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Size-segregated distribution of ambient particulate matter (PM) was determined using a micro-orifice uniform deposition impactor (MOUDI) and a nano-MOUDI in southern Taiwan. Eleven water-soluble ionic species including six anions (NO3−, SO42−, Cl−, F−, NO2−, Br−) and five cations (NH4+, Na+, K+, Ca2+, Mg2+) for particulate inorganic ions and five gaseous pollutants (i.e., HNO2, HNO3, HCl, SO2, NH3) were analyzed during episode and non-episode periods. The particulate mass concentration was about 30 μg/m3higher at night than during the day, and it reached 162 μg/m3during the episode periods. The difference was mainly attributable to the particle size of 0.1–2.5 μm. Nitrate, sulfate, ammonium, and chloride ions were the dominant inorganic ions in PM. HONO and NH3concentrations were high at night; in contrast, HNO3, HCl, and SO2were high during the day. The equivalent ratio of ([NO3−] + 2[SO42−])/[NH4+] was about 0.98 and revealed a high correlation between ([NO3−] + 2[SO42−]) and [NH4+] that clearly pointed to ammonium neutralization or condensation of ammonium nitrate and ammonium sulfate in PM0.32. The precursor gases and ionic species in different particle sizes did not reveal a strong correlation, which could be attributed to the complex of source emissions, atmospheric reactions and meteorological parameters in the area.Implications: Size-segregated distribution and chemical compositions of atmospheric aerosols play important roles in their visibility reduction, health effects, and toxicity in urban areas. Inorganic ionic species are major constituents in particulate matter, except carbonaceous chemicals. In this work, the compositions of water-soluble ions in particulate matter and acid/base gaseous pollutants (such as HNO2, HNO3, HCl, SO2, NH3) were determined during the day and at night during episode and non-episode periods from 2006 to 2007 in southern Taiwan. [ABSTRACT FROM AUTHOR]

Facilely synthesized peroxidase-like nanozymes with high catalytic activity and stability may serve as effective biocatalysts. The present study synthesizes peroxidase-like nanozymes with multinuclear active sites using two-dimensional (2D) metal-organic framework (MOF) nanosheets and evaluates them for their practical applications. A simple method involving a one-pot bottom-up reflux reaction is developed for the mass synthesis of (Cu-S) n MOF 2D nanosheets, significantly increasing production quantity and reducing reaction time compared to traditional autoclave methods. The (Cu-S) n MOF 2D nanosheets with the unique coordination of Cu(I) stabilized in Cu-based MOFs demonstrate impressive activity in mimicking natural peroxidase. The active sites of the peroxidase-like activity of (Cu-S) n MOF 2D nanosheets were predominantly verified as Cu(I) rather than Cu(II) of other Cu-based MOFs. The cost-effective and long-term stability of (Cu-S) n MOF 2D nanosheets make them suitable for practical applications. Furthermore, the inhibition of the peroxidase-like activity of (Cu-S) n MOF nanosheets by glutathione (GSH) could provide a simple strategy for colorimetric detection of GSH against other amino acids. This work remarkably extends the utilization of (Cu-S) n MOF 2D nanosheets in biosensing, revealing the potential for 2D (Cu-S) n MOFs.