Topsoil pollution in highway medians in the State of São Paulo (Brazil): determination of potentially toxic elements using synchrotron radiation total reflection X-ray fluorescence

Bi3+ and Tb3+ Co-doped Cs2AgInCl6 Lead-free double perovskite nanocrystals for detection of temperature and copper ions

The content of Cu²⁺ in lubricating oil and lubricant temperature are important indicators predicting mechanical failure. Therefore, developing a nontoxic fluorescence probe is necessary to detect Cu²⁺ and temperature in lubricating oil. The lead-free inorganic double perovskite nanocrystals (NCs) Cs₂AgInCl₆ are potential candidates. However, the low fluorescence intensity and the high excitation energy required of Cs₂AgInCl₆ NCs limit their practical applications. In this study, Bi³⁺ and Tb³⁺ were successfully co-doped into Cs₂AgInCl₆ NCs via the hot-injection method. The doping of Bi³⁺ produces a broad emission originating from self-trapped excitons and reduces the excitation energy, allowing commercial LEDs as excitation sources. Tb³⁺ ions doping offers characteristic emission peaks (⁵D₀-⁷F_J) of Tb³⁺ ions and improves the fluorescence intensity of Cs₂AgInCl₆ NCs. Furthermore, the Cs₂AgInCl₆: Bi³⁺/Tb³⁺ NCs have been employed as optical thermometry, which provide a temperature calibration curve with the maximum absolute and relative sensitivities of 2.15% K^-1 at 350 K and 2.25% K^-1 at 303 K in the temperature range of 303-423 K, respectively. Finally, the nanocrystals have been applied to detect Cu²⁺ in lubricating oil. The fluorescent probe shows a good detection sensitivity of 8.94 × 10^-4 nM^-1 and a low detection limit of 14.3 nM in the range of 10-300 nM. This work not merely offers a novel way for improving the luminescence performances of double perovskite NCs Cs₂AgInCl₆, but broadens their potential for detection of Cu²⁺ and temperature.

A remote sensing framework to map potential toxic elements in agricultural soils in the humid tropics

Soil contamination by potentially toxic elements (PTEs) is one of the greatest threats to environmental degradation. Knowing where PTEs accumulated in soil can mitigate their adverse effects on plants, animals, and human health. We evaluated the potential of using long-term remote sensing images that reveal the bare soils, to detect and map PTEs in agricultural fields. In this study, 360 soil samples were collected at the superficial layer (0-20 cm) in a 2574 km² agricultural area located in São Paulo State, Brazil. We tested the Soil Synthetic Image (SYSI) using Landsat TM/ETM/ETM+, Landsat OLI, and Sentinel 2 images. The three products have different spectral, temporal, and spatial resolutions. The time series multispectral images were used to reveal areas with bare soil and their spectra were used as predictors of soil chromium, iron, nickel, and zinc contents. We observed a strong linear relationship (-0.26 > r > -0.62) between the selected PTEs and the near infrared (NIR) and shortwave infrared (SWIR) bands of Sentinel (ensemble of 4 years of data), Landsat TM (35 years data), and Landsat OLI (4 years data). The clearest discrimination of soil PTEs was obtained from SYSI using a long term Landsat 5 collection over 35 years. Satellite data could efficiently detect the contents of PTEs in soils due to their relation with soil attributes and parent materials. Therefore, distinct satellite sensors could map the PTEs on tropics and assist in understanding their spatial dynamics and environmental effects.

Proposal of new distribution coefficients (Kd) of potentially toxic elements in soils for improving environmental risk assessment in the State of São Paulo, southeastern Brazil

Soil solid-solution distribution coefficients (K_d) are used in predictive environmental models to assess public health risks. This study was undertaken to determine K_d for potentially toxic elements (PTE) Cd, Co, Cr, Cu, Ni, Pb, and Zn in topsoil samples (0-20 cm) from 30 soils in the State of São Paulo, southeastern Brazil. Batch sorption experiments were carried out, and PTE concentrations in the equilibrium solution were determined by High Resolution Inductively Coupled Plasma Mass Spectrometry (HR-ICPMS). Sorption data was fitted to the Freundlich model. The K_d values were either obtained directly from the slope coefficients of C-type isotherms or derived from the slope of the straight line tangent to the non-linear L-type and H-type isotherms. Stepwise multiple regression models were used to estimate the K_d values through the combined effect of a number of soil attributes [pH_H2O, effective cation exchange capacity (ECEC) and contents of clay, organic carbon, and Fe (oxy)hydroxides]. The smallest variation in K_d values was recorded for Cu (105-4598 L kg^-1), Pb (121-7020 L kg^-1), Ni (6-998 L kg^-1), as variation across four orders of magnitude was observed for Cd (7-14,339 L kg^-1), Co (2-34,473 L kg^-1), and Cr (1-21,267 L kg^-1). The K_d values for Zn were between 5 and 123,849 L kg^-1. According to median values of K_d, PTE were sorbed in the following preferential order: Pb > Cu > Cd > Ni > Zn > Cr > Co. The K_d values were best predicted using metal-specific and highly significant (p < 0.001) linear regressions that included pH_H2O, ECEC, and clay contents. The K_d values reported in this study are a novel result that can help minimize erroneous estimates and improve both environmental and public health risk assessments under humid tropical edaphoclimatic conditions.

