Course:EOSC270/2023/Roadway Runoff

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What is the problem?

·      What human actions cause the problem?

·      Where does the problem occur?

·      How pervasive is the problem?


Roadway runoff is the flow of water from land roadways to coastal marine ecosystems and estuaries. Runoff typically contains solid and liquid particles that are lifted out of pavement by the flow of water over roads. Runoff particles are frequently composed of harmful substances which can inflict damage upon organisms in marine ecosystems.

Background

Figure 1. Runoff in Urban Environments

Runoff, in its most general form, is a component of the water cycle from the atmosphere to the continents and oceans. During rain events, water falls to the Earth and seeps into permeable surfaces or flows down slopes where it’s eventually collected in rivers, lakes, or oceans. Roadways assist water in flowing down into rivers, and oceans via drainage infrastructure because of its smooth paved surface. Unlike permeable surfaces like soil, water cannot be absorbed into pavement. When water flows over pavement, sediment that was previously adhered to the road is easily washed away with the water. The contaminated water is typically routed through estuaries or drainage infrastructure which eventually makes its way into the ocean. Roadway runoff events are typically triggered by precipitation from weather such as storms and atmospheric rivers[1]. Depending on the setting, runoff water typically contains a broad range of pollutants, chemicals, waste, and bacteria[2]. Runoff particles can cause cellular damage to organisms, which can chronically hinder a range of behaviours in marine organisms[3]. Some runoff particles are dangerous enough that they can kill select species. Runoff particles start to accumulate in the food chain at lower trophic levels. Filter feeders such as bivalves are highly prone to ingesting runoff particles from the water column. These particles are then transferred through other organisms as they bioaccumulate in higher trophic levels[3].

Causes of Roadway Runoff

Roadway runoff events occur when falling precipitation flows over paved surfaces. Precipitation that causes immediate runoff comes mostly from rain and most commonly occurs with thunderstorms, showers, drizzles, or atmospheric river events. In cities where rain is plentiful, roadway runoff can consistently affect marine ecosystems as frequently as it rains. However, even in locations with drier weather, dangerous runoff particles can be “baked” into the roadways and remain there until a precipitation event occurs. When a storm occurs after a lengthy dry-spell, most of the pollutants on the roadway are released all at once in a ‘first flush’ which causes a massive flux of runoff particles into marine ecosystems[4]. These flush events can be particularly hazardous to residents of coastal cities when runoff consists of dangerously high levels of bacteria and pollutants[5].

Atmospheric Rivers

Figure 2. Radar Echo of an Atmospheric River

Atmospheric rivers are particularly concerning for hazardous occurrences of runoff as they account for 20-30% of North America and Europe’s annual rainfall[6]. On the west coast of North America, atmospheric river events frequently occur in winter. Mid-latitude cyclones originating from the West Pacific can advect tons of moist air towards the coast of Canada and the United States as they translate Eastward across the Pacific. Upon reaching the coast, the atmospheric river materializes into prolonged periods of heavy rainfall and flooding[7]. Because the flushing of runoff particles is directly linked to the intensity of rain reaching the surface, intense precipitation events cause large roadway runoff events[4][8]. All of this precipitation is concerning for marine ecosystems because it usually means all of the pollutants on roadways will be completely flushed into local estuaries and oceans in a short period of time.

Effects of Roadway Runoff on Coastal Marine Ecosystems and Organisms

Coastal Marine Ecosystems, such as kelp forests and estuaries, are both highly important due to their high productivity and role as biodiversity hotspots. Roadway runoff often contains pollutants such as oil, heavy metals, and chemicals that are unnatural to these environments. Due to this, their introduction can be detrimental to these ecosystems and subsequently have huge effects on other marine ecosystems.

Seasonal Considerations

Figure 3. Road salts. Credit: Z22

Winter:

In cold weather climates, de-icing salts are frequently used on roads during winter to improve safety. When they are washed into waterways and eventually reach coastal ecosystems, they increase salinity. Increased salinity levels can disrupt the growth, photosynthetic productivity, reproduction, and survival of species, especially those adapted to stable environments. Excessive salinity can effect the diversity of species, favoring those that can handle increased salinity variability, leading to decreased biodiversity [9]. Changes in salinity can also affect the halocline and therefore the mixing of water columns, leading to reduced nutrient nutrient distribution and oxygen levels deeper in the water column [10].

