Elsevier

Atmospheric Environment

Volume 105, March 2015, Pages 162-168
Atmospheric Environment

Characterization of CHOS compounds in rainwater from continental and coastal storms by ultrahigh resolution mass spectrometry

https://doi.org/10.1016/j.atmosenv.2015.01.057Get rights and content

Highlights

  • Differences in CHOS compounds in precipitation from two different air mass back-trajectories.

  • Presence of organo-sulfate and reduced organo-sulfur species in precipitation.

  • Highly condensed reduced organo-sulfur compounds only in continental precipitation.

Abstract

Rainwater from four continental and three coastal storms was collected and analyzed by (−) ESI Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). This study presents a comprehensive comparison of the CHOS molecular formulas of rainwater dissolved organic matter from these two different storm trajectories. There were 899 and 695 total molecular formula assignments in the continental and coastal storms respectively. Of these, 33% and 15% were unique to continental and coastal storms. Kendrick mass analysis of methylene units highlighted oligomers present in both storm types illustrating their ubiquitous occurrence in atmospheric waters. There was also evidence of organo-sulfate containing molecular formulas as well as highly condensed aromatic structures containing one sulfur and one oxygen. These condensed aromatic sulfur containing structures likely originate from fossil fuel sources and were only detected in continental derived rainwater.

Introduction

Elucidating the composition of rainwater dissolved organic matter (DOM) has remained at the forefront of atmospheric research principally because of its central role in a host of fundamentally important atmospheric processes (Mullaugh et al., 2011, Willey et al., 2012). Rainwater DOM is a complex heterogeneous mixture of organic compounds, the composition of which remains to a large extent unknown (Altieri et al., 2012, Mitra et al., 2013). This is particularly true when describing organic entities that contain one or more sulfur atoms (Zhao et al., 2013). Organo-sulfur containing compounds play a pivotal role in the formation of secondary organic aerosols (SOA) (Karambelas et al., 2014, Surratt et al., 2007) leading to high molecular weight oligomers. These compounds are of particular interest in the chemistry of the troposphere because they can enhance hydroscopicity of droplets acting as cloud condensation nuclei (Hung et al., 2014).

Unraveling the composition of organic sulfur species in atmospheric waters is hindered primarily by the difficulty in describing molecular formulas of a suite of analytes present in very low abundances in a complex matrix. Recent analyses of atmospheric waters by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) demonstrated that individual molecular formulas of organic moieties can be assigned with great accuracy. Altieri et al. (2009) used FT-ICR MS to investigate the provenance and elemental composition of rainwater organic sulfur species in rain from an anthropogenically impacted location in New Jersey, USA. The authors suggested that the organo-sulfates likely contributed to the large percentage of uncharacterized water-soluble organic carbon species in atmospheric organic matter and that several organo-sulfates could be used as tracers for SOA formed under highly acidic conditions. Sulfur containing molecular formulas were also found in cloud water dissolved organic matter were CHOS compounds with reduced forms of S were observed in addition to organo sulfates (Zhao et al., 2013).

Altieri et al. (2009) and Zhao et al. (2013) were important studies because they demonstrated the utility of FT-ICR MS in describing organo-sulfur species in atmospheric waters. One of the most important uncertainties regarding organo-sulfur speciation is how the molecular distribution of the various species is influenced by storm origin as determined by air mass back trajectory. The significance of storm origin on organic matter composition was underscored in a recent study by Mead et al. (2013) utilizing FT-ICR MS to analyze H,C,O compounds in rainwater collected from both continental and coastal derived storms. Approximately 25% of the roughly 2000 assigned CHO molecular formulas were unique to each storm classification indicating the importance of air mass back trajectory on the composition of rainwater DOM. Analysis of the unique molecular formula assignments highlighted distinct groupings of various bio- and geo-molecular classes with coastal storms containing unique formulas representative of carbohydrate-like compounds while continental storms had lipid-like formulas. Mead et al. (2013) also found that continental storms contained condensed aromatic structures derived from fossil fuel combustion sources similar to black carbon which were not present in coastal rain events. The present study represents the first detailed analysis of organ-sulfur containing compounds in rainwater by FT-ICR MS collected on an event basis from a series of continental and coastal storms at one geographical location. The data generated therefore provide the most comprehensive examination to date of the chemical formulas of the organo-sulfur containing components of rainwater DOM from various air-mass back trajectories.

Section snippets

Sample collection

Precipitation event samples were collected on the University of North Carolina Wilmington campus (34°13.9′N, 77°52.7′W) located approximately 8.5 km from the Atlantic Ocean. Automatic Sensing Wet/Dry Precipitation Collectors (four Aerochem-Metrics (ACM) Model 301) were used to collect samples. The precipitation collectors housed 4 L glass beaker placed within a HDPE plastic bucket. All glassware used for rain collection, filtration apparatus and storage containers were baked at 450 °C in a

Rainwater bulk properties

A total of seven rain samples collected from both continental (4) and coastal (3) rain events were analyzed. A description of the chemical characteristics of each rain event and corresponding back trajectories can be found elsewhere (Mead et al., 2013). There was a higher percentage of unique molecular formula assignments in continental derived storms compared to coastal storms with almost double the molecular formula assignments of CHOS compounds (Table 1). The average unique molar ratios of

Implications and conclusions

This study represents the first comprehensive examination of CHOS containing molecular formulas from different air mass back trajectories. Continental rain contained a number of organo-sulfate CHOS compounds based upon the observed O:S ratio. Of particular interest was the occurrence of highly condensed aromatic structures containing only one S and one O in continental derived rainwater. To the best of our knowledge, this is the first study to definitively demonstrate the occurrence of these

Acknowledgments

The authors thank the National Science Foundation for financial support under grant AGS-1003078. Work performed at the National High Magnetic Field Laboratory was supported by NSF Division of Materials Research through DMR-11-57490, BP/The Gulf of Mexico Research Initiative to the Deep-C Consortium, the Future Fuels Institute, and the State of Florida.

