Dust Resuspension Research Articles

Characterizing the sources, concentrations and resuspension potential of metals and metalloids in the thoracic fraction of urban road dust

Road dust is a sink and source of metals and metalloids of human health concern. To date, many studies have examined the composition of road dust but there remain critical knowledge gaps on the chemistry of thoracic fractions (< 10 μm) and their patterns of deposition and resuspension. The goal of this study is to characterize the elemental concentrations and sources of thoracic fractions of road dust and their resuspension potential for Toronto, Ontario, Canada. Bulk and thoracic road sweepings were acid digested (HF, HClO4, HNO3 and HCl) and the elemental concentrations measured using ICP-MS. Principal component analysis (PCA) was applied to infer source emissions. Annual elemental loadings to roads were estimated using data on total sweepings collected by the City of Toronto. The mass amounts of metals and metalloids (< 10 μm) available for resuspension were calculated assuming a contribution of 10% to total loadings for this fraction.The median trace element concentrations in city sweepings (n = 64) ranged from highest to lowest as follows: Mn > Zn > Ba > Cr > Cu > Pb > V > Ni > Sn > Mo > Co > As > Sb > Cd. Iron, Cr, Ni, Co, Mo and Cu levels were significantly associated with road class, with the highest concentrations measured for the expressway. Most elements, especially Sb and Zn, were enriched in thoracic sweepings. The PCA results demonstrate the importance of non-fossil fuel, traffic-related elemental emissions. Difficulties in identifying sources, given uncertainties regarding overlapping chemical profiles, are also highlighted. Significant elemental loadings to roads were estimated to occur, with the largest amounts identified for Fe, Al, Mn, Zn, Cr and Cu. Road dust resuspension is predicted to be the most important source of emissions for Fe, Al, Mn, Cr, V, Sn, Mo, Co and Sb.

Effect of silt loading on particle concentration in the atmosphere from resuspended road dust through particulate matter dispersion modeling

Particulate matter (PM) is one of the most dangerous pollutants in urban environments, and studies have linked it to many adverse health effects. Resuspended road dust makes up a large portion of PM. Therefore, monitoring and estimating the contribution of resuspended dust to PM is vital. In this study, emission rates of fine and coarse PM from different roads of Vellore City in Tamil Nadu, India, is estimated using silt loading protocol adapted by U.S. EPA. Silt load samples are collected from 8 different roads in the study region. The emission rates estimated using silt loading and fleet weight are then used to model the dispersion of PM throughout the study region using AERMOD. Hotspots of high PM concentration are identified at various locations frequented by commuters in the study region. Areas around educational institutions and hospitals in the region show highly elevated levels of PM. This study illustrates that resuspension of road dust can contribute significantly to PM in urban centers. Fine PM concentration exceeding 500 μg/m3 raises concerns about the health of commuters in the study region. This justifies the need for more regulations aiming at reducing the contribution of PM from resuspended road dust to overall urban PM.

Source identification and exposure assessment to PM10 in the Eastern Carpathians, Romania

Observations of particulate matter less than 10 µm (PM10) were conducted from January to December in 2015 in the Ciuc basin, Eastern Carpathians, Romania. Daily concentrations of PM10 ranged from 10.90 to 167.70 µg/m3, with an annual mean concentration of 46.31 µg/m3, which is higher than the European Union limit of 40 µg/m3. Samples were analyzed for a total of 21 elements. O, C and Si were the most abundant elements accounting for about 85% of the PM10 mass. Source identification showed that the elemental composition of PM10 is represented by post volcanic activity, crustal origin, and anthropogenic sources, caused by the resuspension of crustal material, sea salt and soil dust. The average PM10 composition was 72.10% soil, 20.92% smoke K, 13.84% salt, 1.53% sulfate and 1.02% organic matter. The back-trajectory analysis showed that the majority of PM10 pollution comes from the West, Southwest and South.

Size distributions and health risks of particle-bound toxic elements in the southeast coastland of China.

