File(s) under permanent embargo
Temporal variation of faecal indicator bacteria in tropical urban storm drains
journal contribution
posted on 2015-01-01, 00:00 authored by E Ekklesia, P Shanahan, Lloyd ChuaLloyd Chua, H S EikaasHuman faecal contamination poses a widespread hazard for human health. In urban areas, sewer leakage may be an important cause of faecal pollution to surface water. Faecal indicator bacteria (FIB) are the most widely used indicators to monitor surface water quality. However, assessing whether a water body is meeting water quality criteria is made difficult by the high variability of FIB concentrations over time. In this study, the variation of FIB concentration in surface water from tropical urban catchments is investigated. Eleven urban sub-catchments were sampled hourly over 24-hr and samples analysed for FIB. It was found that FIB show a diurnal pattern that is characterised by daytime FIB concentrations that are significantly higher than nighttime FIB concentrations. This observed diurnal variation of FIB closely follows that of sewer flows and contrasts with observations in rural streams where FIB concentrations are known to be low in the daytime and high during the night. Field tracer tests provide qualitative evidence of sewage exfiltration and transport to drains via preferential flow paths. The diurnal FIB variation and field tracer tests indicate the likelihood of surface water contamination due to leaking sewers. The results further suggest that contamination of surface-water drains is likely a widespread problem in tropical urban areas due to extensive drainage networks and the persistence of FIB under tropical conditions. Because of FIB variation over time, the time at which samples are collected is important in being able to capture the daily maximum and minimum FIB concentrations. The Kruskal-Wallis test shows that hourly sampling from 04:00 to 07:00 and from 12:00 to 15:00 results in significantly different FIB concentration (minimum and maximum, respectively). Furthermore, the Wilcoxon-Mann-Whitney test shows that sampling at 12:00 and 14:00 results in significantly higher FIB concentrations, while sampling at 05:00 and 04:00 or 05:00 and 06:00 results in significantly lower FIB concentrations, than sampling at other hours of the day.
History
Journal
Water researchVolume
68Pagination
171 - 181Publisher
ElsevierLocation
Amsterdam, The NetherlandsPublisher DOI
ISSN
1879-2448eISSN
1879-2448Language
engPublication classification
C Journal article; C1.1 Refereed article in a scholarly journalCopyright notice
2014, ElsevierUsage metrics
Categories
No categories selectedKeywords
faecal indicator bacteriaurban storm draindiurnal variationScience & TechnologyTechnologyLife Sciences & BiomedicinePhysical SciencesEngineering, EnvironmentalEnvironmental SciencesWater ResourcesEngineeringEnvironmental Sciences & EcologyESCHERICHIA-COLI CONCENTRATIONSDRY WEATHERWATER-QUALITYSURF ZONEVARIABILITYCALIFORNIABEACHIDENTIFICATIONCONTAMINATIONPATHOGENS
Licence
Exports
RefWorks
BibTeX
Ref. manager
Endnote
DataCite
NLM
DC