Oxygen isotope analysis of levoglucosan, a tracer of wood burning, in experimental and ambient aerosol samples.

RATIONALE: Levoglucosan is formed from cellulose during biomass burning. It is therefore often used as a specific tracer to quantify the contribution of wood burning to the aerosol loading. The stable oxygen isotope composition (δ18 O value) of biomass is determined by the water cycle and varies regionally, and hence the δ18 O value of levoglucosan could help to identify source regions of organic aerosols. METHODS: After solvent extraction of the organic fraction and concentration steps, a recently developed methylation derivatisation technique was applied on experimental (i.e. controlled wood-burning experiments) and on ambient aerosol samples from Switzerland and Lithuania. The method achieves sufficient compound separation for isotope analysis in atmospheric particulate matter, enabling δ18 O analysis of levoglucosan by gas chromatography/pyrolysis-isotope ratio mass spectrometry (GC/Pyr-IRMS), with a precision better than 1.0 ‰ and an accuracy of 0.3 ‰. RESULTS: The δ18 O value of the levoglucosan released during controlled wood-burning experiments was not significantly different from the cellulose δ18 O values, which implies very little or no isotope fractionation during wood burning under the given conditions. While the δ18 O values of levoglucosan in Swiss samples were as expected for the source region, those in Lithuania were 1-4 ‰ lower than expected. This may be due to differences in vegetation (grass vs wood) or burning conditions (high vs low temperatures). CONCLUSIONS: Low oxygen isotope fractionation between cellulose and levoglucosan and clear differences in levoglucosan δ18 O values between the Swiss and Lithuanian ambient samples demonstrate that our new method is useful for source appointment studies on wood-burning-derived aerosols.

Characteristics of black carbon aerosol mass concentration over the East Baltic region from two-year measurements.

Continuous measurements of black carbon (BC) aerosol mass concentration were performed at a background site Preila (55°55'N, 21°00'E, 5 m a.s.l., Lithuania) during the period 2008-2009. The data were used to characterize the BC mass concentration distribution over the East Baltic region. High increase in aerosol BC concentration was associated with the change in air mass characteristics and biomass burning during the winter heating season and spring wildfires. Monthly means of BC concentration ranged from 212 to 1268 ng m(-3) and the highest hourly means of concentration were from 4800 to 6300 ng m(-3), predominantly in spring and winter months. During the October-April period the BC mass concentrations were about twice as high as those in the summertime. The BC diurnal pattern in winter was typically different from that in spring indicating the seasonal variation of the atmospheric boundary layer height. The weekday/weekend difference was not strongly pronounced because the BC concentrations in Preila are mainly affected by long-range transport or local sources. Typical periodicities caused by anthropogenic and meteorological influences have been identified using Fourier analysis. It was shown that domestic heating appears as a 365 day periodicity; traffic slightly contributes 5-7 day peaks in the spectrum and elevated long-range BC can be identified as characteristic peaks with periodicities in the range from 16 to 29 days.Temporal evolution and transport of BC aerosols were interpreted by the air mass backward trajectory analysis in conjunction with the examination of the wavelength dependence on the aethalometer data. Air masses originated from the North Atlantic Ocean and Scandinavia were favourable for lower BC concentrations (350 ng m(-3)), while the BC level associated with the Western Europe airflows was significantly higher (970 ng m(-3)). The mean values of Ångström exponent of the absorption coefficient (monthly means 1.45 ± 0.25 and 0.84 ± 0.50 over January and June, respectively) revealed that the BC concentration observed over the East Baltic is influenced by submicron sized particles as a result of incomplete biomass combustion during the winter season.

On the seasonal aerosol pollution levels and its sources in some primary schools in Vilnius, Lithuania.

Aerosol particle number (PNC) and mass concentrations (PMC) were studied in 11 primary schools during the 2017-2018 school years (from September to May) in Vilnius, Lithuania, with the aim to evaluate the main aerosol pollution sources and its levels. Expeditious information on the total aerosol particle concentration over the full range of sizes (from 0.01 to > 1 µm) was estimated using a condensation particle counter (CPC). Particle number and mass concentrations in the size range of 0.3-10 µm were measured and estimated using an optical particle sizer (OPS). The use of aerosol particle size spectra (OPS) in school lodgements facilitated the identification of the main sources of indoor air pollution. The main sources responsible for the elevated levels of indoor PN and PM aerosol concentrations were determined: local canteens in the absence of ventilation (particle concentrations up to 97,500 part/cm3 (CPC)), the school-grader activity during the lesson breaks (275-586 µg/m3), soft furniture and carpets in the classrooms and corridors (~ 200 µg/m3), and in some cases (city center) elevated outdoor aerosol pollution levels (16800-18,170 part/cm3). Elevated aerosol pollution levels were also due to the occasional sources: construction works during lessons (200-1000 µg/m3), scraping the exterior walls of buildings near schools (up to 1600 µg/m3), and the use of petrol-powered trimmers during cutting of green plantings (22500-66,400 part/cm3 (CPC)).

