TY - JOUR
T1 - Coal fly ash
T2 - linking immersion freezing behavior and physicochemical particle properties
AU - Grawe, Sarah
AU - Augustin-Bauditz, Stefanie
AU - Clemen, Hans-Christian
AU - Ebert, Martin
AU - Hammer, Stine Eriksen
AU - Lubitz, Jasmin
AU - Reicher, Naama
AU - Rudich, Yinon
AU - Schneider, Johannes
AU - Staacke, Robert
AU - Stratmann, Frank
AU - Welti, Andre
AU - Wex, Heike
N1 - This research was conducted in the framework of the DFG funded Ice Nuclei research UnIT (INUIT, FOR1525), WE 4722/1-2, SCHN1138/2-2. We thank the anonymous suppliers of the CFA samples, the Lippendorf power plant, Mette Sidelmann and Merete Bilde (Department of Chemistry, Aarhus University, Denmark) for water-activity measurements, Michael Lorenz (Semiconductor Physics Group, University of Leipzig, Germany) for providing access to the XRD instrument, Anke Rödger, Khanneh W. Fomba, Anett Dietze, Susanne Fuchs, and Dominik van Pinxteren (TROPOS, Leipzig, Germany) for bulk chemical composition analysis, Xianda Gong (TROPOS, Leipzig, Germany) for helpful discussions, Roswitha Heller (Leibniz Institute of Surface Modification, Leipzig, Germany) and Jens Voigtländer (TROPOS, Leipzig, Germany) for introduction to the optical microscopes, and Thomas Conrath (TROPOS, Leipzig, Germany) for technical support. Author contributions. SG wrote the manuscript with contributions from HCC, SEH, NR, and HW. LACIS measurements and data evaluation were performed by SG, SAB, and JL. LINA measurements and data evaluation were performed by JL and SG. HCC performed ALABAMA measurements and data analysis with the support of JS. SEH sampled particles with the impactor and performed the ESEM/EDX particle analysis together with ME. NR measured with WISDOM and provided BET results. AW performed SPIN measurements and data evaluation. RS performed XRD measurements. SG, SAB, FS, and HW discussed the immersion freezing results and further experiments after the campaign. HW procured the CFA samples and coordinated the campaign. All co-authors proofread and commented on the manuscript.
PY - 2018/10/2
Y1 - 2018/10/2
N2 - To date, only a few studies have investigated the potential of coal fly ash particles to trigger heterogeneous ice nucleation in cloud droplets. The presented measurements aim at expanding the sparse dataset and improving process understanding of how physicochemical particle properties can influence the freezing behavior of coal fly ash particles immersed in water.Firstly, immersion freezing measurements were performed with two single particle techniques, i.e., the Leipzig Aerosol Cloud Interaction Simulator (LACIS) and the SPectrometer for Ice Nuclei (SPIN). The effect of suspension time on the efficiency of the coal fly ash particles when immersed in a cloud droplet is analyzed based on the different residence times of the two instruments and employing both dry and wet particle generation. Secondly, two cold-stage setups, one using microliter sized droplets (Leipzig Ice Nucleation Array) and one using nanoliter sized droplets (Welzmann Supercooled Droplets Observation on Microarray setup) were applied.We found that coal fly ash particles are comparable to mineral dust in their immersion freezing behavior when being dry generated. However, a significant decrease in immersion freezing efficiency was observed during experiments with wet-generated particles in LACIS and SPIN. The efficiency of wet-generated particles is in agreement with the cold-stage measurements. In order to understand the reason behind the deactivation, a series of chemical composition, morphology, and crystallography analyses (single particle mass spectrometry, scanning electron microscopy coupled with energy dispersive X-ray microanalysis, X-ray diffraction analysis) were performed with dry- and wet-generated particles. From these investigations, we conclude that anhydrous CaSO4 and CaO - which, if investigated in pure form, show the same qualitative immersion freezing behavior as observed for dry-generated coal fly ash particles - contribute to triggering heterogeneous ice nucleation at the particle-water interface. The observed deactivation in contact with water is related to changes in the particle surface properties which are potentially caused by hydration of CaSO4 and CaO. The contribution of coal fly ash to the ambient population of ice-nucleating particles therefore depends on whether and for how long particles are immersed in cloud droplets.
AB - To date, only a few studies have investigated the potential of coal fly ash particles to trigger heterogeneous ice nucleation in cloud droplets. The presented measurements aim at expanding the sparse dataset and improving process understanding of how physicochemical particle properties can influence the freezing behavior of coal fly ash particles immersed in water.Firstly, immersion freezing measurements were performed with two single particle techniques, i.e., the Leipzig Aerosol Cloud Interaction Simulator (LACIS) and the SPectrometer for Ice Nuclei (SPIN). The effect of suspension time on the efficiency of the coal fly ash particles when immersed in a cloud droplet is analyzed based on the different residence times of the two instruments and employing both dry and wet particle generation. Secondly, two cold-stage setups, one using microliter sized droplets (Leipzig Ice Nucleation Array) and one using nanoliter sized droplets (Welzmann Supercooled Droplets Observation on Microarray setup) were applied.We found that coal fly ash particles are comparable to mineral dust in their immersion freezing behavior when being dry generated. However, a significant decrease in immersion freezing efficiency was observed during experiments with wet-generated particles in LACIS and SPIN. The efficiency of wet-generated particles is in agreement with the cold-stage measurements. In order to understand the reason behind the deactivation, a series of chemical composition, morphology, and crystallography analyses (single particle mass spectrometry, scanning electron microscopy coupled with energy dispersive X-ray microanalysis, X-ray diffraction analysis) were performed with dry- and wet-generated particles. From these investigations, we conclude that anhydrous CaSO4 and CaO - which, if investigated in pure form, show the same qualitative immersion freezing behavior as observed for dry-generated coal fly ash particles - contribute to triggering heterogeneous ice nucleation at the particle-water interface. The observed deactivation in contact with water is related to changes in the particle surface properties which are potentially caused by hydration of CaSO4 and CaO. The contribution of coal fly ash to the ambient population of ice-nucleating particles therefore depends on whether and for how long particles are immersed in cloud droplets.
UR - http://www.scopus.com/inward/record.url?scp=85053778082&partnerID=8YFLogxK
U2 - 10.5194/acp-18-13903-2018
DO - 10.5194/acp-18-13903-2018
M3 - مقالة
SN - 1680-7316
VL - 18
SP - 13903
EP - 13923
JO - Atmospheric Chemistry and Physics
JF - Atmospheric Chemistry and Physics
IS - 19
ER -