateau, United States. Soil samples were sieved and the erodible fraction was placed in 1 by 0.2 by 0.015 m trays. Water drops 4.5 mm in diameter were applied to the soil surface at a known density, which, after drying, created various percentages of crust cover. The trays were placed inside a wind tunnel to assess U*t. which was determined by systematically wind speed until an increase was observed in total suspended particulate concentration inside the tunnel. No significant differences in U*t were found among 0, 15, and 30% cover but significant differences in U*t were found between 60 and 100% cover. The U*t of 100% crust cover was about twice that of 0% cover. Crust crushing energy, which influences abrasion, did not vary across crust cover treatments. The Single‐event Wind Erosion Evaluation Program (SWEEP) revealed the similar influence of crust cover on U*t. The SWEEP adequately simulated U*t for 0, 15, and 30% crust cover but overestimated U*t for 60 and 100% cover. These results suggest that crusts effectively protect the soil from wind erosion by increasing U*t.

Distribution of particulate matter and ammonia and physicochemical properties of fine particulate matter in a layer house

High concentrations of particulate matter (PM) and ammonia (NH3) in poultry houses have adverse effects on the health of workers and animals. The present study investigated the distribution of the PM in different size fractions and NH3, as well as analyzing the physicochemical properties of fine particulate matter (PM2.5) in an enclosed layer house. The detection was taken from 5:00 to 21:00 in every 2 h for a 7-d continuous monitoring using a DustTrak II model 8532 aerosol monitor for PM concentrations and a JK40-IV portable gas detector for NH3 concentrations. The concentrations of inhalable particulate matter (PM10), total suspended particles (TSP), and NH3 were significantly higher in the rear of the chicken house compared to the front (P < 0.05). The PM10, TSP, and NH3 concentrations inside the layer house were significantly higher than outside (P < 0.001). The concentrations of PM10 and TSP were both highest at the first feeding time at 7:00. The PM2.5/PM10, PM2.5/TSP, and PM10/TSP concentration ratios at 5:00 were highest with 0.84, 0.62, and 0.74, respectively. Airflow speed showed a significant correlation with other measured microclimatic variables. Organic carbon was the primary constituent of PM2.5 collected from the layer house. It was also observed that mass percentage of elements C and O were both the highest by energy spectrum diagrams of PM2.5. The ultrastructure of PM2.5 revealed that there were mineral particles derived from feed, feces, or the ground and that smoke polymers came from ambient air. In conclusion, air quality was better at the front than at the middle and rear of the layer house. Air quality outside was better than that inside the house. Chicken activities primarily caused the PM10 and TSP concentrations to increase in the chicken house. The main components of PM2.5 in the layer house were organic matter and minerals, which were mostly derived from feed, feces, and ground dust.