Are children playgrounds safe play areas? Inorganic analysis and lead isotope ratios for contamination assessment in recreational (Brazilian) parks

In city playgrounds, there is a potential risk of harming children’s health by contamination coming from anthropogenic activities. With the aim to determinate the sources and the risk of hazardous elements, soil samples were collected in 19 selected playgrounds of different urban and rural areas from the Rio Grande do Sul state (Brazil). The concentration of 23 metals and metalloids and lead isotopic ratios were determined by ICP-MS. The methodology proposed here, firstly, classified the parks according to the average metal content by means of the NWACs (Normalized-and-Weighted Average Concentrations) and assess the contamination risk determining the Contamination Factors (CFs). Finally, statistical tools (correlation analysis and principal component analysis) were used to identify the most important contamination sources. The statistical tools used, together with lead isotopic composition analysis of the samples, revealed that coal combustion is the main source of contamination in the area. Vegetation was identified as a barrier for the contamination coming from the city. Nonetheless, some of the soils present a possible toxicological risk for humans. In fact, Cr, Sb, and Pb concentrations were higher than the Residential Intervention Values (VIRs) defined by the Environmental Protection Agency of the State of São Paulo, also in Brazil

The effect of calcium oxalates in the weathering steel surface

International audienc

Bioimpact on weathering steel surfaces: Oxalates formation and the elucidation of their origin

International audienceThis study was carried out to elucidate the causes of irregularities and discolorations on the surface of parts of a weathering steel sculpture which had been in contact with wood pallets. Non-destructive analysis of the samples by Raman spectroscopy revealed the presence of iron oxalates and calcium oxalates. Thermodynamic modeling suggested that the detected oxalates were produced by the reaction of oxalic acid, a potential metabolite excreted by microorganisms, and elements present in the steel surface such as iron. Carotenoids including β-carotene and astaxanthin, biomarkers for a large number of prokaryotic and eukaryotic microorganisms, were also detected in samples

Protective ability index measurement through Raman quantification imaging to diagnose the conservation state of weathering steel structures

International audienceWeathering steel was designed to resist against the atmospheric impact due to the development of a characteristic rust layer that protects the metal by reducing the corrosion rate. This rust layer is formed by different iron (oxy-hydr)oxides that acts as a barrier and provides the protective ability. In order to check the conservation state trough the protective capability, it is necessary to calculate the so-called protective ability index (PAI). It mainly takes into account the ratio (α/γ) between the mass of goethite (α-FeOOH) and lepidocrocite (γ-FeOOH), present in the rust layer of weathering steel. Raman spectroscopy, apart from a qualitative technique, is recently becoming a semi quantitative approach. Therefore, it is a valuable tool for the calculation of the mentioned index. This paper is a widening of a previous work in which it was uncovered a problem in different weathering steel sculptures which are exposed to a Cl− and SO2-rich urban atmosphere because they present different esthetical problems on their surfaces, such as detachments of steel chips, discolorations and irregularities. In order to relate these problems on the surface and the rust layer composition, PAI calculations were performed from the phase identification obtained from Raman imaging and using spectra decomposition to quantify each compounds. Although goethite and lepidocrocite were the most commonly detected compounds, hematite, akaganeite and magnetite were also identified. Hematite is a sub product formed in rich SO2 atmospheres; therefore, a PAI with its content is proposed. Protective indexes obtained for the different artworks exposed in different places provide quantitative clues for the conservation diagnosis of weathering steel structures