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[26P-pm113S] Spatial variation of sulfate in Asia and its impact in aerosol acidity on a remote background site
[Introduction]
Sulfate, ammonium, and nitrate are typically the most abundant inorganic ions in atmospheric particles, depending on location and season. Among the aqueous aerosol species, the hydronium (H+) quantified with a logarithmic scale, pH, which is a fundamental property of aerosol plays an important role in many atmospheric processes, catalyzing the conversion of isoprene oxidation products to form secondary organic aerosols, affecting the gas-particle partitioning of semivolatile species. This study extends our analysis of particle pH from Japan, presents the source variations of sulfate affect particle pH, and determine whether the long-range atmospheric transportation process will affect the local acidity of the particles.
[Methods]
Total suspended particulate (TSP) were collected every 7 consecutive days, from January 7, 2005, to December 25, 2009, at Kanazawa University Wajima Air Monitoring Station (WAMS). The water-soluble inorganic ions (WSIIs) including Cl-, NO3-, SO42-, Na+, NH4+, K+, Mg2+, Ca2+ were measured using an ion chromatograph after extraction. pH was predicted by a thermodynamic equilibrium model for the K+-Ca2+-Mg2+-NH4+-Na+-SO42--NO3--Cl--H2O aerosol system (ISORROPIA -Ⅱ). Source apportionment was performed by Positive Matrix Factorization (PMF) and Concentration Weighted Trajectory (CWT).
[Results]
PMF seasonal analysis shows a high contribution of secondary sulfate (52.3 %) during summer, which can strongly affect particle pH. The produced CWT values were plotted on surface maps, presented in various figures below for every season (Fig. 1). The high acidity particle in summer is mainly from Korea and the Sea of Japan. The autumn and winter show low concentration, mainly characterized by the potential source of the Sea of Japan and Northeast China. In the spring, although it shows high concentration in the area of the Sea of Japan, it is prone to long-range transportation of dust in spring, which inhibits the increase of the pH of particles. This work also proves that even in the remote background site, the particle acidity had a strong relationship with anthropogenic sources.
Sulfate, ammonium, and nitrate are typically the most abundant inorganic ions in atmospheric particles, depending on location and season. Among the aqueous aerosol species, the hydronium (H+) quantified with a logarithmic scale, pH, which is a fundamental property of aerosol plays an important role in many atmospheric processes, catalyzing the conversion of isoprene oxidation products to form secondary organic aerosols, affecting the gas-particle partitioning of semivolatile species. This study extends our analysis of particle pH from Japan, presents the source variations of sulfate affect particle pH, and determine whether the long-range atmospheric transportation process will affect the local acidity of the particles.
[Methods]
Total suspended particulate (TSP) were collected every 7 consecutive days, from January 7, 2005, to December 25, 2009, at Kanazawa University Wajima Air Monitoring Station (WAMS). The water-soluble inorganic ions (WSIIs) including Cl-, NO3-, SO42-, Na+, NH4+, K+, Mg2+, Ca2+ were measured using an ion chromatograph after extraction. pH was predicted by a thermodynamic equilibrium model for the K+-Ca2+-Mg2+-NH4+-Na+-SO42--NO3--Cl--H2O aerosol system (ISORROPIA -Ⅱ). Source apportionment was performed by Positive Matrix Factorization (PMF) and Concentration Weighted Trajectory (CWT).
[Results]
PMF seasonal analysis shows a high contribution of secondary sulfate (52.3 %) during summer, which can strongly affect particle pH. The produced CWT values were plotted on surface maps, presented in various figures below for every season (Fig. 1). The high acidity particle in summer is mainly from Korea and the Sea of Japan. The autumn and winter show low concentration, mainly characterized by the potential source of the Sea of Japan and Northeast China. In the spring, although it shows high concentration in the area of the Sea of Japan, it is prone to long-range transportation of dust in spring, which inhibits the increase of the pH of particles. This work also proves that even in the remote background site, the particle acidity had a strong relationship with anthropogenic sources.