Open AccessFrost flower chemical composition during growth and its implications for aerosol production and bromine activation
Author(s) -
AlvarezAviles Laura,
Simpson William R.,
Douglas Thomas A.,
Sturm Matthew,
Perovich Donald,
Domine Florent
Publication year - 2008
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2008jd010277
Subject(s) - frost (temperature) , sea salt aerosol , sea salt , sulfate , bromine , sea ice , chemical composition , seawater , brine , atmospheric sciences , aerosol , environmental science , geology , environmental chemistry , chemistry , oceanography , geomorphology , organic chemistry
Frost flowers have been proposed to be the major source of sea‐salt aerosol to the atmosphere during polar winter and a source of reactive bromine during polar springtime. However little is known about their bulk chemical composition or microstructure, two important factors that may affect their ability to produce aerosols and provide chemically reactive surfaces for exchange with the atmosphere. Therefore, we chemically analyzed 28 samples of frost flowers and parts of frost flowers collected from sea ice off of northern Alaska. Our results support the proposed mechanism for frost flower growth that suggests water vapor deposition forms an ice skeleton that wicks brine present on newly grown sea ice. We measured a high variability in sulfate enrichment factors (with respect to chloride) in frost flowers and seawater from the vicinity of freezing sea ice. The variability in sulfate indicates that mirabilite precipitation (Na 2 SO 4 · 10 H 2 O) occurs during frost flower growth. Brine wicked up by frost flowers is typically sulfate depleted, in agreement with the theory that frost flowers are related to sulfate‐depleted aerosol observed in Antarctica. The bromide enrichment factors we measured in frost flowers are within error of seawater composition, constraining the direct reactive losses of bromide from frost flowers. We combined the chemical composition measurements with temperature observations to create a conceptual model of possible scenarios for frost flower microstructure development.