This study summarized the results of surveys for arsenic since 2008 and surveys for dissolved ions and trace elements since 2015, and described characteristics on distribution for chemical composition at the regional areas along the MR and Bassac (Hậu) River (BR). Groundwater samples were collected from existing wells in 8 provinces and 1 city. The authors used Piper and Stiff diagram that reflect the chemical composition of groundwater to respond to varying horizontal and vertical distributions. |