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.

Seasonal and Multivariate Characteristics of Atmospheric Gases, Particulate Matter and Heavy Metals in Lagos-Suburban

“…All council permits were obtained and local approval was acquired and no further obstruction was recorded. An average of 10 samples was collected from each of the 10 locations [12]. Following the meteorological forecast, the rains were collected in a new sample bottle rinsed twice with distilled water.…”

“…Furthermore, another 20 mL of analytical grade nitric acid was added to the beaker and boiling continued until a 10 mL volume was left. The final aliquot was filtered and the filtrate was stored in a 100 ml amber bottle in the dark until further analysis was conducted [12]. The blank values were determined by analyzing unused filter papers via the procedure described above.…”

“…In the Nigerian FMEnv standard for SPM, it is taken as 250 µg/m 3 per 24 hr mean, hence only dry season mean values exceeded this threshold. The data obtained were compared to the E.U regulation and the EPA standard on the suspended particulate matter [12]. The primary EPA standard focusing on human health protection regulates 75 µg/m 3 which is taken as an annual geometric mean.…”

“…Furthermore, chemical mass balance modeling extracts information from a large number of samples and data, which limited our study. Hence according to [12], the multivariate analysis is applied when grouping and relationship variations need to be statistically expressed. The Pearson's correlation describes the total variance in the study by a linear model that ranges from -1 to 1.…”

“…Particulate heavy metal accumulation poses a great potential threat to human health. They are classified as systemic toxicants which can induce multiple organ damage even at low concentrations [12]. Also according to the US environmental protection agency, they have been classified as human carcinogens with increasing ecological and global public health concerns [13].…”