Multivariate analysis and spatial distribution of suspended particulate metals of Abakaliki and Enugu in Southeastern Nigeria

Abstract

Background

The atmosphere is usually contaminated by heavy metals from different natural and anthropogenic sources. The levels of heavy metals in the atmosphere often become harmful and cause environmental pollution with serious health consequences to humans when their concentrations exceed certain threshold limits. The determination of the atmospherically suspended particulate matter in general and toxic trace metallic concentrations in particular, is, therefore, necessary for the evaluation of the sources and fate of atmospherically deposited suspended particulate matter. The assessment of the concentration levels of suspended particulate trace metals like Zn and Pb in the cities of Enugu and Abakaliki southeastern Nigeria was performed to assess the concentrations of atmospherically suspended metals in the area, their sources, and their pollution status.

Results

Results of the study showed that Zn concentration levels were not significant at all the sampling points, while the concentrations of Pb particulate matter which ranged from 0.11 to 0.91 µg/m³ exceeded the international revised EPA Pb standard of 0.15 µg/m³ but within the approved Federal Ministry of Environment (FMEnv) Nigeria, 24 h long duration of 1 µg/m³, and National Ambient Air Quality Standard (NAAQS) 1 h duration (1 µg/m³). The enrichment factor (EF) showed that Pb had a dominant crustal source, while Zn was determined to be of minor to moderate crust enrichment. The multivariate analysis carried out using principal component analysis (PCA) based on varimax rotation and Hierarchical Cluster Analysis (HCA) plotted in biplot and dendrogram diagrams revealed the levels of dependency and grouping, whereas Pearson’s Correlation Coefficient (PC) revealed a strong link between the two metallic pollutants

Conclusion

This study therefore which applied statistical and pollution assessment of atmospherically suspended particulate matter has revealed the importance of monitoring atmospherically suspended materials resulting from anthropogenic sources like mining, quarrying, construction, etc. Similarly, the use of statistical techniques like PCA, HCA, and Pearson’s Correlation Coefficient to the study of ambient air quality has proved to be a useful tool in the assessment of atmospheric pollution. The findings of the present study therefore will be invaluable in the monitoring of particulate matter pollution of the atmosphere and their control measures, especially in mining districts.