Journal
INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH
Volume 14, Issue 3, Pages -Publisher
MDPI AG
DOI: 10.3390/ijerph14030306
Keywords
Escherichia coli; sediment microbial quality; riverbed sediment disturbance; sediment resuspension; public health risk; water resource management; alternative water sources; watr resources monitoring
Funding
- Water Research Commission (WRC), South Africa (WRC) [K5/2169, K5/2147]
- National Research Foundation (NRF) of South Africa
- Tshwane University of Technology (TUT)
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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 degrees 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 m(3)/s could cause bed particle entrainment; while similar to 1.57-7.23 m(3)/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.
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