Hydroxymethanesulfonic acid in size-segregated aerosol particles at nine sites in Germany

Abstract

Abstract. In the course of two field campaigns, size-segregated particle samples were collected at nine sites in Germany, including traffic, urban, rural, marine, and mountain sites. During the chemical characterisation of the samples some of them were found to contain an unknown substance that was later on identified as hydroxymethanesulfonic acid (HMSA). HMSA is known to be formed during the reaction of S(IV) (HSO3− or SO32−) with formaldehyde in the aqueous phase. Due to its stability, HMSA may can act as a reservoir species for S(IV) in the atmosphere and is therefore of interest for the understanding of atmospheric sulphur chemistry. However, no HMSA data are available for atmospheric particles from Central Europe and even on a worldwide scale, data are scarce. Thus, the present study now provides a representative dataset with detailed information on HMSA concentrations in size-segregated Central European aerosol particles. HMSA mass concentrations in this dataset were highly variable: HMSA was found in 224 out of 738 samples (30%), sometimes in high mass concentrations exceeding those of oxalic acid. In average over all 154 impactor runs, 31.5 ng m−3 HMSA were found in PM10, contributing 0.21% to the total mass. The results show that the particle diameter, the sampling location, the sampling season and the air mass origin impact the HMSA mass concentration. Highest concentrations were found in the particle fraction 0.42–1.2 μm, at urban sites, in winter and with eastern (continental) air masses, respectively. The results suggest that HMSA is formed during aging of pollution plumes. A positive correlation of HMSA with sulphate, oxalate and PM is found (R2 > 0.4). The results furthermore suggest that the fraction of HMSA in PM slightly decreases with increasing pH.

Global Importance of Hydroxymethanesulfonate in Ambient Particulate Matter: Implications for Air Quality

“…As is discussed below, we also detect and attempt to quantify the presence of HMS in samples from Singapore; the Po Valley, Italy; and Shijiazhuang, China. The rest of the sites with observational evidence of HMS shown in Figure 1 are from previous reports at 17 sites including nine in Germany (Scheinhardt et al, 2014), one in the United Kingdom (Dall'Osto et al, 2009), four in the United States (Dixon & Aasen, 1999; Lee et al, 2003; Whiteaker & Prather, 2003), one in Japan (Suzuki et al, 2001), and two in Beijing (Ma et al, 2020; Song et al, 2019).…”

“…Black dots indicate sites where at least trace amounts of HMS have been detected in new observations from the IMPROVE network; Shijiazhuang, China; Po Valley, Italy; and Singapore. Triangles indicate sites where HMS has previously been observed: Germany (Scheinhardt et al, 2014), the United Kingdom (Dall'Osto et al, 2009), the United States (Dixon & Aasen, 1999; Lee et al, 2003; Whiteaker & Prather, 2003), Japan (Suzuki et al, 2001), and Beijing (Ma et al, 2020; Song et al, 2019). Open circles indicate IMPROVE sites from which at least one chromatogram was examined but where HMS was not found.…”

“…A reanalysis of AMS observations in Beijing and new IC measurements have also suggested the likely presence of HMS there in winter (Ma et al, 2020; Song et al, 2019). HMS has also recently been detected in field campaigns in the Po Valley, Italy (Gilardoni et al, 2016; Paglione et al, 2020), and previously in the United Kingdom, Germany, Japan, and the United States (Dall'Osto et al, 2009; Dixon & Aasen, 1999; Lee et al, 2003; Scheinhardt et al, 2014; Suzuki et al, 2001; Whiteaker & Prather, 2003).…”

“…HMS was subsequently observed as a significant S (IV) species in low clouds or fog (Munger et al, 1983, 1984, 1986), and HMS chemistry was also included in some early atmospheric chemistry models (Jacob, 1986; Jacob & Hoffmann, 1983). However, despite sporadic identification of HMS in aerosols (Dixon & Aasen, 1999; Scheinhardt et al, 2014; Whiteaker & Prather, 2003), it has been mostly overlooked as a potential contributor to atmospheric sulfur since the 1980s.…”

Brown Carbon Production by Aqueous-Phase Interactions of Glyoxal and SO2

“…Glyoxal, like other aldehydes, (4,11) reacts rapidly with S(IV) compounds in aqueous media, reversibly forming sulfonate adduct molecules (12) containing C-S bonds. (13) No further products are observed in the dark when oxidants are excluded, leading to the conclusion that sulfonates serve only as condensed-phase atmospheric reservoirs for aldehydes and S(IV), (14) thereby increasing SO2 partitioning (12) and glyoxal uptake into clouds. (15) However, when exposed to air, aqueous mixtures of glyoxal and sodium sulfite (which have pH > 7 due to sulfite basicity) quickly produce the redox-active, aromatic compound tetrahydroxybenzoquinone (THBQ) (16) at the air-water interface.…”