Single‐particle mass spectrometry of tropospheric aerosol particles

Abstract

[1] The Particle Analysis by Laser Mass Spectrometry (PALMS) instrument has measured the composition of single particles during a number of airborne and ground-based campaigns. In the regions studied, 30% to over 80% of the aerosol mass in the free troposphere was carbonaceous material. Most of this carbonaceous material was probably organic. Although there were variations in their amounts, over 90% of accumulation mode particles away from local sources were internal mixtures of sulfates and carbonaceous material. Within this internal mixing, there was variation in the pattern of carbonaceous peaks in the spectra, especially in peaks related to organic acids. Particles with a biomass burning signature were a significant fraction of accumulation mode particles even far from fires. The accumulation mode near the ocean surface off the coasts of California and New England had significant numbers of carbonaceous-sulfate particles whereas at Cape Grim, Tasmania, the organic-sulfate particles were apparently all smaller than 160 nm. Three kinds of nitrate were evident: on mineral particles, on carbonaceous-sulfate particles when the sulfate was fully neutralized, and at temperatures below about 198 K. Most mineral particles showed evidence of the uptake of nitrates and chloride. A peak that probably represents protonated pyridine appears in some spectra in the free troposphere.

Comparison between CARIBIC Aerosol Samples Analysed by Accelerator-Based Methods and Optical Particle Counter Measurements

“…To increase the apparent density to a value of 1.5 g cm −3 by increasing the carbon concentration in an attempt to reach more plausible value, the carbon concentrations need to be multiplied by approximately 2. This would increase the carbon-to-sulphate mass ratio average over all samples to 0.8, and for stratospheric samples carbon to sulphate mass ratio would become larger than 0.5, which is not in line with studies based on another analytical method (Murphy et al, 2006(Murphy et al, , 2007. In addition, studies of volcanic aerosol based on CARIBIC aerosol samples (Martinsson et al, 2009) agree well with studies based on other methods (Schmale et al, 2010;Carn et al, 2011) in the relation between the carbonaceous and sulphurous fractions of the aerosol.…”

“…The carbonaceous fraction is another major component of the aerosol in this region (Murphy et al, 1998(Murphy et al, , 2006Nguyen et al, 2008, Friberg et al, 2014. Black carbon constitutes a small fraction of the total carbon (Schwarz et al, 2010;Friberg et al, 2014).…”

Performance of an Aerodyne Aerosol Mass Spectrometer (AMS) during Intensive Campaigns in China in the Summer of 2006

“…The presence of Rb in ambient aerosol has been identified by a single-particle mass spectrometer (Murphy et al 2006), although the signal intensity was very small. The presence of Cs in aerosol has never been reported to the best of our knowledge.…”

Experimental evidence for excess entropy discontinuities in glass-forming solutions

“…Organic aerosol particles are, among other emission sources, produced by biomass burning in the tropics 10,11 and they are ubiquitous in the troposphere (see Kanakidou et al 12 ). Murphy et al 13 and Froyd et al 14 detected particles that consist largely of organic material at the tropical tropopause level. The high viscosity of these particles could kinetically limit water uptake and thus inhibit the formation of cirrus clouds.…”