Spatio-temporal Variations in the Physico-chemical and Bacteriological Qualities of Groundwater in Selected Areas of Manila

Abstract

This longitudinal study aims to determine spatio-temporal variations of physicochemical and bacteriological qualities of ground water collected from two sampling sites in Manila. Groundwater samples from two sites were collected monthly. The samples were then assayed for its salinity, pH, optical density and specific gravity. Moreover, the bacteriological qualities were also determined by a routine water analysis for the presence of total and fecal coliforms and heterotrophic plate counts using nutrient agar with varying concentrations of sodium chloride. The isolated bacteria were phenotypically identified and characterized using the BBL Crystal ID. The groundwater was also observed to be brackish, turbid and with high specific gravity Results also indicate spatial variations of all the physico-chemical parametersexcept for the pH. No temporal variations were observed among the collected samples across time. Furthermore, all collected samples were negative for coliforms. However, only Site A was said to be positive for heterophic plate count and its growth was optimized upon the addition of 5% NaCl. Interestingly, the growth of bacteria in the heterotrophic plate count had a positive significant correlation with all the physico-chemical parameters except for pH. Ergo, the findings of the study could imply a potential saltwater intrusion as evidenced of the high salinity of groundwater and the growth of halotolerant bacteria from the collected samples. Keywords: BBL crystal ID; bacteriological; spatio-temporal