Influences of the 2010 Eyjafjallajökull volcanic plume on air quality in the northern Alpine region

A series of major eruptions of the Eyjafjallajökull volcano in Iceland started on 14 April 2010 and continued until the end of May 2010. The volcanic emissions moved over nearly the whole of Europe and were observed first on 16 April 2010 in Southern Germany with different remote sensing systems from the ground and space. Enhanced PM10 and SO2 concentrations were detected on 17 April at mountain stations (Zugspitze/Schneefernerhaus and Schauinsland) as well as in Innsbruck by in situ measurement devices. On 19 April intensive vertical mixing and advection along with clear-sky conditions facilitated the entrainment of volcanic material down to the ground. The subsequent formation of a stably stratified lower atmosphere with limited mixing near the ground during the evening of 19 April led to an additional enhancement of near-surface particle concentrations. Consequently, on 19 April and 20 April exceedances of the daily threshold value for particulate matter (PM10) were reported at nearly all monitoring stations of the North Alpine foothills as well as at mountain and valley stations in the northern Alps. The chemical analyses of ambient PM10 at monitoring stations of the North Alpine foothills yielded elevated Titanium concentrations on 19/20 April which prove the presence of volcanic plume material. Following this result the PM10 threshold exceedances are also associated with the volcanic plume. The entrainment of the volcanic plume material mainly affected the concentrations of coarse particles (>1 μm) – interpreted as volcanic ash – and ultrafine particles (<100 nm), while the concentrations of accumulation mode aerosol (0.1–1 μm) were not changed significantly. With regard to the occurrence of ultrafine particles, it is concluded that their formation was triggered by high sulphuric acid concentrations which are necessarily generated by the photochemical processes in a plume rich in sulphur dioxide under high solar irradiance. It became evident that during the course of several days, the Eyjafjallajökull volcanic emissions influenced the near-surface atmosphere and thus the ambient air quality. Although the volcanic plume contributed to the overall exposure of the population of the northern Alpine region on two days, only minor effects on the exacerbation of respiratory and cardiovascular symptoms can be expected

Particle size distribution factor as an indicator for the impact of the Eyjafjallaj&ouml;kull ash plume at ground level in Augsburg, Germany.

During the time period of the Eyjafjallajokull volcano eruption in 2010 increased mass concentration of PM(10) (particulate matter, diameter &lt; 10 mu m) were observed at ground level in Augsburg, Germany. In particular on 19 and 20 April 2010 the daily PM10 limit value of 50 mu g m(-3) was exceeded. Because ambient particles are in general a complex mixture originating from different sources, a source apportionment method (positive matrix factorization (PMF)) was applied to particle size distribution data in the size range from 3 nm to 10 mu m to identify and estimate the volcanic ash contribution to the overall PM10 load in the ambient air in Augsburg. A PMF factor with relevant particle mass concentration in the size range between 1 and 4 mu m (maximum at 2 mu m) was associated with long range transported dust. This factor increased from background concentration to high levels simultaneously with the arrival of the volcanic ash plume in the planetary boundary layer. Hence, we assume that this factor could be used as an indicator for the impact of the Eyjafjallajokull ash plume on ground level in Augsburg. From 17 to 22 April 2010 long range transported dust factor contributed on average 30% (12 mu g m(-3)) to PM10. On 19 April 2010 at 20:00 UTC+1 the maximum percentage of the long range transported dust factor accounted for around 65% (35 mu g m(-3)) to PM10 and three hours later the maximum absolute value with around 48 mu g m(-3) (61 %) was observed. Additional PMF analyses for a Saharan dust event occurred in May and June 2008 suggest, that the long range transported dust factor could also be used as an indicator for Saharan dust events

Spatial and temporal variability of PM₁₀ sources in Augsburg, Germany.

