EMEP Station Research Articles

Decadal trends (2009–2018) in Saharan dust transport at Mt. Martano EMEP station, Italy

Saharan dust advections in the Mediterranean Basin are widely studied and subjected to specific regulations due to their impact on the air quality of European cities. As a natural phenomenon, their contribution to PM should be accurately quantified in order to correctly evaluate their impact in anthropized areas. The identification and quantification of Saharan dust advections should be carried out in rural regional background sites. However, there is a lack of suitable sites in Central and Southern Italy, despite its strategic positioning in the Central Mediterranean area. The rural regional background site of Monte Martano site can fill this gap. This study aims at characterising the 10 years climatology of dust at the Monte Martano (MM) site and integrate it in the wider Mediterranean Basin monitoring network. Monte Martano is barely affected by local emissions, with average PM10 concentration of 11.0 ± 7.4 μg m−3, and a marked seasonality compatible with the evolution of the planetary boundary layer (PBL) during the year. Saharan dust advections contribute for 45.9 days per year on average, with a dust load that accounts for 48% of the background PM10 value. The Saharan dust advections' frequency, duration and intensity were evaluated, and a clear seasonality was detected, with minimum probability in summer and long-lasting events mainly occurring in spring and autumn. The dust load calculation was performed with 3 different methods, the EU guideline method, the modified DIAPASON methodology specifically designed for Central Italy and the DREAM8b model. The comparison between the three methods showed a substantial overestimation of the dust load by the model, while the two experimental methods are in accordance (R = 0.97). In conclusion, the MM site has proven to be suitable for Saharan dust monitoring in Central Italy, providing a new insight in the Central Mediterranean Saharan dust observation network.

Analysis of sulfate aerosols over Austria: a case study

Abstract. An increase in the sulfate aerosols observed in the period 1–6 April 2014 over Austria is analyzed using in situ measurements at an Austrian air quality background station, lidar measurements at the closest EARLINET stations around Austria, CAMS near-real-time data, and particle dispersion modeling using FLEXPART, a Lagrangian transport model. In situ measurements of SO2, PM2.5, PM10, and O3 were performed at the air quality background station Pillersdorf, Austria (EMEP station AT30, 48∘43′ N, 15∘55′ E). A CAMS aerosol mixing ratio analysis for Pillersdorf and the lidar stations Leipzig, Munich, Garmisch, and Bucharest indicates the presence of an event of aerosol transport, with sulfate and dust as principal components. For the sulfate layers identified at Pillersdorf from the CAMS analysis, backward- and forward-trajectory analyses were performed, associating lidar stations with the trajectories. The lidar measurements for the period corresponding to trajectory overpass of associated stations were analyzed, obtaining the aerosol layers, the optical properties, and the aerosol types. The potential sources of transported aerosols were determined for Pillersdorf and the lidar stations using the source–receptor sensitivity computed with FLEXPART, combined with the MACCity source inventory. A comparative analysis for Pillersdorf and the trajectory-associated lidar stations showed consistent aerosol layers, optical properties and types, and potential sources. A complex pattern of contributions to sulfate over Austria was found in this paper. For the lower layers (below 2000 m) of sulfate, it was found that central Europe was the main source of sulfate. Medium to smaller contributions come from sources in eastern Europe, northwest Africa, and the eastern US. For the middle-altitude layers (between 2000 and 5000 m), sources from central Europe (northern Italy, Serbia, Hungary) contribute with similar emissions. Northwest Africa and the eastern US also have important contributions. For the high-altitude layers (above 5000 m), the main contributions come from northwest Africa, but sources from the southern and eastern US also contribute significantly. No contributions from Europe are seen for these layers. The methodology used in this paper can be used as a general tool to correlate measurements at in situ stations and EARLINET lidar stations around these in situ stations.

