Preprints  

Our study explores particles in Arctic soils and streams that influence ice formation in clouds. By analysing these environments, we identified specific microorganisms producing these particles. This research, which measured these particles in Arctic streams for the first time, provides new insights into their ecological role and transfer from soil to water. Our findings help us understand their production, sources, and potential impact on climate.

The COVID-19 lockdown measures in 2020 reduced emissions of various substances improving air quality. However, PM2.5 stayed unchanged due to NH₃ and related chemical transformations. Higher humidity favoured more SO₄^2- production so as accumulated NH₃ did. Excess NH₃ neutralised HNO₃ towards NO₃^-. In high NH₃ conditions such as those in 2020, a small reduction of NO_x levels drives faster oxidation toward NO₃^- and slower deposition of total inorganic NO₃^- causing high secondary PM2.5.

Dust deposition flux was investigated in lutruwita/Tasmania, Australia, between 2016 and 2021. Results show that the use of direct measurement of aluminium, iron, thorium and titanium in aerosols to estimate average dust deposition fluxes limits biases associated with using single elements. Observations of dust deposition fluxes in the Southern Hemisphere are critical to validate model outputs and better understand the seasonal and interannual impacts of dust deposition on biogeochemical cycles.

We evaluated the performance of four cascade impactors for collecting and analyzing organic markers in airborne UFP under laboratory and field conditions. The cut-off was influenced by both impactor design and aerosol mixture. Two key factors caused variations in mass concentrations: evaporation of semi-volatile compounds and bounce of larger particles and fragments. Our findings highlight the complexities of accurately separating and analyzing organic marker mass concentrations in airborne UFP.

This study shows that electrostatic dispersion can influence time-evolution of the charge and size distributions of radioactive and nonradioactive particles in the atmosphere. Three approaches with different levels of complexity are proposed to couple electrostatic dispersion with microphysical and radiological processes. These approaches can be useful to better understand the behavior of particles in atmospheric systems with radiation sources.

The exact point at which a given assembly of molecules represent an atmospheric molecular cluster or a particle remains ambiguous. Using quantum chemical methods we here explore the cluster-to-particle transition point. Based on our results, we deduce a property-based criteria for defining “freshly nucleated particles (FNPs)”, that act as a boundary between discrete cluster configurations and bulk particles.

This study examines new particle formation (NPF) in the Bolivian Andes at Chacaltaya mountain (CHC) and the urban El Alto-La Paz area (EAC). Days are clustered into four categories based on NPF intensity. Differences in particle size, precursor gases, and pollution levels are found. High NPF intensities increased Aitken mode particle concentrations at both sites, while volcanic influence selectively diminished NPF intensity at CHC but not EAC. This study highlights NPF dynamics in the Andes.

With the recently developed instrument CIC (cluster ion counter) we can observe dynamics of small air ions and intermediate air ions. Furthermore we can observe condensation sink and formation and growth rates for intermediated ions.

The performances of different particle lung deposited surface area (LDSA^al) measurement methods (Partector, ELPI+, SMPS/DMPS) were compared in ambient conditions. As LDSA^al is a health-relevant metric and rather easy to utilise in air quality monitoring, it is crucial to know how the different methods agree as there are clear differences in their operation. In all, comparison of different methods can be complicated, but, still, the methods agree rather well in terms of local pollution (<400 nm).

Black Carbon (BC) is a pollutant from combustion that affects the climate and is harmful to health. We tested four different small BC sensors with a reference in Helsinki. The sensors compared well with the reference. As a sensor network they were able to capture differences in BC. Changes in temperature (T) and relative humidity (RH) caused error in the measurement. To reduce the effects of T and RH on BC sensors, more robust boxes should be developed or corrections should be applied.

Although spray flame synthesis (SFS) is a promising approach to prepare nano materials with tailored properties, the impurity formation is not fully understood in SFS. To contribute to this topic, maghemite nanoparticles were prepared by SFS, and two complementary experimental approaches were used to investigate the evolution of soot and carbonaceous surface adsorbates. The methodological procedure and the data provided can be used to denote/compare SFS-materials more reliably in the future.

Several papers have reported on electrospray technique and they have shown that uniform thin films with different surface morphologies can be deposited. Nonetheless, the studies do not give a systematic way of designing different surface morphologies and most outcomes are based on a trial-and-error method. Therefore, in this study a systematic way of designing thin films of different surface morphologies using electrospray technique has been developed.