Source apportionment of ambient particulate matter (PM10) was carried out using daily chemical composition data collected in winter 2006/07 and winter 2007/08 in Augsburg, Germany. Six factors have been identified and were associated with secondary nitrate, secondary sulfate, residential and commercial combustion, NaCl, re-suspended dust and traffic emissions. Comparing the source profiles between winter 2006/07 and winter 2007/08 showed that they were similar for both winters, except the combustion and traffic emissions factors. The spatial variation of particulate sources was evaluated by analysis of data collected at eight sampling sites during a one-month intensive campaign in winter 2007/08. Secondary nitrate, secondary sulfate as well as residential and commercial combustion factors showed strong correlations and low coefficient of divergence (COD) values among eight sites, indicating that they are uniformly distributed in urban area. By contrast, traffic emissions factor and NaCl were highly heterogeneously distributed. These two factors were enhanced greatly at the traffic site and are the cause of elevated PM10 mass concentration at traffic site. It means that for some specific sources of particles showing pronounced spatial variability a central monitoring site could not assess the absolute concentrations across an urban area. Thus, cautions should be taken when approximating average human exposure to these particle sources in long-term epidemiological studies

Selection of key ambient particulate variables for epidemiological studies - applying cluster and heatmap analyses as tools for data reduction.

The success of epidemiological studies depends on the use of appropriate exposure variables. The purpose of this study is to extract a relatively small selection of variables characterizing ambient particulate matter from a large measurement data set. The original data set comprised a total of 96 particulate matter variables that have been continuously measured since 2004 at an urban background aerosol monitoring site in the city of Augsburg, Germany. Many of the original variables were derived from measured particle size distribution (PSD) across the particle diameter range 3 nm to 10 &mu;m, including size-segregated particle number concentration, particle length concentration, particle surface concentration and particle mass concentration. The data set was complemented by integral aerosol variables. These variables were measured by independent instruments, including black carbon, sulfate, particle active surface concentration and particle length concentration. It is obvious that such a large number of measured variables cannot be used in health effect analyses simultaneously. The aim of this study is a pre-screening and a selection of the key variables that will be used as input in forthcoming epidemiological studies. In this study, we present two methods of parameter selection and apply them to data from a two-year period from 2007 to 2008. We used the agglomerative hierarchical cluster method to find groups of similar variables. In total, we selected 15 key variables from 9 clusters which are recommended for epidemiological analyses. We also applied a two-dimensional visualization technique called &quot;heatmap&quot; analysis to the Spearman correlation matrix. 12 key variables were selected using this method. Moreover, the positive matrix factorization (PMF) method was applied to the PSD data to characterize the possible particle sources. Correlations between the variables and PMF factors were used to interpret the meaning of the cluster and the heatmap analyses

Source apportionment of ambient particles: Comparison of positive matrix factorization analysis applied to particle size distribution and chemical composition data.

Positive matrix factorization (PMF) method was used to identify the sources of ambient particles (PM10) in Augsburg in winter 2006/07. The analyses were carried out separately with particulate chemical composition (PCC) data at an urban traffic site and with particle size distribution (PSD) data at an urban background site on daily and hourly base, respectively. For PCC data, six factors are identified and associated with NaCl (6.7% of PM10), secondary sulfate (13.0%), biomass burning (13.3%), secondary nitrate (30.5%), traffic emission (16.5%) and re-suspended dust (20.0%). For PSD data, seven factors are identified and are associated with fresh and aged traffic sources, secondary aerosols, stationary combustion, nucleation particles, re-suspended dust and long range transported dust. The two traffic factors were dominated by ultrafine particles (diameter &lt; 100 nm), and accounted for 25% and 40% of total particle number concentration (NC). Stationary combustion factor, consisting of particles around 100 nm, accounted for 26% of total NC. Re-suspended dust was mainly composed of particles with diameters &gt; 2.5 mu m. The two different approaches (PCC and PSD data) led to comparable results with strong correlations for secondary nitrate and sulfate/secondary aerosols (r = 0.92), which are considered to origin mainly from long range transport. Traffic emissions (r = 0.52) and re-suspended dust (r = 0.62) showed weaker correlation due to influences of local sources at the different sites