Calculating ambient aerosol surface area concentrations using aerosol light scattering enhancement measurements

Current Challenges in Visibility Improvement in Southern China

“…Changes in aerosol scattering coefficient and aerosol optical hygroscopicity need to be monitored to ascertain that future visibility improvement actions are effectively decreasing κ sca and VSE (following the blue arrow in Figure d). Research on aerosol radiative effects and climate change would also greatly benefit from such continuous observations. ,,− Visibility improvement actions taken in the PRD would also provide valuable experience for other regions in southern China, where visibility improvement is possibly facing the same challenges.…”

Dust-Dominated Coarse Particles as a Medium for Rapid Secondary Organic and Inorganic Aerosol Formation in Highly Polluted Air

“…Using bulk chemistry and physical properties in analyzing sulfate formation in different size ranges might lead to significant bias and wrong conclusions; (2) while PM 2.5 is generally more acidic, showing pH values within the mostly reported range of 3–5, coarse particles typically reveal a pH higher than 5 (Figure S13a), , which (alone from the pH perspective) is in favor of the photosensitization, O 3 , and NO 2 oxidation pathways, among which the NO 2 route has been often proposed to be the dominating sulfate production route in the North China Plain. ,, However, compared to PM 2.5 , ambient coarse particles lack in liquid water contents (Figure S13b), which is not in favor of the proposed aqueous phase sulfate formation routes (including the aqueous phase SO 2 oxidation by H 2 O 2 , NO 2 , O 3 , or TMI catalysis). Interfacial sulfate formation routes (such as interfacial H 2 O 2 oxidation) should also be more favored by fine particles in terms of the ambient aerosol surface area . Thus, it remains less understood how dust particles promoted sulfate formation.…”

“…Interfacial sulfate formation routes (such as interfacial H 2 O 2 oxidation) should also be more favored by fine particles in terms of the ambient aerosol surface area. 71 Thus, it remains less understood how dust particles promoted sulfate formation. Nevertheless, it has been reported in laboratory studies that the photochemical uptake of NO 2 and H 2 O 2 on dust can produce strong oxidants such as HONO and OH radicals, 15,66 which might have played a role in the production of sulfate as well as nitrate and SOA; (3) field studies concerning heterogeneous reactions on dust have been mainly focusing on dust storm events, observing increased HONO production and promoted new particle formation when dust was mixed with anthropogenic pollution.…”

Influence of aerosol copper on HO<sub>2</sub> uptake: a novel parameterized equation

“…The approximate calculation of HO 2 concentration gradients within the aerosol particle condensed phase also cause deviations for larger particles or high copper equivalent concentration. Organic content of an aerosol particle may affect several important parameters in the uptake model (Lakey et al, 2016b(Lakey et al, , 2015. For example, the aerosol pH, hygroscopic properties of the aerosol, the rate of diffusion of HO 2 within the aerosol, and a reduction in the concentration of Cu 2+ via the formation of complexes could affect the ability of Cu to undergo redox reactions with HO 2 and O − 2 .…”

“…Many model studies (Lakey et al, 2015;Martinez et al, 2003;Tie et al, 2001;Whalley et al, 2015) suggest that the heterogeneous uptake of HO 2 radicals affects the global distribution of trace gases and the atmospheric oxidant capacity, especially in regions with high aerosol loading or low NO x concentration. The importance of aerosol chemistry as a sink for ozone precursors in North China Plain has been suggested in many model studies (Li et al, 2019b;Lou et al, 2014).…”