Evaluation of commonly used filter substrates for the measurement of aerosol trace element solubility

Clifton S. Buck, Adina Paytan

Limnol. Oceanogr. Methods 10:790-806 (2012) | DOI: 10.4319/lom.2012.10.790

ABSTRACT: The published literature describing aerosol trace element fractional solubility measurements is characterized by a wide range of observed fractional solubilities. Whereas some of this variability is derived from natural differences in the chemical characteristics of the aerosol source material, the use of different sample collection and processing protocols by the scientific community has also confounded efforts to understand aerosol solubility. Bulk aerosol samples were collected at a coastal site over a nine-month period and used to assess the influence of filter material on aerosol solubility measurements. Two hundred samples were extracted with ultrapure deionized water and focused on the solubility of ten trace elements (Al, P, Ti, V, Mn, Fe, Ni, Cu, Zn, and Pb) of interest to the GEOTRACES program. Aerosol samples were collected on eight different filter types and extracted using a flow-through "instantaneous" extraction method. In many cases, the operationally defined aerosol trace element solubility differed depending on filter type. Major anion concentrations and trace element fractional solubility were found to differ 58% and 60% of the time, respectively. Filter blank concentrations are also reported for the various filter types. This work, in conjunction with the 2008 GEOTRACES Aerosol Intercalibration study, should aid the design of future research efforts by the wider marine aerosol community and allow better comparisons among published data.