Atmospheric particles collected during the ICARTT 2004 field experiment at ground based sites at Appledore Island (Al), New Hampshire, Chebogue Point (CP), Nova Scotia, and aboard the R/V Ronald Brown(RB) were analyzed using Fouriertransform infrared (FIR) spectroscopy to quantify organic mass (OM) and organic functional groups. Several of these spectra contain a unique absorbance peak at 3500 cm-1. Laboratory calibrations identify this peak with phenol functional groups. The phenol groups are associated with seawater-derived emissions based on correlations with tracer volatile organic compounds (VOCs) and ions, and potential source contribution function (PSCF) analysis. On the basis of the measured absorptivities, the project average phenol group concentrations are 0.24 ± 0.18 μg m-3 (4% of the total OM) at Al, 0.10 ± 0.6 μg m-3 (5% of the total OM) at CP, and 0.08 ± 0.09 μg m-3 (2% of the total OM) on board the RB, with detection limits typically between 0.06 and 0.11 μg m-3. The spectra were partitioned into three primary factors using positive matrix factorization (PMF) sufficient to explain more than 95% of the measured OM. The fossil fuel combustion factor contributed 40% (Al), 34% (CP), and 43% (RB) of the total OM; the terrestrial biogenic factor contributed 20% (Al), 30% (CP), and 27% (RB). The seawater-derived factor contributed 40% (Al), 36% (CP) and 29% (RB) of the OM and showed similar correlations to tracers as the phenol group.