Previous studies showed the presence of multiple emerging organic contaminants (EOCs) in urban surface waters of Singapore even though there are no obvious direct wastewater discharges. In this study, we investigated the occurrence and distribution of 17 pharmaceuticals and personal care products (PPCPs) and endocrine disruptive compounds (EDCs) in a tropical urban catchment of Singapore. Monthly samples were collected from a reservoir and its 5 upstream tributaries during a 16-month period. Analysis of samples showed all sites had measurable PPCP and EDC concentrations, with caffeine (33.9-2980 ng/L), salicylic acid (5-838 ng/L), acetaminophen (<4-485.5 ng/L), BPA (<2-919.5 ng/L) and DEET (13-270 ng/L) being the most abundant. Marked differences in concentrations of target analytes between the reservoir and upstream tributaries were observed, and were tentatively attributed to the spatial differences in source inputs, water dilution capacity as well as natural attenuation of EOCs. Significant correlations between EOCs and conductivity, dissolved oxygen, chlorophyll a, turbidity, nutrients and cumulative precipitation were observed. These factors appeared to affect the distribution and attenuation of EOCs, depending on their physicochemical properties. Rainfall also influenced the temporal distribution of caffeine, BPA, triclosan, fipronil and DEET in the reservoir. Ecological risk assessment showed that caffeine, acetaminophen, estrone, BPA, triclosan and fipronil may warrant further survey. In particular, BPA levels exceeded the literature-based Predicted No-Effect Concentration (PNEC) value, highlighting the need for source control and/or water remediation in this urban catchment.
Keywords: Endocrine disruptors; Liquid chromatography–tandem mass spectrometry; PPCPs; Risk assessment; Surface water.
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