Genrik Mordas

On Operation of the Ultra-Fine Water-Based CPC TSI 3786 and Comparison with Other TSI Models (TSI 3776, TSI 3772, TSI 3025, TSI 3010, TSI 3007)

In this study we examined performance characteristics of an ultrafine water condensation particle counter (UWCPC, TSI3786). The detection efficiency was investigated using different temperature differences between saturator and growth tube. The cut-sizes D90, D50, D10, and D0 were determined by fitting a two-free-parameter equation to the experimental data. The determined cut-sizes were comparable (± 8%) with other two widely used fitting equations. The cut-sizes were studied changing the growth tube temperature from 65 to 78°C and varying the saturator temperature from 8 to 20°C. For silver particles the smallest detected cut-size D50 was 2.9 nm, and the largest one –4.5 nm, and in default operation conditions it was 3.9 nm. Additionally, the effect of particle chemical composition on the detection efficiency was studied. The cut-sizes D50 were 2 2.9, 2.3, and 1.8 nm for silver, ammonium sulfate, and sodium chloride particles, respectively. A concentration calibration was performed with high particle number concentrations. Within ±10% accuracy the highest reliable measured number concentration was 100000 cm −3 . The determined detection efficiency of the UWCPC was compared with other commercial CPCs (TSI3785, TSI3776, TSI3772, TSI3025, TSI3010, TSI3007) using default operation regimes of the instruments. The results show that the tested UWCPC has a larger cut-size for silver particles than do butanol-based ultrafine CPCs (TSI3776, TSI3025), but smaller cut-size than other tested TSI CPCs. In default operation regime, the tested TSI3776 had the lowest detection limit (D50% = 3.2 nm) of the silver particles, and the corresponding size of TSI3025 was 3.6 nm.

Detection Efficiency of a Water-Based TSI Condensation Particle Counter 3785

In this article we present observations on the detection efficiency of a recently developed TSI 3785 Water Condensation Particle Counter (WCPC). The instrument relies on activation of sampled particles by water condensation. The supersaturation is generated by directing a saturated airflow into a “growth tube,” in which the mass transfer of water vapor is faster than heat transfer. This results in supersaturated conditions with respect to water vapor in the centerline of a “growth tube.” In this study, the cut-off diameter, that is, the size, where 50% of the sampled particles are successfully activated, varied from 4 to 14 nm for silver particles as a function of temperature difference between the saturator and the growth tube. The solubility of the sampled particles to water played an important role in the detection efficiency. Cut-off diameters for ammonium sulphate and sodium chloride particles were 5.1 and 3.6–3.8 nm, respectively at nominal operation conditions. Corresponding cut-off diameter for hydrophobic silver particles was 5.8 nm.

Nanometer Particle Detection by the Condensation Particle Counter UF-02proto

In this study we present a method for how to improve the particle detection efficiency of condensation particle counters. The recently developed swirling flow condensation particle counter UF-02proto was studied. Investigations show that at default regime (when the temperature difference between the saturator and the condenser is 32.5°C) an instrument background is 0.002 cm−3, a maximum measurable number concentration is 100000 cm−3, and an instrument cut-size D50 is 4.4 nm. Increasing the temperature difference, the homogeneous nucleation starts around the temperature difference of 39.0°C. Subsequent temperature difference increasing enhances the number concentration of the nucleated particles. However, the experimental results show that the nucleation process can be prevented using existing aerosol particles in the supersaturated region. For example, when the number concentration of 15 nm silver particles exceeds 4000 cm−3 then the homogeneous nucleation inside CPC disappears. The detection efficiency was investigated as a function of the temperature difference operating instrument in default and in nucleation regime. The lowest reliable instrument cut-size D50 was 1.8 ± 0.2 nm when the temperature difference exceeded 43.5°C.

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.

Spatial Distribution of Carbonaceous Aerosol in the Southeastern Baltic Sea Region (Event of Grass Fires)

The aerosol chemical composition in air masses affected by large vegetation fires transported from the Kaliningrad region (Russia) and southeast regions (Belarus and Ukraine) during early spring (March 2014) was characterized at the remote background site of Preila, Lithuania. In this study, the chemical composition of the particulate matter was studied by high temporal resolution instruments, including an Aerosol Chemical Speciation Monitor (ACSM) and a seven-wavelength aethalo-meter. Air masses were transported from twenty to several hundred kilometres, arriving at the measurement station after approximately half a day of transport. The concentration-weighted trajectory analysis suggests that organic aerosol particles are mainly transported over the Baltic Sea and the continent (southeast of Belarus). Results show that a significant fraction of the vegetation burning organic aerosol is transformed into oxidised forms in less than a half-day. Biomass burning aerosol (BBOA) was quantified from the ACSM data using a positive matrix factorization (PMF) analysis, while its spatial distribution was evaluated using air mass clustering approach.

Optical Properties of the Urban Aerosol Particles Obtained from Ground Based Measurements and Satellite-Based Modelling Studies

Applications of satellite remote sensing data combined with ground measurements and model simulation were applied to study aerosol optical properties as well as aerosol long-range transport under the impact of large scale circulation in the urban environment in Lithuania (Vilnius). Measurements included the light scattering coefficients at 3 wavelengths (450, 550, and 700 nm) measured with an integrating nephelometer and aerosol particle size distribution (0.5–12 μm) and number concentration ( > 0.5 μm) registered by aerodynamic particle sizer. Particle number concentration and mean light scattering coefficient varied from relatively low values of 6.0 cm−3 and 12.8 Mm−1 associated with air masses passed over Atlantic Ocean to relatively high value of 119 cm−3 and 276 Mm−1 associated with South-Western air masses. Analysis shows such increase in the aerosol light scattering coefficient (276 Mm−1) during the 3rd of July 2012 was attributed to a major Sahara dust storm. Aerosol size distribution with pronounced coarse particles dominance was attributed to the presence of dust particles, while resuspended dust within the urban environment was not observed.