Evaluating top soil trace element pollution in the vicinity of a cement plant and a former open-cast uranium mine in central Argentina

Purpose Heavy metals are especially dangerous because of their persistence and toxicity. Soil behaves as a sink of heavy metals by aerial deposition of particles emitted by different human activities. The aims of this work were to identify the levels and sources of heavy metal and trace elements in agricultural and residential areas in Argentina and to evaluate the enrichment of total and HCl-extracted heavy metals. Materials and methods Ninety-four topsoil samples were collected in Cordoba, Argentina (0-10 cm). The majority of the samples were subject to agricultural practices. The possible metal pollution sources were a cement plant and an industrial waste incinerator, a former open-cast uranium mine, petrochemical, and mechanical and metallurgical industries among others. The elements As, Ba, Ca, Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Na, Nd, Rb, Sb, Sc, Se, Sm, Ta, Tb, Th, U, Yb, and Zn were measured by neutron activation analysis, and Co, Cu, Fe, Mn, Ni, Pb, and Zn were partially extracted by 0.5-M HCl and measured using atomic absorption spectroscopy. Several nonparametric statistics were performed to the dataset in order to accomplish the objectives of the study. Results and discussion The mean total Ba concentration exceeded soil quality guidelines for residential areas, with the maximum total As and Co concentrations surpassing the agricultural and residential limits stated in national and international legislations. The elements As and Ba were found to be controlled by parent factors, whereas Ca, Co, Cr, Cu, Mn, Ni, Pb, and Zn were controlled by both anthropogenic and pedogenic factors. A cement plant was the main source of Ca, Co, Cr, Cu, Mn, Ni, Pb, and Zn, whereas lanthanides, Fe, K, U, and also Zn were associated with a former open-cast operation uranium mine. A correlation analysis showed that soil organic matter and pH had strong associations with 0.5-M HCl-extracted Co, Cu, Mn, Ni, Pb, and Zn. Conclusions Fe-normalized enrichment factors calculated for 0.5-M HCl-extracted heavy metals are potentially significant for characterizing the element bioavailability, the anthropogenic contamination, and the anomaly assessment. According to soil quality guidelines for environmental health, the human and wildlife populations in Cordoba Province might be experiencing toxic As, Ba, Co, Cr, Ta, U, and Zn effects. Therefore, mitigation strategies should be performed on an abandoned mine (Schlagintweit Uranium Mine), Yocsina, Despenaderos, and Oliva.