| Περίληψη: | A new method for the measurement of the water solubility distribution of atmospheric organic aerosol was developed. This method is based on the extraction of organic aerosol collected on filters, using different amounts of water and measurement of the corresponding Water Soluble Organic Carbon (WSOC) concentration. The solubility distribution is then estimated using the solubility basis set. The proposed approach can quantify the solubility distribution in the 10-3-1 g L-1 range.
The method was applied on both ambient and source-specific aerosol. 58-63% of the atmospheric urban background organic aerosol analyzed had water solubility higher than 1 g L-1. 11% of the fresh cooking organic aerosol had water solubility higher than 0.1 g L-1, while 80% had solubility lower than 10-3 g L-1. The solubility of the COA increased significantly after aging. The fraction of COA with solubility greater than 0.1 g L−1 more than doubled, increasing to 55%.
Additionally, a new method for the measurement of Henry’s law constant distribution of atmospheric organic aerosol components was developed and tested. The method is based on the separation of the OA constituents by volatility and then measurement of the water solubility distribution of each fraction. The results showed that an important fraction of the biogenic secondary organic aerosol with volatility equal to 1 μg m-3 (about 50%) has Henry’s law constant between 4x104 and 4x105 M atm-1.
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