Phase transitions of sea-salt/water mixtures at low temperatures: Implications for ozone chemistry in the polar marine boundary layer

Koop T, Kapilashrami A, Molina LT, Molina MJ (2000)
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 105(D21): 26393-26402.

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Zeitschriftenaufsatz | Veröffentlicht | Englisch
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Abstract / Bemerkung
We present laboratory experiments employing differential scanning calorimetry as well as how cell microscopy to study the microphysics of aqueous NaCl and sea-salt solutions and droplets at temperatures below 273 K. The freezing and melting points of ice and other precipitates were determined in NaCl and sea-salt bulk samples as well as in emulsion samples. Using flow cell microscopy, we have determined the deliquescence and efflorescence relative humidities of NaCl and sea-salt droplets at temperatures between 249 and 773 K, extending the existing room temperature data to polar conditions. Our measurements suggest that sea-salt aerosols will most likely be liquid most of the time under polar marine boundary conditions. In addition, we show that sea-salt aerosols or seawater spray deposited on the polar ice pack will remain partly liquid down to 230 K, with concentrations of Cl- and Br- increasing by more than an order of magnitude upon cooling when compared to normal seawater concentrations. This is likely to enhance the rate at which heterogeneous bromine activation reactions occur in the sea-salt deposits. Such reaction rate enhancements with decreasing temperatures are currently not implemented in chemical models, and might help explain the fast bromine activation and subsequent ozone destruction observed during ozone depletion events in the polar marine boundary layer in spring.
Erscheinungsjahr
Zeitschriftentitel
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
Band
105
Zeitschriftennummer
D21
Seite
26393-26402
ISSN
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Koop T, Kapilashrami A, Molina LT, Molina MJ. Phase transitions of sea-salt/water mixtures at low temperatures: Implications for ozone chemistry in the polar marine boundary layer. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES. 2000;105(D21):26393-26402.
Koop, T., Kapilashrami, A., Molina, L. T., & Molina, M. J. (2000). Phase transitions of sea-salt/water mixtures at low temperatures: Implications for ozone chemistry in the polar marine boundary layer. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 105(D21), 26393-26402. doi:10.1029/2000jd900413
Koop, T., Kapilashrami, A., Molina, L. T., and Molina, M. J. (2000). Phase transitions of sea-salt/water mixtures at low temperatures: Implications for ozone chemistry in the polar marine boundary layer. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 105, 26393-26402.
Koop, T., et al., 2000. Phase transitions of sea-salt/water mixtures at low temperatures: Implications for ozone chemistry in the polar marine boundary layer. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 105(D21), p 26393-26402.
T. Koop, et al., “Phase transitions of sea-salt/water mixtures at low temperatures: Implications for ozone chemistry in the polar marine boundary layer”, JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, vol. 105, 2000, pp. 26393-26402.
Koop, T., Kapilashrami, A., Molina, L.T., Molina, M.J.: Phase transitions of sea-salt/water mixtures at low temperatures: Implications for ozone chemistry in the polar marine boundary layer. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES. 105, 26393-26402 (2000).
Koop, Thomas, Kapilashrami, A., Molina, L. T., and Molina, M. J. “Phase transitions of sea-salt/water mixtures at low temperatures: Implications for ozone chemistry in the polar marine boundary layer”. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 105.D21 (2000): 26393-26402.