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One of the major problems of the present era is air pollution, not only for its impact on climate change but also for the diseases provoked by this scourge. Among the most concerning air pollutants is particulate matter, since it can travel long distances and affect the entire globe. Antarctica is extremely sensitive to climate change and essential for regulating temperature and permitting life on Earth. Therefore, air quality studies in this region are extremely important. The aim of this review is to present the work conducted on the identification and detection of aerosols and particulate matter in the Antarctic region in the last 20 years. These studies revealed a large number of organic and inorganic species. Organochlorine pesticides or polychlorinated biphenyls represent almost 50% of the organic fraction detected in Antarctica. Furthermore, heavy metals such as Hg and Pb were also found in the region related to anthropogenic activities. To summarize, this work detailed different analytical techniques and data processing to help characterize Antarctic aerosols and their potential sources. [ABSTRACT FROM AUTHOR]

One of the major problems of the present era is air pollution, not only for its impact on climate change but also for the diseases provoked by this scourge. Among the most concerning air pollutants is particulate matter, since it can travel long distances and affect the entire globe. Antarctica is extremely sensitive to climate change and essential for regulating temperature and permitting life on Earth. Therefore, air quality studies in this region are extremely important. The aim of this review is to present the work conducted on the identification and detection of aerosols and particulate matter in the Antarctic region in the last 20 years. These studies revealed a large number of organic and inorganic species. Organochlorine pesticides or polychlorinated biphenyls represent almost 50% of the organic fraction detected in Antarctica. Furthermore, heavy metals such as Hg and Pb were also found in the region related to anthropogenic activities. To summarize, this work detailed different analytical techniques and data processing to help characterize Antarctic aerosols and their potential sources.

The linkage between precipitation and recharge is still poorly understood in the Central America region. This study focuses on stable isotopic composition in precipitation and groundwater in the northern mountainous region of the Central Valley of Costa Rica. During the dry season, rainfall samples corresponded to enriched events with high deuterium excess. By mid-May, the Intertropical Convergence Zone poses over Costa Rica resulting in a depletion of18O/16O and2H/H ratios. A parsimonious four-variable regression model (r2 = 0.52) was able to predict daily δ18O in precipitation. Air mass back trajectories indicated a combination of Caribbean Sea and Pacific Ocean sources, which is clearly depicted in groundwater isoscape. Aquifers relying on Pacific-originated recharge exhibited a more depleted pattern, whereas recharge areas relying on Caribbean parental moisture showed an enrichment trend. These results can be used to enhance modelling efforts in Central America where scarcity of long-term data limits water resources management plans. [ABSTRACT FROM AUTHOR]

Human health burdens associated with long-term exposure to particulate matter (PM) are substantial. The metrics currently recommended by the World Health Organization for quantification of long-term health-relevant PM are the annual average PM 10 and PM 2.5 mass concentrations, with no low concentration threshold. However, within an annual average, there is substantial variation in the composition of PM associated with different sources. To inform effective mitigation strategies, therefore, it is necessary to quantify the conditions that contribute to annual average PM 10 and PM 2.5 (rather than just short-term episodic concentrations). PM 10 , PM 2.5 , and speciated water-soluble inorganic, carbonaceous, heavy metal and polycyclic aromatic hydrocarbon components are concurrently measured at the two UK European Monitoring and Evaluation Programme (EMEP) ‘supersites’ at Harwell (SE England) and Auchencorth Moss (SE Scotland). In this work, statistical analyses of these measurements are integrated with air-mass back trajectory data to characterise the ‘chemical climate’ associated with the long-term health-relevant PM metrics at these sites. Specifically, the contributions from different PM concentrations, months, components and geographic regions are detailed. The analyses at these sites provide policy-relevant conclusions on mitigation of (i) long-term health-relevant PM in the spatial domain for which these sites are representative, and (ii) the contribution of regional background PM to long-term health-relevant PM. At Harwell the mean (± 1 sd) 2010–2013 annual average concentrations were PM 10 = 16.4 ± 1.4 μg m − 3 and PM 2.5 = 11.9 ± 1.1 μg m − 3 and at Auchencorth PM 10 = 7.4 ± 0.4 μg m − 3 and PM 2.5 = 4.1 ± 0.2 μg m − 3 . The chemical climate state at each site showed that frequent, moderate hourly PM 10 and PM 2.5 concentrations (defined as approximately 5–15 μg m − 3 for PM 10 and PM 2.5 at Harwell and 5–10 μg m − 3 for PM 10 at Auchencorth) determined the magnitude of annual average PM 10 and PM 2.5 to a greater extent than the relatively infrequent high, episodic PM 10 and PM 2.5 concentrations. These moderate PM 10 and PM 2.5 concentrations were derived across the range of chemical components, seasons and air-mass pathways, in contrast to the highest PM concentrations which tended to associate with specific conditions. For example, the largest contribution to moderate PM 10 and PM 2.5 concentrations – the secondary inorganic aerosol components, specifically NO 3 − – were accumulated during the arrival of trajectories traversing the spectrum of marine, UK, and continental Europe areas. Mitigation of the long-term health-relevant PM impact in the regions characterised by these two sites requires multilateral action, across species (and hence source sectors), both nationally and internationally; there is no dominant determinant of the long-term PM metrics to target. [ABSTRACT FROM AUTHOR]

