Ice nucleation properties of K-feldspar polymorphs and plagioclase feldspars
<p>The relation between the mineralogical characteristics of size-selected feldspar particles from 50 to 800 nm and their ability to act as ice-nucleating particles (INPs) in the immersion mode is presented. Five polymorph members of K-feldspar (two microclines, orthoclase, adularia...
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| Language: | English |
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Copernicus Publications
2019-08-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/19/10901/2019/acp-19-10901-2019.pdf |
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| author | A. Welti A. Welti U. Lohmann Z. A. Kanji |
| author_facet | A. Welti A. Welti U. Lohmann Z. A. Kanji |
| author_sort | A. Welti |
| collection | DOAJ |
| description | <p>The relation between the mineralogical characteristics of
size-selected feldspar particles from 50 to 800 nm and their ability to act
as ice-nucleating particles (INPs) in the immersion mode is presented. Five
polymorph members of K-feldspar (two microclines, orthoclase, adularia and
sanidine) and four plagioclase samples (three labradorites and a pericline
sample) are tested. Microcline was found to be the most active INP in the
immersion mode consistent with previous findings. Samples were selected for
their differences in typical feldspar properties such as crystal structure,
bulk and trace elemental composition, and ordering of the crystal lattice.
The properties mentioned are related to the temperature of feldspar
crystallization from the magma during formation. Properties characteristic of low-temperature feldspar formation coincide with an increased ability to
nucleate ice. Amongst the samples investigated, ice nucleation is most
efficient on the crystallographically ordered, triclinic K-feldspar species
microcline, while the intermediate and disordered monoclinic K-feldspar
polymorphs orthoclase and sanidine nucleate ice at lower temperatures. The
ice nucleation ability of disordered triclinic <span class="inline-formula">Na∕Ca</span>-feldspar is comparable
to disordered K-feldspar. The conditions of feldspar rock formation also
leave a chemical fingerprint with varying abundance of trace elements in the
samples. X-ray fluorescence spectroscopy analysis was conducted to determine
metal oxide and trace elemental composition of the feldspar samples. The
analysis revealed a correlation of trace metal abundance with median
freezing temperatures (<span class="inline-formula"><i>T</i><sub>50</sub></span>) of the K-feldspar samples allowing us to sort
them for their ice nucleation efficiency according to the abundance of
specific trace elements. A pronounced size dependence of ice nucleation
activity for the feldspar samples is observed, with the activity of smaller-sized particles scaling with surface area or being even higher compared to
larger particles. The size dependence varies for different feldspar samples.
In particular, microcline exhibited immersion freezing even for 50 nm
particles which is unique for heterogeneous ice nucleation of mineral dusts.
This suggests that small microcline particles that are susceptible to
long-range transport can affect cloud properties via immersion freezing far
away from the source. The measurements generally imply that temperatures at
which feldspars can affect cloud glaciation depend on the transported
particle size in addition to the abundance of these particles.</p> |
| first_indexed | 2024-12-10T04:58:03Z |
| format | Article |
| id | doaj.art-3cc7c1efbb60479aa79f161706f053f3 |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-10T04:58:03Z |
| publishDate | 2019-08-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-3cc7c1efbb60479aa79f161706f053f32022-12-22T02:01:27ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242019-08-0119109011091810.5194/acp-19-10901-2019Ice nucleation properties of K-feldspar polymorphs and plagioclase feldsparsA. Welti0A. Welti1U. Lohmann2Z. A. Kanji3Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, 8092, Switzerlandnow at: Finnish Meteorological Institute, Helsinki, 00101, FinlandInstitute for Atmospheric and Climate Science, ETH Zurich, Zurich, 8092, SwitzerlandInstitute for Atmospheric and Climate Science, ETH Zurich, Zurich, 8092, Switzerland<p>The relation between the mineralogical characteristics of size-selected feldspar particles from 50 to 800 nm and their ability to act as ice-nucleating particles (INPs) in the immersion mode is presented. Five polymorph members of K-feldspar (two microclines, orthoclase, adularia and sanidine) and four plagioclase samples (three labradorites and a pericline sample) are tested. Microcline was found to be the most active INP in the immersion mode consistent with previous findings. Samples were selected for their differences in typical feldspar properties such as crystal structure, bulk and trace elemental composition, and ordering of the crystal lattice. The properties mentioned are related to the temperature of feldspar crystallization from the magma during formation. Properties characteristic of low-temperature feldspar formation coincide with an increased ability to nucleate ice. Amongst the samples investigated, ice nucleation is most efficient on the crystallographically ordered, triclinic K-feldspar species microcline, while the intermediate and disordered monoclinic K-feldspar polymorphs orthoclase and sanidine nucleate ice at lower temperatures. The ice nucleation ability of disordered triclinic <span class="inline-formula">Na∕Ca</span>-feldspar is comparable to disordered K-feldspar. The conditions of feldspar rock formation also leave a chemical fingerprint with varying abundance of trace elements in the samples. X-ray fluorescence spectroscopy analysis was conducted to determine metal oxide and trace elemental composition of the feldspar samples. The analysis revealed a correlation of trace metal abundance with median freezing temperatures (<span class="inline-formula"><i>T</i><sub>50</sub></span>) of the K-feldspar samples allowing us to sort them for their ice nucleation efficiency according to the abundance of specific trace elements. A pronounced size dependence of ice nucleation activity for the feldspar samples is observed, with the activity of smaller-sized particles scaling with surface area or being even higher compared to larger particles. The size dependence varies for different feldspar samples. In particular, microcline exhibited immersion freezing even for 50 nm particles which is unique for heterogeneous ice nucleation of mineral dusts. This suggests that small microcline particles that are susceptible to long-range transport can affect cloud properties via immersion freezing far away from the source. The measurements generally imply that temperatures at which feldspars can affect cloud glaciation depend on the transported particle size in addition to the abundance of these particles.</p>https://www.atmos-chem-phys.net/19/10901/2019/acp-19-10901-2019.pdf |
| spellingShingle | A. Welti A. Welti U. Lohmann Z. A. Kanji Ice nucleation properties of K-feldspar polymorphs and plagioclase feldspars Atmospheric Chemistry and Physics |
| title | Ice nucleation properties of K-feldspar polymorphs and plagioclase feldspars |
| title_full | Ice nucleation properties of K-feldspar polymorphs and plagioclase feldspars |
| title_fullStr | Ice nucleation properties of K-feldspar polymorphs and plagioclase feldspars |
| title_full_unstemmed | Ice nucleation properties of K-feldspar polymorphs and plagioclase feldspars |
| title_short | Ice nucleation properties of K-feldspar polymorphs and plagioclase feldspars |
| title_sort | ice nucleation properties of k feldspar polymorphs and plagioclase feldspars |
| url | https://www.atmos-chem-phys.net/19/10901/2019/acp-19-10901-2019.pdf |
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