Integration of ecological indicators to assess a multitemporal impact of cement industries

The present study evaluated an integrated biomonitoring approach based on three different bioindicators: tree rings, lichens, and beetles in a complex environment (urban-industrial-forest). In Central Italy, four sampling sites were selected to assess the anthropogenic impact of cement plants taking into account (1) long-term exposure (1988-2020) through the analysis of trace elements in tree rings of Quercus pubescens; (2) medium-term exposure (2020-2021) through the analysis of trace elements in thalli (outermost portions) of the lichen Xanthoria parietina; (3) short-term exposure in spring 2021 through the bioaccumulation and evaluation of sample vitality in transplants of the lichen Evernia prunastri and a periodic survey of entomological biodiversity carried out during spring and summer 2021. Trace elements of industrial origin were found in tree rings, with different levels of accumulation between 1988 and 2020 and a maximum in 2012. Native thalli of the lichen X. parietina showed an overall low bioaccumulation of trace elements except for Cr, probably reflecting the influence of national lockdown measures. The transplants of E. prunastri showed a weak stress response in the industrial and urban sites, but not in the forest, and identified Tl and V as the main elements contributing to atmospheric contamination, with peaks at the industrial sites. Concerning the beetles, a significantly lower number of species was found at the Semonte industrial site.

Identification and quantification of trace metal(loid)s in water-extractable road dust nanoparticles using SP-ICP-MS

Resuspension of road dust is a major source of airborne particulate matter (PM) in urban environments. Inhalation of ultrafine particles (UFP; < 0.1 μm) represents a health concern due to their ability to reach the alveoli and be translocated into the blood stream. It is therefore important to characterize chemical properties of UFPs associated with vehicle emissions. We investigated the capability of Single-Particle ICP-MS (SP-ICP-MS) to quantify key metal(loid)s in nanoparticles (NPs; < 0.1 μm) isolated from road dust collected in Toronto, Canada. Water extraction was performed to separate the <1-μm fraction from two different road dust samples (local road vs. arterial road) and a multi-element SP-ICP-MS analysis was then conducted on the samples' supernatants. Based on the particle number concentrations obtained for both supernatants, the metal(loid)-containing NPs could be grouped in the following categories: high (Cu and Zn, > 1.3 × 1011 particles/L), medium (V, Cr, Ba, Pb, Sb, Ce, La), low (As, Co, Ni, < 4.6 × 109 particles/L). The limit of detection for particle number concentration was below 5.5 × 106 particles/L for most elements, except for Cu, Co, Ni, Cr, and V (between 0.9 and 7.7 × 107 particles/L). The results demonstrate that road dust contains a wide range of readily mobilizable metal(loid)-bearing NPs and that NP numbers may vary as a function of road type. These findings have important implications for human health risk assessments in urban areas. Further research is needed, however, to comprehensively assess the NP content of road dust as influenced by various factors, including traffic volume and speed, fleet composition, and street sweeping frequency. The described method can quickly characterize multiple isotopes per sample in complex matrices, and offers the advantage of rapid sample scanning for the identification of NPs containing potentially toxic transition metal(loid)s at a low detection limit.

Abundance, spatial variation, and sources of rare earth elements in soils around ion-adsorbed rare earth mining areas

Rare earth elements (REEs) concentrated in soils have attracted increasing attention about their impact on soil health as emerging contaminants. However, the sources of REEs enriched in soils are diverse and need to be further investigated. Here, surface soil samples were collected from southern Jiangxi Province, China. REEs contents and soil physicochemical properties were determined, and cerium (Ce) and europium (Eu) anomalies were calculated. Moreover, we established a model to further identify the main sources of REEs accumulation in the studied soils. Results show that the abundance of soil REEs reveals larger spatial variation, suggesting spatially heterogeneous distribution of REEs. The median content of light REEs in soils (154.5 mg kg^-1) of the study area was higher than that of heavy REEs and yttrium (35.8 mg kg^-1). In addition, most of the soil samples present negative Ce anomalies and all the soil samples present negative Eu anomalies implying the combined effect of weathering and potential exogenous inputs on soil REEs. Positive matrix factorization modeling reveals that soil REEs content is primarily influenced by soil parent materials. Potential anthropogenic sources include mining-related leachate, traffic exhaust, and industrial dust. These results demonstrate that the identification of sources of soil REEs is an important starting point for targeted REEs sources management and regulation of excessive and potentially harmful REEs levels in the soil.