Size-fractionated samples were collected at five coastal urban sites in Fujian Province, southeast China, in 2016 and 2017 to determine the trace elements using ICP-MS. Ca, Fe, Al, Mg, and K were the most abundant elements among the studied elements in TSP, much higher than those of heavy metals. The annual mean concentrations of Pb, As, V, Ni, Cd, and Mn were within the acceptable limits of the World Health Organization and the Ministry of Ecology and Environment of China while Cr(VI) exceeded the limits. Most elements exhibited clear seasonal patterns with maxima over the cold season and minima over the warm season. The spatial variabilities in concentrations of the measured elements were not significant except Ni and V. However, the size distribution pattern of each element was quite similar across the region. Characteristic size distributions of elements allowed identification of three main groups: (a) unimodal distribution in the coarse fraction for Ca, Al, Mg, and Ba; (b) unimodal distribution in the fine fraction for Pb, Se, As, Ag, V, Ni, Zn, and Cd; and (c) bimodal or multimodal distribution for Fe, Mn, Cr, K, and Cu. The combination of the size-fractionated concentrations, enrichment factors, correlation coefficients, and factor analysis offered the identification of mixed sources such as vehicular exhaust and wear, heavy fuel oil combustion, and resuspension of road dust. Non-carcinogenic health risks associated with inhalable exposure to airborne metals were higher than the safety threshold (hazard index > 1) across the region, suggesting non-carcinogenic health risks via inhalation. Mn, V, and Ni contributed 74-83% of the total non-carcinogenic risk. The assessment investigation of carcinogenic health risks revealed V and Cr(VI) as elements with the largest carcinogenic risks, accounting for more than 95% of the overall inhalation risk. Nevertheless, the carcinogenic risks for children and adults were between 10-6 and 10-4, within the range considered acceptable by the US EPA. In terms of the size-fractionated risk, PM2.5 contributed 43-50% and 39-44% of the total non-carcinogenic and carcinogenic risks, respectively, indicating the potential health hazard of coarse particle-bound toxic metals was not negligible.

Gaseous and particulate reactive nitrogen species in the indoor air of selected households in New Delhi.

The present study reports the indoor abundance of inorganic trace gases (NH3, NO2 and SO2) and their corresponding particulates (NH4+, NO3- and SO42-) along with other major ionic species present in the aerosol form (Cl-, F-, Na+, K+, Ca2+ and Mg2+), in the urban households of megacity Delhi (India). Two different households (DH site and MH site) were selected in the city based on the variation in the land use patterns of the locations in which they were situated. Trace gases followed the order NH3 > SO2 > NO2 at both the sites with NH3 contributing about 90% and 85% to the total Nr species at DH and MH sites, respectively. NH3 showed maximum indoor concentrations during monsoon season whereas NO2 and SO2 were higher during winter season. The gas to particle conversion of the inorganic trace gases was studied by calculating their oxidation ratios which followed the order SOR > NOR > NHR, indicating that SO2 showed more oxidative conversion to SO42- as compared to NO2 and NH3 in the indoor setup. The chemical composition of the particulates revealed that Ca2+ and SO42- were the most abundant cation and anion, respectively, among the measured ionic species at both sites and the concentrations of all the major ions were higher for the industrial MH site as compared to the residential DH site. Source apportionment using principal component analysis and mass ratios showed that indoor activities such as cooking, cleaning along with others such as biomass burning and dust resuspension were responsible for the indoor composition of particulates at DH site whereas outdoor influences such as coal burning and industrial emissions from local sources were prominent at MH site due to its industrialized surroundings. For naturally ventilated households (such as the present study), it was observed that the emissions generated indoors as well as the characteristic outdoor influences seem to influence the overall indoor air composition and quality.

A synthesis review on atmospheric wet deposition of particulate elements: scavenging ratios, solubility, and flux measurements

