In the spring and summer of 2006 the air quality in southern Finland was affected by two major bi... more In the spring and summer of 2006 the air quality in southern Finland was affected by two major biomass fire smoke episodes. At the Virolahti background station, closest to the eastern fire areas, the episodes lasted altogether several weeks. The high point in spring was 25 April and in summer 13 August. In spring the aerosol detected at Virolahti originated
The influence of a change from daily to weekly sampling of bulk precipitation on the obtained dep... more The influence of a change from daily to weekly sampling of bulk precipitation on the obtained deposition values was studied with parallel sampling for 8 months at the station of Virolahti in 2004. Due to dry deposition, the deposition values of the whole period were found to be 5–70% higher from weekly sampling than from daily sampling, the biggest difference being for K+, Ca2+, Mg+ and Na+. The collection efficiencies of the summer sampler and the winter sampler compared to the standard rain gauge were studied from daily sampling in 1991–2003 and weekly sampling in 2004–2008. The performance was best in summer and in winter with rain samples (median value 85–88%), while the median value for daily snow samples was 72%. In winter, the total sum of precipitation collected in the daily sampler and the weekly sampler was 78% and 69%, respectively. The deficit in the weekly sampler in winter was concluded to be due to evaporation, while from the summer sampler no evaporation seemed to occur. Use of the precipitation amount measured by the standard rain gauge when calculating annual precipitation-weighted mean values gave higher mean concentrations than the use of the precipitation measured by the deposition sampler itself, the biggest difference of 8–11% being in the sea-salt ions Cl−, Mg+ and Na+. It was concluded that the concentration and deposition values measured by daily and weekly bulk sampling are incompatible, and should not be combined into the same time series.
Polycyclic aromatic hydrocarbons (PAH compounds) were measured in the PM 10 fraction [from ambien... more Polycyclic aromatic hydrocarbons (PAH compounds) were measured in the PM 10 fraction [from ambient air] at Virolahti, Finland. The sampling site is located in a rural area in the south-eastern corner of Finland, near the Russian border. Altogether, 51 daily and 85 weekly filter samples were collected in 2007e2008. The yearly average concentration of benzo(a)pyrene at Virolahti in 2007 was 0.21 ng m À3 , which is well below the annual target value of 1 ng m À3 set by the European Union. The positive matrix factorization (PMF) method was applied in source apportionment for daily PAH data combined with other pollutant data. A three-factor solution of the PMF analysis with 28 components was chosen. These three factors were identified as long-range transported secondary particles (F1), combustion (F2) and a sea-salt factor (F3). The conditional probability function (CPF) was used to combine wind direction sectors with the PMF factors. In cases F1 and F2, pollutants mainly originated from the south-east, whereas pollutants in F3 came from the south-western sector.
Particulate matter measurements were performed at the Akrotiri research station on the island of ... more Particulate matter measurements were performed at the Akrotiri research station on the island of Crete (Greece) using an 8-stages Andersen non-viable impactor. The main purpose of the current work was to measure the ambient levels of PM 10 particulate matter as well as the concentrations of metals and ions in 8 different PM size fractions with aerodynamic diameter cutoff at 9, 5.8, 4.7, 3.3, 2.1, 1.1, 0.7, 0.4 and a back-up filter for particles below 0.4 µm.
