Application of pollution indices to determine pollution intensities in the groundwater of Gopalganj (south-central part), Bangladesh

Abstract

Heavy metals (HMs) contamination in groundwater (GW) is a serious concern due to growing urbanization, industrialization, and contemporary farming practices. The GW in the Gopalganj district of Bangladesh is particularly vulnerable to this pollution. The purpose of this research is to evaluate the pollution intensities in shallow groundwater (SGW) using multiple pollution indices, including Heavy-metal Pollution Index (HPI), Heavy-metal Evaluation Index (HEI), Degree of Contamination (Cd), Synthetic Pollution Index (SPI), Metal Index (MI), and Ecological Risk Index (ERI). As a consequence, the concentrations of arsenic (As), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) were measured using the Particle-induced X-ray Emission (PIXE) method. Roughly 30.58% of the samples exceeded the acceptable level of As. The concentration of the other two metals also excedded, namely Fe and Mn, were 99.42% and 48.00%, respectively. According to HPI, 85.29% of the samples were unsuitable for drinking, 10.59% were questionable, and the rest 4.12% of the samples were suitable for drinking purposes. The HEI depicted that 82.94% of SGW were high pollution, 14.12% were medium pollution, and the remaining 2.94% were low pollution status. In addition, the Cd and MI results exhibited that the majority of the samples were highly contaminated. The SPI values showed that 54.71% of samples were unfit for drinking, 44.12% were highly polluted, and only 1.17% were moderately polluted. The ERI evaluated that 12.94% of the SGW posed moderate ecological risk, while 86.47% posed low ecological risks. In addition, Pearson Correlation, Principal Component Analysis (PCA), and Cluster Analysis (CA) were performed to scrutinize the pollution source and factors influencing SGW quality. The individuality of this research was that we used different indices to determine the pollution intensities, which will be a valuable tool for indigenous planners and policymakers, surveying the decision-making and reduction of pollution activities occurring throughout the study area.