Water quality studies in Kranji catchment, Singapore: use of organic tracers and polyethylene devices for identifying potential sewage sources

摘要

The objective of this study was to identify organic compounds that could serve as indicators of potential humannfecal contamination sources to the Kranji Reservoir in Singapore and could be used as confirmation indicatorsnalong with bacteria indicators. The compounds chosen as potential tracers were nonylphenol (NP) and nonylphenolnethoxylates (NPEs), as these are indicative of sewage and have been found at measurable concentrations innrivers and streams elsewhere in Asia. Polyethylene devices (PEDs) were used as passive samplers to measure NPnand NPEs in stormwater drains in Kranji Catchment, deployed in areas of different land use in order to obtain annoverview of concentration ranges across the catchment and provide an indication of where and why these compoundsncould be found. Laboratory results showed that NP and NPEs were present in non-residential areas andnpreliminary modeling of corresponding water concentrations indicates potentially risky concentrations of NP innthe water in some stormwater drains. More information is needed on detergents in Singapore to further evaluatenusing NPEs as sewage indicators. Future studies should be done to confirm concentrations in Kranji Catchmentnwater to verify if there is a risk to the ecosystem’s health as NP and NPEs are known endocrine disruptors.