Co-located long-term routine measurements of sulphur dioxide with the impregnated filter method a... more Co-located long-term routine measurements of sulphur dioxide with the impregnated filter method and a pulsed fluorescence analyser at four Finnish background stations were compared. The data consist of 9 years of parallel measurements at the Virolahti station and 8, 7 and 2 years in Uto¨, Oulanka and Ä hta¨ri, respectively, between the years 1993-2001. During the whole study period, the daily SO 2 concentrations measured with the analyser and the filter method showed excellent agreement in Virolahti (number of daily data pairs 2748, r 2 ¼ 0:99) and Uto¨(n ¼ 2328; r 2 ¼ 0:97), and no systematic relative error between the two methods was found. Also in Oulanka (n ¼ 2131; r 2 ¼ 0:99) and Ä hta¨ri (n ¼ 643; r 2 ¼ 0:97) the linear model described the data well. However, in Oulanka the analyser produced 16% and in Ä hta¨ri 10% higher results than the filter method. The difference would decrease to 12% in Oulanka and to 8% in Ä hta¨ri if the concentrations were given at the same reference pressure. At all stations also a small constant error (analyser4filter) of the order of 0.03-0.06 mg S m À3 was discerned. The role of nitrogen oxide, volatile organic compounds and water vapour interferences as well as extreme temperatures were studied but no clear systematic influence by them on the daily differences between the two methods was detected. r
The SO2 emissions from the Kola Peninsula in Arctic Russia (totalling around 600 Gg(SO2) yr−1 at ... more The SO2 emissions from the Kola Peninsula in Arctic Russia (totalling around 600 Gg(SO2) yr−1 at the beginning of the 1990s) produce an atmospheric SO2 concentration gradient to the northernmost Europe. This gradient covers the range from >50 μg m−3 in the vicinity of the sources to 1 μg m−3 in Finnish Lapland. In the present study, the measured sulphur concentrations in Scots pine needles were compared with the estimated distribution of atmospheric SO2. The total sulphur concentrations in the needles ranged from 741 to 2017 mg kg−1. Strongly elevated concentrations (> 1200 mg kg−1) were found within 40 km from the smelters corresponding to an area where the annual mean atmospheric SO2 concentration exceeded 10 μg m−3. The foliar sulphur concentrations (total, organic and inorganic) show a high correlation with the estimated mean SO2 concentration distribution in the air. Consequently the foliar sulphur concentrations reflected the atmospheric sulphur load well. The data presented here show that uptake via stomata is an important deposition pathway also in the arctic conditions with a short growing season.
We present the concentration trends and the atmospheric exposure of sulfur and nitrogen compounds... more We present the concentration trends and the atmospheric exposure of sulfur and nitrogen compounds in different transport sectors during the period 1981-2000, based on the air quality data of the Finnish Meteorological Institute. Sulfur and nitrogen concentrations in air and precipitation were assessed from background stations covering the whole country. A significant decrease of more than 60% was observed in the concentrations of all sulfur compounds throughout the country during 1981-2000. In the 1990's, significant trends were detected in all sulfur time series, with the exception of sulfate in precipitation at the northernmost stations. On the other hand, the concentrations of oxidized nitrogen compounds in air and precipitation have declined only slightly or not at all, especially in the 1990's. This is attributed to the fairly small domestic and European NO(x) emission reductions after 1981. The ammonium concentration in precipitation has declined by more than 50% during 1981-2000. The atmospheric sulfur exposure was found to be dominated by transport from the West and South-West sectors during summer, whereas in winter all the southward sectors were important. The largest decline in the sectoral sulfur concentrations has taken place already before 1991, with a more pronounced reduction during winter than during summer. The atmospheric nitrogen exposure was mainly dominated by transport from the sectors between west and south, but in the latter half of the study period there seems to have been a slight shift towards increased transport from the eastern and northern sectors.
This study presents a summary of Finnish air quality monitoring results up to year 2000. The data... more This study presents a summary of Finnish air quality monitoring results up to year 2000. The data was obtained from the air quality monitoring data management system (ILSE) maintained by the Finnish Meteorological Institute. Since 1994 practically all Finnish routine air quality monitoring results from the measurement networks maintained by the municipalities and enterprises have been annually collected to this system. In 2000 there were 278 measured time series from 128 monitoring stations in 58 municipalities. The approach of this study is a comparison of the monitoring results with the operative guideline, limit and threshold values. The temporal development of air quality is also studied and comparisons to results from other European stations are presented.
