Impact of the SARS-CoV-2 lockdown measures in Southern Spain on PM10 trace element and gaseous pollutant concentrations.

Trace element concentrations within PM10, gaseous pollutants (NO2 and SO2), and PM10 levels were studied during the Covid-19 lockdown at a regional level in Southern Spain (Andalusia). Pollutant concentrations were compared considering different mobility periods (pre-lockdown, lockdown, and relaxation) in 2020 and previous years (2013-2016). An acute decrease in NO2 levels (<50%) was observed as a consequence of traffic diminution during the confinement period. Moreover, a lower reduction in PM10 levels and a non-clear pattern for SO2 levels were observed. During the lockdown period, PM10 elements released from traffic emissions (Sn and Sb) showed the highest concentration diminution in the study area. Regarding the primary industrial sites, there were no significant differences in V, Ni, La, and Cr concentration reduction during 2020 associated with industrial activity (stainless steel and oil refinery) in Algeciras Bay. Similarly, concentrations of Zn showed the same behaviour at Cordoba, indicating that the Zn-smelter activity was not affected by the lockdown. Nevertheless, stronger reductions of Cu, Zn, and As in Huelva during the confinement period indicated a decrease in the nearby Cu-smelter emissions. Brick factories in Bailen were also influenced by the confinement measures, as corroborated by the marked decrease in concentrations of Ni, V, Cu, and Zn during the lockdown compared to that from previous years. This work has shown the baseline concentrations of trace elements of PM10, which is of great value to air quality managers in order to minimise pollution levels by applying the confinement of the population, affecting both traffic and industrial anthropogenic activities.

Contribution of anthropogenic and natural sources in PM10 during North African dust events in Southern Europe.

The influence of North African (NAF) dust events on the air quality at the regional level (12 representative monitoring stations) in Southern Europe during a long time series (2007-2014) was studied. PM10 levels and chemical composition were separated by Atlantic (ATL) and NAF air masses. An increase in the average PM10 concentrations was observed on sampling days with NAF dust influence (42 µg m-3) when compared to ATL air masses (29 µg m-3). Major compounds such as crustal components and secondary inorganic compounds (SIC), as well as toxic trace elements derived from industrial emissions, also showed higher concentrations of NAF events. A source contribution analysis using positive matrix factorisation (PMF) 5.0 of the PM10 chemical data, discriminating ATL and NAF air mass origins, allowed the identification of five sources: crustal, sea salt, traffic, regional, and industrial. A higher contribution (74%) of the natural sources to PM10 concentrations was confirmed under NAF episodes compared with ATL. Furthermore, there was an increase in anthropogenic sources during these events (51%), indicating the important influence of the NAF air masses on these sources. The results of this study highlight that environmental managers should take appropriate actions to reduce local emissions during NAF events to ensure good air quality.

Hazardous trace elements in thoracic fraction of airborne particulate matter: Assessment of temporal variations, sources, and health risks in a megacity.

The deleterious health effects of thoracic fractions seem to be more related to the chemical composition of the particles than to their mass concentration. The presence of hazardous materials in PM10 (e.g., heavy metals and metalloids) causes risks to human health. In this study, twelve trace elements (Cd, Cr, Pb, Zn, Cu, Ni, Sn, Ba, Co, As, V, and Sb) in 315 samples of ambient PM10 were analyzed. The samples were collected at an urban background site in a Latin American megacity (Bogota, Colombia) for one year. The concentrations and temporal variabilities of these elements were examined. According to the results, Cu (52 ng/m3), Zn (44 ng/m3), Pb (25 ng/m3), and Ba (20 ng/m3) were the traces with the highest concentrations, particularly during the dry season (January to March), which was characterized by barbecue (BBQ) charcoal combustion and forest fires. In addition, the differences between the results of weekdays and weekends were identified. The determined enrichment factor (EF) indicated that Zn, Pb, Sn, Cu, Cd, and Sb mainly originated from anthropogenic sources. Moreover, a speciation analysis of inorganic Sb (EF > 300) was conducted, which revealed that Sb(V) was the main Sb species in the PM10 samples (>80%). Six causes for the hazardous elements were identified based on the positive matrix factorization (PMF) model: fossil fuel combustion and forest fires (60%), road dust (19%), traffic-related emissions (9%), copper smelting (8%), the iron and steel industry (2%), and an unidentified industrial sector (2%). Furthermore, a health risk assessment of the carcinogenic elements was performed. Accordingly, the cancer risk of inhalation exposure to Co, Ni, As, Cd, Sb(III), and Pb was negligible for children and adults at the sampling site. For adults, the adjusted Cr(VI) level was slightly higher than the minimal acceptable risk level during the study period (1.4 × 10-6).