References (54)

  • P.J. Seaton et al.

    Seasonal and temporal characterization of dissolved organic matter in rainwater by proton nuclear magnetic resonance spectroscopy

    Atmos. Environ.

    (2013)
  • S.D.H. Shi et al.

    Comparison and interconversion of the two most common frequency-to-mass calibration functions for Fourier transform ion cyclotron resonance mass spectrometry

    Int. J. Mass Spectrom.

    (2000)
  • M.W. Southwell et al.

    Seasonal variability of formaldehyde production from photolysis of rainwater dissolved organic carbon

    Atmos. Environ.

    (2010)
  • S. Staudt et al.

    Aromatic organosulfates in atmospheric aerosols: synthesis, characterization, and abundance

    Atmos. Environ.

    (2014)
  • A.V. Tolmachev et al.

    Trapped-ion cell with improved DC potential harmonicity for FT-ICR MS

    J. Am. Soc. Mass Spectrom.

    (2008)
  • H. Zhang et al.

    Secondary organic aerosol formation via 2-methyl-3-buten-2-ol photooxidation: evidence of acid-catalyzed reactive uptake of epoxides

    Environ. Sci. Technol. Lett.

    (2014)
  • K.E. Altieri et al.

    Molecular characterization of water soluble organic nitrogen in marine rainwater by ultra-high resolution electrospray ionization mass spectrometry

    Atmos. Chem. Phys.

    (2012)
  • K.E. Altieri et al.

    Oligomers, organosulfates, and nitrooxy organosulfates in rainwater identified by ultra-high resolution electrospray ionization FT-ICR mass spectrometry

    Atmos. Chem. Phys.

    (2009)
  • G.B. Avery et al.

    Rainwater monocarboxylic and dicarboxylic acid concentrations in southeastern North Carolina, USA, as a function of air-mass back-trajectory

    Atmos. Environ.

    (2006)
  • R.R. Draxler et al.

    An overview of the Hysplit_4 modeling system for trajectories, dispersion, and deposition

    Aust. Met. Mag.

    (1998)
  • L.E. Hatch et al.

    Measurements of isoprene-derived organosulfates in ambient aerosols by aerosol time-of-flight mass spectrometry – part 1: single particle atmospheric observations in Atlanta

    Environ. Sci. Technol.

    (2011)
  • Y. Iinuma et al.

    Laboratory chamber studies on the formation of organosulfates from reactive uptake of monoterpene oxides

    Phys. Chem. Chem. Phys.

    (2009)
  • N. Kaiser et al.

    A novel 9.4 tesla FTICR mass spectrometer with improved sensitivity, mass resolution, and mass range

    J. Am. Soc. Mass Spectrom.

    (2011)
  • A. Karambelas et al.

    Contribution of isoprene epoxydiol to urban organic aerosol: evidence from modeling and measurements

    Environ. Sci. Technol. Lett.

    (2014)
  • R. Kieber et al.

    Chromophoric Dissolved Organic Matter (CDOM) in rainwater, Southeastern North Carolina, USA

    J. Atmos. Chem.

    (2006)
  • R.J. Kieber et al.

    Organic complexation of Fe(II) and its impact on the redox cycling of iron in rain

    Environ. Sci. Technol.

    (2005)
  • R.J. Kieber et al.

    Chromophoric dissolved organic matter (CDOM) in rainwater, southeastern North Carolina, USA

    J. Atmos. Chem.

    (2006)
  • Cited by (27)

    • Influence of COVID-19 lockdown on the variation of organic aerosols: Insight into its molecular composition and oxidative potential

      2022, Environmental Research
      Citation Excerpt :

      Earlier studies have proven that they are formed from acid-catalyzed and/or NO3-initialed oxidation reactions that are related to the combustion of fossil fuel (especially coal) or biogenetic sources (Cai et al., 2020). As a result, the remarkable decrease of NO2 and SO2 (Fig. 1) may be highly correlated to the reduction of OSs and nitrooxy-OSs, as both of these components were originated from the combustion of fossil fuel (Mead et al., 2015). Figure S5 showed the relative intensity of identified 19 organosulfates from anthropogenic (A) and biogenic (B) sources as well as the ratio of the total intensity between these sources.

    • Source and formation process impact the chemodiversity of rainwater dissolved organic matter along the Yangtze River Basin in summer

      2022, Water Research
      Citation Excerpt :

      Like the number distribution, the total abundances of CHO and CHON compounds accounted for 29.0 − 81.0% and 7.6–33.5%, respectively (Figure S2). Although the ranges of mean O/C and H/C ratios in this study were comparable with previous studies on wet precipitation (Bianco et al., 2018; Mead et al., 2015; Mead et al., 2013; Zhao et al., 2013), it can be seen that the distribution of samples in the VK diagram was highly variable from region to region (Fig. 1 and Table S10), which may be related to the complex sources of air masses and the influence of local aerosols during the precipitation events. The reasons for this variability will be investigated in detail below.

    View all citing articles on Scopus
    View full text