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Stormwater flowing into catch basin carries contaminants to our waterways. Photo: Ben McLeod (CC BY-NC-SA 2.0)

PSI scientists are working to identify chemicals in stormwater

This much we know: Stormwater is nasty stuff. The state of Washington has called it one of the leading threats to the Puget Sound ecosystem. It can kill salmon within hours and it contributes to all kinds of health problems for species ranging from orcas to humans. What we don’t know, however, is exactly what’s in it.

Rain and snowmelt wash an untold number of toxic chemicals from our streets and other impervious surfaces directly into our waterways, but there is no such thing as typical stormwater. It simply includes whatever is picked up along the way, be it PCBs or petroleum.

That poses some big questions for scientists who want to understand how stormwater affects area wildlife. Why do some species of salmon die after exposure to stormwater and not others? How much do automobiles contribute to the problem? Do the nastiest chemicals come from leaking oil or car tires or the asphalt from the roads themselves? The questions are seemingly infinite.

Understanding how to identify chemicals in stormwater could go a long way toward solving the problem, scientists say. Now several scientists at the Puget Sound Institute and the University of Washington Center for Urban Waters are developing new techniques for analyzing the chemical composition of stormwater.

They recently published a paper outlining some of these techniques in the journal Environmental Science. The paper was co-authored with collaborators from NOAA and the Washington Stormwater Center. The authors used “time-of-flight” mass spectrometry to identify novel compounds in runoff and fish tissues that were present in amounts as small as the parts per billion. Work is still in the early stages, but so far the authors have found everything from the usual suspects like petroleum products to DEET and caffeine. “Further characterization of highway runoff and fish tissues,” the paper reads, “suggests that many novel or poorly characterized organic contaminants exist in urban stormwater runoff and exposed biota.”


Du, B., Lofton, J. M., Peter, K., Gipe, A. D., James, C. A., McIntyre, J. K., Scholz, N.L., Baker, J.E. & Kolodziej, E. P. (2017). Development of Suspect and Non-Target Screening Methods for Detection of Organic Contaminants in Highway Runoff and Fish Tissue with High-Resolution Time-of-Flight Mass Spectrometry. Environmental Science: Processes & Impacts.