Assessment of Metal Immission in Urban Environments Using Elemental Concentrations and Zinc Isotope Signatures in Leaves of Nerium oleander

Abstract

A thorough understanding of spatial and temporal emission and immission patterns of air pollutants in urban areas is challenged by the low number of air-quality monitoring stations available. Plants are promising low-cost biomonitoring tools. However, source identification of the trace metals incorporated in plant tissues (i.e., natural vs anthropogenic) and the identification of the best plant to use remain fundamental challenges. To this end, Nerium oleander L. collected in the city of Zaragoza (NE Spain) has been investigated as a biomonitoring tool for assessing the spatial immission patterns of airborne metals (Pb, Cu, Cr, Ni, Ce, and Zn). N. oleander leaves were sampled at 118 locations across the city, including the city center, industrial hotspots, ring-roads, and outskirts. Metal concentrations were generally higher within a 4 km radius around the city center. Calculated enrichment factors relative to upper continental crust suggest an anthropogenic origin for Cr, Cu, Ni, Pb, and Zn. Zinc isotopes showed significant variability that likely reflects different pollution sources. Plants closer to industrial hotspots showed heavier isotopic compositions (δZn up to +0.70‰), indicating significant contributions of fly ash particles, while those far away were isotopically light (up to -0.95‰), indicating significant contributions from exhaust emissions and flue gas. We suggest that this information is applied for improving the environmental and human risk assessment related to the exposure to air pollution in urban areas.

Tobacco plant as possible biomonitoring tool of red mud dust fallout and increased natural radioactivity

“…The importance of monitoring air-related pollution has been shown by Shotyk in Germany (Shotyk et al, 2015) and Kosior in Poland (Kosior et al, 2017). The data and concentration ranges obtained to measure lichen, moss, some higher plant metals and NORM levels (Grodzinskaya et al, 2019;Galhardi et al, 2017;Martín et al, 2018) are in line with the results obtained using our measurement techniques. The ranges of our obtained values are in perfect agreement with other studies reporting Po-210 environmental concentrations (Reszka and Wołoszyn, 2007;Shotyk et al, 2015;Kosior et al, 2017, Galhardi et al, 2017.…”

“…Tree bark (Birke et al, 2018) and tree leaves from various species such as sweet chestnut (Martin et al, 2009), Acacia sp. (Attahiru et al, 2015) and Nerium oleander (Martín et al, 2018), in their natural habitat, have reportedly been used for heavy metal pollution bioindication.…”

A Global Assessment of Copper, Zinc, and Lead Isotopes in Mineral Dust Sources and Aerosols

“…Figure 7 shows the δ-values for Zn and Cu in urban aerosols. Studies were conducted in several cities, including Barcelona (Spain, Ochoa Gonzalez et al, 2016), London (UK, Ochoa Gonzalez et al, 2016;Dong et al, 2017), Zaragoza (Martín et al, 2018), and Metz (France, Cloquet et al, 2006). Gioia et al (2008) as well as Souto-Oliveira et al (2018 reported Cu and Zn isotope compositions from São Paulo, Brazil.…”

Traffic restrictions during COVID-19 lockdown improve air quality and reduce metal biodeposition in tree leaves

“…As a complement and/or alternative to these traditional chemical air pollution assessment methods, biomonitoring tools have recently gained interest specially using trees due to their unique characteristics. Foliar metal profiling is representative of atmospheric metal deposition (El-Khatib et al, 2019) and is proposed as an efficient biomonitoring method for urban pollution assessment with some advantages such as low cost, and if widely distributed, better recording of spatial air quality and appropriate for long time accumulation of pollutants ( Smodiš et al, 2004 ; Tomasevic et al, 2004; Doganlar et al, 2012 , Martín et al, 2018 ). On the other hand, some limitations of biomonitoring are related to morphological structures, physiology and chemical composition of biological matrices can affect pollutant deposition ( Jiang et al, 2018 ).…”