Levels, oral bioaccessibility and health risk of sand-bound potentially harmful elements (PHEs) in public playgrounds: Exploring magnetic properties as a pollution proxy

Children in urban environments are exposed to potential harmful elements (PHEs) through variable exposure media. Playing activities in outdoor playgrounds have been considered of high concern due to children's exposure to sand-bound PHEs through unintentional or intentional sand ingestion. Furthermore, the affinity of magnetic particles with dust-bound PHEs in playgrounds has been reported. In this study, playground sands (PG sands) from public playgrounds in the city of Thessaloniki, N. Greece were sampled and the levels, the contamination degree, oral bioaccessibility and exposure assessment of PHEs were evaluated. In addition, low-cost and fast magnetic measurements (i.e. mass specific magnetic susceptibility, χ_lf) were explored as potential pollution and health risk proxies. Mineralogically, siliceous PG sands dominated, while morphologically angular magnetic particles and Fe-rich "spherules" of anthropogenic origin were revealed and verified by enhanced χ_lf values. The average total elemental contents exhibited a descending order of Mn > Ba > Cr > Zn > Ni > Pb > Cu > Co > As > Sn > Bi > Cd, however only Cd, Bi, Pb, Cr, As and Zn were presented anthropogenically enhanced. Notable increase on PHEs levels and finer sand fractions were observed with continuous sand use. Anthropogenically derived elements (i.e. Cd and Pb with high I_geo values) exhibited higher bioaccessible fractions in PG sands and considered easily soluble in gastric fluids through ingestion. However, increased risks were found for specific PHEs (especially Pb) only in a worst case exposure scenario of an intentional sand ingestion (pica disorder). Statistical analysis results revealed a linkage of anthropogenic components with sand-bound magnetic particles. Moreover, the recorded high affinity of Pb contents (in an enhanced magnetized sub-set of PG sands) and bioaccessible Cd fractions with χ_lf provide a preliminary indication on the successful applicability of low-cost and fast magnetic measurements in high impacted playground environments.

Identification of refractory zirconia from catalytic converters in dust: An emerging pollutant in urban environments

Using catalytic converters is one of the most effective methods to control vehicle emissions. A washcoat of cerium oxide-zirconia (CeO₂-ZrO₂) has been used to enhance the performance of the catalytic converter device. To date, the prevalence of this material in the environment has not been assessed. In this study, we present evidence of the existence of inhalable zirconia in urban dust. Samples of the washcoat, exhaust pipe, topsoil, and road dust were analyzed by X-ray fluorescence, X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, photoluminescence (PL) spectroscopy, and thermally stimulated luminescence (TSL). The results showed a CeO₂-ZrO₂ phase separation after sintering. This causes the emission of ZrO₂, CeO₂, and CeZrO_x particles smaller than 1 μm, which can likely reach the alveolar macrophages in the lungs. The Ce-Zr content in road dust exceeds geogenic levels, and a significant correlation of 0.87 (p < 0.05) reflects a common anthropic source. Chronic exposure to such refractory particles may result in the development of non-occupational respiratory diseases. The inhalable crystalline compounds emitted by vehicles are a significant environmental health hazard, revealing the need for further investigation and assessment of zirconia levels generated by automobiles in urban areas worldwide.

Relationship between concentration of rare earth elements in soil and their distribution in plants growing near a frequented road

Rare earth elements (REEs) are a group of elements whose concentration in numerous environmental matrices continues to increase; therefore, the use of biological methods for their removal from soil would seem to be a safe and reasonable approach. The aim of this study was to estimate the phytoextraction efficiency and distribution of light and heavy (LREEs and HREEs) rare earth elements by three herbaceous plant species: Artemisia vulgaris L., Taraxacum officinale F.H. Wigg. and Trifolium repens L., growing at a distance of 1, 10, and 25 m from the edge of a frequented road in Poland. The concentration of REEs in soil and plants was highly correlated (r > 0.9300), which indicates the high potential of the studied plant species to phytoextraction of these elements. The largest proportion of REEs was from the group of LREEs, whereas HREEs comprised only an inconsiderable portion of the REEs group. The dominant elements in the group of LREEs were Nd and Ce, while Er was dominant in the HREEs group. Differences in the amounts of these elements influenced the total concentration of LREEs, HREEs, and finally REEs and their quantities which decreased with distance from the road. According to the Friedman rank sum test, significant differences in REEs concentration, mainly between A. vulgaris L., and T. repens L. were observed for plants growing at all three distances from the road. The same relation between A. vulgaris L. and T. officinale was observed. The efficiency of LREEs and REEs phytoextraction in the whole biomass of plants growing at all distances from the road was A. vulgaris L. > T. officinale L. > T. repens L. For HREEs, the same relationship was recorded only for plants growing at the distance 1 m from the road. Bioconcentration factor (BCF) values for LREEs and HREEs were respectively higher and lower than 1 for all studied plant species regardless of the distance from the road. The studied herbaceous plant species were able to effectively phytoextract LREEs only (BCF > 1); therefore, these plants, which are commonly present near roads, could be a useful tool for removing this group of REEs from contaminated soil.

