Multi-isotope approach of Pb, Cu and Zn in urban aerosols and anthropogenic sources improves tracing of the atmospheric pollutant sources in megacities

Abstract

Studies including multiple isotope systems in aerosols promises unparalleled insights into sources and pathways of metals in the atmosphere. However, such studies remain rare because of the challenges associated with small sample sizes and low analyte masses of the target elements. Here, we present the first study combining accurate and precise determination of Pb, Cu and Zn isotopic ratios in aerosols and anthropogenic materials collected in São Paulo, Brazil. We use a sequential ion chromatography procedure with two different resins for the separation and purification of the analytes. Multi collector mass spectrometry is used for the accurate and precise determination of the isotope ratios. Long term analytical reproducibilities are ±0.035 for 206Pb/204Pb, ± 0.13‰ for δ65CuNIST and ±0.1‰ for δ66ZnJMC (±2σ). Accuracy is assessed using certified reference materials (CRM NIST 2783 aerossol, BRP-1 and others). We analyzed 57 source samples (road dust, tires, cement, road tunnel aerosol) and 113 aerosol samples collected between 2013 and 2015. The results for São Paulo are critically compared with previously published data from studies conducted in São Paulo, London and Barcelona. The key findings are: 1. The isotope signatures for Zn in tires (δ66ZnJMC = 0.16 ± 0.14, 2σ, n = 9) and road dust (δ66ZnJMC = 0.17 ± 0.19, 2σ, n = 13) are similar in São Paulo and London suggesting that this isotope system can be used as element specific tracers for non-exhaust traffic. 2. 206Pb/207Pb vs δ66ZnJMC and δ66ZnJMC vs δ65CuNIST multi-isotopic diagrams successfully separate wear off from cars including tires and brakes, car exhaust, industrial emissions and cement sources and improves the discrimination of air pollutant sources. 3. The source identification based on isotope ratios agrees source apportionement based on emissions inventory from these cities. 4. We present Pb, Cu and Zn isotopic data for the first time for the CRM NIST 2783 and BRP-1. These new data will enable future intercalibration and quality controls in other laboratories. Our study confirms that stable isotope ratio analysis have a great potential for element specific source characterization (e.g., separating non combustion traffic sources from combustion sources) for Cu, Zn and Pb. Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site.

Copper, Zinc and Lead Isotopic Delta Values and Isotope Ratios of Various Geological and Biological Reference Materials

“…2013, Souto‐Oliveira et al . 2019). Thus, a second passage of the Cu fraction using the same column was conducted to eliminate the residual matrix elements.…”

“…Recently, studies on the combination of Cu, Zn and Pb isotopes have begun to identify and distinguish the contribution of each pollution source in atmospheric samples (Souto‐Oliveira et al . 2018, 2019, Schleicher et al . 2020).…”

Trace metal dynamics in an industrialized Brazilian river: A combined application of Zn isotopes, geochemical partitioning, and multivariate statistics

“…Furthermore, non-traditional isotope systems, notably the zinc isotopes, have been successfully applied as tracers of anthropogenic emissions and lowtemperature biogeochemical processes in large river basins (Chen et al, 2009b;Desaulty and Petelet-Giraud, 2020;Petit et al, 2015;Zimmermann et al, 2020). Zn isotope compositions (expressed as δ 66/64 ZnJMC notation) are used as source identification tools (Araújo et al, 2017a;Li et al, 2019;Tonhá et al, 2020;Xia et al, 2020), which can distinguish between lithogenic materials derived from weathering processes (+0.28 ± 0.05 ‰) (Chen et al, 2013) and anthropogenic materials, such as road dust (+0.08 to +0.17 ‰) and tire-wear (+0.00 to +0.22 ‰) (Dong et al, 2017;Souto-Oliveira et al, 2019).…”

Copper, zinc and lead isotope signatures of sediments from a mediterranean coastal bay impacted by naval activities and urban sources

“…Thus, Pb isotope ratios (eg., 206 Pb/ 207 Pb) are conservative through biogeochemical processes (Komárek et al, 2008). Therefore, their ratios are convenient environmental tracers in the diverse or multiple pollution contexts like the urban atmosphere (Souto-Oliveira et al, 2019, mining operations and metallurgy (Dolgopolova et al, 2006), urban sewage, and agricultural practices (Charalampides and Manoliadis, 2002). Zinc isotopes fractionate significantly during redox and evaporation processes during ore refining (smelting and electroplating industry ), and coal combustion (Gonzalez and Weiss, 2015;Kavner et al, 2008;Yin et al, 2015).…”

“…Since anthropogenic Cu may derive either from sulfides or oxide ore deposits, Cu isotope systematics can help discriminate the different anthropogenic and natural sources. In environmental studies, Cu isotopes have been a useful tracer in urban aerosol samples (Souto-Oliveira et al, 2019 and in surrounding soils impacted by metallurgical (Mihaljevič et al, 2019;Šillerová et al, 2017) and vineyard activities (Babcsányi et al, 2016;El Azzi et al, 2013), however their applicability in complex and reactive aquatic systems has been more challenging (Araújo et al, 2019;Petit et al, 2013;Viers et al, 2018).…”