Geochemical assessment of groundwater quality using Nemerov's pollution index: a micro-level study in the groundwater critical zone of western Rajasthan, India.

Abstract

The pollution index is a helpful tool for assessing the quality of groundwater. To assess the water quality in the southern segment of Barmer District (Rajasthan), India, we collected 20 samples of groundwater from the post-monsoon 2021 and pre-monsoon 2022 periods. Physicochemical parameters such as pH, electrical conductivity (EC), total hardness, Cl^-, SO₄^--, F^-, NO₃^-, total dissolved solids, Ca²⁺, and Mg²⁺ were analyzed. To better understand the spatial and temporal variations, maps were generated in the Geographic Information System (GIS) environment in association with the seasonal correlation matrix. Nemerov's index method was used for determining the pollution level of groundwater sources. The results showed that there was significant spatial and temporal variation in the concentration level of physicochemical parameters. The correlation matrix revealed that the level of positive correlation among the parameters was higher during the pre-monsoon period of 2022 compared to the post-monsoon period of 2021. The result was evaluated using the standard set by the World Health Organization and the Bureau of Indian Standards. According to the result obtained from Nemerov's index technique, most parameters were within safe conditions in both seasons except for EC and NO₃^-. The results indicated that the improved Nemerov index technique can represent the status of groundwater more accurately.