Dataset: Element quotas of individual phytoplankton cells from samples collected on the US GEOTRACES Arctic cruise GN01 (HLY1502) on USCGC Healy in August-October 2015

Single-cell SXRF samples were collected from the surface mixed layer using the GEOTRACES rosette. Whole water samples were preserved with 0.25% trace-metal clean buffered glutaraldehyde (Twining et al., 2003) and centrifuged onto Au or SiN TEM windows. Grids were briefly rinsed with a drop of ultrapure water and dried in a Class-100 cabinet. SXRF analysis was performed using the 2-ID-E beamline at the Advanced Photon source (Argonne National Laboratory) following the protocols of Twining et al. (2011). Each cell was raster scanned with a focused 10 keV x-ray beam with a diameter of approximately 0.5 micrometers (µm).