TIME SERIES ANALYSIS OF AIR POLLUTANTS RECORDED FROM ROMANIAN EMEP STATIONS AT MOUNTAIN SITES

The present study analyzes the background pollution in Romania using official data reported for recorded air pollutants from the automated regional stations located at three mountain sites. A series of key figures regarding the trend of background pollution at Romanian mountain sites was extracted based on annual average concentrations recorded between 2010 and 2013 i.e. 8.8 5.2 g NO2/m3, 5.3 1.6 g SO2/m3, 0.075 0.035 g CO/m3, 3.2 0.9 g C6H6/m3 and 11.4 6.9 g PM10/m3. A case study is presented for EM-3 EMEP Station (RO0008R, Poiana Stampei) located in the north of Romania. Multivariate techniques provided the trends and patterns of collected data structure. Meteorological input data were long time series (1961-2012) of air pressure, air temperature, precipitations, sunshine hours, cloud cover, and relative humidity in the area. Strong correlations were observed between air pollutants, and between air pollutants and meteorological factors. The latent factors resulted from the Principal Component Analysis have explained the total variance in the data structure of Poiana Stampei as follows: factor 1 meteorology; factor 2 aerosols; and factor 3 heavy metals. NOAA HYSPLIT backward trajectory model was applied to overview the most probable source region of two pollution episodes (NO2 and SO2) at EM-3 location. The results confirmed that meteorological processes, local topography and air mass trajectory controlled significantly the amount of air pollution in the studied area.

Lead in atmospheric precipitation: Analysis of atmospheric precipitation pollution monitoring data for location “Kamenicki vis”, Serbia

In this paper an overview of data collected during monitoring of lead content in atmospheric precipitation on GAW/EMEP (Global Atmosphere Watch/European Monitoring and Evaluation Programme) station ?Kamenicki Vis?, Serbia from 2000 to 2010 is given. Annual arithmetic mean concentrations, weighted arithmetic mean concentrations, and median of week samples are presented. Obtained data was compared with results of analysis of atmospheric precipitation collected on experimental EMEP station ?Zeleno brdo?, Serbia and discussed in scope of European average levels of lead content in precipitation and air. Significant increase of average annual lead content in precipitation was observed in 2003 and 2007. Observed peaks can not be seen on average European trends thus lead to conclusion that recorded increases are characteristic for local region. In order to further discuss nature and direction of possible sources of detected lead pollution short analysis of lead emission data was performed. An effort was made to gather data from the counties that lay in directions from which dominant winds blow as well as for Serbia. For this purpose total national emissions from LRTAP (Long-range transboudary air pollution) Convention emission inventory report and EMEP emission inventory were used as well as data published by relevant national authorities. According to these emission levels, majority of surrounding countries couldn?t have contributed much to the recorded increases of lead content in precipitation. However, several possible sources were revealed. In all studied countries emission levels steadily dropped during the analyzed period, whereas only for Serbia different trend was observed. Presented data leads to conclusion that recorded increase of lead content in precipitation in 2003 probably originates from trans-boundary contributions, while increases in 2007 and onwards may come from Serbia?s own emissions.

Air Masses and Weather Types: A Useful Tool for Characterizing Precipitation Chemistry and Wet Deposition

This study is an analysis of 344 days with rainfall recorded during five years in a remote regional background EMEP (Cooperative Programme for the Monitoring and Evaluation of the Long Range Transmission of Air Pollutants in Europe) station in Spain. The chemical composition of the rainwater associated with air masses (nine categories) and weather types (26 categories) was characterized. The chemical composition of rainwater was dominated by calcium (Ca2+) and sulphate (SO42−-S), with VWM (Volume Weighted Mean) during the period studied (2002–2006), with 55 μeq/L and 34 μeqS/L, respectively. Calcium, sodium (Na+), ammonium (NH4+-N) and magnesium (Mg2+) seem to be dominant components in the neutralization of the rainwater. By applying Pearson correlations, principal component analysis and enrichment factors, it is possible to identify source types for the precipitation constituents. Interannual and intra-annual variability was also been studied. High calcium levels are associated with the frequent intrusions of Saharan dust that occur during the summer, and the maximums of chlorine and sodium in the winter may be due to the greater amount of maritime air recorded during this season. Wet deposition was determined by focusing on nitrogen deposition, registering mean annual values of 155 mgN/m2/year (from the NO3−-N) and 165 mgN/m2/year (from the NH4+-N).

Sensitivity of Beech Trees to Global Environmental Changes at Most North-Eastern Latitude of Their Occurrence in Europe

The present study aimed to detect sensitivity of beech trees (Fagus sylvatica L.) to meteorological parameters and air pollution by acidifying species as well as to surface ozone outside their north-eastern distribution range. Data set since 1981 of Preila EMEP station enabled to establish that hot Summers, cold dormant, and dry and cold first-half of vegetation periods resulted in beech tree growth reduction. These meteorological parameters explained 57% variation in beech tree ring widths. Acidifying species had no significant effect on beech tree growth. Only ozone was among key factors contributing to beech stand productivity. Phytotoxic effect of this pollutant increased explanation rate of beech tree ring variation by 18%, that is, up to 75%. However, due to climate changes the warmer dormant periods alone are not the basis ensuring favourable conditions for beech tree growth. Increase in air temperature in June-August and decrease in precipitation amount in the first half of vegetation period should result in beech tree radial increment reduction. Despite the fact that phytotoxic effect of surface ozone should not increase due to stabilization in its concentration, it is rather problematic to expect better environmental conditions for beech tree growth at northern latitude of their pervasion.

