Â鶹ÒùÔº

Study shows organonitrates in atmospheric particles vary with altitude

While atmospheric particles directly affect climate (e.g., cloud formation), sampling atmospheric particles aloft is practically challenging. Therefore, a full understanding of how particle composition is linked to environmental function remains limited.

To address this issue, a multi-institutional team of researchers used a tethered balloon system to collect atmospheric particles in a vertical profile up to 750 meters above ground level. Collected atmospheric particles were subsequently analyzed to determine the constituent organic molecules to examine the difference in composition between ground and aloft samples.

The team found that aloft particles contained more organonitrate molecules than those collected at ground level, and that increase was affected by cloud coverage, relative humidity, and wind variance.

While measuring and determining the composition of atmospheric particles collected at ground level is comparatively straightforward, this study shows that such a strategy may misrepresent the true vertically resolved composition of the atmosphere.

In particular, the varied, vertically resolved composition may significantly change the atmospheric function and lifetime of particles, resulting in corresponding impacts on climate.

This research, in Environmental Science & Technology, reveals new information that can be applied to atmospheric models.

Using measurements supported by the Atmospheric Radiation Measurement (ARM) user facility, a Department of Energy (DOE) Office of Science user facility, a tethered balloon system was used at the Southern Great Plains atmospheric observatory in Oklahoma to collect atmospheric particles from ground and aloft levels. Collected samples were later analyzed for their organic molecular composition using high-resolution mass spectrometry at the Environmental Molecular Sciences Laboratory (EMSL), also a DOE Office of Science user facility.

Overall, this study highlights the importance of considering vertically resolved organic molecular composition (particularly for organonitrates) and hypothesizes that aqueous-phase transformations and vertical wind variance may be key variables affecting the molecular composition of organic aerosols above the Earth's surface.