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Arsenic in groundwater and sediment in the Mekong River delta, Vietnam

2010; Elsevier BV; Volume: 158; Issue: 8 Linguagem: Inglês

10.1016/j.envpol.2010.05.001

1873-6424

Thi Hanh Hoang, Sunbaek Bang, Kyoung‐Woong Kim, My Hoa Nguyen, Duy Minh Dang,

Heavy Metal Exposure and Toxicity

A study of groundwater and sediment during 2007-2008 in the Mekong River delta in Vietnam (MDVN) revealed that 26%, 74%, and 50% of groundwater samples were above the US EPA drinking water guidelines for As (10 microg/L), Mn (0.05 mg/L), and Fe (0.3 mg/L). The range of As, Fe, and Mn concentrations in the MDVN were <0.1-1351 microg/L, <0.01-38 mg/L, and <0.01-14 mg/L, respectively. Elevated levels of As were found in groundwater at sampling sites close to the Mekong River and in wells less than 60-70 m deep. An inverse relationship was found between As and Mn concentrations in groundwater. Sediment samples from An Giang and Dong Thap had the highest As concentrations (18 mg/kg and 38 mg/kg, respectively). Arsenic sediment occurred mainly in the poorly crystalline Fe oxide phases. Reductive dissolution of the Fe oxide phase is not necessarily the dominant mechanism of As release to groundwater.