The geochemical evolution of brines from phosphogypsum deposits in Huelva (SW Spain) and its environmental implications.

The present study focuses on the geochemistry of large phosphogypsum deposits in Huelva (SW Spain). Phosphogypsum slurry waste from fertiliser production was disposed in large ponds containing aqueous waste (i.e. brines) and exposed to weathering. These evaporation ponds were found to be dynamic environments far from attaining steady state conditions where a number of trace pollutants are subjected to temporal variations in response to changing environmental conditions. Chemical, mineralogical and morphological data were used to improve our understanding on the dynamics of a large number of elements in the phosphogypsum-brine-evaporation deposits system. Weekly sampling of brines over the course of 1 yr indicated a substantial enrichment in potentially harmful elements (e.g. As, Cr, Cu, F, Ni, U, V, Zn) present in time-dependent concentrations. The evaporation deposits formed multi-layered precipitates of chlorides, sulphates, phosphates and fluorides containing a large number of pollutants in readily soluble forms. The precipitation sequence revealed a time-dependent composition reflecting alternating precipitation and re-dissolution processes associated with seasonal changes in the local weather conditions. Concatenation of precipitation/re-dissolution stages was found to progressively enrich the brines in pollutants. These findings were supported by the observations from a tank experiment simulating the phosphogypsum-brine-evaporation deposits system under laboratory conditions. Given the substantially high concentrations of pollutants present in mobile forms in the brine-salt system, actions to abate these compounds should be implemented.

Physicochemical characterization and sources of the thoracic fraction of road dust in a Latin American megacity.

Road dust has been identified as one of the main sources of outdoor PM10 in Bogota (a Latin American megacity), but there are no studies that have analyzed the physicochemical characteristics and origins of its respirable fraction. A characterization of inorganic compounds (water soluble ions, major and trace elements, organic and elemental carbon) and an analysis of source contributions to the PM10 fraction of road dust were carried out in this study. A total of twenty road dust samples, selected from representative industrial, residential and commercial areas, were swept and resuspended to obtain the thoracic fraction. Size distribution by laser diffraction and individual particle morphology by Scanning Electron Microscopy were also evaluated. The data obtained revealed that the volume (%) of thoracic particles was higher in samples from industrial zones where heavy vehicular traffic, industrial emissions and deteriorated pavements predominated. Crustal elements were the most abundant species, accounting for 49-62% of the thoracic mass, followed by OC (13-29%), water-soluble ions (1.4-3.8%), EC (0.8-1.9%) and trace elements (0.2-0.5%). The Coefficient of Divergence was obtained to identify the spatial variability of the samples. A source apportionment analysis was carried out considering the variability of chemical profiles, enrichment factors and ratios of Fe/Al, K/Al, Ca/Al, Ti/Al, Cu/Sb, Zn/Sb, OC/TC and OC/EC. By means of a PCA analysis, five components were identified, including local soils and pavement erosion (63%), construction and demolition activities (13%), industrial emissions (6%), brake wear (5%) and tailpipe emissions (4%). These components accounted for 91% of the total variance. The results provide data to understand better one of the main sources of PM10 emissions in Bogota, such as road dust. These data will be useful to optimize environmental policies, and they may be used in future studies of human health and air quality modeling.

