Missed Evaporation from Atmospherically Relevant Inorganic Mixtures Confounds Experimental Aerosol Studies

Abstract

Sea salt aerosol particles are highly abundant in the atmosphere and play important roles in the global radiative balance. After influence from continental air, they are typically composed of Na + , Cl − , NH 4 + , and SO 4 2− and organics. Analogous particle systems are often studied in laboratory settings by atomizing and drying particles from a solution. Here, we present evidence that such laboratory studies may be consistently biased in that they neglect losses of solutes to the gas phase. We present experimental evidence from a hygroscopic tandem differential mobility analyzer and an aerosol mass spectrometer, further supported by thermodynamic modeling. We show that, at normally prevailing laboratory aerosol mass concentrations, for mixtures of NaCl and (NH 4 ) 2 SO 4 , a significant portion of the Cl − and NH 4 + ions are lost to the gas phase, in some cases, leaving mainly Na 2 SO 4 in the dry particles. Not considering losses of solutes to the gas phase during experimental studies will likely result in misinterpretation of the data. One example of such data is that from particle water uptake experiments. This may bias the explanatory models constructed from the data and introduce errors inte predictions made by air quality or climate models.

Detecting pH of Sub-Micrometer Aerosol Particles Using Fluorescent Probes

“…There are a few potential reasons for the discrepancies between pH bulk_electrode and pH particle_paper . Both previous modeling and experimental studies suggested that gas-particle partitioning of chemical species changes following nebulization of solutions, , suggesting that the particle generation process may alter pH. In addition, it should also be noted that pH papers were exposed to air in the laboratory for photo-taking purposes following sample preparation.…”

Highly Hygroscopic Aerosols Facilitate Summer and Early‐Autumn Cloud Formation at Extremely Low Concentrations Over the Central Arctic Ocean

“…Since the Aitken mode is still present in the droplet residuals and therefore must have activated prior to sampling, possible explanations are that either (1) the peak SS at the onset of the cloud formation was often higher than 1%, which is within the possible range from model simulations presented in Bulatovic et al (2021), or, more likely, (2) the water uptake on those particles is generally too slow for droplet activation to occur in the short residence time of the particles in the CCNC cloud chamber, as previously suggested by Leck and Svensson (2015), or (3) that the drying process evaporated not only water, but also a fraction of the solute, which would affect the residuals ability to reactivate into a droplet, as suggested by Rissler et al (2023). The presence of an Aitken mode in the residuals is unlikely due to sampling artifacts by the GCVI, such as droplet break up, particle capture by wake effect, or ice crystal shattering, which start occurring at larger crystal diameters than those sampled in these events, as extensively discussed in Karlsson et al (2021Karlsson et al ( , 2022.…”

Plant Photocatalysts: Photoinduced Oxidation and Reduction Abilities of Plant Leaf Ashes under Solar Light

“…A photozyme, a new type of nanozyme working under light irradiation, is an enzyme that catalyzes photochemical reactions [53,66]. Quite a few TiO 2 -based photocatalytic artificial enzymes were synthesized, and exhibit excellent peroxide-like specificity under visible light irradiation.…”