A full-scale bioretention cell in Vancouver reduced 6PPD-quinone mass loadings by about 10-fold, according to a peer-reviewed study published in 2023.
Researchers investigated whether bioretention could reduce 6PPD-quinone, a transformation product of 6PPD, an additive used in vehicle tires. The study combined a field experiment with modelling to examine how the stormwater system affected the chemical's movement through the system.
Vancouver Bioretention Cell Tested for Tire-Derived Chemical
The researchers studied a full-scale, mature bioretention cell in Vancouver.
Bioretention cells are stormwater-management systems designed to collect and treat runoff. The Vancouver system was tested to determine how effectively it could reduce 6PPD-quinone mass loadings.
The researchers conducted a field experiment in which they introduced 6PPD-quinone along with tracer compounds into the system and measured the resulting concentrations and mass reaching the underdrain.
The study was published in Environmental Science & Technology Letters in 2023.
Field Experiment Showed About 95% Reduction to the Underdrain
The field experiment showed an approximately 95% reduction in 6PPD-quinone mass reaching the underdrain.
This figure applies specifically to the field experiment. It should not be interpreted as a universal claim that the bioretention cell removes 95% of the chemical from every storm or every type of stormwater system.
The researchers then used the field data to model how the bioretention system could perform under different storm conditions.
Study Reported an Approximately 10-Fold Reduction
The researchers reported an approximately 10-fold reduction in 6PPD-quinone mass loadings to receiving waters.
That finding is reflected in the title of the study: “Bioretention Cells Provide a 10-Fold Reduction in 6PPD-Quinone Mass Loadings to Receiving Waters: Evidence from a Field Experiment and Modeling.”
The 10-fold reduction is the study's central overall finding, based on evidence from the field experiment and modelling.
Modeling Predicted More Than 90% Reduction Under Typical Storm Conditions
The researchers also modelled the performance of the bioretention system under different storm events.
The modelling indicated that stormwater bioretention systems could mitigate more than approximately 90% of 6PPD-quinone loadings to streams under most typical storm conditions.
The paper describes these typical conditions in terms of storms with a return period of less than two years.
This modeled result is separate from the approximately 95% reduction observed in the field experiment. The 95% figure concerns mass reaching the tested system's underdrain, while the >90% figure describes modeled mitigation of loadings to streams under the specified storm conditions.
What Is 6PPD-Quinone
6PPD-quinone is a transformation product of 6PPD, an additive used in vehicle tires.
6PPD can react with ozone to form 6PPD-quinone. The compound can be transported in stormwater runoff and has been identified as highly toxic to some fish species.
Why the Vancouver Study Matters
The 2023 research provided field and modelling evidence that bioretention can substantially reduce 6PPD-quinone mass loadings associated with stormwater.
The field experiment found an approximately 95% reduction in the chemical's mass reaching the underdrain, while the study's modelling indicated that more than approximately 90% of 6PPD-quinone loadings to streams could be mitigated under most typical storm conditions.
The findings should not be treated as a universal removal rate for every rain garden, bioretention cell or rainfall event. They describe the results of the Vancouver field experiment and the conditions examined through the study's modelling.