Atmospheric dry and wet deposition of particulate matter controls its lifetime in air and contributes to the environmental burden of toxic pollutants and thus has important implications on human and ecosystem health. This synthesis review focuses on atmospheric wet deposition of particulate elements and analyzed their scavenging ratios (i.e., ratio of concentration in precipitation to that in ambient air), solubility, and wet deposition flux measurements based on published studies in the literature, aiming to gather updated knowledge that can be used for modeling their wet deposition. Our analysis finds that scavenging ratios of a specific element have a narrow range. Overall, elemental scavenging ratios for snow are approximately three times higher than those for rain. Elements that are bound to coarse (PM2.5–10) particles have larger scavenging ratios than those bound to fine (PM2.5) particles, except for Fe and Si. Solubility of elements in rainwater ranges from 8% (Fe) to 94% (Ca). Solubility is moderately correlated with scavenging ratio, possibly explaining the lower scavenging ratios of Fe and Si compared with other elements with similar fine fractions. Data collected from North America, Europe, the Middle East, and Asia show that the wet fluxes of Al and Fe are orders of magnitude greater than those of routinely monitored anthropogenic elements (Zn, Pb, Cu, Ni, Cd, Cr). Wet deposition fluxes of particulate elements in the Middle East exceed those in other regions, likely due to regional transport of dust and soil resuspension. Fluxes from all regions are a factor of two to three times greater in industrialized and urban locations than in rural and remote locations because of industrial, vehicular, and soil and mineral dust emissions. Dry deposition fluxes are usually greater than wet deposition fluxes, although to varying degrees according to co-located measurements. Based on the relationships between scavenging ratio and the elemental PM2.5 fraction under rain and snow conditions, we derived regression equations for estimating scavenging ratios of particulate elements for which measurements are limited. Such knowledge and data improve the quantification of atmospheric deposition fluxes for an expanded list of metals and metalloids and the understanding of pathways contributing to ecological risk.

Use of Black Poplar Leaves for the Biomonitoring of Air Pollution in an Urban Agglomeration.

Trees are considered to be an effective tool for metal pollution biomonitoring. In the present study, the concentration of metals (Cu, Pb, Zn, Cd, Co, Ni, Fe, Mn, and Al) in black poplar leaves (Populus nigra L.), together with the concentration of PM10, PM2.5, PM1, and total suspended particles (TSP), was used for the air pollution biomonitoring in 12 sites from various areas of Cluj-Napoca city, Romania. The concentration of PM10 in the air was high, but their metal content was low. However, Cu, Pb, and Zn were moderately enriched, while Cd was highly enriched in PM10 due to anthropogenic sources. The average metal concentration in leaves decreased in the order Zn>>Fe>Mn>Al>Pb>Ni>Cu>Co>Cd and increased with the increase of PM10 concentration, indicating that poplar leaves are sensitive to air pollution. The principal component analysis indicated that traffic, waste burning, road dust resuspension, and soil contamination are the main anthropogenic sources of metals in poplar leaves. The results indicated that black poplar leaves are a suitable biomonitoring tool for metal pollution, in urban environments.

Biomonitoring of Potentially Toxic Elements in Two Polluted Areas from Lurigancho-Chosica Using the genus Tillandsia latifolia and T. purpurea as Biomonitor.

In the present study, an urban and industrial area were evaluated through a biomonitoring study employing the Tillandsia purpurea and T. latifolia species as a biomonitor. Plants were collected from a non-contaminated area and transplanted and exposed for three months into study areas to determine metal accumulation. Sixteen elements (Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Ni, Pb, Rb, Sb, V, and Zn) were measured using ICP-MS analysis. Datasets were assessed by one-way ANOVA, exposed-to-baseline (EB) ratio, and principal component analysis. Results showed significant differences among study areas for most elements, but no differences were found between species. According to EB ratios, As, Cd, Cr, Cu, Fe, Ni, Pb, Sb, V, and Zn showed EB ratios > 1.75 for both Tillandsia species around the industrial area, indicating influence from the Smelter plant. Ba, Sb, and Zn showed EB ratios > .1.75 in the urban area for both plants, indicating the releasing of pollutants from vehicular sources. PCA showed that most elements are derived from vehicular sources, industrial activities, and dust resuspension.

