Principal Component Analysis of the Chemical Radicals in the Water from Hand-Dug Wells in Akure Metropolis, South West Nigeria

Research Article

Austin J Environ Toxicol. 2016; 2(2): 1015.

Principal Component Analysis of the Chemical Radicals in the Water from Hand-Dug Wells in Akure Metropolis, South West Nigeria

Idowu AA¹*, Nnamdi ASO², Godknows IM³ and Akinyomi OK²

¹Department of Chemistry, Federal University of Agriculture, Nigeria

²Department of Statistic, Federal University of Agriculture, Nigeria

3Department of Statistic, University of Ibadan, Nigeria

*Corresponding author: Adeogun Abideen Idowu, Department of Chemistry, Federal University of Agriculture, Abeokuta, Nigeria

Received: August 27, 2016; Accepted: November 08, 2016; Published: November 10, 2016


This study assessed the chemical radicals water in hand dug wells in Akure metropolis, Ondo State Southwest Nigeria. Forty hand dug wells were sampled within the metropolis, using standard laboratory techniques, the water samples were analyzed for chemical radical parameters such as; calcium, magnesium, sodium potassium, iron, lead, silicate, phosphate, sulphate, bicarbonate, chloride, nitrite and nitrates. The resulting data were subjected to Principal Component Analysis (PCA) and Cluster Analysis. The first principal components only accounts for about 34% of the variation in the data and four components were needed to account for 67% of the variation. Also worthy of note is the fact that these first four components have eigenvalues substantially larger than the last nine components. A biplot of the first few principal components revealed the data structure as falling into three groups. To visualize this cluster group, the hierarchical cluster approach was adopted using the average linkage. The results of the analysis have helped in the optimization of the parameters that led to the levels of the radicals in the samples.

Keywords: Chemical radicals; Hand dug wells; Correlation; Principal components analysis; Eigenvalues


Accessibility and quality of water supply, as well as quality of sanitation facilities available to households or communities is an important factor in determining the quality of life of the people and the potential for poverty alleviation [1-3]. Large areas of urban environment in Nigeria do not have network connections; the public water supply system itself is riddled with so many leakages that affect water quality. Consequently, urban water supplies in Nigeria are supplemented with alternative sources and this in most cases is by way of commercialization. Alternative source of water supply commonly found in Nigeria includes the hand dug wells. It is common beliefs that water from hand dug wells are not safe for human consumption due to their poor water quality.

Water quality refers to the chemical, physical and biological characteristics of water and is a measure of the condition of water relative to the requirements of one or more biotic species and or to any human need or purpose [4,5]. Water quality is most frequently used by reference to a set of standards against which compliance can be assessed and it determines the goodness of water for particular purposes [6]. The most common standards used to assess water quality relates to health of ecosystems, safety of human contact and drinking water [6]. The measurement of chemical variables in the water promotes a better understanding of the aquatic environment. Although, these variables produce large set of data which are often difficult to interpret [7-9].

Data interpretation of multidimensional measurements can be approached by the application of chemometric methods such as Principal Component Analysis (PCA) [7,10-16]. PCA is a powerful statistical tool for compressing data and extraction of information. It can reduce the dimensionality of a data set consisting of a large number of interrelated variables, while retaining the variability present in a data set as much as possible. This reduction is achieved by transforming the data set into a new set of variables, the Principal Components (PCs), which are orthogonal (non-correlated) and arranged in decreasing order of importance. However, it is well known that PCA, like any other multivariate statistical method, is sensitive to outliers, missing data and poor linear correlation between variables due to their poor distribution. As a result, data transformations have a large impact on PCA. In this regard one of the most powerful approaches to improve PCA appears to be Robust Principal Component Analysis (RPCA), which diminishes the influence of outliers [7,17-18].

In this study robust principal component analysis and cluster analysis approach were applied to the chemical radicals parameters of water from hand dug well in Akure. The results are discussed based on the role of water quality as a pollution indicator and to identify the contribution of natural and anthropogenic factors to water quality variations in temporal and spatial patterns.

Materials and Methods

Study area

This study dwells on the statistical analysis of the chemical components of the water in the hand-dug wells in Akure Township. This town lies between the longitude 5.01° E and 5.63° E and latitude 7-01° N and 7.63° N. it is the Capital of Ondo State in Southwestern Nigeria (Figure 1). The local geology of Akure Township has earlier been described [19-24].