Geochemical Characterization of Groundwater and Mineralogical Assessment in Hatiya Island, Southeastern Coastal Region of Bangladesh

Abstract

Groundwater is a vital source of fresh water for drinking and agricultural purposes in the region of Hatiya Island, Bangladesh, yet is subject to contamination by natural and anthropogenic activities. To address this issue, this research aims to examine hydrogeochemical characterization of water and its suitability for irrigation and drinking uses on different indices utilizing a combined geochemical method, multivariate statistical approaches, and geospatial analysis. Results of hydrogeochemical analyses of groundwater samples from the intermediate aquifer (60–140 m) represent the order of cations, anions, and metals concentration as Na+ >Mg2+ >Ca2+ >K+, Cl− >HCO3− >NO3− >SO42− and Fe>I>Br>Mn>As, respectively. Saltwater intrusion has been detected to be the most important hydrogeochemical process influencing the chemistry of groundwater. Principal Component Analysis, Pearson’s Correlation matrix, and Hierarchical Cluster Analysis indicate that groundwater quality is highly governed by geogenic influences. We combined this information into a drinking water quality index map, finding that 40% of the groundwater samples are suitable for human consumption, whereas 60% are unfit for drinking. The analysis and evaluation of irrigation quality parameters revealed that 54% of the groundwater samples are in excellent or good condition for agricultural uses, however, the other 46% samples are unsuitable. The methods employed in this study can be used to assess the current status of groundwater quality and monitor the extent of contamination in the coastal region of Bangladesh, and other deltaic countries. For the abundance of heavy mineral presence, the southern part of the island has a much higher concentration of heavy minerals than the northern part. The heavy mineral assemblages are characterized by predominance of garnet and opaque minerals followed by zircon, and rutile where higher amount of opaque minerals have been found in the northern part whereas higher content of garnet has been found in the southern part of Hatiya region.