COMPARISON OF INORGANIC CHEMICAL COMPOSITIONS OF TOTAL SUSPENDED AND RESPIRABLE PARTICULATES IN DIFFERENT REGIONS OF CAIRO

The inorganic chemical composition of atmospheric Total Suspended Particulate (TSP) and Particulate Matter with an aerodynadic diameter less than 10 µm (PM10) in different regions of Cairo, in spring and autumn of 2018 was illustrated in this work. The results showed that the highest concentration of TSP and PM10 were close to industrial and heavy traffic areas “Tabbin, Helwan, Shobra Elkhimah and Fifth Settlement area”. The results showed that dust mass concentrations in Shobra Elkhimah were higher than all the other locations in both TSP and PM10. These results were pointed out in both spring and autumn. The results showed that the concentration of heavy metals in Helwan area was higher than all other locations. These concentrations suggest that heavy metals pollution in Helwan was more serious. Ration analysis of soluble ions showed that sodium and chloride were not from sea salt but sodium might be from the resuspension of soil dust, and chloride might be associated with the activities of burning. Potassium had diversity of sources other than burning of biomass. Sulfate and nitrate were mostly from fossil fuel origin. The 16NO3-> / 16SO4-> ratios in Tabbin were higher than in Helwan and Shobra Elkhimah for two types of particles during spring and autumn, indicating that the contribution of stationary emission to total particles in Tabbin were higher than in Helwan and Shobra Elkhimah.

Trends in particle matter and its elemental composition in Santiago de Chile, 2011 – 2018

ABSTRACT Daily fine (PM2.5) and coarse (PM10-2.5) particle matter (PM) samples collected at Parque O’Higgins station in downtown Santiago de Chile have been studied to find the trends in concentration from 1998 to 2018. Elemental concentration was obtained using X-ray fluorescence (XRF). Regression models from previous studies indicate that the PM2.5 and PM10-2.5 fractions have had a continuous decrease since 1988 mostly due to several policy control measures carried out over several decades. PM2.5 has decreased from 68.3 in 1988 to 27.6 μg/m3 in 2018 (60.4%). However, if only the last 8 years are considered (2011–2018), a leveling off can be observed in PM10-2.5 and PM2.5, which points to a change in the tendency. Cluster analysis of the elements in the fine and coarse fractions were identified to evaluate trends in the contributing sources. In the fine fraction, the mass contribution of crustal elements (Si, Al, Ca, and Fe) has remained stable in the last 8 years, and mass contribution of elements (Pb, Br, and Cl) associated to anthropogenic sources (traffic, wood burning) has also remained stable in the same period. For the coarse fraction, the contribution of one group of elements associated to crustal or anthropogenic sources has remained stable, and another group has decreased in the last 8 years. The leveling off can be ascribed to decreased rainfall during the last 8 years that have promoted soil dryness and resuspension of dust facilitated by wind or vehicular traffic. Mean temperatures have increased in the last 30 years, but have not contributed directly to the leveling of the concentration. Implications: Regression models indicate that the PM2.5 (fine) and PM10-2.5 (coarse) fractions at Parque O’Higgins station in Santiago de Chile have had a continuous decrease since 1988 mostly due to several policy control measures carried out over several decades. However, in the last 8 years (2011–2018), a leveling off can be observed in PM10-2.5 and PM2.5. X-ray fluorescence (XRF) analysis was performed in the fine fractions indicating that the mass contribution of crustal elements (Ca, Al, Si, Fe) to the fine fraction has remained stable. This phenomenon can be ascribed to decreased rainfall during the last 8 years that have promoted soil dryness and resuspension of dust facilitated by wind or vehicular traffic. The crustal elements in the coarse fraction have also remained stable.

Assessment of trace metal concentration in the ambient air of the Prayagraj City during Diwali festival-a case study.

The study evaluated the particulate matter trend and trace element concentrations, during the Diwali week for two consecutive years, November 2018 and October 2019. Diwali celebrations worsen the city's air quality from poor to a severe category of air quality index (AQI). A peak rise in PM10 concentration was found on Diwali day, 1.8 times more than a normal day of the same period. The concentration was 5.6-fold more than the permissible limit prescribed by National Ambient Air Quality Standards (NAAQS), India, and 11.26-fold higher than the permissible limit of World Health Organization (WHO). The more firework bursting in the year 2019 results in the rise of PM10 concentration by 132% compared with the previous year. Lead (Pb), a carcinogen, was found in higher levels, in Diwali samples of year 2019. The average metal concentration on Diwali day was found in the following order: Pb (396.17) > Cu (70.34) > Mn (66.34) > Cr (29.66) > Ni (4.96) in year 2019 while Ni (195.20) > Pb (149.45) > Mn (64.85) > Cu (13.44) in year 2018. A significant positive correlation between Cr and Pb, Cu and Pb, Cr and Cu, and with PM10 have been observed, indicating their emission from a common source and the contribution of firecrackers to particulate pollution. Principal component analysis (PCA) identified the contribution of the bursting of firecrackers and vehicular emissions towards PM10 pollution in the year 2019 and vehicular emissions and dust resuspension in the year 2018 over the megacity Prayagraj.

