Ice-nucleating particles in Canadian Arctic sea-surface microlayer and bulk seawater
The sea-surface microlayer and bulk seawater can contain ice-nucleating particles (INPs) and these INPs can be emitted into the atmosphere. Our current understanding of the properties, concentrations, and spatial and temporal distributions of INPs in the microlayer and bulk seawater is limited....
| Main Authors: | , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-09-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/17/10583/2017/acp-17-10583-2017.pdf |
| Summary: | The sea-surface microlayer and bulk seawater can contain
ice-nucleating particles (INPs) and these INPs can be emitted into
the atmosphere. Our current understanding of the properties,
concentrations, and spatial and temporal distributions of INPs in the
microlayer and bulk seawater is limited. In this study we
investigate the concentrations and properties of INPs in microlayer
and bulk seawater samples collected in the Canadian Arctic during
the summer of 2014. INPs were ubiquitous in the microlayer and bulk
seawater with freezing temperatures in the immersion mode as high as
−14 °C. A strong negative correlation (<i>R</i> = −0. 7,
<i>p</i> = 0. 02) was observed between salinity and freezing temperatures
(after correction for freezing depression by the salts). One
possible explanation is that INPs were associated with melting sea
ice. Heat and filtration treatments of the samples show that the
INPs were likely heat-labile biological materials with sizes between
0.02 and 0.2 µm in diameter, consistent with previous
measurements off the coast of North America and near Greenland in
the Arctic. The concentrations of INPs in the microlayer and bulk
seawater were consistent with previous measurements at several other
locations off the coast of North America. However, our average
microlayer concentration was lower than previous observations made
near Greenland in the Arctic. This difference could not be explained
by chlorophyll <i>a</i> concentrations derived from satellite
measurements. In addition, previous studies found significant INP
enrichment in the microlayer, relative to bulk seawater, which we
did not observe in this study. While further studies are needed to
understand these differences, we confirm that there is a source of
INP in the microlayer and bulk seawater in the Canadian Arctic that
may be important for atmospheric INP concentrations. |
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| ISSN: | 1680-7316 1680-7324 |