Dry spells:

During periods of low rainfall, pollutants can be absorbed into roads, resulting in a large amount of pollutants being released when rain does come[11]. When this burst of pollutants is released, the presence of various pollutants has a direct correlation to buildup time. This can overload the already highly pressured filtering systems in coastal ecosystems and organisms[12]. This can be especially highlighted in Coho Salmon, which return to their home streams following first flush events, and then experience kill events due to various pollutants (6PPD Quinone).

Effects of Contaminants

Pollutants from roadway runoff can have various impacts on coastal marine ecosystems:

Bioaccumulation and Biomagnification:

Bioaccumulation is the process through which toxins can build up within the tissues of an organism. This occurs as the intake of these toxins is faster than the organism can get rid of them, leading to accumulation. Biomagnification, on the other hand, is an effect of bioaccumulation. Meaning that as you move up trophic levels, you will see more of the toxins present the higher you go, as higher trophic level organisms will consume more toxins than lower ones. This leads to top predators having very high levels of toxins, and therefore also leads humans to consume large amounts of these substances[13].

Oil/Grease:

Figure 4. Pelican covered in oil. Credit: Governor Jindal’s office.

Oil and grease introduced into marine environments have many detrimental effects on organisms. There are a few different “types” of oil that our introduced to our oceans, light oil (think car gas) and heavy oils (think black, sticky oil)[14]. When either of these oils enters a marine environment, a majority floats on the surface while a smaller amount lies on the seafloor, and an even smaller amount creates underwater oil plumes [15]. The organisms that are most affected are those that live on the surface, such as seabirds or sea otters. When they are covered in oil, both organisms can experience irritation to their skin and, more importantly, can lose their ability to retain body heat and buoyancy, both critical for their survival. Chemicals present in oil and grease can enter the tissues of organisms through bioaccumulation and biomagnification. They have the effects of reduced growth rates, reproduction issues, and degradation of tissues. Benthic invertebrates are particularly susceptible, because they are often relatively immobile (compared to finfish) and are filter feeders. Finfish, on the other hand, are much better suited to surviving oil spills as they live in parts of the water column where oils are not as common, however, oil can have detrimental effects on their larvae and eggs[14]. These effects are especially prominent in coastal ecosystems, where natural filtering systems can be overwhelmed easily by the constant input from roadway runoff.

Heavy metals:

Roadway runoff introduces heavy metals such as mercury, lead, arsenic, and others. Once in marine ecosystems, they also enter organisms through bioaccumulation. They have detrimental effects such as leading to neurological damage, reproductive issues, and physical deformities [16]. One example of this is mercury poisoning, which causes the previously mentioned effects in organisms, including humans that consume affected marine life[17].

Sediment:

Sediments such as asphalt, sand, and dirt can be introduced to marine organisms through erosion from road use. Once in a marine ecosystem, they raise water turbidity and decrease photosynthetic activity, disrupting primary production and having huge effects on these ecosystems. In addition to disrupting primary production, sediments also have been shown to smother coral reefs, affecting their ability to feed, grow, and reproduce, all essential functions. Due to the decreased ability of coral to thrive, macroalgae are favored to grow due to the high nutrient availability in those ecosystems [18].

Chemicals:

Figure 5. Algae bloom in Florida. Credit: John Cassani

As discussed with the previous pollutants, chemicals can have huge effects on marine organisms and ecosystems. One metric that can be used to quantify the severity of roadway is an excess amount of chlorophyll-a, which is often an indicator of enhanced algal growth from eutrophication. This, in turn, leads to a reduction in water quality and the abundance and diversity of fish. This can have cascading effects on food webs due to missing functional groups in ecosystems[19]. In addition to this, algal blooms can block sunlight from reaching photosynthetic producers, further pressuring the ecosystem. In addition to this, when this algae eventually dies, it consumes oxygen, leading to hypoxia and making it difficult for other organisms to thrive [20].

What are our current management practices?

Introduction

When considering the type of stormwater infrastructure (e.g., bioswales, retention basins, permeable pavements) to mitigate runoff pollution, it will be important to discuss the purpose, types and efficacy behind these so called green infrastructure. Depending on the types of stormwater infrastructure, these systems can filter out harmful pollutants such as the 6PPD-Quionne along with other solids, bacteria, nutrients (phosphorous, nitrogen), metals (total forms and dissolved forms) to an extent. These systems can also promote evapotranspiration when bioretention media and gravel act as storage for the stormwater, which can later be accessed by the plant roots. As the stormwater flows through these bioretention systems, excess nutrients like nitrogen and phosphorous can be taken up by the plants, and metals along with other solids can be trapped between the vegetation [21]. If these current BMP are not effective at filtering out and capturing these unwanted substances within the stormwater, then governments and other stakeholders should consider investing, assessing and implementing alternative or novel methods that are cost-effective and promising.

