Assessment of groundwater quality in the coastal aquifers of Bachok using hydrogeochemical analysis

Abstract

In Kelantan, fresh groundwater has been reported to be one of the major sources of water supply in the state. It is widely adopted and utilized by various users to meet their needs especially in domestic, irrigation and industrial sectors. The overwhelming use and over abstraction on the groundwater resources had caused the imbalance of groundwater which results in the depletion of groundwater level. Over time, this trend will cause the negative impact on the groundwater quality for both short and long term. The problems of groundwater quality are not only related to man-made but also natural pollution. To understand this phenomenon, hydrogeochemical studies has been carried out on groundwater samples along the coastal aquifers of Bachok. The results of analysis carried out showed the following concentration ranges: pH (6.8-6.9), EC (75.9-1520 μS/em), TDS (125-2188 mg/L), turbidity (11-66 mg/L), Ca2+ (0.03-5.81 mg/L), Mg2+ (<0.03-6.22 mg/L), Na+ (<0.02-5.69 mg/L), K+ (2.76-5.78 mg/L), HCO3- (74-271 mg/L), Cl- (8.1-680 mg/L), SO42- (≤3 mg/L), NO31 (0.03- 1.48 mg/L), Fe2+ (<0.02-1.92 mg/L) and Mn2+ (≤0.03 mg/L). The results are assessed and compared with guidelines drinking-water quality from World Health Organization (WHO). The hydrogeohemical facies for groundwater S1, S2 and S4 is Ca-Mg-Cl-SO4, whereas the hydrogeochemical facies for S3 is Ca-Mg-HCO3. Based on the findings obtained from this study, all groundwater samples are classified as fresh water and chemically suitable for drinking water except one sample is in poor-quality water which might be affected by the percolation of the sewage and the dissolution of minerals.