ABSTRACT The trends in the atmospheric concentrations of the main gaseous and particulate polluta... more ABSTRACT The trends in the atmospheric concentrations of the main gaseous and particulate pollutants in urban, industrial and rural environments across Finland were estimated for the period of 1994–2007. The statistical analysis was based on generalized least-squares regression with classical decomposition and autoregressive moving average (ARMA) errors, which was applied to monthly-averaged data. In addition, three alternative methods were tested. Altogether 102 pollutant time series from 42 sites were analyzed. During the study period, the concentrations of SO2, CO and NOx declined considerably and widely across Finland. The SO2 concentrations at urban and industrial sites were approaching background levels. The reductions in NOx and CO concentrations were comparable to those in national road traffic emissions. A downward trend was detected in half of the NO2 time series studied, but the reductions were not as large as would be expected on the basis of emission trends, or from NOx concentrations. For O3, neither the mean nor peak values showed large changes in background areas, but were increasing in the urban data. For PM10, five of the 12 urban time series showed decreasing mean levels. However, the highest concentrations, typically attributable to the problematic springtime street dust, did not decrease as widely. The reduction of the long-range transported major ions, mainly driven by the large-scale reduction in sulphur emissions, possibly plays a significant part in the decreases in the mean PM10 concentrations. It was shown that the handling of the serially-correlated data with the ARMA processes improved the analysis of monthly values. The use of monthly rather than annually-averaged data helped to identify the weakest trends.
Vehicle exhaust emissions Urban NO 2 concentrations NOeNO 2 eO 3 equilibrium Total oxidant model ... more Vehicle exhaust emissions Urban NO 2 concentrations NOeNO 2 eO 3 equilibrium Total oxidant model Limit values Helsinki Finland
Particulates can cause respiratory problems or can trigger cardio-vascular diseases. Some Europea... more Particulates can cause respiratory problems or can trigger cardio-vascular diseases. Some European cities, besides local PM, may also suffer from additional impact of remote sources of particles, which is independent from the local emissions. For these settlements, it is ...
The purpose of the study is to identify long-range transport patterns that may have an important ... more The purpose of the study is to identify long-range transport patterns that may have an important influence on PM10 levels in three European cities at different latitudes, namely Thessaloniki, Szeged and Helsinki. A further aim is to separate medium-and long-range PM10 transport for these cities. 4-day, 6-hourly three-dimensional (3D) backward trajectories arriving at these locations at 1200 GMT were computed using the HYSPLIT model over a 5-year period from 2001 to 2005. A k-means clustering algorithm using the Mahalanobis metric was applied in order to develop trajectory types. The 3D delimination of the clusters by the function "convhull" is a novel approach. Two statistical indices were used to evaluate and compare critical daily PM10 exceedances corresponding to the trajectory clusters.
In the spring and summer of 2006 the air quality in southern Finland was affected by two major bi... more In the spring and summer of 2006 the air quality in southern Finland was affected by two major biomass fire smoke episodes. At the Virolahti background station, closest to the eastern fire areas, the episodes lasted altogether several weeks. The high point in spring was 25 April and in summer 13 August. In spring the aerosol detected at Virolahti originated
The influence of a change from daily to weekly sampling of bulk precipitation on the obtained dep... more The influence of a change from daily to weekly sampling of bulk precipitation on the obtained deposition values was studied with parallel sampling for 8 months at the station of Virolahti in 2004. Due to dry deposition, the deposition values of the whole period were found to be 5–70% higher from weekly sampling than from daily sampling, the biggest difference being for K+, Ca2+, Mg+ and Na+. The collection efficiencies of the summer sampler and the winter sampler compared to the standard rain gauge were studied from daily sampling in 1991–2003 and weekly sampling in 2004–2008. The performance was best in summer and in winter with rain samples (median value 85–88%), while the median value for daily snow samples was 72%. In winter, the total sum of precipitation collected in the daily sampler and the weekly sampler was 78% and 69%, respectively. The deficit in the weekly sampler in winter was concluded to be due to evaporation, while from the summer sampler no evaporation seemed to occur. Use of the precipitation amount measured by the standard rain gauge when calculating annual precipitation-weighted mean values gave higher mean concentrations than the use of the precipitation measured by the deposition sampler itself, the biggest difference of 8–11% being in the sea-salt ions Cl−, Mg+ and Na+. It was concluded that the concentration and deposition values measured by daily and weekly bulk sampling are incompatible, and should not be combined into the same time series.
