title: Microbial Remobilisation on Riverbed Sediment Disturbance in Experimental Flumes and a Human-Impacted River: Implication for Water Resource Management and Public Health in Developing Sub-Saharan African Countries.
abstract: Resuspension of sediment-borne microorganisms (including pathogens) into the water column could increase the health risk for those using river water for different purposes. In the present work, we (1) investigated the effect of sediment disturbance on microbial resuspension from riverbed sediments in laboratory flow-chambers and in the Apies River, Gauteng, South Africa; and (2) estimated flow conditions for sediment-borne microorganism entrainment/resuspension in the river. For mechanical disturbance, the top 2 cm of the sediment in flow-chambers was manually stirred. Simulating sudden discharge into the river, water (3 L) was poured within 30 s into the chambers at a 45° angle to the chamber width. In the field, sediment was disturbed by raking the riverbed and by cows crossing in the river. Water samples before and after sediment disturbance were analysed for Escherichia coli. Sediment disturbance caused an increase in water E. coli counts by up to 7.9-35.8 times original values. Using Shields criterion, river-flow of 0.15-0.69 m³/s could cause bed particle entrainment; while ~1.57-7.23 m³/s would cause resuspension. Thus, sediment disturbance in the Apies River would resuspend E. coli (and pathogens), with possible negative health implications for communities using such water. Therefore, monitoring surface water bodies should include microbial sediment quality.
authors.affiliation: Departments of Biotechnology, Vaal university of Technology, Private Bag X021, Andries Potgieter Blvd, Vanderbijlpark 1911, South Africa. lutherkinga@yahoo.fr.
authors.forename: Akebe Luther King
authors.initials: AL
authors.lastname: Abia
authors.affiliation: School of Civil & Environmental Engineering, University of the Witwatersrand, Johannesburg 2050, South Africa. Chris.James@wits.ac.za.
authors.forename: Chris
authors.initials: C
authors.lastname: James
authors.affiliation: Natural Resources and the Environment, CSIR, P.O. Box 395, Pretoria 0001, South Africa. eubombajaswa@csir.co.za.
authors.forename: Eunice
authors.initials: E
authors.lastname: Ubomba-Jaswa
authors.affiliation: Department of Environmental, Water and Earth Science, Tshwane University of Technology, Arcadia Campus, 175 Nelson Mandela Drive, Pretoria 0001, South Africa. mombamnb@tut.ac.za.
authors.forename: Maggy Ndombo
authors.initials: MN
authors.lastname: Benteke Momba
mesh_terms: D017954:Africa South of the Sahara; D003906:Developing Countries; D004784:Environmental Monitoring; D004926:Escherichia coli / Q000302:isolation & purification*; D019015:Geologic Sediments / Q000382:microbiology*; D006801:Humans; D011634:Public Health; D045483:Rivers / Q000382:microbiology*; D013019:South Africa; D062066:Water Resources
keywords: Escherichia coli; alternative water sources; public health risk; riverbed sediment disturbance; sediment microbial quality; sediment resuspension; water resource management; water resources monitoring