Short-term effects of ultrafine particles on daily mortality by primary vehicle exhaust versus secondary origin in three Spanish cities.

BACKGROUND: Evidence on the short-term effects of ultrafine particles (with diameter<100nm, UFP) on health is still inconsistent. New particles in ambient urban air are the result of direct emissions and also the formation of secondary UFP from gaseous precursors. We segregated UFP into these two components and investigated their impact on daily mortality in three Spanish cities affected by different sources of air pollution. METHODS: We separated the UFP using a method based on the high correlation between black carbon (BC) and particle number concentration (N). The first component accounts for aerosol constituents emitted by vehicle exhaust (N1) and the second for the photochemical new particle formation enhancements (N2). We applied city-specific Poisson regression models, adjusting for long-term trends, temperature and population dynamics. RESULTS: Mean BC levels were higher in Barcelona and Tenerife (1.8 and 1.2µg·m-3, respectively) than in Huelva (0.8µg·m-3). While mean UFP concentrations were similar in the three cities, from which N1 was 40% in Barcelona, 46% in Santa Cruz de Tenerife, and 27% in Huelva. We observed an association with N1 and daily mortality in Barcelona, by increasing approximately 1.5% between lags 0 and 2, per an interquartile increase (IQR) of 3277cm-3, but not with N2. A similar pattern was found in Santa Cruz de Tenerife, although none of the associations were significant. Conversely, in the industrial city of Huelva mortality was associated with N2 at lag 0, by increasing 3.9% per an IQR of 12,032·cm-3. CONCLUSION: The pattern and origin of UFP determines their short-term effect on human health. BC is possibly the better parameter to evaluate the health effects of particulate vehicle exhaust emissions, although in areas influenced by domestic solid fuel combustion this should also be taken into account.

Antimony speciation as geochemical tracer for anthropogenic emissions of atmospheric particulate matter.

The chemical composition of atmospheric particulate matter (PM) has been studied at the cities of Cordoba and Granada (South of Spain) between 2007 and 2013, considering urban background, traffic and industrial monitoring stations. The results of Principal Component Analysis (PCA) indicated that geochemical anomalies observed in the ambient air of Cordoba (mainly Cu, Zn, Pb and Cd) are closely related to the geochemical profile obtained from fugitive metallurgy emissions of brass industries. These findings have been confirmed performing an Sb speciation analysis of PM10 samples, which allowed to distinguish between Sb(III) and Sb(V). The percentage of Sb(V) in PM10 found in the traffic station of Granada was 64-69%. At Cordoba, the percentage of Sb(V) was found to be higher (73-77%) at both urban background and traffic stations, indicating a possible second source of Sb in the PM of this city. The PM10 samples from the industrial station of Cordoba showed a 85-86% of Sb(V). A similar percentage (84-88%) of Sb(V) was found for the fugitive emissions of the brass industries, confirming this industrial source of Sb. These results show that Sb speciation can be a useful geochemical tracer to identify anthropogenic sources (traffic and industrial) emissions of PM.

Geochemical anomalies of toxic elements and arsenic speciation in airborne particles from Cu mining and smelting activities: influence on air quality.

A characterization of chemical composition and source contribution of PM10 in three representative environments of southwest Spain related to mining activities (mineral extraction, mining waste and Cu-smelting) has been performed. A study of geochemical anomalies was conducted in the samples collected at the three stations between July 2012 and October 2013. The influence of Cu-smelting processes was compared to other mining activities, where common tracers were identified. The Cu and As concentrations in the study area are higher than in other rural and urban stations of Spain, in which geochemical anomalies of As, Se, Bi, Cd, and Pb have been reported. The results of source contribution showed similar geochemical signatures in the industrial and mining factors. However, the contribution to PM10 is different according to the type of industrial activity. These results have been confirmed performing an arsenic speciation analysis of the PM10 samples, in which the mean extraction efficiency of arsenic depended on the origin of the samples. These finding indicate that the atmospheric particulate matter emitted from Cu-smelting has a high residence time in the atmosphere. This indicates that the Cu-smelter can impact areas of high ecological interest and considered as clean air.