Polycyclic aromatic hydrocarbons (PAH compounds) were measured in the PM 10 fraction [from ambien... more Polycyclic aromatic hydrocarbons (PAH compounds) were measured in the PM 10 fraction [from ambient air] at Virolahti, Finland. The sampling site is located in a rural area in the south-eastern corner of Finland, near the Russian border. Altogether, 51 daily and 85 weekly filter samples were collected in 2007e2008. The yearly average concentration of benzo(a)pyrene at Virolahti in 2007 was 0.21 ng m À3 , which is well below the annual target value of 1 ng m À3 set by the European Union. The positive matrix factorization (PMF) method was applied in source apportionment for daily PAH data combined with other pollutant data. A three-factor solution of the PMF analysis with 28 components was chosen. These three factors were identified as long-range transported secondary particles (F1), combustion (F2) and a sea-salt factor (F3). The conditional probability function (CPF) was used to combine wind direction sectors with the PMF factors. In cases F1 and F2, pollutants mainly originated from the south-east, whereas pollutants in F3 came from the south-western sector.
Particulate matter measurements were performed at the Akrotiri research station on the island of ... more Particulate matter measurements were performed at the Akrotiri research station on the island of Crete (Greece) using an 8-stages Andersen non-viable impactor. The main purpose of the current work was to measure the ambient levels of PM 10 particulate matter as well as the concentrations of metals and ions in 8 different PM size fractions with aerodynamic diameter cutoff at 9, 5.8, 4.7, 3.3, 2.1, 1.1, 0.7, 0.4 and a back-up filter for particles below 0.4 µm.
Co-located long-term routine measurements of sulphur dioxide with the impregnated filter method a... more Co-located long-term routine measurements of sulphur dioxide with the impregnated filter method and a pulsed fluorescence analyser at four Finnish background stations were compared. The data consist of 9 years of parallel measurements at the Virolahti station and 8, 7 and 2 years in Uto¨, Oulanka and Ä hta¨ri, respectively, between the years 1993-2001. During the whole study period, the daily SO 2 concentrations measured with the analyser and the filter method showed excellent agreement in Virolahti (number of daily data pairs 2748, r 2 ¼ 0:99) and Uto¨(n ¼ 2328; r 2 ¼ 0:97), and no systematic relative error between the two methods was found. Also in Oulanka (n ¼ 2131; r 2 ¼ 0:99) and Ä hta¨ri (n ¼ 643; r 2 ¼ 0:97) the linear model described the data well. However, in Oulanka the analyser produced 16% and in Ä hta¨ri 10% higher results than the filter method. The difference would decrease to 12% in Oulanka and to 8% in Ä hta¨ri if the concentrations were given at the same reference pressure. At all stations also a small constant error (analyser4filter) of the order of 0.03-0.06 mg S m À3 was discerned. The role of nitrogen oxide, volatile organic compounds and water vapour interferences as well as extreme temperatures were studied but no clear systematic influence by them on the daily differences between the two methods was detected. r
The SO2 emissions from the Kola Peninsula in Arctic Russia (totalling around 600 Gg(SO2) yr−1 at ... more The SO2 emissions from the Kola Peninsula in Arctic Russia (totalling around 600 Gg(SO2) yr−1 at the beginning of the 1990s) produce an atmospheric SO2 concentration gradient to the northernmost Europe. This gradient covers the range from >50 μg m−3 in the vicinity of the sources to 1 μg m−3 in Finnish Lapland. In the present study, the measured sulphur concentrations in Scots pine needles were compared with the estimated distribution of atmospheric SO2. The total sulphur concentrations in the needles ranged from 741 to 2017 mg kg−1. Strongly elevated concentrations (> 1200 mg kg−1) were found within 40 km from the smelters corresponding to an area where the annual mean atmospheric SO2 concentration exceeded 10 μg m−3. The foliar sulphur concentrations (total, organic and inorganic) show a high correlation with the estimated mean SO2 concentration distribution in the air. Consequently the foliar sulphur concentrations reflected the atmospheric sulphur load well. The data presented here show that uptake via stomata is an important deposition pathway also in the arctic conditions with a short growing season.
