Seasonal Variability in Physico-Chemical Attributes of Spring Water in Nagaland, India

This study evaluated the seasonal variability of spring water quality across four districts of Nagaland, viz., Dimapur, Phek, Mokokchung, and Noklak. Forty sampling stations were investigated in rainy, summer, and winter seasons for key physico-chemical parameters such as pH, free CO₂, total alkalinity, chloride, conductivity and total dissolved solids (TDS). Results revealed distinct spatio- temporal differences. Mean pH values indicated higher alkalinity during rainy and summer months (up to 6.6 in Noklak) and lower in winter (5.2 in Mokokchung). Free CO₂ concentrations were consistently elevated in Noklak and Phek during winter (17. mg/l and 12.1 mg/l, respectively), reflecting increased solubility at low temperatures. Total alkalinity reached maximum levels in Mokokchung during the rainy season (53.8 mg/l) but declined sharply in winter (13.1 mg/l). Chloride concentrations peaked in Dimapur and Phek during the rainy season (>65 mg/l), while Noklak exhibited strong seasonal contrasts. Conductivity was highest in Mokokchung (125.0 μS/cm, rainy season), and TDS values were most elevated in Noklak (85.8 mg/l, rainy season). Across all districts, the general sequence was rainy > summer > winter for solute parameters, whereas free CO₂ peaked in winter. Despite these variations, all parameters except pH remained within BIS/ICMR/WHO permissible limits. These findings provide baseline data on spring water parameters in the hilly regions of Northeast India and emphasize the need for extended monitoring of additional physico-chemical, biological parameters and heavy metals contaminants to ensure long-term drinking water safety.