Costa Rica is located on the Central American Isthmus, which receives moisture inputs directly from the Caribbean Sea and the Eastern Pacific Ocean. This location includes unique mountainous and lowland microclimates, but only limited knowledge exists about the impact of relief and regional atmospheric circulation patterns on precipitation origin, transport, and isotopic composition. Therefore, the main scope of this project is to identify the key drivers controlling stable isotope variations in daily-scale precipitation of Costa Rica. The monitoring sites comprise three strategic locations across Costa Rica: Heredia (Central Valley), Turrialba (Caribbean slope), and Caño Seco (South Pacific slope). Sporadic dry season rain is mostly related to isolated enriched events ranging from −5.8‰ to −0.9‰ δ 18 O. By mid-May, the Intertropical Convergence Zone reaches Costa Rica resulting in a notable depletion in isotope ratios (up to −18.5‰ δ 18 O). HYSPLIT air mass back trajectories indicate the strong influence on the origin and transport of precipitation of three main moisture transport mechanisms, the Caribbean Low Level Jet, the Colombian Low Level Jet, and localized convection events. Multiple linear regression models constructed based on Random Forests of surface meteorological information and atmospheric sounding profiles suggest that lifted condensation level and surface relative humidity are the main factors controlling isotopic variations. These findings diverge from the recognized ‘amount effect’ in monthly composite samples across the tropics. Understanding of stable isotope dynamics in tropical precipitation can be used to a) enhance groundwater modeling efforts in ungauged basins where scarcity of long-term monitoring data drastically limit current and future water resources management, b) improve the re-construction of paleoclimatic records in the Central American land bridge, c) calibrate and validate regional circulation models. [ABSTRACT FROM AUTHOR]

The goal of this research is to determine trends and sources of airborne particulates in the centre of Lisbon, by using speciated particulate-matter data and back-trajectory analyses. Results showed that, in 2007, the annual PM2.5 concentration exceeded the World Health Organization recommended levels. PM2.5 diurnal variability and the ratio between weekdays’ and weekends’ concentrations indicated that traffic contributed highly to decreasing air quality. Air back-trajectory analysis showed that maritime air mass transport had a significant role on air quality in Lisbon, promoting the decrease of anthropogenic aerosol concentrations. [ABSTRACT FROM AUTHOR]