Several Bioretention Management Practices (BMP)/ Methods

Rain Gardens:

Rain gardens are landscaped depressions allow for pollutant removal through filtration and plant absorption by directing water flow from impervious surfaces like roofs and driveways to itself. After filtering the water through a mixture of soil, plants and gravel, the rest of the water can go into the stormwater drain.

Depending on the proximity of the garden from gas stations and industrial areas, it may be advisable to add an impervious liner to the bottom of the rain garden to prevent infiltration into the groundwater. As for rain gardens located near cold water (trout) streams, bioretention can allow for the water to reach a tolerable level before water passes from the hot surface, such as parking lots and roads, into the bioretention rain garden, into stormwater drain. The water carried by the stormwater drain can negatively affect trout and other species living in cold water streams which are highly sensitive to changes in water temperatures[22].

Grassed Swales:

Within this storm water management practice, there are three types of design variations which include grassed channel, dry swale and wet swale. For grassed channel, they are designed to deal with smaller drainage areas of 1 acre or less. Dry swale are larger than grassed swales and generally incorporate fabricated soil beds to promote water infiltration into the soil. There can also be a underdrain system, which carries the stormwater that flows through into the storm drain system. As for wet swales, they have a permanent pool and wetland vegetation. There are standing water in the pools as the wet swales intersect with the groundwater. Wet swale should be used in areas not residential as the standing water may become a breeding ground for mosquitoes [23].

Investigating the Mechanism of Denitrification within Bioretention:

While we do know that green infrastructure removes the nitrogen from the stormwater, the mechanism is was not clear previously. Denitrification is the best and most desirable outcome because it removes the nitrogen from the environment completely. After measuring the Stormwater runoff volumes, nitrogen concentrations, and nitrate isotope ratios (δ15N-NO3− and δ18O-NO3−) for 24 storm events within 14 months, Burgis et al. discovered variation during the seasons were there was greater nitrate concentration reduction during the warmer events compared to the colder events [24].

Although bioretention has denitrification potential, it is infrequent and less effective than other methods such as plant update and infiltration. These latter methods are primarily responsible for the nitrogen surface effluent reductions. Only approximately 1.4% of the total reduced nitrate surface effluent load over the monitoring period was attributable to denitrification. Denitrification occurred during periods of time where there was increased hydraulic retention time, which promotes denitrification [24].

Figure 6. Bioretention Efficacy Figure from Charles et al.

According to the figure shown, the bioretention's performance is effective with respect to the average concentration reduction, total load reduction and nitrate/ TDN (total dissolved nitrogen) load percentage. While concentration tells one about the concentration of a particular substance per one liter of water, the load of something captures the entire scope of substance with respect to the concentration, flow rate and time [24].

Efficacy of these BMP types: Comparing and Contrast

Metals, Bacteria, Total Suspended Solids and Nutrients

According to the International Stormwater BMP Database 2016 summary statistics, most BMP types analyzed work well to positively remove the metals, bacteria, total suspended solids and total nitrogen from the stormwater[25]. Should these metals and other substances get into the stormwater, one can see deleterious, ecological consequence to both marine life and humans living in close proximity to the storm water discharge. However, the water research scientist from the institute state that the removal of total phosphorus is negative, meaning that significant amounts of total phosphorus are still passing through the bioretention. Through another report published by the foundation in 2020, scientists have reached the same conclusion about the positive effects of BMP types to remove the metals and the other substances contrasting the poor performance of bioretention, grass swales and grass strips do poorly to reduce phosphorous[26]. These scientists have also mentioned these phosphorous export found from these specific types of BMP are likely due to the presence of phosphorus -rich soils and planting media for the studies within the BMP database. These suggest that media mixes and fertilization are important considerations for BMP designs.

Comparing Bioretention and Bioswale for Salts Used in Deicing

While green infrastructure (GI) appears to be a promising urban stormwater management practice, GI is not designed to remove salt. Scientists monitored two roadside infiltration-based GI practices in Northern Virginia over 28 precipitation events. Both the bioretention and bioswale significantly reduced effluent surface loads of CI- and Na+ (76% to 82%), but they can only temporarily retain and infiltrate salts, delaying their release to surface waters. GI was able to store a small percentage of Na+, but scientists could not observe long-term CI-storage. Ultimately, infiltration GI can buffer surface waters from salt, but the majority of the salt removed from the stormwater eventually infiltrates into the groundwater [27].

