Groundwater quality of arsenic contaminated aquifers in the Munshiganj district, Bangladesh using water quality index

Abstract

About 47% shallow tubewells (STWs) in Munshiganj district, Bangladesh, contain arsenic (As) concentrations above 50 ppb. The groundwaters with elevated arsenic (As) concentrations are using for domestic (principally for drinking) and irrigation (principally for rice cultivation) purposes. STWs water qualities have been assessed for both domestic and irrigation purposes. A total of 45 (43 from Munshiganj and 2 from Dhaka city) groundwater samples were collected and analyzed for chemical constituents on 2015 (January and March), 2016(February) and 2017(September). The ions abundances for cations and anions were Na+ > Ca2+ > Mg2+ > Fe2+ > K+ > Mn2+ and HCO3− > Cl− > SO42− > NO3−, respectively. Based on piper diagram, 68.89% samples were Ca-Mg-HCO3 type (68.89%). About 40.00% samples were “unsuitable” for drinking purpose according to WQI. The sodium hazards were assessed by Wilcox and The US salinity laboratory staff (USSL) diagrams showed that most of the samples were suitable for irrigation except for 13.33% (6 samples) with EC values exceeded 2000 μS/cm. STWs are not suitable for drinking purposes, although suitable for irrigation purposes based on the quality of the water.

Keywords

• Rock-water interactions
• Gibb's ratio
• Weighted arithmetic index