The determination of the chemical composition of rainfall related to the origin of the air masses, in two urban sites in Greece during the year 2006, is investigated in this study. Two model automatic rain samplers were installed, the first in the city of Larissa, Thessaly, central Greece and the second in Heraklio, Attica, a northern suburb of Athens. The concentrations (ppm) of the major cations (H+, Na+, K+, Ca2+ NH4+ and Mg2+) and major anions (NO3-, NO2-, HCO3-, and SO42-), as well as total hardness (ppm CaCO3), pH and electric conductivity in 25 °C (μS/cm) for 27 rainfall samples -11 samples in Larissa and 16 samples in Heraklio (Athens)- were determined. In Larissa, the figures of pH range from 5.13 to 6.13 while in Heraklio (Athens), the pH within the range 5.62 to 7.88 indicates a shift of the rainfalls towards alkalinity. The electric conductivity in Larissa ranges from 16.30 μS/ cm to 110.60 μS/cm and in Heraklio (Athens) from 7.00 μS/ cm to 151.00 μS/cm. The analysis showed that Ca2+ and Mg2+ appear the highest concentrations out of the examined cations, while HCO3- and SO4M-2 present the highest concentrations within the anions. Moreover, in order to find out the origin of the air masses, the air mass back trajectories were calculated using the HYSPLIT 4 model of Air Resources Laboratory of NOAA for two different levels: 1500 and 3000 m (a.m.s.l.). [ABSTRACT FROM AUTHOR]

The goal of this study is to determine the chemical composition of rain, in the wider region of Athens, Greece for the time period 1st September 2001 to 31st August 2002. Two model automatic rain samplers were installed in the Meteorological Station of Laboratory of Climatology (latitude: 37° 58′ N, longitude: 23° 47′ E) inside the Athens University Campus and in a site at Heraklio Attica, a northern suburb of Athens (latitude: 38° 03′ N, longitude: 23° 45′ E). The concentrations (μeq l−1) of the major cations (H+, Na+, K+, Ca2+ and Mg2+) and anions (Cl−, $$ {\text{NO}}^{ - }_{3} $$ , $$ {\text{HCO}}^{ - }_{3} $$ και $$ {\text{SO}}^{{2 - }}_{4} $$ ), as well as pH and conductivity of rain in 39 total samples were determined. The figures of pH range from 6.4 to 8.4 and conductivity from 8 to 207 μS cm−1. The analysis showed that Ca2+ ions are abundant within all examined samples, while $$ {\text{HCO}}^{ - }_{3} $$ and $$ {\text{SO}}^{{2 - }}_{4} $$ present the highest concentrations from the anions. In order to find out the origin of the air masses, the air mass back trajectories were calculated. Five sectors of the origin of air masses were revealed: the North, the South, the Local, the West and the East sector. Multivariate methods included Factor Analysis and Discriminant Analysis were applied to the examined ion concentrations and three main factors were extracted, which discriminated the ions according to their origin. The first group of ions is interpreted as the result of the anthropogenic activity, the second group represents the acidity–alkalinity independently of their source and the third one the marine influence. [ABSTRACT FROM AUTHOR]

Abstract: The current work presents dry deposition fluxes of trace metals to the Southern and Northern Levantine Basin of the Eastern Mediterranean Sea. The dry depositional inputs were calculated taking into account (i) the spatial gradients in metal aerosol concentrations across the Levantine Basin (using concentrations from two location, Erdemli, Turkey and Tel Shikmona, Israel over a 3 year sampling period), (ii) the air mass origins, (iii) air mass temporal influence across the north and south Levantine basins and (iv) fine/coarse elemental aerosol size mass distributions allowing the use of new elemental settling velocities. Two distinct airflow sectors were defined at each site; North (N) and southwest (SW), having different temporal influences at each site (the temporal ratio of SW:N was 1.85 and 0.43 at Tel Shikmona and Erdemli, respectively). Temporal airflow weighted aerosol concentrations were then calculated for each site. The applied settling velocities calculated using size fractioned aerosol samples () collected from Erdemli and from the literature, yielded higher (compared to previous work) settling velocities for Cu, Pb, and Zn being 1.1, 0.8 and 0.9cms−1, respectively. Total dry deposition fluxes for the crustal elements (Al, Fe and Mn) were consistent with previous studies for the region; however, Cu, Pb, and Zn were much higher, in part, due to the larger adopted settling velocities. Using sequential leach data, the “exchangeable” as well as total elemental dry inputs were presented for both the north and south Levantine basins. Comparison with limited literature wet deposition would suggest that the dry deposition pathway is a more significant input for Cu, Pb, and possibly Al and Fe. The “exchangeable” dry atmospheric inputs of Pb, Cu and Cd to the southern basin were orders of magnitude greater than dissolved riverine inputs. A similar comparison could not be made for the northern basin owing to absence of riverine input data. [Copyright &y& Elsevier]

