A tiny but powerful pollutant traced to car tires has quietly worked its way through the Hillsborough River, according to new research. Over a 10 month stretch, Florida International University scientists detected the tire derived compound 6PPD-quinone in every single water sample they collected. Levels jumped after heavy rains and clustered around downtown stormwater outfalls, which points to routine road runoff instead of a one time industrial spill and raises fresh questions about how the region monitors and manages stormwater pollution.
FIU team tracks ‘first-flush’ spikes after storms
Researchers at Florida International University built an automated sampling and analysis setup, then used it to test the lower Hillsborough River across ten sampling events between 2023 and 2024. They found 6PPD-quinone in every sample they pulled. “When we have the first big rain event, we get these big pulses of stormwater into our rivers and canals,” FIU researcher Kassidy Troxell said, according to FIU News. The team repeatedly saw the highest concentrations near urban stormwater outfalls in downtown Tampa, a pattern that strongly suggests roadway runoff is the main route into the river.
Peer-reviewed paper reports concentrations and timing
The peer reviewed study, published in Environmental Pollution, reported 6PPD-quinone concentrations roughly between 0.29 and 11.60 nanograms per liter, with a mean of about 1.82 nanograms per liter, and a strong correlation between spikes and rainfall. The authors note that these measurements fall within the lower range of urban surface water values reported elsewhere, but they emphasize the rainfall driven and seasonal dynamics in the lower river. According to the paper, the dataset represents the first record of 6PPD and 6PPD-quinone in Florida surface waters and sets a baseline for future monitoring efforts.
How tire chemistry creates a river pollutant
The compound 6PPD-quinone forms when 6PPD, an antioxidant added to tires, reacts with ozone and other agents on road surfaces. Tiny bits of tire wear then wash into storm drains and nearby waterways. The transformation product has been linked to acute fish mortality in other regions, and federal researchers now list 6PPD-quinone as an emerging contaminant of concern, according to U.S. EPA. Scientists point out that the same chemistry that helps keep tires from breaking down can create a very toxic compound under the right environmental conditions…