Urban NH3 levels and sources in six major Spanish cities.

A detailed spatial and temporal assessment of urban NH3 levels and potential emission sources was made with passive samplers in six major Spanish cities (Barcelona, Madrid, A Coruña, Huelva, Santa Cruz de Tenerife and Valencia). Measurements were conducted during two different periods (winter-autumn and spring-summer) in each city. Barcelona showed the clearest spatial pattern, with the highest concentrations in the old city centre, an area characterised by a high population density and a dense urban architecture. The variability in NH3 concentrations did not follow a common seasonal pattern across the different cities. The relationship of urban NH3 with SO2 and NOX allowed concluding on the causes responsible for the variations in NH3 levels between measurement periods observed in Barcelona, Huelva and Madrid. However, the factors governing the variations in A Coruña, Valencia and Santa Cruz de Tenerife are still not fully understood. This study identified a broad variability in NH3 concentrations at the city-scale, and it confirms that NH3 sources in Spanish urban environments are vehicular traffic, biological sources (e.g. garbage containers), wastewater treatment plants, solid waste treatment plants and industry. The importance of NH3 monitoring in urban environments relies on its role as a precursor of secondary inorganic species and therefore PMX. Further research should be addressed in order to establish criteria to develop and implement mitigation strategies for cities, and to include urban NH3 sources in the emission inventories.

Chemical and microbiological characterization of atmospheric particulate matter during an intense African dust event in Southern Spain.

This study presents the results of the physicochemical characterization of particulate matter associated with an important dust event from the Sahara area that occurred in the South of Spain in 2010. The chemical composition of the samples reflected the dominance of the crustal component of sand from the Sahara desert, although the presence of Mo, Ti, and V trace elements indicated that the dust contained industrial material; probably collected in its transport from Africa. Microbial biodiversity associated with the dust was low, but dominated by Firmicutes and Proteobacteria. Some Firmicutes (belonging to the genus Bacillus and Sporosarcina) were cultured on solid and liquid medium, which suggested that the transported microbes were alive or present as spores that germinated under favorable conditions. These cultivable microbes in the form of spores were highly resistant to desiccation, heat, and UV light.

Contribution of mine wastes to atmospheric metal deposition in the surrounding area of an abandoned heavily polluted mining district (Rio Tinto mines, Spain).

The present study seeks to estimate the impact of abandoned mine wastes on the levels and chemical profile of total atmospheric deposition in one of the oldest and largest mining districts in Europe (Rio Tinto mines, Iberian Pyrite Belt), on the basis of a complete geochemical characterization of particulate matter samples periodically collected in five sampling stations located around the mining district between March 2009 and February 2011. The annual levels of total bulk deposition (soluble and insoluble fractions) registered in the Rio Tinto Mining District ranged between 18 and 43 g/m(2) depending on the distance from the sampling station with regard to the mine waste deposits. As a general pattern in the area, high mass levels of Zn and Cu were deposited in a range of 9-62 mg/m(2) not only in the insoluble but also in the soluble fraction. Other potentially toxic trace elements such as As, Sb, Ba, Pb, Sn and Bi showed greater deposition fluxes in the locations closest to the mine waste deposits. A principal component analysis with a Multilinear Regression Analysis certifies the presence of two common sources in the mining area: 1) a mineral factor composed mainly of elements derived from silicate minerals (Al, Ca, Sr, Ti, Li, Mg, Mn, K, Na and Fe), mixed with other anthropogenic species (NH4(+), SO4(2-), NO3(-)) within the village closest to the mine; and 2) a marine factor composed of Na, Cl, Mg, SO4(2-) and Sr. In addition, a mine waste factor made up of toxic elements (Cu, Zn, Ga, As, Sb, Ba, Pb, Sn, Cd and Bi) has been recognized in the sampling sites exposed to dust-bearing winds downwind of the mining area, suggesting that mine wastes are a relevant source of heavy-mineral particles with potentially adverse environmental effects to surrounding soils, plants and humans.