Major anions and cations were analyzed in a wet-only precipitation study for 16 months. The pH exhibited large variation, from 4.07 to 8.51 pH units. Twenty-eight percent of the observed rain volume had pH <5, whereas 42% of the rains had pH >6, as is usually observed in the Mediterranean. Comparison with our work of 15 years ago indicates a free acidity reduction by ∼18%, non-sea-salt sulfate ions reduction of ∼40% and nitrate ions reduction of 66%. Chloride and all cation concentrations were similar in the present work and that carried out in 1985–86 indicating similar sources, namely aerosol and crustal material as in MS. Calcium ions were the dominating neutralization ions. The annual wet-only deposition rates were calculated for the major species and were found to be comparable to those reported in past studies. Deposition of calcium ions dominates all deposited species, except sea salt, and indicates its significance in the neutralizing mechanisms of soils of the region, if neutralization is needed. Air mass back trajectories calculated for all analyzed samples, revealed four sectors of origin of air masses: NW to NE Europe, northern Africa, local and western Mediterranean, each with a specific chemistry. Cluster analysis and factor analysis also discriminated the samples by their sources. The main sources derived from the statistical analysis were: marine aerosols, alkalinity–acidity as inferred by the calcium ion concentrations from crustal sources and hydronium ions mainly from anthropogenic activities and ammonium salts of sulfate and nitrate also mainly from anthropogenic activities. These sources were closely correlated with the geographic sectors obtained from the air mass back trajectories. [Copyright &y& Elsevier]

The Lesser Antilles is an intermediate zone located between the Caribbean Sea and the Atlantic Ocean. This area is frequently affected by the major long range Saharan dust transportation from West African desert sources. The aerosols optical properties are provided by the AEronet Robotic NETwork (AERONET) measurement sites in Puerto Rico, Guadeloupe, and Barbados. Thus, Aerosols Optical Depth (AOD), Angstrom Exponent (AE), Volume Particle Size Distribution (VPSD), complex refractive indexes, and Single Scattering Albedo (SSA) were used to define the predominant type of atmospheric particles namely sea salt aerosols, mineral dust or aerosols mixture. Obtained results show that aerosols in the atmospheric column (AOD) and surface dust measurements (P M 10) are well correlated with correlation coefficients of 0.72 and 0.81 respectively for Puerto Rico, and Guadeloupe. Detailed analysis of optical data associated to daily P M 10 concentrations highlighted that dust phenomenon can be observable below P M 10 threshold of 50 μ g ∕ m 3 given by the European directives to detect dust episodes. Indeed, for Caribbean islands, episodes of desert dust phenomenon have been detected from 35 μ g ∕ m 3 . The climatological assessment of monthly dust events observed in Puerto Rico, Guadeloupe, and Martinique between 2006 and 2016 highlighted a low dust season from November to February and a high dust season from May to August. Both seasons are separated by two transition dust periods: March to April and September to October. Lastly, the day-to-day back trajectories (NOAA-HYSPLIT) illustrated the general atmospheric circulation and show three main dust transportation routes: the North West African Path (62.7%); the South West African Path (20.8%) ; and the North East Atlantic Path (15.1%). By computing the average P M 10 concentrations bring from each path, we notice that South West African Path is the most loaded in mineral dust because he comes from one of the most persistently active and intense dust sources in the world, i.e. Bodélé Depression in northern Chad. • Microphysical characterization of aerosol particles in Caribbean islands is studied. • Surface dust concentrations are linked to aerosol optical properties. • A new PM10 threshold linked to African dust in the Lesser Antilles is proposed. • General circulation of dusty air mass paths in the North Atlantic area is identified. • Impact of desert dust phenomenon on vertical temperature profile is highlighted. [ABSTRACT FROM AUTHOR]