Personal deposited dose and its influencing factors at several Greek sites: an analysis in respect to seasonal and diurnal variations.

The deposited dose in the human respiratory tract and its influencing factors were investigated for 8 urban/suburban locations within Greek cities. A dosimetry model (ExDoM2) was implemented assuming a 24-h exposure scenario to ambient PM10 whereby regional deposition rates were obtained. Simulations were performed considering three cases (Sahara dust, cold, and warm periods) with seasonal and diurnal variations examining the relative sources and other influencing factors in each case. Health risk indexes such as the relative risk and attributable fraction were also estimated. Overall, higher daily deposited dose was obtained for all urban compared with suburban locations (p < 0.05) and for cold compared with the warm periods (252-820 μg for cold period and 300-686 μg for warm period) for all locations. This finding was associated with increased deposition rate on cold period during evening/night hours, as a result of significant heating emissions. Besides that, most of the urban locations showed relative comparable deposition rates during the day, compared with the daily mean, for the two periods (cold and warm), indicating that urban-associated sources such as exhaust emissions and road dust resuspension contribute similarly to the deposited dose irrespectively of the season. Finally, the highest deposited dose was obtained during Sahara dust events ranged from 1881 to 4648 μg.

Contamination and Potential Risk Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) and Heavy Metals in House Settled Dust Collected from Residences of Young Children

House settled dust (HSD) contains various hazardous materials, including polycyclic aromatic hydrocarbons (PAHs) and metals. Exposure to toxicants contained in HSD is of paramount concern especially in the case of young children, due to their particular behavioral characteristics. In this context, extracts of sieved vacuum cleaner dust from 20 residences with young children were examined for the presence of PAHs and trace metals, in Athens, Greece. The results indicated that PAHs and metals were ubiquitous in the studied residences. The calculated enrichment factors (EF) of trace metals indicated that Cu, Se, Zn, Hg, Cd, and Pb were mainly of anthropogenic. According to the PCA analysis, the main sources of household dust were: smoking inside the houses, combustion processes, resuspension of soil dust, and vehicle traffic. In general, the cancer risk due to PAHs exposure was found lower than the threshold value. The ingestion of house dust was the most important route of exposure to metals. The dose of almost all elements for the children was found 1–2 orders of magnitude lower than the corresponding reference values. Both the carcinogenic and noncarcinogenic risks of exposure were within the safety limits.

Development and evaluation of a mobile laboratory for collecting short-duration near-road fine and coarse ambient particle and road dust samples

ABSTRACT This study used fine and coarse PM concentrator technology in a Mobile Particle Concentrator Platform (MPCP) designed and built to allow the collection of large amounts of ambient PM, enabling time-resolved speciation analysis, which would not be feasible using conventional methods. One hour of sampling yielded sufficient sample loading for trace elemental analysis using X-Ray Fluorescence (XRF). In addition, we developed a novel Road Dust Aerosolizer (RDA) sampler in order to collect PM2.5 and PM10 surface road dust in situ. This sampler aerosolizes dust from the road surface, simulating ambient road dust resuspension, resulting in measured PM composition and size more appropriately (and less labor-intensive) than those obtained from studies using bulk road dust sieved and re-suspended in the laboratory. Overall, our modified fine and coarse particle concentrators yielded good reproducibility between co-located samples and sufficient loading for trace elemental analysis. For particle mass concentration, we observed a relative error of 3% and 4% among pairs of filters for fine and coarse concentrators, respectively; confirming that the mass collected on an unweighted quartz filter in parallel with a Teflon filter will have the same PM mass as the weighed Teflon filter. For samples with elements that are well above the LOD, relative uncertainty values were between 5% and 10% for the fine and 3% and 10% for the coarse. Our results show that the RDA system has an excellent precision for mass and elements as well. The relative error for mass is 7% for PM10 and 3% for PM2.5 within pairs and ranged from 2 to10% for elements. In conclusion, we developed a method for collecting PM10 and PM2.5 near-road air and surface road dust for short durations, which allows investigation of the composition of direct (airborne) and indirect (re-suspended road dust) non-tailpipe vehicular emissions. Implications: The methods we developed in this study allow the collection of one-hour PM10-2.5 and PM2.5–0.2 samples from near-road ambient air at several distances from the same roadway in 1 day, and collection of road dust directly from the road surface, with sufficient loading for trace elemental analysis. This will allow investigation of the composition of direct (airborne) and indirect (re-suspended road dust) vehicular emissions.

