title: Seasonal variability of faecal indicator bacteria numbers and die-off rates in the Red River basin, North Viet Nam.
abstract: The Red River is the second largest river in Viet Nam and constitutes the main water source for a large percentage of the population of North Viet Nam. Here we present the results of an annual survey of Escherichia coli (EC) and Total Coliforms (TC) in the Red River basin, North Viet Nam. The objective of this work was to obtain information on faecal indicator bacteria (FIB) numbers over an annual cycle and, secondly, to determine the die-off rates of these bacterial indicators. Monthly observations at 10 stations from July 2013-June 2014 showed that TC and EC reached as high as 39100 cfu (colony forming units) 100 ml(-1) and 15300 colonies 100 ml(-1), respectively. We observed a significant seasonal difference for TC (p < 0.05) with numbers being higher during the wet season. In contrast, no significant seasonal difference was found for EC. The FIB die-off rates ranged from 0.01 d(-1) to a maximum of 1.13 d(-1) for EC and from 0.17 d(-1) to 1.33 d(-1) for TC. Die-off rates were significantly higher for free bacteria than for total (free + particle attached) bacteria, suggesting that particle attachment provided a certain level of protection to FIB in this system.
authors: Institute of Natural Product Chemistry, Viet Nam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay, Hanoi, Viet Nam.|Institut de Recherche pour le Développement (IRD), iEES -Paris, UMR 242, Centre IRD Nord, 32 avenue Henri Varagant, Bondy, F-93143, France.
authors: Huong Thi Mai
authors: HT
authors: Nguyen
authors: Institute of Natural Product Chemistry, Viet Nam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay, Hanoi, Viet Nam.
authors: Quynh Thi Phuong
authors: QT
authors: Le
authors: UMR METIS, Université de Pierre et Marie Curie, 4 Place Jussieu, 75005, Paris, France.
authors: J
authors: J
authors: Garnier
authors: Institut de Recherche pour le Développement (IRD), iEES-Paris UMR 242, c/o Soils and Fertilizers Research Institute (SFRI), Hanoi, Viet Nam.
authors: J-L
authors: JL
authors: Janeau
authors: Institut de Recherche pour le Développement (IRD), iEES -Paris, UMR 242, Centre IRD Nord, 32 avenue Henri Varagant, Bondy, F-93143, France.
authors: E
authors: E
authors: Rochelle-Newall
mesh_terms: D004755:Enterobacteriaceae / Q000254:growth & development* / Q000302:isolation & purification; D004784:Environmental Monitoring; D004926:Escherichia coli / Q000254:growth & development* / Q000302:isolation & purification; D005243:Feces / Q000382:microbiology*; D006801:Humans; D045483:Rivers / Q000382:microbiology*; D012621:Seasons; D014744:Vietnam; D014871:Water Microbiology; D014876:Water Pollution