Data from: Seasonal investigation of ultrafine particle organic composition in an eastern Amazonian rainforest

Reports on the composition of ultrafine (<100 nm in diameter)
particles in the Amazon are scarce, due in part to the fact that new
particle formation has rarely been observed near ground level.
 Ultrafine particles near the surface have nevertheless been
observed, leaving open questions regarding the sources and chemistry of
their formation and growth, particularly as these vary across seasons.
 Here we present measurements on the composition of ultrafine
particles collected in the Tapaj\'{o}s National Forest (2.857° S,
54.959° W) during three different seasonal periods: 10 - 30 September 2016
(SEP), 18 November - 23 December 2016 (DEC), and 22 May - 21 June 2017
(JUN).  Size-selected (5 - 70 nm) particles were collected daily
(22 h) using an offline sampler.  Samples collected during the
three time periods were compiled and analyzed using liquid chromatography
coupled to Orbitrap high resolution mass spectrometry.  Our
findings suggest a sustained influence of isoprene organosulfate chemistry
on ultrafine particles in the different periods.  We present
chemical evidence that biological spore fragmentation impacted ultrafine
particle composition  during the late wet season (JUN), while
chemical markers for biomass burning and secondary chemistry peaked during
the dry season (SEP, DEC).  Higher oxidation states and degrees
of unsaturation were observed for organics in the dry season (SEP, DEC),
suggesting greater extents of aerosol aging. Finally, applying a
volatility parameterization to the observed compounds suggests organic
sulfur species are likely key drivers of new particle growth in the region
due to their low volatility compared to other species.