Heavy metal pollution index for assessment of seasonal groundwater supply quality in hillside area, Kalasin, Thailand

Abstract Agriculture is a major activity in most rural areas in northern Thailand. The aim of this study was to assess the heavy metal pollution index (HPI) for water supply quality in a rural village in Kalasin Province named Kaeng Ka-am village located in the hillside area of Phu Phan mountain. The concentration of heavy metals including iron (Fe), manganese (Mn), and zinc (Zn) in groundwater supply has been analyzed by the atomic absorption spectrometer. The groundwater supplied samples were collected from eight different locations in and around the region which covers agricultural and municipal area during the monsoon and post-monsoon seasons. The results were evaluated in accordance with the drinking water quality standards suggested by the World Health Organization and Thailand Department of Health Standards. Most of the samples were found within limit except for Fe and Mn contents during the monsoon season at three sampling locations which is above the desirable limit, i.e., 0.3 mg/L. The mean values of HPI were 70 and 46 in the monsoon and the post-monsoon season, respectively, and these values are well below the critical index limit of 100.