Exposure to fine, ultrafine particles and black carbon in two preschools in nur-sultan city of kazakhstan.

Children in preschools were studied as an exceptionally vulnerable group to lung diseases due to their immature immune system. Few data are available in the literature addressing the exposure of children in preschools to ultrafine (>10nm) particles. Exposure of children to fine, ultrafine (10nm-1µm) particles and black carbon particles present inside and near two preschools in Nur-Sultan, Kazakhstan, during Fall 2019 was investigated. For Preschool I, the average daily (6h) indoor (outdoor) PM1 , PM2.5 , and PM10 concentrations over three-week measurements were 15.0 (SD 12.5)µg/m3 , 34.6 (SD 35.1)µg/m3 , and 47.2 (SD 45.2)µg/m3 , respectively. Average indoor UFP concentrations (>10.0nm) including candle burning events were 5.20×103 (SD 8.80×103 )particles/cm3 , with the background UFP concentration to be 3.30×103 (SD 1.80×103 )particles/cm3 . In Preschool II, the average UFP concentration (>30.0nm) in the morning and afternoon was 3.94×103 (SD 5.34×102 ) and 3.36×103 (SD 1.90×103 )particles/cm3 , respectively. Indoor black carbon (BC) concentrations were correlated with the outdoor smoking activity. The major sources of the indoor particles in the preschools were dust resuspension, candle burning, and infiltrated outdoor particles.

COVID-19 driven changes in the air quality; a study of major cities in the Indian state of Uttar Pradesh.

Amid the COVID-19 pandemic, there has been an unprecedented cessation of outdoor anthropogenic activities leading to a significant improvement of the environment across the world. However, the positive impacts on the environment are not expected to last long as countries have started to gradually come out of lockdown and engage in aggressive measures to regain the pre-COVID-19 levels of economic activity. The present study provides for an assessment of air quality changes during the period of lockdown and unlocking across 9 major cities in the Indian state of Uttar Pradesh, including three cities (Ghaziabad, Noida, and Greater Noida) in the national capital region, which have frequently been included among the most polluted cities in the world. The pollutant load in a vertical column of air during March–July 2020 has been analyzed and compared with the corresponding period’s pollution load in 2019. In addition, a detailed analysis of the ground-level changes in pollution load for Ghaziabad, Noida, and Greater Noida is also presented, along with the changes in local meteorology. A significant reduction in the total column density of NO2, CO and ground-level pollution load of PM10, PM2.5, NO2, and SO2 have been observed. In contrast, an increase in total column density of SO2 across all the cities (except Kanpur) and ground-level concentration of CO (in Noida and Greater Noida) and O3 (in Noida) was evident. The improvement in air quality (with respect to particulate matter) can primarily be attributed to the restrictions on construction and demolition activities, reduced re-suspension of roadside dust, and the restrictions on the movement of vehicles. A significant decline in the average summer temperature was recorded, and it can plausibly be attributed to lower radiative forcing due to reduced pollutant load in the atmosphere.

