Concentration and emission sources of airborne metals in particulate matter in the industrial district of Médio Paraíba, state of Rio de Janeiro, Brazil

Historical ferrous slag induces modern environmental problems in the Moravian Karst (Czech Republic)

Ferrous slag produced by a historic smelter is washed from a slagheap and transported by a creek through a cave system. Slag filling cave spaces, abrasion of cave walls / calcite speleothems, and contamination of the aquatic environment with heavy metals and other toxic components are concerns. We characterize the slag in its deposition site, map its transport through the cave system, characterize the effect of slag transport, and evaluate the risks to both cave and aqueous environments. The study was based on chemical and phase analysis supported laboratory experiments and geochemical modeling. The slag in the slagheap was dominated by amorphous glass phase (66 to 99 wt%) with mean composition of 49.8 ± 2.8 wt% SiO₂, 29.9 ± 1.6 wt% CaO, 13.4 ± 1.2 wt% Al₂O₃, 2.7 ± 0.3 wt% K₂O, and 1.2 ± 0.1 wt% MgO. Minerals such as melilite, plagioclase, anorthite, and wollastonite / pseudowollastonite with lower amounts of quartz, cristobalite, and calcite were detected. Slag enriches the cave environment with Se, As, W, Y, U, Be, Cs, Sc, Cd, Hf, Ba, Th, Cr, Zr, Zn, and V. However, only Zr, V, Co, and As exceed the specified limits for soils (US EPA and EU limits). The dissolution lifetime of a 1 mm³ volume of slag was estimated to be 27,000 years, whereas the mean residence time of the slag in the cave is much shorter, defined by a flood frequency of ca. 47 years. Consequently, the extent of slag weathering and contamination of cave environment by slag weathering products is small under given conditions. However, slag enriched in U and Th can increase radon production as a result of alpha decay. The slag has an abrasive effect on surrounding rocks and disintegrated slag can contaminate calcite speleothems.

Monitoring of particulate matter (PM2.5 and PM10) in San Juan city, Argentina, using active samplers and the species Tillandsia capillaris

The concentration of particulate matter (PM2.5 and PM10) was studied in San Juan city, Argentina, during winter and spring of 2017. Samplers of particulate matter (PM) and individuals of the plant species Tillandsia capillaris were placed in the centre of the city to be used as a biomonitors of atmospheric particulate matter. The PM filters and PM deposited in T. capillaris leaves were analysed to measure particle concentration and concentrations of elements (K, Ca, Mn, Fe, Cu, Zn, Br, Sr, Ba and Pb) using X-ray fluorescence by synchrotron radiation (SR-XRF). Linear regression analysis showed significant positive correlations between PM concentration in the atmosphere and the particles deposited on T. capillaris leaves. The elements quantified in PM2.5 and PM10 filters were subjected to a principal component analysis, which showed the presence of three emission sources in the study area (soil, vehicular traffic and industry) in both fractions. It was not possible to conduct this analysis with the elements obtained from the extraction of T. capillaris leaves, since most of them are solubilised at the moment of extraction. Biomonitoring with T. capillaris might be used to estimate the concentration of particulate matter in large areas or in remote sites with no electrical power supply to run active samplers. Further studies should be carried out in other regions, and more variables should be incorporated to obtain increasingly deterministic models.

Elemental Composition of PM2.5 Aerosol in a Residential-Industrial Area of a Mediterranean Megacity

Very little is known about the elemental composition and possible sources of fine aerosol particles from Mediterranean megacities. Fine aerosol particles were collected at a residential-industrial area in Greater Cairo, Egypt, during the period from October 2010 to May 2011. The elemental compositions of the collected samples were quantified by using a homemade energy dispersive x-ray fluorescence spectrometer, whereas black carbon was quantified by a black smoke detector. Fifteen elements have been quantified. Of these constituents, Ca, C, Cl, S, and Fe had the highest concentrations: greater than 1 µg m^-3. The overall mean mass concentration of the collected samples equals 70 µg m^-3; this value exceeds the European Union annual Air Quality Standard levels. The individual elemental concentrations of the fine particles were found to be dominated by elements linked to mineral dust. Most of the monthly variations of elemental concentrations can be attributed to seasonal meteorological conditions. Other possible sources were vehicle-exhaust and industrial activities. The results pinpoint the problem of identifying different sources when one source, in this case, the nearby deserts, is dominant. The results from this study contribute to the growing knowledge of concentrations, composition, and possible sources of ambient fine particulate matter.