Impact of abandoned mine waste on atmospheric respirable particulate matter in the historic mining district of Rio Tinto (Iberian Pyrite Belt).

This work documents for the first time the levels and composition of atmospheric particulate matter in the historic mining district of Rio Tinto (Spain) to estimate the contribution and impact of resuspended particles from hazardous mine waste on air quality. The resuspended mine waste dust contributes notably (32%) to the total concentrations of toxic trace metals (Bi, As, Cu, Pb, Cd, Zn and Sb) into the atmosphere, with the consequent impact on public health.

Variations in vanadium, nickel and lanthanoid element concentrations in urban air.

The emission of trace metal pollutants by industry and transport takes place on a scale large enough to alter atmospheric chemistry and results in measurable differences between the urban background of inhalable particulate matter (PM) in different towns. This is particularly well demonstrated by the technogenic release into the atmosphere of V, Ni, and lanthanoid elements. We compare PM concentrations of these metals in large datasets from five industrial towns in Spain variously influenced by emissions from refinery, power station, shipping, stainless steel, ceramic tiles and brick-making. Increased La/Ce values in urban background inhalable PM, due to La-contamination from refineries and their residual products (fuel oils and petcoke), contrast with Ce-rich emissions from the ceramic related industry, and clearly demonstrate the value of this ratio as a sensitive and reliable tracer for many point source emissions. Similarly, anomalously high V/Ni values (>4) can detect the influence of nearby high-V petcoke and fuel oil combustion, although the use of this ratio in urban background PM is limited by overlapping values in natural and anthropogenic materials. Geochemical characterisation of urban background PM is a valuable compliment to the physical monitoring of aerosols widely employed in urban areas, especially given the relevance of trace metal inhalation to urban health issues.

Organic speciation of atmospheric particles in Alvão Natural Park (Portugal).

PM(10) continental rural background aerosols were collected during a summer field campaign (August-September 2006) at Lamas de Olo in the upper zone of the Alvão Natural Park, a mountain region of northern Portugal. In addition to the determination of the carbonaceous content by a thermal-optical method, the organic speciation of aerosols was performed by gas chromatography-mass spectrometry in an effort to evaluate photo-oxidation products of biogenic volatile organic compounds and other markers for source characterization. The detailed analysis revealed relatively high concentrations of polyols and short-chain dicarboxylic, tricarboxylic, hydroxycarboxylic, and oxocarboxylic acids, many of which are thought to be indicators of secondary aerosol formation, accounting for about 70% of global chromatographically resolved mass. Major photo-oxidation products of alpha- and beta-pinene have been detected. The tracers for the photo-oxidation of isoprene comprise two diastereoisomeric 2-methyltetrols, C(5)-alkene triols, and 2-methylglyceric acid, which have only recently been elucidated. In addition, the occurrence of levoglucosan and other biomass combustion tracers indicates that the site was affected by wildfires. This source contributed to more than 80% of the organic carbon mass during a period of strong forest fire influence.

Arsenic speciation of atmospheric particulate matter (PM10) in an industrialised urban site in southwestern Spain.

An arsenic speciation study has been performed in PM10 samples collected on a fortnight basis in the city of Huelva (SW Spain) during 2001 and 2002. The arsenic species were extracted from the PM10 filters using a NH2OH x HCl solution and sonication, and determined by HPLC-HG-AFS. The mean bulk As concentration of the samples analyzed during 2001 and 2002 slightly exceed the mean annual 6 ng m(-3) target value proposed by the European Commission for 2013, arsenate [As(V)] being responsible for the high level of arsenic. The speciation analyses showed that As(V) was the main arsenic species found, followed by arsenite [As(III)] (mean 6.5 and 7.8 ng m(-3) for As(V), mean 1.2 and 2.1 ng m(-3) for As(III), in 2001 and 2002, respectively). The high levels of arsenic species found in PM10 in Huelva have a predominant industrial origin, such as the one from a nearby copper smelter, and do not present a seasonal pattern. The highest daily levels of arsenic species correspond to synoptic conditions in which the winds with S and SW components transport the contaminants from the main emission source. The frequent African dust outbreaks over Huelva may result in an increment of mass levels of PM10, but do not represent a significant input of arsenic in comparison to the anthropogenic source. The rural background levels of arsenic around Huelva are rather high, in comparison to other rural or urban areas in Spain, showing a relatively high atmosphere residence time of arsenic. This work shows the importance of arsenic speciation in studies of aerosol chemistry, due to the presence of arsenic species [As(III) and As(V)] with distinct toxicity.

