Micropollutants in Urban Runoff from Traffic Areas: Target and Non-Target Screening on Four Contrasted Sites

Abstract

Although runoff from trafficked urban areas is recognized as a potentially significant pathway of micropollutants, runoff pollution remains poorly documented, except for relatively few historical pollutants such as some metals and hydrocarbons. Therefore, in this work, road and parking lot runoff from four sites with contrasting traffic levels were analyzed for a very broad spectrum of molecules and elements. A total of 128 pollutants and micropollutants were monitored, including inorganic (n = 41) and organic (n = 87) pollutants. Both the dissolved and particulate phases were considered. For a reduced number of samples, non-targeted screening by high-resolution mass spectrometry (HRMS) was carried out. For targeted screening, the contamination profiles were quite homogeneous, but the concentrations significantly differed between the different sites. Sites with the highest traffic density exhibited the highest concentrations for polycyclic aromatic hydrocarbons (PAHs), some traffic-related metals, alkylphenols and phthalates. Overall, for most micropollutants, the parking lot runoff exhibited the lowest concentrations, and the specificity of this site was confirmed by its HRMS fingerprint. Non-target screening allowed the sites to be discriminated based on the occurrence of specific compounds. Unlike the results of targeted screening, the HRMS intra-site variability was lower than its inter-site variability. Unknown substances were tentatively identified, either characteristic of each site or ubiquitous of all samples.

Road Runoff Characterization: Ecotoxicological Assessment Combined with (Non-)Target Screenings of Micropollutants for the Identification of Relevant Toxicants in the Dissolved Phase

“…Runoff was collected from a storm drain (R site) or from a gully (C site). Details about the sampling methodology as well as extended results of target screening of micropollutants are provided in [9], published in the same special issue. In this work, only a fraction of samples from both sites were analyzed with HRMS or (eco)toxicological approaches, due to limited available volumes at the time of the experiments.…”

“…Targeted screening involved the analysis of 128 pollutants, including 41 inorganic and 87 organic pollutants or groups of substances, and is fully described in [9].…”

“…The two study sites were chosen because of their contrasted situation in terms of traffic: a road with high traffic (C site) and an area with moderate traffic (R site). Detailed analyses of both sites at all sampling dates are provided in [9] (this issue) and summarized in Table 1 for samples selected in this work. Briefly, the C site is characterized by higher TSS concentrations, correlating with its high traffic, while these concentrations vary widely in the R site, with the highest concentrations possibly related to a building site nearby.…”

“…Road runoff (RR) is constituted of a complex matrix of over 600 different micropollutants mainly originating from traffic, whose release can contribute to environmental degradation and cause a threat to aquatic organisms [7]. These pollutants include particles such as tire residues and dust, and molecules such as petrochemicals, metals, but also polycyclic aromatic hydrocarbons (PAHs), herbicides, phthalates, or alkylphenols [1,3,8,9].…”

“…Target analysis is one of the major tools to characterize wastewater and RR, allowing the detection and quantification of contaminants in the ng/L range [1,[9][10][11]. Nevertheless, studies relying on target analysis do not detect nor evaluate pollutants on which no information exist, such as emerging contaminants, transformation products, and metabolites, or which have not been searched specifically [12].…”