Effects of season and aquifer on groundwater quality in the Mekong delta: A case study in Dong Thap province

Assessment of groundwater quality in Dong Thap province, Mekong Delta Vietnam, was based on monitoring data of 19 wells with 20 water quality parameters in March, June, August and December 2024 and combined with WPI, GWQI and correlation, PCA and CA analysis.The results showed that groundwater quality in the study area is quite good, with less variation between months and seasons of the year, but varies greatly according to the aquifer.The parameters exceeding QCVN and WHO only accounted for 25% (TH, TDS, Cl -, SO 4 2-, Fe) originating mainly from soil and rock weathering; however, microbiological pollution (coliform and E.coli) was relatively high.The results of the WPI and GWQI analyses showed that the water quality in the dry season was relatively better than in the rainy season, and the water in deep aquifers was always better than in shallow aquifers.The water quality was mainly in the very good, good (WPI) and excellent, good (GWQI) groups.The results of the CA analysis showed that the average water quality of 19 monitored wells was divided into five groups.PCA analysis showed that seven PC groups explained 73.09% of the groundwater quality, and the sources of groundwater pollution in the locality were mainly natural, such as weathering, the interaction between water and rock, besides from artificial sources, such as waste from domestic activities, agricultural production and industrial wastewater.