title: Contamination of drinking water resources in the Mekong delta floodplains: arsenic and other trace metals pose serious health risks to population.
abstract: This study presents a transnational groundwater survey of the 62,000 km(2) Mekong delta floodplain (Southern Vietnam and bordering Cambodia) and assesses human health risks associated with elevated concentrations of dissolved toxic elements. The lower Mekong delta generally features saline groundwater. However, where groundwater salinity is <1 g L(-)(1) Total Dissolved Solids (TDS), the rural population started exploiting shallow groundwater as drinking water in replacement of microbially contaminated surface water. In groundwater used as drinking water, arsenic concentrations ranged from 0.1-1340 microg L(-)(1), with 37% of the studied wells exceeding the WHO guidelines of 10 microg L(-)(1) arsenic. In addition, 50% exceeded the manganese WHO guideline of 0.4 mg L(-)(1), with concentrations being particularly high in Vietnam (range 1.0-34 mg L(-)(1)). Other elements of (minor) concern are Ba, Cd, Ni, Se, Pb and U. Our measurements imply that groundwater contamination is of geogenic origin and caused by natural anoxic conditions in the aquifers. Chronic arsenic poisoning is the most serious health risk for the ~2 million people drinking this groundwater without treatment, followed by malfunction in children's development through excessive manganese uptake. Government agencies, water specialists and scientists must get aware of the serious situation. Mitigation measures are urgently needed to protect the unaware people from such health problems.
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, CH-8600 Dübendorf, Switzerland. johanna.buschmann@eawag.ch
authors.forename: Johanna
authors.initials: J
authors.lastname: Buschmann
authors.forename: Michael
authors.initials: M
authors.lastname: Berg
authors.forename: Caroline
authors.initials: C
authors.lastname: Stengel
authors.forename: Lenny
authors.initials: L
authors.lastname: Winkel
authors.forename: Mickey L
authors.initials: ML
authors.lastname: Sampson
authors.forename: Pham Thi Kim
authors.initials: PT
authors.lastname: Trang
authors.forename: Pham Hung
authors.initials: PH
authors.lastname: Viet
mesh_terms: D001151:Arsenic / Q000032:analysis*; D020261:Arsenic Poisoning / Q000453:epidemiology; D002160:Cambodia; D004784:Environmental Monitoring / Q000379:methods; D062665:Epidemiological Monitoring; D005843:Geography; D006801:Humans; D008345:Manganese / Q000032:analysis; D025341:Principal Component Analysis; D054712:Salinity; D014744:Vietnam; D014867:Water / Q000032:analysis*; D014873:Water Pollutants / Q000032:analysis*; D014876:Water Pollution / Q000009:adverse effects*; D014881:Water Supply / Q000032:analysis* / Q000592:standards
chemical_list: D014873:Water Pollutants; D014867:Water; D008345:Manganese; D001151:Arsenic