BRIDGE methodology-based quality standards to assess aquifer chemical status in the southwest Bengal Basin, Bangladesh.

Assessment of natural background levels (NBLs) of compositional groundwater parameters helps to identify the potential threats to groundwater resources. This study is the first attempt to apply the pre-selection-based BRIDGE (Background cRiteria for the IDentification of Groundwater thrEshold) methodology to calculate the NBLs and threshold values (TVs) of major groundwater constituents in the southwest Bengal Basin, Bangladesh. A database consisting of 78 groundwater samples was used to assess the NBLs and associated TVs of the major groundwater parameters (EC, Ca, Mg, Na, K, Cl, NO, SO, PO, Mn, and Fe).