Temporal variations of fine and coarse particulate matter sources in Jeddah, Saudi Arabia

This study provides the first comprehensive analysis of the seasonal variations and weekday/weekend differences in fine (aerodynamic diameter <2.5 μm; PM_2.5) and coarse (aerodynamic diameter 2.5-10 μm; PM_2.5-10) particulate matter mass concentrations, elemental constituents, and potential source origins in Jeddah, Saudi Arabia. Air quality samples were collected over 1 yr, from June 2011 to May 2012 at a frequency of three times per week, and analyzed. The average mass concentrations of PM_2.5 (21.9 μg/m³) and PM₁₀ (107.8 μg/m³) during the sampling period exceeded the recommended annual average levels by the World Health Organization (WHO) for PM_2.5 (10 μg/m³) and PM₁₀ (20 μg/m³), respectively. Similar to other Middle Eastern locales, PM_2.5-10 is the prevailing mass component of atmospheric particulate matter at Jeddah, accounting for approximately 80% of the PM₁₀ mass. Considerations of enrichment factors, absolute principal component analysis (APCA), concentration roses, and backward trajectories identified the following source categories for both PM_2.5 and PM_2.5-10: (1) soil/road dust, (2) incineration, and (3) traffic; and for PM_2.5 only, (4) residual oil burning. Soil/road dust accounted for a major portion of both the PM_2.5 (27%) and PM_2.5-10 (77%) mass, and the largest source contributor for PM_2.5 was from residual oil burning (63%). Temporal variations of PM_2.5-10 and PM_2.5 were observed, with the elevated concentration levels observed for mass during the spring (due to increased dust storm frequency) and on weekdays (due to increased traffic). The predominant role of windblown soil and road dust in both the PM_2.5 and PM_2.5-10 masses in this city may have implications regarding the toxicity of these particles versus those in the Western world where most PM health assessments have been made in the past. These results support the need for region-specific epidemiological investigations to be conducted and considered in future PM standard setting.

IMPLICATIONS

Temporal variations of fine and coarse PM mass, elemental constituents, and sources were examined in Jeddah, Saudi Arabia, for the first time. The main source of PM_2.5-10 is natural windblown soil and road dust, whereas the predominant source of PM_2.5 is residual oil burning, generated from the port and oil refinery located west of the air sampler, suggesting that targeted emission controls could significantly improve the air quality in the city. The compositional differences point to a need for health effect studies to be conducted in this region, so as to directly assess the applicability of the existing guidelines to the Middle East air pollution.

Evaluating the mutagenicity of the water-soluble fraction of air particulate matter: A comparison of two extraction strategies

Many studies have focused on assessing the genotoxic potential of the organic fraction of airborne particulate matter. However, the determination of water-soluble compounds, and the evaluation of the toxic effects of these elements can also provide valuable information for the development of novel strategies to control atmospheric air pollution. To determine an appropriate extraction method for assessing the mutagenicity of the water-soluble fraction of PM, we performed microwave assisted (MW) and ultrasonic bath (US) extractions, using water as solvent, in eight different air samples (TSP and PM10). Mutagenicity and extraction performances were evaluated using the Salmonella/microsome assay with strains TA98 and TA100, followed by chemical determination of water-soluble metals. Additionally, we evaluated the chemical and biological stability of the extracts testing their mutagenic potential and chemically determining elements present in the samples along several periods after extraction. Reference material SRM 1648a was used. The comparison of MW and US extractions did not show differences on the metals concentrations, however positive mutagenic responses were detected with TA98 strain in all samples extracted using the MW method, but not with the US bath extraction. The recovery, using reference material was better in samples extracted with MW. We concluded that the MW extraction is more efficient to assess the mutagenic activity of the soluble fraction of airborne PM. We also observed that the extract freezing and storage over 60 days has a significant effect on the mutagenic and analytical results on PM samples, and should be avoided.

Airborne iron across major urban centers in South Korea between 1991 and 2012

In this study, the distribution of airborne iron (Fe), one of the most abundant heavy metals in the Earth's crust was investigated to describe the basic features of i'ts pollution in various urban locations. The spatiotemporal distribution of Fe concentrations in seven major South Korean cities exhibited unique patterns to reflect differences as to Fe sources reflected in the relative enrichment in coastal relative to inland areas. In addition, the analysis of long-term trends of different metal species indicated that Fe levels maintained a fairly constant trend, while there had been a noticeable decline in concentrations of other metals (Cd, Cr, Cu, Mn, and Ni). The relative robustness of our correlation analysis was assessed by comparing (1) the Fe concentrations among cities, and (2) Fe with other metals at a given city. Fe concentrations were also partly explainable by the frequency of Asian dust events in most cities, with the observed spatial gradients in such relationships.

Evolution of particulate matter and associated metal levels in the urban area of Rio de Janeiro, Brazil

The levels of total suspended particles and airborne particulate trace metals were determined in three locations. Two of these locations are in the metropolitan area of Rio de Janeiro, where the main source of pollution is vehicular traffic. The remaining location is in a suburban area characterized by industrial and vehicular emissions, as well as natural input. Enrichment factors found in the downtown area for Zn, Cu, Pb and Cd were in the interval 21-3237, indicating an important contribution of anthropogenic sources. In the suburban area, Zn levels were unusually high (596.8-5475.4 ng m(-3)) and may be attributed to the proximity of a company that produces lubricants and lubricant additives.