Chemical composition of wet precipitation at the background EMEP station in Víznar (Granada, Spain) (2002–2006)

This study describes winter precipitation chemistry data (2002–2006) from a remote regional background EMEP station located at Víznar (Granada, Spain). The rainwater samples collected were analyzed for pH, major ion concentrations and conductivity. Wet-only precipitation chemistry was dominated by Ca 2+, SO 4 2− and Cl − and the station did not have an acid rain problem (pH lies between 5.8 and 7.4). The samples were classified into nine groups of origin considering the back-trajectory and the chemical composition of the precipitation due to its meteorological origin. Saharan air masses at 1500 m and 3000 m a.g.l. seem to have an important influence on chemical rain composition. Among the marine air masses, the Mediterranean air mass carries the smallest amount of contaminants. Important correlations have been found between acidic anions (SO 4 2− and NO 3 −) and crustal-derived cations (Mg 2+, Ca 2+, and K +), suggesting the absorption of acid elements contained in aerosols, such as sulfuric acid and nitric acid, and the subsequent reaction with alkaline components rich in carbonate materials contained in particulate matter. Principal Component Factor Analysis was used in order to provide quantitative insights into the sources of specific chemical components in precipitation. Enrichment factors relative to soil and seawater have also been calculated. Although both Mg 2+ and K + have a crustal origin, a certain marine contribution is also observed.

ECHMERIT V1.0 – a new global fully coupled mercury-chemistry and transport model

Abstract. Mercury is a global pollutant due to its long lifetime in the atmosphere. Its hemispheric transport patterns and eventual deposition are therefore of major concern. For the purpose of global atmospheric mercury chemistry and transport modelling the ECHMERIT model was developed. ECHMERIT, based on the global circulation model ECHAM5 differs from most global mercury models in that the emissions, chemistry (including general tropospheric chemistry and mercury chemistry), transport and deposition are coupled on-line to the GCM. The chemistry mechanism includes an online calculation of photolysis rate constants using the Fast-J photolysis mechanism, the CBM-Z tropospheric gas-phase mechanism and aqueous-phase chemistry based on the MECCA mechanism. Additionally, a mercury chemistry mechanism that incorporates gas and aqueous phase mercury chemistry is included. A detailed description of the model, including the wet and dry deposition modules, and the implemented emissions is given in this technical report. First model testing and evaluation show a satisfactory model performance for surface ozone and mercury mixing ratios (with a mean bias of 1.46 nmol/mol for ozone and a mean bias of 13.55 fmol/mol for TGM when compared with EMEP station data). Requirements regarding measurement data and emission inventories which could considerably improve model skill are discussed.

Relationship Between 4-Day Air Mass Back Trajectories and Metallic Components in PM10 and PM2.5 Particle Fractions in Zagreb Air, Croatia

This paper presents a study on the relationship between trace metal concentrations and the state of the atmosphere at the Croatian EMEP station Puntijarka, Zagreb. PM(10) and PM(2.5) particle fractions are hazardous in terms of morbidity and hospitalization due to cardiovascular and respiratory diseases, and in terms of total mortality. In Zagreb, PM(10) and PM(2.5) monitoring started on a daily basis at a sampling site located in the northern, residential part of the city. Trace metal concentrations were determined from daily samples. Air mass back trajectories were used to determine particulate air pollution from local and remote sources. The investigation has shown a statistically significant association between air mass back trajectories and metallic air concentration levels.

Evaluation and application of a statistical model for assessment of long-range transported proportion of PM 2.5 in the United Kingdom and in Finland

