High-Resolution Mass Spectrometric Profiling of Stormwater in an Australian Creek

Stormwatercarries a large mixture of chemicals that areresponsible for the pollution of various water systems. Urban stormwater runoff is a major source of pollutantsinto receivingwater bodies. The pollutant profile of stormwater samples collectedfrom an Australian creek during a major storm event in 2020 was investigatedusing high-resolution mass spectrometry and chemometric tools. Thesamples were solid phase-extracted and analyzed by liquid chromatographycoupled to a quadrupole time-of-flight mass spectrometer (LC-QToF-MS/MS).The detected features were prioritized using two independent but complementaryworkflows to identify the highly abundant stormwater-related compounds.A total of 174 features were detected at elevated levels during thestorm. Four compounds were identified to a confidence level of 1 and11 at level 2, including nonpolymeric surfactants, plastic additives,rubber and resin-related products, and natural products. Forty twopercent were characterized as oligomers such as poly(ethylene glycol)(PEG)-related compounds and octylphenol ethoxylates. Due to a lackof database experimental data, many compounds remained unidentified.Compounds belonging to the same class were clustered using GlobalNatural Product Social (GNPS) Molecular Networking analysis,highlighting the benefit of this platform in environmental analysis.The prioritization workflow used here is characterized as an effectivetool for assessing key stormwater-related compounds and identifyingwhich should receive attention in assessing the environmental effectsof stormwater-related chemicals.