Global Alliance against Chronic Respiratory Diseases demonstration project: aerosol pollution and its seasonal peculiarities in primary schools of Vilnius.

BACKGROUND: The growing public health concern caused by non-communicable diseases in urban surroundings cannot be solved by health care alone; therefore a multidisciplinary approach is mandatory. This study aimed to evaluate the airborne aerosol pollution level in primary schools as possible factor influencing origin and course of the diseases in children. METHODS: Seasonal aerosol particle number concentration (PNC) and mass concentration (PMC) were studied in the randomly selected eleven primary schools in the Lithuanian capital, Vilnius, as model of a middle-size Eastern European city. Total PNC in the size range from 0.01 to >1.0 µm in diameter was measured using a condensation particle counter. Using an optical particle sizer, PNC was measured and PMC estimated for particles from 0.3 to 10.0 µm. A descriptive statistics was used to estimate the aerosol pollution levels. RESULTS: During all seasons, local cafeterias in the absence of ventilation were the main sources of the elevated levels of indoor PMC and PNC (up to 97,500 particles/cm). The other sources of airborne particulates were the children's activity during the lesson breaks with PMC up to 586 µg/m. Soft furniture, carpets in the classrooms and corridors were responsible for PMC up to 200 µg/m. Outdoor aerosol pollution (up to 18,170 particles/cm) was higher for schools in city center. Elevated air pollution in classrooms also resulted from intermittent sources, such as construction work during classes (200-1000 µg/m) and petrol-powered lawn trimmers (up to 66,400 particles/cm). CONCLUSION: The results of our survey show that even in a relatively low polluted region of Eastern Europe there are big differences in aerosol pollution within middle-sized city. Additional efforts are needed to improve air quality in schools: more frequent wet cleaning, monitoring the operation of ventilation systems, a ban on construction works during school year, on a use of sandblasting mechanisms in the neighborhood of schools.

Tree-ring formation as an indicator of forest capacity to adapt to the main threats of environmental changes in Lithuania.

Global changes occurring under different environmental conditions have changed stand competition, as well as nutrient and light availability, which has resulted in changes in productivity. Therefore, in the present study, the characteristics of tree-ring width formation of the prevailing Lithuanian tree species, Norway spruce, Scots pine and silver and downy birch, and key factors resulting in their differences during the last 36-year period were investigated at forest sites located on poor mineral oligotrophic and on nutrient-rich organic mesoeutrophic soils. The aim of the study was as follows: first, to separately detect the maximum possible seasonal effect of three groups of variables - meteorology, acidifying pollutants and surface ozone on the stem basal area increment (BAI) of the evaluated tree species; second, to assess the significance of each group of variables affecting the BAI of these tree species integrally with the remaining groups of variables. Norway spruce was found to be well adapted to recent environmental changes, which makes it one of the most favourable tree species for silviculture in the northeastern part of Europe. The rapid increases recorded in growth intensity since 1980 were attributed to the increase in air temperature, precipitation amount, nitrogen deposition during the vegetative stage and reductions in SO2 concentrations and S deposition. Scots pine demonstrated the highest level of resilience and capacity to adapt to recent global changes because its reaction to both negative and favourable environmental factors was best expressed. Silver and downy birch tree reactions to the effects of air concentrations of acidifying compounds, their deposition and surface ozone concentrations were the least expressed; however, a significant decline in growth intensity indicated that these tree species experienced a reduced resistance to recent changes in environmental conditions in the mature and over-mature age groups.

Concentration and species diversity of airborne fungi near busy streets in Lithuanian urban areas.

The investigations on air pollution in industrial cities of Lithuania: Vilnius, Alytus, Kaunas, Marijampole and Elektrenai were aimed at detecting the presence of fungi and aerosol particles during different seasons of the year. Sampling of fungal spores was carried out at 20 sampling sites. Active air sampling was performed simultaneously with the use of passive sedimentation plates. Data on the spread of various micromycete species in the air of cities contaminated with various pollutants are presented. Micromycetes of 430 species belonging to 165 genera, 19 families, 13 orders, 4 classes, and 3 phylla were isolated and identified. We found 21 species, 11 genera, 7 families from Ascomycota, 6 species, 1 genus, 1 family from Oomycota, 45 species, 15 genera, 8 families from Zygomycota. Mitosporic fungi comprised 138 genera, 358 species, and comprised the vast majority of identified species: 358 out of 430 (83.25 %). Conditionally pathogenic species were also isolated. It was concluded that the abundance of such fungi as Aspergillus niger, A. fumigatus, Cladosporium herbarum, Alternaria alternata, Aureobasidium pullulans in the air can be a significant criterion for the evaluation of air pollution.