Fecal Contamination of Shallow Tubewells in Bangladesh Inversely Related to Arsenic

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• 作者：Alexander van Geen ; Kazi Matin Ahmed ; Yasuyuki Akita ; Md. Jahangir Alam ; Patricia J. Culligan ; Michael Emch ; Veronica Escamilla ; John Feighery ; Andrew S. Ferguson ; Peter Knappett ; Alice C. Layton ; Brian J. Mailloux ; Larry D. McKay ; Jacob L. Mey ; Marc L. Serre ; P. Kim Streatfield ; Jianyong Wu ; Mohammad Yunus
• 刊名：Environmental Science & Technology
• 出版年：2011
• 出版时间：February 15, 2011
• 年：2011
• 卷：45
• 期：4
• 页码：1199-1205
• 全文大小：932K
• 年卷期：v.45,no.4(February 15, 2011)
• ISSN：1520-5851

文摘

The health risks of As exposure due to the installation of millions of shallow tubewells in the Bengal Basin are known, but fecal contamination of shallow aquifers has not systematically been examined. This could be a source of concern in densely populated areas with poor sanitation because the hydraulic travel time from surface water bodies to shallow wells that are low in As was previously shown to be considerably shorter than for shallow wells that are high in As. In this study, 125 tubewells 6鈭?6 m deep were sampled in duplicate for 18 months to quantify the presence of the fecal indicator Escherichia coli. On any given month, E. coli was detected at levels exceeding 1 most probable number per 100 mL in 19鈭?4% of all shallow tubewells, with a higher proportion typically following periods of heavy rainfall. The frequency of E. coli detection averaged over a year was found to increase with population surrounding a well and decrease with the As content of a well, most likely because of downward transport of E. coli associated with local recharge. The health implications of higher fecal contamination of shallow tubewells, to which millions of households in Bangladesh have switched in order to reduce their exposure to As, need to be evaluated.