Concentrations and solubility of trace elements in fine particles at a mountain site, southern China: regional sources and cloud processing

Abstract

Abstract. The concentrations and solubility of twelve trace elements in PM2.5 at Mt. Lushan, southern China, were investigated during the summer of 2011 and the spring of 2012. The average PM2.5 mass was 55.2 ± 20.1 μg m−3 during the observation period. Temporal variations of all trace elements including total and water-soluble fractions with several dust storm spikes in total fractions of Al and Fe were observed. The enrichment factor (EF) values were 1 order of magnitude higher for the water-soluble fractions versus the total fractions of trace elements. Four major emission sources, namely nonferrous metal mining and smelting (for Cr, As, Ba and parts of Zn), coal combustion (for Pb, Zn, Se, Cu and Mn), crustal materials (for Al and Fe) and municipal solid waste incineration (for Cd and Mo), were classified by principal component analysis (PCA). Trajectory cluster analysis and the potential source contribution function (PSCF) consistently identified the Yangtze River delta (YRD), the Pearl River delta (PRD), and the neighbouring provinces of Mt. Lushan as the major source regions and transport pathways for anthropogenic elements. Northern China was identified as a major source region for crustal elements. It should be noted that apart from the YRD, the area around Mt. Lushan has become the most significant contributor to the solubility of most trace elements. Element solubility can be partially determined by emission sources. However, enhanced solubility of trace elements corresponding to increased concentrations of sulfate after the occurrence of cloud events indicated significant effects of cloud processing on aerosol element dissolution. Metal particles mixed with sulfate in cloud droplet residues were further investigated through transmission electron microscopy (TEM) analysis. Irreversible alteration of particle morphology by cloud processing was confirmed to be highly responsible for the enhancement of trace element solubility. The findings from this study imply an important role of regional anthropogenic pollution and cloud processing in the evolution of aerosol trace element solubility during transport in the troposphere.

Evolution of trace elements in the planetary boundary layer in southern China: Effects of dust storms and aerosol‐cloud interactions

“…Most elements had similar solubility in coarse and fine aerosols during nondust periods, while As, Pb, and Ba appeared to be more soluble in fine mode than coarse mode, with a solubility discrepancy of ~10%. In addition, trace elements in fine aerosols at Mount Heng showed approximately comparable solubility with those at Mount Lushan [ Li et al ., ], except for more soluble Se and Cd and less soluble Cu and Fe. However, the declined solubility of trace elements in both coarse and fine aerosols during dust periods was clearly observed, indicating the suppressed dissolution of aerosol elements by dust storms, which was largely attributable to the decreased aerosol acidity (see Text S3) from abundant alkaline substances.…”

“…Fe was the most predominant trace element in both fine and coarse aerosols at Mount Heng during nondust periods, followed by Al and Zn, but their concentrations were obviously lower than those at Mount Tai in the North China Plain [ Deng et al ., ]. High concentrations of toxic Pb (108.6 ng m −3 ), As (21.1 ng m −3 ), and Cd (5.55 ng m −3 ) in fine aerosols were observed at Mount Heng, which were likely contributed by the heavy metal pollution in the Chang‐Zhu‐Tan city clusters and were comparable to the levels at Mount Lushan [ Li et al ., ]. However, overall, most trace elements at Mount Heng had lower concentrations than those at Mount Dinghu in the Pearl Delta Region [ Yang et al ., ].…”

“…Solubility of trace elements in TSP and PM 2.5 at Mount Heng (this study) and in PM 2.5 at Mount Lushan [ Li et al ., ].…”

Characteristics and Sources of Hourly Trace Elements in Airborne Fine Particles in Urban Beijing, China

“…In addition, some TEs can serve as important catalysts in sulfate formation and thus further result in degradation of the air quality (Harris et al, ; He et al, ). Some transition metal ions can also affect the HO x budgets and thereby influence the oxidation capacity of the atmosphere (Fomba et al, ; Li et al, ). Although several studies have found that the formation of sulfate was associated with TEs (Clements et al, ; Gankanda et al, ; Harris et al, ; He et al, ; Huang et al, ; Xie et al, ), the statistical relationship between TEs and sulfate formation has not been systemically investigated due to inadequate in situ observation data.…”

Air quality in the middle and lower reaches of the Yangtze River channel: A cruise campaign

“…One-eighth of the sample filter and the blank filter were cut into fragment and digested at 151 170 ℃ for 4 h in a high pressure Teflon digestion vessel with 3 mL of HNO3 and 1 mL of 152 HClO4 (Wang et al, 2006;Li et al, 2015b). After cooling, the digested solution was filtered and 153 diluted to 15 mL with less than 2% acidity with ultrapure Mill-Q water.…”