Distribution of Emerging Contaminants in the Aquatic Environments of Melbourne, Australia: PFAS and Synthetic Musks

<p dir="ltr">Waterways are experiencing growing impacts from chemical pollution; however, effective management of this issue is hindered by a lack of sufficient scientific data. Therefore, emerging contaminants (ECs) with the potential to harm the environmental and limited environmental occurrence data, including per- and poly-fluorinated alkyl substances (PFAS) and synthetic musks (SMs) were selected to study for their environmental occurrence in the greater Melbourne area (GMA), Australia. The distribution of these compounds across urban areas is not well understood, nor is their potential input from industrial and urban sources. SMs lack validated quantitative analytical methods and have been scarcely studied in Australia, with no prior research conducted in the GMA. In contrast, a small number of PFAS are currently quantifiable. The primary aims of this research were to determine the urban background concentrations of 33 PFAS and 11 SMs in environmental surface waters, examine their distribution across different land-use types, and to develop a method for quantifying SMs. To accomplish this, surface water samples were collected from sites selected based on their predominant catchment land-uses, identified using Geographic Information System (GIS) mapping, which comprised of residential, industrial, municipal wastewater treatment plants (WWTPs), and rural. </p><p dir="ltr">In Chapter 3, a survey of 33 PFAS was conducted in surface water and sediment samples from 65 sites with varying land-uses across the GMA. Urban background concentrations of PFAS were determined, along with their associations to different land-use types. PFAS were detected at 98 % of sites, suggesting widespread diffusion from common anthropogenic sources. Elevated concentrations of perfluoroalkyl sulfonic acids (PFSAs) including PFOS were found in industrial areas, indicating their ongoing use by industries. The perfluoroalkyl carboxylic acids (PFCAs) including PFOA, were evenly distributed across the urban environment, suggesting that PFCAs and their precursors are used throughout urban areas and subject to atmospheric diffusion. The short-chain PFCA, PFBA was detected in both urban and rural areas, demonstrating its high propensity for atmospheric dispersal. This study confirms the broad urban presence of three major PFAS classes—FTSs, PFSAs, and PFCAs—and highlights the need for regulatory and industrial efforts to prioritise their reduction. </p><p dir="ltr">To enable the quantification of synthetic musks (SMs) in surface waters, in Chapter 4, an analytical method was developed and validated to quantify 11 SMs using solid phase extraction (SPE) and gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). The SM compounds were selected based on their likely current use (i.e., those with high production volumes and previously reported in the literature), potential harm to aquatic ecosystems, and the availability of analytical standards. They included seven polycyclic musks (PCMs), three nitro musks (NMs), and one macrocyclic musk (MCM). Experimental parameters were optimised to maximise analyte recoveries during extractions from surface waters using Oasis hydrophobic-lipophilic balance solid phase extraction (HLB SPE) cartridges. This included optimisation of elution solvents, cartridge drying method, and matrix water pH and salinity. Laboratory handling conditions were also investigated, which included the determination of recoveries from nitrogen blowdown and long-term sample storage. The GC-MS/MS method was optimised for injection solvent, injection volume, column temperature program, multiple reaction monitoring (MRM) transitions, collision energies (CEs), and MS dwell times. The method quantification limits (MQLs) ranged from 2 to 13 ng/L, and all analytes showed acceptable linearity (R² > 0.99). Matrix-matched corrected recoveries ranged from 80–120 % across the linear range. Validation experiments for intra- and inter-day precision indicated expanded uncertainties (U' at 95 % confidence with a coverage factor of 2) of 27-44 %, well below the acceptable limit of 50 % as defined from EU proficiency tests and outlined in SANTE/11312/2021. This method provides a solid foundation for further optimisation, validation, and analysis of SMs in environmental samples. </p><p dir="ltr">As SM are rarely included in monitoring programs and are often only investigated in wastewater impacted environments, Chapter 5 reported the associations of SMs to land-uses using data obtained from a survey of surface waters from 25 sites in the GMA. This used the validated extraction and analysis methodology described in Chapter 4. Passive samplers collected during the sampling campaign enabled the production of additional semi-quantitative data, revealing that a greater number of SMs were present (seven) than was detected in the grab water samples (four). The SMs galaxolide, tonalide, cashmeran, celestolide, traseolide, phantolide and musk ketone were detected in urban waterways. Galaxolide was detected at the highest concentrations of all SMs (maximum water concentration = 1553.84 ng/L), with treated wastewater as the major source to the urban environment, although residential areas were also a major source. Tonalide was found across the study area, suggesting widespread atmospheric transport. Dissolved cashmeran was detected at 60 % of residential areas, suggesting it may have entered waters directly from domestic activities. Musk ketone which is internationally banned in cosmetics was prevalent in industrial areas indicating the source may be non-cosmetic fragrances. Findings presented in Chapter 5 illustrate that while wastewater is an important source of SMs, especially galaxolide, residential areas and industrial areas are also contributing to urban pollution from a range of SMs and that they may have moved between catchments atmospherically. The presence of both PCMs and NMs across the urban environment highlights the need for targeted regulatory actions and reduction strategies to mitigate their environmental impact. </p><p dir="ltr">This work increases analytical capabilities for SMs and provides background concentration data for both PFAS and SMs. These findings are instrumental in guiding future monitoring efforts and in establishing environmentally relevant toxicity thresholds. Although the present research focused on 33 PFAS and 11 SMs, the potential for additional ECs is vast, with thousands of PFAS remaining unexamined. Consequently, the chemical pollution reported in these studies is likely to be an underestimated. Further development and application of analytical techniques are recommended, such as the use of Total Organic Fluorine (TOF) testing to measure total PFAS, and Quadrupole Time-of-Flight (Q-TOF) mass spectrometry to identify other ECs. Given the evolving trends of chemical pollution in the environment, continuous monitoring is advised to guide effective management strategies.</p>