We have developed a simple statistical model for the estimation of the long-range transport (LRT) contribution to PM 2.5 concentrations. The modelling is based on linear regressions of the ‘Co-operative programme for monitoring and evaluating the long-range transmission of air pollutants in Europe’ (EMEP) background ionic components (SO 4 2−, NO 3 −, NH 4 +) with the monitored PM 2.5 concentrations. We present an evaluation and application of the model against data measured in the United Kingdom (UK) and in Finland. We have studied the correlation of ion sum values with the PM 2.5 data measured at two EMEP stations in Finland (i.e., a comparison of ionic sum and PM 2.5 at one station). The statistical correlations of the PM 2.5 concentrations with the ion sum values were very high ( R 2 varied from 0.77 to 0.83) at both of the stations considered; this provides confidence that the ion sum is a good proxy variable for the LRT PM 2.5. The comparison of different modelling options using the data measured in the UK showed that the regression model gave systematically substantially better results than the model using merely sulphate concentrations. Similarly, using the distance weighted ion sum based on data from two EMEP stations gave better correlation, compared with the option of using only one EMEP station. The evaluated average LRT contribution accounted for 35–37% of the regional air PM 2.5 concentrations in UK from 1998 to 2000. The corresponding contributions at two urban stations in London were 24–31%. We conclude that the model is a useful and simple tool for the assessment of LRT PM 2.5 that is applicable within a fairly good accuracy.

PASSIVE AIR SAMPLING OF PERSISTENT ORGANIC POLLUTANTS IN TWO ESTONIAN AIR MONITORING STATIONS

The Environmental Chemistry and Ecotoxicology Group of Lancaster University, United Kingdom, has completed a large European-scale air sampling campaign within the framework of the project, POPs Fate Modelling. Samplers were deployed at remote, rural and urban locations (71 stations) in 22 countries, two Estonian stations – Lahemaa-background EMEP station and Kohtla-Jarve industrial (oil shale chemistry) region station – among them. This paper presents data on a range of polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (hexachlorocyclobenzene (HCB), hexachlorocyclohexane (HCH), ppDDE, ppDDT), polybrominated diphenyl ethers (PBDEs) and polychlorinated naphthalenes (PCN) determined in ambient air samples collected at Estonian stations.

Ten years of light hydrocarbons (C 2–C 6) concentration measurements in background air in Finland

Light hydrocarbons (C 2–C 6) have been measured at two background stations, Utö (EMEP station) and Pallas (GAW station), in Finland since 1994. Utö is a small, rocky island in the Baltic Sea southwest of the mainland and Pallas is located in Lapland. Canister samples were taken twice a week and analyzed in a laboratory using gas chromatography. Maximum concentrations are observed in winter due to the very limited amount of daylight and hence of hydroxyl radicals. During spring the concentrations start declining as more light becomes available, and for most of the compounds minimum concentrations are measured during summer. Concentrations are lower at Pallas than on Utö, indicating more aged air there. Only isoprene, ethene and propene have higher concentrations at Pallas, due to natural emissions. Higher concentrations are measured in air masses coming from Central Europe and Russia, whereas air masses coming from the North Sea and the Arctic are cleaner. During the ten years of measurements, the concentrations of ethyne, pentanes and hexanes have decreased by about 10–40%, although only few of these trends are significant. However, the compounds with long lifetimes (ethane and propane) show an increasing trend especially at Pallas. Butane concentrations are also increasing at Pallas. This can indicate an increase of the VOC emissions in areas more distant than Europe.

Chemical composition of rainwater at EMEP station in Ankara, Turkey

The chemical characteristics of rainfall and its seasonal variation at the EMEP (The Cooperative Programme for Monitoring and Evaluation of the Long-Range Transmission of Air Pollutants in Europe) station located in Cubuk, Ankara were studied for the period between September 1994 and December 1996. The station is located in a rural area about 50 km north of Ankara and is considered as a background station for air pollution. The rainwater samples collected were analyzed for pH, major ions concentrations and conductivity. Seasonal variations for some major ions are pronounced. Generally, maximum concentrations appeared in winter or autumn, and minimum concentrations in spring or summer seasons. The average pH of rainwater samples is around 6.3 due to neutralization. Only about 4% of the rain samples had a pH below 5.0 and about 15% of the total rainwater samples had a pH below 5.6. This reflects strong inputs of alkaline species to rainwater samples in this location. The average pH of the samples higher than 5.6 observed in rural area of Ankara is due to a high loading of calcium ions in the form of CaCO 3 because of the alkaline nature of the soil. There is a strong relationship between pHs and other ions in summer. However, in winter, a weak relationship is found between SO 4 2−, NO 3 −, Na + and Mg 2+. On the other hand, relationships between the conductivity and SO 4 2− concentration are stronger in summer than in winter. The low concentrations of H + found in rainwater samples from Cubuk suggests that an important portion of H 2SO 4 and HNO 3 have been neutralized by alkaline particles in the atmosphere. Weak correlations are found between the hydrogen ions and SO 4 2− or NO 3 − ions for all seasons because of neutralization of these ions with alkaline particles. The dust-rich local and surrounding limestone environment might have caused the high concentration of Ca 2+ in Cubuk area. The relatively high concentration of NH 4 + observed at Cubuk is suspected to be due to surrounding agricultural activity. This agricultural activity has been found to be effective not only in spring, but also in autumn and winter to cause neutralization of the rainwater.