Trace element contents in fine particulate matter (PM2.5) in urban school microenvironments near a contaminated beach with mine tailings, Chañaral, Chile

Air quality in schools is an important public health issue because children spend a considerable part of their daily life in classrooms. Particulate size and chemical composition has been associated with negative health effects. We studied levels of trace element concentrations in fine particulate matter (PM_2.5) in indoor versus outdoor school settings from six schools in Chañaral, a coastal city with a beach severely polluted with mine tailings. Concentrations of trace elements were measured on two consecutive days during the summer and winter of 2012 and 2013 and determined using X-ray fluorescence. Source apportionment and element enrichment were measured using principal components analysis and enrichment factors. Trace elements were higher in indoor school spaces, especially in classrooms compared with outdoor environments. The most abundant elements were Na, Cl, S, Ca, Fe, K, Mn, Ti, and Si, associated with earth's crust. Conversely, an extremely high enrichment factor was determined for Cu, Zn, Ni and Cr; heavy metals associated with systemic and carcinogenic risk effects, whose probably origin sources are industrial and mining activities. These results suggest that the main source of trace elements in PM_2.5 from these school microenvironments is a mixture of dust contaminated with mine tailings and marine aerosols. Policymakers should prioritize environmental management changes to minimize further environmental damage and its direct impact on the health of children exposed.

Phytoextraction of rare earth elements in herbaceous plant species growing close to roads

The aim of study was to determine the phytoextraction of rare earth elements (REEs) to roots, stems and leaves of five herbaceous plant species (Achillea millefolium L., Artemisia vulgaris L., Papaver rhoeas L., Taraxacum officinale AND Tripleurospermum inodorum), growing in four areas located in close proximity to a road with varied traffic intensity. Additionally, the relationship between road traffic intensity, REE concentration in soil and the content of these elements in plant organs was estimated. A. vulgaris and P. rhoeas were able to effectively transport REEs in their leaves, independently of area collection. The highest content of REEs was observed in P. rhoeas leaves and T. inodorum roots. Generally, HREEs were accumulated in P. rhoeas roots and leaves and also in the stems of T. inodorum and T. officinale, whereas LREEs were accumulated in T. inodorum roots and T. officinale stems. It is worth underlining that there was a clear relationship between road traffic intensity and REE, HREE and LREE concentration in soil. No positive correlation was found between the concentration of these elements in soil and their content in plants, with the exception of T. officinale. An effective transport of REEs from the root system to leaves was observed, what points to the possible ability of some of the tested plant species to remove REEs from soils near roads.

Platinum group element and cerium concentrations in roadside environments in Toronto, Canada

Platinum (Pt), palladium (Pd) and rhodium (Rh) are accumulating globally in the environment, due to their use as catalysts to control automotive exhaust emissions. While environmental increases in platinum metal concentrations have been well documented for a number of countries, published data for Canada have been missing to date. The aim of this study is to examine the concentrations of Pt, Pd and Rh, as well as Ce, in soils and dust as a function of traffic volume in Toronto, Ontario. Soils and road and underpass dust were collected from two sites with medium and high volumes of traffic. Samples were acid digested and co-precipitated with Hg (for Pd) and Te (for Pt and Rh), prior to measurement using ICP-Q-MS. Palladium occurred at the highest levels in samples, followed by Pt and Rh. Median concentrations for all soil samples were 63 μg Pd/kg, 8.7 μg Pt/kg, 1.7 μg Rh/kg and 41 mg Ce/kg. The results support existing data regarding PGE accumulation trends in urban and roadside environments, due to their use as catalysts in automotive catalytic converters. This study also confirms a shift toward the heavier use of Pd as the catalyst of choice in recent years, as reflected in the higher concentrations measured for this metal relative to Pt and Rh. The results highlight a need to continue monitoring the accumulation of PGE, most notably Pd, in urban environments.

Biomonitoring of metals for air pollution assessment using a hemiepiphyte herb (Struthanthus flexicaulis)

This work presents first results on elemental characterization of a parasite plant, Struthanthus flexicaulis, collected in urban, industrial and rural areas of Rio de Janeiro state, Brazil, in order to evaluate this plant as a biomonitor of metals pollution. The results were also compared to those obtained for fine particulate matter (PM2.5) collected from filters in nearby locales. The concentrations of PM2.5 measured in the filters were between 8.0 and 18.0 μg m(-3); in some places, these measurements were higher than the 10 μg m(-3), concentration recommended by the World Health Organization (WHO). Samples of the leaves and filters with PM were submitted to acid extraction, and the extracts were employed to determine major elements (Ba, Ca, Fe, K, Mg, P and S) by ICP OES and minor elements (Cr, Cu, La, Mn, Pb, Sr, Ti and Zn) by ICP-MS. Elements' extraction efficiency was evaluated by applying the method to the certified reference materials (CMR) of tomato leaves (NIST 1573(rd)) and urban dust (NIST 1648a). The concentrations of Ca, K and Mg were higher in leaves, while Ba, Ca, K and Zn showed higher concentrations in the PM. As expected, rural sites presented lower metal content. Enrichment factor (EF) and principal component analysis with multiple linear regression analysis (PCA-MLRA) were applied to the concentrations of elements in PM2.5 and in the leaves. Anthropogenic sources could be identified with both tools, which supports the use of S. flexicaulis as a biomonitor.