TY - JOUR
T1 - Insignificant impact of freezing and compaction on iron solubility in natural snow
AU - Mukherjee, Pami
AU - Glamoclija, Mihaela
AU - Gao, Yuan
N1 - Funding Information:
This research was supported by NSF OCE Award 1435871 and Rutgers TA-GA development grant. The authors are grateful to Alexei Khalizov and Evert Elzinga for helpful discussions. The authors are grateful to the anonymous reviewers for constructive comments that helped substantially improve this manuscript. The authors are also thankful to Tinayi Xu, Guojie Xu, Lasita Bhattacharya, and Songyun Fan for help with sample collection and analysis.
Publisher Copyright:
© 2018, Springer Science+Business Media B.V., part of Springer Nature.
PY - 2018/9/1
Y1 - 2018/9/1
N2 - To explore the freezing effect on iron (Fe) solubility in natural environments, especially in Polar regions, event based freshly fallen snow samples were collected at Newark, New Jersey on the US East Coast for two consecutive winter seasons (2014–2015 and 2015–2016). These samples were analyzed for the concentrations of soluble iron (Fesol) using UV-Vis Spectroscopy and filterable iron (Fefil) and total iron (Fetot) using Atomic Absorption Spectroscopy. The average fractional solubility of the Fesol (the portion that passes through a 0.22 μm pore-size filter) with respect to the total Fe in the samples was 23.3 ± 12.2%, with the majority of the soluble Fe being present as Fe(III). Approximately 48.5% of the total Fe existed as Fefil (the portion that passes through 0.45 μm pore size filter media). No significant correlation was found between the soluble ionic species and soluble Fe. Six snow events were kept frozen for 10 days, and analyzed in periodic intervals to study the post-freezing modification in Fe solubility. Events 1 and 2 showed increasing trend in the soluble Fe concentrations; however, the events 5, 6, 7, and 8 showed no noticeable increments. The pattern shown in Events 1 and 2 is associated with high fraction of Fefil and one unit pH drop, suggesting that the freeze-induced modification in Fe solubility could be linked with the amount of Fefil and the acidity change in the samples. To further investigate the freeze-induced compaction of particles, samples from three events 6, 7, and 10 were analyzed by SEM-STEM-EDS microscopy, and the results showed that due to freezing, in general, the particles in the ice-melt counterparts tend to compact and cluster and form larger aggregates compared to the particles in snow-melt. These results show, despite the freeze-induced compaction in snow was observed from STEM images, the snow freezing might not have significant effect in increasing Fe solubility from materials in the snow. These results further suggest that freezing process with fresh snow in high-latitude regions may not impose significant modification on Fe solubility in snow.
AB - To explore the freezing effect on iron (Fe) solubility in natural environments, especially in Polar regions, event based freshly fallen snow samples were collected at Newark, New Jersey on the US East Coast for two consecutive winter seasons (2014–2015 and 2015–2016). These samples were analyzed for the concentrations of soluble iron (Fesol) using UV-Vis Spectroscopy and filterable iron (Fefil) and total iron (Fetot) using Atomic Absorption Spectroscopy. The average fractional solubility of the Fesol (the portion that passes through a 0.22 μm pore-size filter) with respect to the total Fe in the samples was 23.3 ± 12.2%, with the majority of the soluble Fe being present as Fe(III). Approximately 48.5% of the total Fe existed as Fefil (the portion that passes through 0.45 μm pore size filter media). No significant correlation was found between the soluble ionic species and soluble Fe. Six snow events were kept frozen for 10 days, and analyzed in periodic intervals to study the post-freezing modification in Fe solubility. Events 1 and 2 showed increasing trend in the soluble Fe concentrations; however, the events 5, 6, 7, and 8 showed no noticeable increments. The pattern shown in Events 1 and 2 is associated with high fraction of Fefil and one unit pH drop, suggesting that the freeze-induced modification in Fe solubility could be linked with the amount of Fefil and the acidity change in the samples. To further investigate the freeze-induced compaction of particles, samples from three events 6, 7, and 10 were analyzed by SEM-STEM-EDS microscopy, and the results showed that due to freezing, in general, the particles in the ice-melt counterparts tend to compact and cluster and form larger aggregates compared to the particles in snow-melt. These results show, despite the freeze-induced compaction in snow was observed from STEM images, the snow freezing might not have significant effect in increasing Fe solubility from materials in the snow. These results further suggest that freezing process with fresh snow in high-latitude regions may not impose significant modification on Fe solubility in snow.
KW - Freeze-induced compaction
KW - Iron solubility
KW - Scanning electron microscopic analysis
KW - Urban snow events
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U2 - 10.1007/s10874-018-9375-2
DO - 10.1007/s10874-018-9375-2
M3 - Article
AN - SCOPUS:85044191831
SN - 0167-7764
VL - 75
SP - 247
EP - 270
JO - Journal of Atmospheric Chemistry
JF - Journal of Atmospheric Chemistry
IS - 3
ER -