Effect of Trace Components of Seawater on Water Content of Sea-Salt Aerosol

The effects of trace components of seawater on water content of sea-salt aerosol have been investigated by infrared spectroscopy and thermal analysis. Seawater droplets of a median diameter ca 0.35μm have been formed by atomizing an artificial seawater under ambient conditions. Humidity of the sea-salt aerosol was controlled by humidifying dried sea-salt aerosol or dehumidifying the seawater droplets. As a result, it was proven that the water content of dried sea-salt aerosol was much higher than that of NaCl aerosol due to the hydration of the trace components of seawater. In addition, the crystallization point of dried sea-salt aerosol shifted to a higher humidity than that of NaCl aerosol. The reason for this is that the crystallization of CaSO4 occurs prior to the NaCl nucleation and it leads to the heterogeneous nucleation when the water content of seawater droplets decreases.