English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

. The implementation of stringent emission regulations has resulted in thedecline of anthropogenic pollutants including sulfur dioxide ( SO2 ),nitrogen oxides ( NOx ), and carbon monoxide (CO). In contrast, ammonia( NH3 ) emissions are largely unregulated, with emissions projected toincrease in the future. We present real-time aerosol and gas measurementsfrom a field study conducted in an agriculturally intensive region in thesoutheastern US during the fall of 2016 to investigate how NH3 affectsparticle acidity and secondary organic aerosol (SOA) formation via thegas–particle partitioning of semi-volatile organic acids. Particle water andpH were determined using the ISORROPIA II thermodynamic model and validatedby comparing predicted inorganic HNO3 - NO 3 - and NH3 - NH 4 + gas–particle partitioning ratios with measured values.Our results showed that despite the high NH3 concentrations (average 8.1±5.2 ppb ), PM 1 was highly acidic with pH values ranging from 0.9to 3.8, and an average pH of 2.2±0.6 . PM 1 pH varied byapproximately 1.4 units diurnally. Formic and acetic acids were the mostabundant gas-phase organic acids, and oxalate was the most abundantparticle-phase water-soluble organic acid anion. Measured particle-phasewater-soluble organic acids were on average 6 % of the totalnon-refractory PM 1 organic aerosol mass. The measured molar fraction ofoxalic acid in the particle phase (i.e., particle-phase oxalic acid molarconcentration divided by the total oxalic acid molar concentration) rangedbetween 47 % and 90 % for a PM 1 pH of 1.2 to 3.4. The measured oxalic acidgas–particle partitioning ratios were in good agreement with theircorresponding thermodynamic predictions, calculated based on oxalic acid'sphysicochemical properties, ambient temperature, particle water, and pH. Incontrast, gas–particle partitioning ratios of formic and acetic acids were not wellpredicted for reasons currently unknown. For this study, higher NH3 concentrations relative to what has been measured in the region in previousstudies had minor effects on PM 1 organic acids and their influence onthe overall organic aerosol and PM 1 mass concentrations.

Characterization of aerosol composition, aerosol acidity, and organic acid partitioning at an agriculturally intensive rural southeastern US site