STREAM Project Studies Salmon-Killing Tire Toxin

Left: STREAM scientists sample urban waterways day or night after a rainfall.
Top right: A spawned out salmon. Bottom right: Hatchlings are likely to die if there are tire toxins in the water.
have an unintended humorous element. Yanru Wang, a PhD
student with STREAM, can often be seen vacuuming the streets
of downtown Vancouver with a Dyson vacuum as she collects
tire wear particles from road surfaces. This kind of work is multidisciplinary. The team has chemists, engineers, ecotoxicologists,
modellers, conservationists, and hydrologists all pitching in. It
also relies on the expertise of specialist groups such as Salmon
Safe BC and Indigenous partners such as the Salish Sea Indigenous Guardians Alliance.
Rodgers will use the 6PPDQ and other data they collect to
create a model intended to show where the most significant
inputs of 6PPDQ are. This will help environmental managers
identify salmon-bearing streams and rivers that are most vulnerable to the toxin. They are also looking at areas where pre-existing
green infrastructure such as rain gardens and ponds may be
reducing 6PPDQ in receiving waters.
The team is also designing ways of removing 6PPDQ from
road runoff before it gets into salmon-bearing waters. “Our current project focuses on green infrastructure systems based on an
earlier study by my team, which showed that some features designed to prevent flooding, such as rain gardens, can be quite ef-
WAT E R C A N A D A . N E T
fective in removing 6PPDQ from road runoff,” explains Scholes.
This earlier modelling work also shows that other elements of the
bioretention cell design can affect 6PPDQ removal rates. Soil
permeability is especially important, and depends on the type
of soil used. The team will build on that work by experimenting
with additions to this green infrastructure. “We have good reason
to believe that some materials can help us capture more 6PPDQ.
Adding these materials to the soil of green infrastructure systems
may help them remove 6PPDQ from the water before it reaches
a stream,” adds Scholes. “These additions might also be able to
remove other pollutants much more efficiently. We are conducting both lab experiments and field testing to make sure our
approach works in the real world.” Once again, this section of the
project relies on a lot of collaboration with partner organizations
including the cities of Vancouver, Surrey, and Burnaby.
Much of the salmon 6PPDQ story has been another depressing tale of the negative impact humans have on the natural environment. However, this project represents a hopeful step towards
addressing that impact through increasing human understanding
of the problem, and the beginnings of the first practical steps
towards reducing our footprint on salmon habitat.
WATER C AN ADA • M ARCH/APRIL 2024
31

Paperturn flipbook