Emerging Risks for Children: Chemical Speciation of Metals in Urban Soils as an Environmental Diagnostic Tool

Children and the elderly are the most vulnerable to health problems, due to possible direct contact with contaminated soil and the inhalation of exhaust fumes. Also, quantifying chemical species of metals in soil is essential for estimating the bioavailability of the metals in the environment. The “Capibaribe Melhor” Project launched by the City Hall of Recife – PE – Brazil includes two large parks, Santana and Caiara. The Project involves environmental education actions, construction of a pier, and squares, with the aim of revamping the Capibaribe River, the city's main body of water, drawing the attention of the local population to the need to preserve the Capibaribe River and, at the same time, offering areas for entertainment and recreation. Parks usually attract the neighboring inhabitants, but their soils contain varying amounts of toxic trace metals such as As, Cd, Cu, Cr, Fe, Hg, Pb, Ni, Sn, Zn, Mn, Si, Pb and Sc, mainly because of atmospheric pollution from vehicles' exhausting pipes. This study aims to determine the metal distribution in geochemical phases of soil in parks and presents the total concentrations of chemical elements in soils collected in parks, obtained by Energy Dispersion X-Ray Fluorescence (EDXRF). The more toxics metals found in this study were: Al, Zn, Cu, and Pb, while the major chemical elements analyzed were Fe, K, Ca, and Si. Sequential extraction showed the presence of major metals (Mn and Fe) and minor ones (Zn and Cu), mainly in the oxidizable phase followed by the leachable or pseudo-residual phase. Only Mn is also highlighted in the leachable fraction. The results emphasize the importance of determining the chemical form of heavy metals in soil in parks to assess the availability and long-term environmental consequences of soil contamination and the effects of these new chemical pollutants that cause so-called noncommunicable diseases (NCDs).