We present the concentration trends and the atmospheric exposure of sulfur and nitrogen compounds... more We present the concentration trends and the atmospheric exposure of sulfur and nitrogen compounds in different transport sectors during the period 1981-2000, based on the air quality data of the Finnish Meteorological Institute. Sulfur and nitrogen concentrations in air and precipitation were assessed from background stations covering the whole country. A significant decrease of more than 60% was observed in the concentrations of all sulfur compounds throughout the country during 1981-2000. In the 1990's, significant trends were detected in all sulfur time series, with the exception of sulfate in precipitation at the northernmost stations. On the other hand, the concentrations of oxidized nitrogen compounds in air and precipitation have declined only slightly or not at all, especially in the 1990's. This is attributed to the fairly small domestic and European NO(x) emission reductions after 1981. The ammonium concentration in precipitation has declined by more than 50% during 1981-2000. The atmospheric sulfur exposure was found to be dominated by transport from the West and South-West sectors during summer, whereas in winter all the southward sectors were important. The largest decline in the sectoral sulfur concentrations has taken place already before 1991, with a more pronounced reduction during winter than during summer. The atmospheric nitrogen exposure was mainly dominated by transport from the sectors between west and south, but in the latter half of the study period there seems to have been a slight shift towards increased transport from the eastern and northern sectors.
This study presents a summary of Finnish air quality monitoring results up to year 2000. The data... more This study presents a summary of Finnish air quality monitoring results up to year 2000. The data was obtained from the air quality monitoring data management system (ILSE) maintained by the Finnish Meteorological Institute. Since 1994 practically all Finnish routine air quality monitoring results from the measurement networks maintained by the municipalities and enterprises have been annually collected to this system. In 2000 there were 278 measured time series from 128 monitoring stations in 58 municipalities. The approach of this study is a comparison of the monitoring results with the operative guideline, limit and threshold values. The temporal development of air quality is also studied and comparisons to results from other European stations are presented.
ABSTRACT The trends in the atmospheric concentrations of the main gaseous and particulate polluta... more ABSTRACT The trends in the atmospheric concentrations of the main gaseous and particulate pollutants in urban, industrial and rural environments across Finland were estimated for the period of 1994–2007. The statistical analysis was based on generalized least-squares regression with classical decomposition and autoregressive moving average (ARMA) errors, which was applied to monthly-averaged data. In addition, three alternative methods were tested. Altogether 102 pollutant time series from 42 sites were analyzed. During the study period, the concentrations of SO2, CO and NOx declined considerably and widely across Finland. The SO2 concentrations at urban and industrial sites were approaching background levels. The reductions in NOx and CO concentrations were comparable to those in national road traffic emissions. A downward trend was detected in half of the NO2 time series studied, but the reductions were not as large as would be expected on the basis of emission trends, or from NOx concentrations. For O3, neither the mean nor peak values showed large changes in background areas, but were increasing in the urban data. For PM10, five of the 12 urban time series showed decreasing mean levels. However, the highest concentrations, typically attributable to the problematic springtime street dust, did not decrease as widely. The reduction of the long-range transported major ions, mainly driven by the large-scale reduction in sulphur emissions, possibly plays a significant part in the decreases in the mean PM10 concentrations. It was shown that the handling of the serially-correlated data with the ARMA processes improved the analysis of monthly values. The use of monthly rather than annually-averaged data helped to identify the weakest trends.
Vehicle exhaust emissions Urban NO 2 concentrations NOeNO 2 eO 3 equilibrium Total oxidant model ... more Vehicle exhaust emissions Urban NO 2 concentrations NOeNO 2 eO 3 equilibrium Total oxidant model Limit values Helsinki Finland
Particulates can cause respiratory problems or can trigger cardio-vascular diseases. Some Europea... more Particulates can cause respiratory problems or can trigger cardio-vascular diseases. Some European cities, besides local PM, may also suffer from additional impact of remote sources of particles, which is independent from the local emissions. For these settlements, it is ...
The purpose of the study is to identify long-range transport patterns that may have an important ... more The purpose of the study is to identify long-range transport patterns that may have an important influence on PM10 levels in three European cities at different latitudes, namely Thessaloniki, Szeged and Helsinki. A further aim is to separate medium-and long-range PM10 transport for these cities. 4-day, 6-hourly three-dimensional (3D) backward trajectories arriving at these locations at 1200 GMT were computed using the HYSPLIT model over a 5-year period from 2001 to 2005. A k-means clustering algorithm using the Mahalanobis metric was applied in order to develop trajectory types. The 3D delimination of the clusters by the function "convhull" is a novel approach. Two statistical indices were used to evaluate and compare critical daily PM10 exceedances corresponding to the trajectory clusters.
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