Background. Increased growth of industrial activities, especially in urban centers, is one of the main sources of toxic substances in Nigeria. The level of these impacts is not well known. Soil and sediment samples from one such industrial area were examined for their mineralogical composition and heavy metals contents in order to assess the level of contamination and potential ecological risk status. Methods. Mineralogical composition of the media and their heavy metals concentrations were determined using X-ray diffractometry and inductively coupled plasma-mass spectrometry methods, respectively. Ecological risk assessment was carried out using single (contamination factor, geo-accumulation index, enrichment factor) and multi-elemental (contamination degree, pollution index and modified pollution index) standard indices. Results. The average heavy metal concentrations in soils and sediments followed the order magnesium (Mn) > chromium (Cr) > lead (Pb) > copper (Cu) > cadmium (Cd) > cobalt (Co) > nickel ...

Rare earth element (REE) composition of atmospheric dust has recently been used to trace potential sources of dust pollution. The present study aimed to determine the sources of atmospheric pollution in the study area using REE patterns and determine their level of pollution. Twenty-five (25) atmospheric dust samples were collected in the study area, with five samples each from an industrial area, traffic area, dumpsite area, residential area and remote area in Ibadan, southwestern Nigeria. In addition, five (5) topsoil and two (2) rock samples (granite gneiss) were collected for comparison. Concentrations of REE were determined by inductively coupled plasma mass spectrometry (ICP-MS). The ratio of lanthanum/cerium (La/Ce), especially in some locations in industrial area (1.5), traffic area (1.5) and to some extent dumpsite area (1.1) was higher than in soil (0.2), upper continental crust (0.5) and the minimum value of fluid catalytic crackers (1.0). Generally, the respective average values of the ratios of La/praseodymium (Pr), La/neodymium (Nd) and La/samarium (Sm) in industrial area (32.1, 7.8 and 52.6) and traffic area (14.9, 4.4 and 26.8) were higher than their respective averages in soil (4.4, 1.1 and 6.2), rock (5.7, 1.9 and 14.1), upper continental crust (4.4, 1.1 and 6.6) and the minimum value in fluid catalytic crackers (5.8, 3.7 and 37.0). Meanwhile, their corresponding value in the dumpsite area, residential area and remote area were lower or similar to the geological background levels. The contamination factors of REEs in the atmospheric dust of the industrial area and traffic area were classified as heavily contaminated, especially with light lanthanoid elements in REE. The degree of contamination of REEs in the atmospheric dust of industrial area (30.9) and traffic area (18.8) fell within the considerable contamination category. The high values of the light lanthanoid ratio and the contamination indices were attributed to their emission from the fired-power plant and vehicular exhaust. Most of the composition of the atmospheric dust was sourced from the local geology of the study area as observed in the residential area and remote area, while the contamination in the industrial area and traffic area was attributed to human activities. The authors declare no competing financial interests.

The harmful health effect of suspended particulate matter (PM₁₀) is mostly associated with its mass concentrations and chemical compositions. Therefore, this study focuses on the determination of the particulate matter (PM₁₀) concentrations and their potentially toxic elements (PTEs) composition from different road networks in Ibadan southwestern, Nigeria. In addition, human health risk assessment was estimated from the PTE data. The PM₁₀ samples were collected from different road networks such as national highway roads (NHR), inner-city major roads (ICR), and remote roads (RRD) in Ibadan, Nigeria. The sampling was carried out with a high-volume air sampler (model #15000 manufactured by Science Resource, Walboro, USA) with a PM₁₀ cut-off on a Whatman cellulose filter during the harmattan period. The PM₁₀ concentrations and PTEs compositions (Al, Ba, Cd, Cu, Fe, La, Mo, Mn, Ni, Pb, V, and Zn) were determined by gravimetry and inductively coupled plasma-optical emission spectrometry (ICP-OES) methods (VISTA-MPX manufactured by Varian Incorporation), respectively. The PM₁₀ concentrations in all three road networks were more than 3 folds higher than World Health Organization (WHO), United State Environmental Protection Agency (USEPA), and United Kingdom Environmental Protection Agency (UKEPA) standards (50 µg/m³) for 24 h. The maximum average contents of Ba, Cd, Cu, La, Mn, Pb, and V, were observed at NHR, while that of Al, Fe, Mo, and Zn, were found at ICR. The principal component analysis (PCA) showed that PC1 (Ba, Cd, Cu, La, Mo, Pb, and V) and PC4 (Zn) were characterised by elemental markers of both exhaust emission and non-exhaust emissions, while PC2 (Mn) and PC3 (Al, Fe) were characterised by crustal elements. The Enrichment factor (EF) analysis classified all the PTEs as moderately to very highly enriched, especially in NHR and ICR, except Al, Fe, and to some extent Mn. Both the maximum and average hazard quotient (HQ) levels of Cd, Cu, Mn, Pb, and Zn were < 1, which was within the permissible level. Also, the carcinogenic risk (CR) was also within the permissible limit.