Geochemistry and origin of PM10 in the Huelva region, Southwestern Spain.

The results of chemical analysis of PM(10) atmospheric dust samples collected between July 2001 and June 2002 in rural and urban background monitoring stations in Huelva (South-western Spain) are reported. In order to identify the sources and quantify their contribution to PM(10), principal component analysis and receptor modelling techniques were performed using independent variables of the complete series of concentrations of PM(10) contents. The Ria of Huelva is considered to be one of the high industrial estates in Spain, where several metallurgical, petrochemical and fertilizer industrial estates are located, surrounded by areas of a high ecological interest such as Doñana National Park. Annual means of 29-33 and 37 micro g PM(10)m(-3) were obtained for the study period in rural and urban monitoring stations, respectively. These values are below the mean annual limit value for 2005 and onwards from the Directive 1999/30/EC [EU, 1999. 1999/30/CE Council Directive relating to limit values for sulphur dioxide, nitrogen dioxide and oxide of nitrogen, particulate matter and lead in ambient air. The Council of the European Union]. High PM(10) episodes in rural and urban areas occurred during African dust events. Episodically, the emissions of plumes from industrial estates reach rural areas causing peak episodes of PO(4)(3-) Cu, Ti Pb and As. Anthropogenic particles arising from metallurgical emissions (pyrite, chalcopyrite and sphalerite) were observed in the rural sites. The annual mean As concentrations measured in PM(10) in the city of Huelva and surrounding rural areas (144 and 84-51mg Askg(-1) in PM(10), respectively) are several times high the concentrations obtained in other Spanish monitoring stations (7-57mg Askg(-1)). The source apportionment analyses allowed the quantification of the contribution to PM(10) of an industrial mixed source in the rural background.

Identification and chemical characterization of industrial particulate matter sources in southwest Spain.

A detailed physical and chemical characterization of coarse particulate matter (PM10) and fine particulate matter (PM2.5) in the city of Huelva (in Southwestern Spain) was carried out during 2001 and 2002. To identify the major emission sources with a significant influence on PM10 and PM2.5, a methodology was developed based on the combination of: (1) real-time measurements of levels of PM10, PM2.5, and very fine particulate matter (PM1); (2) chemical characterization and source apportionment analysis of PM10 and PM2.5; and (3) intensive measurements in field campaigns to characterize the emission plumes of several point sources. Annual means of 37, 19, and 16 microg/m3 were obtained for the study period for PM10, PM2.5, and PM1, respectively. High PM episodes, characterized by a very fine grain size distribution, are frequently detected in Huelva mainly in the winter as the result of the impact of the industrial emission plumes on the city. Chemical analysis showed that PM at Huelva is characterized by high PO4(3-) and As levels, as expected from the industrial activities. Source apportionment analyses identified a crustal source (36% of PM10 and 31% of PM2.5); a traffic-related source (33% of PM10 and 29% of PM2.5), and a marine aerosol contribution (only in PM10, 4%). In addition, two industrial emission sources were identified in PM10 and PM2.5: (1) a petrochemical source, 13% in PM10 and 8% in PM2.5; and (2) a mixed metallurgical-phosphate source, which accounts for 11-12% of PM10 and PM2.5. In PM2.5 a secondary source has been also identified, which contributed to 17% of the mass. A complete characterization of industrial emission plumes during their impact on the ground allowed for the identification of tracer species for specific point sources, such as petrochemical, metallurgic, and fertilizer and phosphate production industries.