Assessment of metals in PM10 filters and Araucaria heterophylla needles in two areas of Quito, Ecuador

The reliability of Araucaria heterophylla needles as a biomonitor was evaluated by analyzing the concentration of metals in PM10 filters and in Araucaria heterophylla needles. The sampling campaign was carried out at two sites in the city of Quito, Ecuador, in 2017–2019. Concentrations of Cr, Cu, K, Mn, Pb, Zn, Ca, Fe, Al and Mg were determined in PM10 filters and in Araucaria heterophylla needles using an Inductively Coupled Plasma – Optical Emission Spectroscopy (ICP-OES). The annual mean concentrations of PM10 ranged between 24.9 and 26.3 μg m−3, exceeding the limit established by the World Health Organization (20 μg m−3). Statistical analyses, performed for the PM10 filters, showed that dust resuspension and anthropogenic activities were important sources for PM10 emissions in the city. Metals related to natural emissions (Ca, Mg, K, Al and Fe) dominated in both types of samples, while the minor metals were those related to anthropogenic emissions (Zn, Cu, Cr and Pb). The former were positively associated with the needle samples, while the latter were associated with PM10 filters. This work not only improved scientific knowledge on the concentrations of PM10 and metals in the Andean city of Quito, but also greatly contributed to the progress of research on the use of Araucaria heterophylla needles as a biomonitor.

Radioactive aerosols monitoring of the surface air near the Shelter object within 1998–2019

The results of long-term monitoring (1998–2019) of radioactive aerosols (RA) in the surface air near the Shelter object (SO) during works on projects implementation on creation of the New Safe Confinement’s “Arch” (NSC) are presented. The composition of long-lived nuclides (LLN) in RA using for assessing the personnel radiation safety are included the following nuclides: Σα-LLN (238, 239, 240Pu, 241Am) and Σβ-LLN (137Cs, 90Sr+90Y, 241Pu). The average activity of Σ-LLN was about 17 mBq/m3 in the end of 1990th in the air near the SO. It was shown that the main decline of aerosol situation near the SO, when RA volumetric activity increased ten-fold as compared to the beginning of 2000s, was due to radioactive dust resuspension during technological works. First, during earthwork at building of foundation strips of the NSC in 2010. During this period, average annual volumetric activity of Σ-LLN was 80 mBq/m3 , and weekly maximum activity rose to 6 mBq/m3 for Σα-LLN and for ΣβLLN to 520 mBq/m3. Second, when dismantling concrete and metal structures of the Shelter object in 2016, average annual activity of Σ-LLN was 62 mBq/m3, and weekly maximum activity reached Σα-LLN — 18 mBq/m3 and Σβ-LLN — 1,400 mBq/m3. After the NSC commissioning the Σ-LLN volumetric activity in the air dropped to 0.8 mBq/m3 in 2019. It is shown that after 2010 in the RA of the surface air there is an increase in the activity of 137Cs, not associated with fuel particles, the average relative share of which in the beginning of 2000s was about 20%, in 2013 reached to 62%, and after 2017 was in the range of 50–55%.

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.

Measurements and modeling of snow albedo at Alerce Glacier, Argentina: effects of volcanic ash, snow grain size, and cloudiness

Abstract. The impact of volcanic ash on seasonal snow and glacier mass balance has been much less studied than that of carbonaceous particles and mineral dust. We present here the first field measurements on the Argentinian Andes, combined with snow albedo and glacier mass balance modeling. Measured impurity content (1.1 mg kg−1 to 30 000 mg kg−1) varied abruptly in snow pits and snow and firn cores, due to high surface enrichment during the ablation season and possibly local or regional wind-driven resuspension and redeposition of dust and volcanic ash. In addition, we observed high spatial heterogeneity, due to glacier topography and the prevailing wind direction. Microscopic characterization showed that the major component was ash from recent Calbuco (2015) and Cordón Caulle (2011) volcanic eruptions, with a minor presence of mineral dust and black carbon. We also found a wide range of measured snow albedo (0.26 to 0.81), which reflected mainly the impurity content and the snow and firn grain size (due to aging). We updated the SNow, ICe, and Aerosol Radiation (SNICAR) albedo model to account for the effect of cloudiness on incident radiation spectra, improving the match of modeled and measured values. We also ran sensitivity studies considering the uncertainty in the main measured parameters (impurity content and composition, snow grain size, layer thickness, etc.) to identify the field measurements that should be improved to facilitate the validation of the snow albedo model. Finally, we studied the impact of these albedo reductions on Alerce Glacier using a spatially distributed surface mass balance model. We found a large impact of albedo changes on glacier mass balance, and we estimated that the effect of observed ash concentrations can be as high as a 1.25 m water equivalent decrease in the annual surface mass balance (due to a 34 % increase in the melt during the ablation season).