Concentrations of selected trace elements in surface soils near crossroads in the city of Bratislava (the Slovak Republic)

It is well known that road transport emits various trace elements into the environment, which are deposited in soils in the vicinity of roads, so-called roadside soils, and thus contributes to the deterioration of their chemical state. The aim of this work was to determine concentrations of some metals and metalloids (arsenic (As), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), antimony (Sb), vanadium (V), and zinc (Zn)) in soils from crossroads with traffic signals, which are characterized by deceleration of vehicles and increased emissions of elements related mainly to brake and tyre wear. The results confirmed a moderate enrichment of soils with Cu, Pb, and Zn (enrichment factor (EF) values > 2) and significant enrichment for Sb (EF > 5), while the other elements showed no or minimal enrichment. The age of crossroads proved to have a positive influence on the accumulation of some elements in soils with the largest differences for Cu, Fe, Pb, Sb, and Zn (p < 0.001). Traffic volumes expressed as the average daily traffic intensity (ADTI) also positively influenced soil concentrations of Cr, Cu, Pb, Sb, and Zn, while distance to the crossroad had a significant negative effect on the soil concentration of Cu, Sb, and Zn (p < 0.001). The stable isotopic ratios of Pb, ²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁶Pb, ranging from 1.1414 to 1.2046 and from 2.0375 to 2.1246, respectively, pointed to the mixed natural-anthropic origin of Pb in the soils of crossroads with a visible contribution of traffic-related sources. Based on the above findings combined with covariance among the studied elements using statistical methods applied to compositionally transformed data, it was possible to show that Cu, Pb, Sb, and Zn clearly originated from road traffic.

Bioaccumulation of Toxic Metals in Children Exposed to Urban Pollution and to Cement Plant Emissions

Cement plants located in urban areas can increase health risk. Although children are particularly vulnerable, biomonitoring studies are lacking. Toenail concentration of 24 metals was measured in 366 children (6-10 years), who live and attend school in a city hosting a cement plant. Living addresses and schools were geocoded and attributed to exposed or control areas, according to modeled ground concentrations of PM₁₀ generated by the cement plant. Air levels of PM₁₀ and NO₂ were monitored. PM₁₀ levels were higher in the exposed, than in the control area. The highest mean PM₁₀ concentration was recorded close to the cement plant. Conversely, the highest NO₂ concentration was in the control area, where vehicular traffic and home heating were the prevalent sources of pollutants. Exposed children had higher concentrations of Nickel (Ni), Cadmium (Cd), Mercury (Hg), and Arsenic (As) than controls. These concentrations correlated each other, indicating a common source. Toenail Barium (Ba) concentration was higher in the control- than in the exposed area. The location of the attended school was a predictor of Cd, Hg, Ni, Ba concentrations, after adjusting for confounders. In conclusion, children living and attending school in an urban area exposed to cement plant emissions show a chronic bioaccumulation of toxic metals, and a significant exposure to PM₁₀ pollution. Cement plants located in populous urban areas seem therefore harmful, and primary prevention policies to protect children health are needed.

Review of the interactions between vehicular emitted potentially toxic elements, roadside soils, and associated biota

Given the large size of the world road network, the land area affected by vehicular emissions is extensive. This review provides the first global picture of the relationships between vehicular emitted potentially toxic elements, roadside soils, and risks to associated biota. The following potentially toxic elements that accumulate in roadside soils have been examined in this review: As, Co, Cr, Cu, Mn, Mo, Ni, Pb, Pd, Pt, Rh, Se, Sb, Sn, Sr, Ti and Zn. The meta-analysis undertaken demonstrated an increase in concentrations of Cd, Pb, Zn, Pt, Pd and Rh in roadside soils compared to the mean global crustal concentrations. Positive correlations between potentially toxic element concentrations in roadside soil, plants, microbes, and animals were observed. Roadside studies have found increased potentially toxic element concentrations in plants and animals with increasing proximity to roads. The mean concentrations of Pb in roadside plants and vertebrates were at values above the World Health Organisation guidelines. Research has shown a range of impacts of potentially toxic elements in roadside soils on microbial activity including decreased litter decomposition, nitrogen fixation, nutrient cycling and enzyme synthesis. However, aside from the impact on microbial communities, there has been little research investigating the impacts of roadside soil elements on the associated biota. Thus, there is a need for research that investigates the toxicity of elements in roadside soils to plants and animals and to investigate the transfer of roadside elements through the food chain, and thus, risks posed to human health and the environment.