The effect of large anthropogenic particulate emissions on atmospheric aerosols, deposition and bioindicators in the eastern Gulf of Finland region

The effect of the emissions from large oil shale fuelled power plants and a cement factory in Estonia on the elemental concentration of atmospheric aerosols, deposition, elemental composition of mosses and ecological effects on mosses, lichens and pine trees in the eastern Gulf of Finland region has been studied. In addition to chemical analysis, fly ash, moss and aerosol samples were analysed by a scanning electron microscope with an energy dispersive X-ray spectrometer (SEM/EDS). The massive particulate calcium emissions, approximately 60 kton/year (1992), is clearly observed in the aerosols, deposition and mosses. The calcium deposition is largest next to the Russian border downwind from the power plants and in south-eastern part of Finland. This deposition has decreased due to the application of dust removal systems at the particulate emission sources. At the Virolahti EMEP station approximately 140 km north from the emission sources, elevated elemental atmospheric aerosol concentrations are observed for Al, Ca, Fe, K and Si and during episodes many trace elements, such as As, Br, Mo, Ni, Pb and V. The acidification of the soil is negligible because of the high content of basic cations in the deposition. Visible symptoms on pine trees are negligible. However, in moss samples close to the power plants, up to 25% of the leaf surface was covered by particles. Many epiphytic lichen species do not tolerate basic stemflow and on the other hand most species are also very sensitive for the SO 2 content in air. Consequently a large lichen desert is found in an area of 2500 km 2 in the vicinity of the power plants with only one out of the investigated 12 species growing.

Optimization of the coating layer for the measurement of ammonia by diffusion denuders

The performance of citric acid, oxalic acid and phosphorous acid as denuder coating layers for the determination of atmospheric ammonia have been studied by means of laboratory and field tests. The parameters evaluated during the study include: collection efficiency, selectivity of the coating layer, stability of the reaction product, operative capacity and stability of the coating layer. The results of this study show that phosphorous acid is a suitable coating layer for a denuder line intended to determine both gaseous ammonia and particulate ammonium in the atmosphere. It has been found that the citric acid coating suffers from an insufficient strength of the bond between collected ammonia and the coating layer, which causes a release of the collected ammonia both towards the air flow and towards the active sites of the denuder glass. The performance of oxalic acid was very good in the determination of gaseous ammonia, but this coating showed to be unsuitable for denuder sampling lines which are intended also for the determination of atmospheric ammonium. The volatilisation of oxalic from the denuder surface, in fact, causes a displacement of nitrate from the Teflon filter and an excess of nitrate ion on the back-up filter. Phosphorous acid-coated denuders were added to the sampling line employed in the EMEP station of Montelibretti. Reliable and interesting results were obtained, which allowed us to detect the presence of gaseous ammonia adsorbed on atmospheric particles.

A climatological analysis of four-day back trajectories from aliartos, Greece

This study presents a flow climatology for Greece based on a survey of climate and synoptic weather types, and a five-year trajectory climatology. Isobaric back trajectories at the 850 and 700 hPa levels were calculated daily at 0 and 12 Z for the years 1983–1987 for the Aliartos, Greece EMEP station, using the Air Resources Laboratory (ARL) trajectory model. Trajectories were classified by direction and speed to examine monthly, seasonal and annual variability in flow characteristics. The main features of the flow are similar from year to year. Dominant transport sectors are NW and W, followed by N, SW and NE. Four-day back trajectories from NW and W usually originate from beyond 2,400 km, while those from other directions tend to originate closer to Greece. Cases of most rapid transport occur in January and December. Potential pollutant source regions are identified corresponding to preferred trajectory directions and distance ranges.

Northern foehn and ground-level ozone at Ispra

High ozone concentrations in tropospheric air are usually related to photochemical processes caused by anthropogenic emission on local or regional scales. In the prealpine region, comparable levels may be reached during foehn events as a result of injections of air masses from the free troposphere. From the analysis of meteorological parameters of the foehn episodes which occurred in 1988 at Ispra and the corresponding ozone levels recorded at the nearby EMEP station, a classification of different events has been attempted. In particular, a correlation between wind speed and ozone level is demonstrated.