Background chloride concentrations in the Bangkok (BK), Phra Pradaeng (PD), and Nakhon Luang (NL) aquifers of Bangkok and surrounding vicinity, Thailand

This study is intended to determine the natural background levels (NBLs) of chloride in the Bangkok (BK), Phra Pradaeng (PD), and Nakhon Luang (NL) aquifers, which are essential groundwater sources for the Bangkok Metropolitan Region. Rising chloride levels, caused by industrial operations and seawater intrusion, are putting the quality of groundwater in these places at greater risk. This shows how important it is to keep a close watch on and manage the situation. This study examines chloride distributions and trends from 2010 to 2020 using statistical methods, Piper diagrams, and checks on ion charge balance. The results show substantial spatial heterogeneity, with much greater chloride levels near the shore and a lot of sodium-chloride (NaCl) water types, which show that coastal factors are quite important. The generated NBLs and temporal assessments furnish evidence to inform targeted surveillance and policy initiatives aimed at preserving long-term groundwater sustainability in Bangkok and its surrounding areas.