A total of fourteen 3-4 day integrated aerosol samples were collected during the US GEOTRACES Western Arctic research cruise (hereafter known as GN01), which took place from 9th August to 12th October 2015 on the USCGC Healy (cruise HLY1502). The cruise track consisted of a northward transect from Dutch Harbor, Alaska, across the Bering Sea, through the Bering Strait and across the Makarov Basin to the North Pole, followed by a return transect across the Canada Basin and back across the Bering Sea to Dutch Harbor.

Bulk aerosol samples for multiple trace element analyses were collected using one of five Tisch Environmental high-volume (~1 m³ air min⁻¹) aerosol samplers (model 5170V-BL). For each deployment, 12 replicate 47 mm diameter Whatman 41 filters were loaded on open-face filter holders (Advantec MFS) installed on the aerosol sampler on a PVC adaptor plate (Shelley et al., 2015). Filters were acid-washed before use to reduce trace element blanks, following the procedure described by Morton et al. (2013). The samplers were deployed on the ship’s flying bridge, ~23 m above sea level, to minimize the influence of sea spray on samples. Samplers were controlled by wind speed and direction, through a Campbell Scientific CR800 data-logger interfaced with an anemometer and wind vane set up in close proximity to the samplers, in order to eliminate contamination from the ship's stack exhaust. This setup was used to restrict sampling to periods when relative wind speed and direction were >0.5 m s⁻¹ and from within ±60° of the bow of the ship, respectively, for at least five continuous minutes.

The soluble aerosol fraction was measured using a variation of the flow-through extraction technique described in Buck et al. (2006). The aerosol-laden filter was placed in a Teflon filter holder over a 0.2 um polycarbonate backing filter. While under vacuum, 100 mL of ultrapure deionized water (>18 MΩ∙cm) was poured over the filter and the leachate solution collected in a 100 mL LDPE bottle. Following acidification with Teflon-distilled hydrochloric acid, the samples were analyzed for trace element concentration by a quadrupole inductively coupled mass spectrometer (Perkin Elmer Nexion 300D) coupled with a SeaFAST3 sample introduction and preconcentration system (Elemental Scientific) at the Skidaway Institute of Oceanography.