EFFECT OF STORM EVENTS ON OCCURRENCE OF 4-NONYLPHENOL IN STROUBLES CREEK WATERSHED

4-Nonlyphenol (4-NP) is an endocrine disrupting chemical that results from the anaerobic breakdown of the nonionic surfactant, nonylphenol polyethoxylate. Nonylphenol polyethoxylates are frequently used in industrial processes as a surfactant, emulsifier, and stabilizer but are also used in household cleaning products, detergents, paints, and adhesives. In areas of significant anthropogenic influence, 4-NP is ubiquitous in the environment and causes negative biological effects at concentrations as low as 1 ug/L; resulting in hermaphroditism, infertility, and reproductive abnormalities. Previous investigations within the Stroubles Creek Watershed have observed elevated 4-NP concentrations in water samples collected within 24-hours of a rainfall event relative to dry weather (baseflow) samples. The objective of the current research is to gain a more detailed understanding of the transport of 4-NP to and within surface waters following storm events. Because 4-NP is hydrophobic, it is hypothesized to attach to suspended particles and accumulate in high concentrations in underlying stream sediments. The high volume of runoff during heavy storm events may re-suspend the sediment and release 4-NP back into water. To test this hypothesis, during storm events water samples are collected on a 30 or 60 minute interval using an ISCO autosampler. Concentrations of 4-NP in water samples were analyzed using Gas Chromatography/tandem Mass Spectrometry (GC/MS/MS). 4-NP has been detected at five times its normal base-flow concentrations during storm events, with observed concentrations increasing throughout the duration of the storm.