To some degree, bioretention and bioswale initially reduced NaCl concentration fluxes through temporary storage and infiltration of Cl- and Na+ into plants, soil and groundwater, while its reduction effects are short-lived. Both of these practices have the ability to mitigate high Cl- and Na+ stormwater runoff loads in the winter. More specifically, bioretention displayed moderate Cl- and Na+ average concentration reduction while bioswale had little concentration reduction for both substances [27].

Real Life Cases

6PPD-Quinone on Coho Salmon in the Pacific Northwest

Figure 7. Proposed reaction of 6PPD into 6PPD-Quinone[28].

N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine, more commonly known as 6PPD, is a tire additive used to prevent degradation from heat and ozone reactions. Through use and wear, it accumulates on roads and reacts with ozone, forming 6PPD-Quinone, a highly toxic form of this compound (see Figure 7)[28]. Eventually, rainwater washes this toxic compound into streams and other waterbodies, where it affects aquatic organisms. A study by Tian et al. finds that acute 6PPD-Q levels in stormwater is linked with increased coho salmon mortality[29], noting respiratory issues and erratic behaviour leading up to their deaths. This poses massive issues in the Pacific Northwest (PNW), where these die-offs occur[28], as the salmon are a key food source for many Indigenous Tribes in the region, as well as for other various wildlife and human communities [29]. For the salmon that can survive these influxes of 6PPD-Q, especially at the start of fall when rain flushes heavily accumulated 6PPD-Q from roads after the long, dry spells of the PNW summers, they may pass on the compound into predators, including humans, that consume them. A scholar commentating on Tian et al.'s article warns that research suggests that 6PPD-Q may have toxic effects on humans as well based on some studies performed on mice and cellular subjects[30].

Figure 8. "Dose-response curves. (A) Dose-response curve for 24-hour juvenile coho exposures to roadway runoff and TWP leachate (n = 365 fish). Error bars represent three replicates of eight fish (except TWP leachate 2, n = 5 fish; Seattle site 1, duplicate of n = 10 fish). 6PPD-quinone concentrations were from retrospective quantification. (B) Dose-response curves for 24-hour juvenile coho exposures to ozone-synthesized 6PPD-quinone (10 concentrations, two replicates, n = 160 fish). Curves were fitted to a four-parameter logistic model. CI, confidence interval." Caption and graphs adapted directly from Tian et al.'s article[28].

The compound is lethal to coho salmon at low concentrations (e.g., <1 μg/L, see Figure 8)[28] even in only a few hours of exposure, and so stringent management is urgently needed to control the damages of its runoff. Washington State has already implemented bans and restrictions on it in 2023, and environmentalists are pushing for greater pre-market testing of these chemicals to prevent other cases like this from happening again[31]. It has been found that 6PPD-Q has adverse effects on other fish species as well[29], raising concerns about the ecological health of coastal and estuary communities like Puget Sound in the PNW, and further compels policy makers to make changes to protect these vital ecosystems. Other measures to mitigate road runoff in these systems such as filtration systems, 6PPD alternatives, and more thorough testing on industrial chemicals are also being explored [28][29].

Copper Brake Pad Runoff in San Francisco Bay

Most vehicular brake pads are made of 1-14% copper[32], and much like 6PPD, wears off of brakes over time, accumulating on roads until being washed by rain water in surrounding systems. San Francisco's high copper levels are significantly attributed to runoff from these brake pads, estimated to be the source of up to half of the copper found there[32]. The brakes also contribute to high levels of other heavy metals that are present in the bay, and the excessive levels of these metals, especially copper, introduce toxicity into these aquatic systems[32]. Raised copper level exposure impairs the olfactory systems of many fish like salmon, leaving them unable to properly navigate their surroundings or sense predators effectively, greatly reducing their ability to survive and reproduce, while acute copper poisoning will simply cause them to die[32]. Another concern is the accumulation of these metals in higher trophic organisms, as mentioned in the above about bioaccumulation and biomagnification, creating risks for those organisms in relation to getting poisoned themselves. More sedimentary life is also endangered by the metal runoff, like mussels and oysters which absorb it, and as they are eaten, higher trophic levels keep accumulating more copper leading to adverse effects moving up yet again[32].

Figure 8. US chemical regulation changes throughout time[32].


Coastal fauna, algae, and other organisms can be disrupted by the excess metals, inhibiting their abilities to photosynthesize, spawn, and survive while invasive species like Salvinia molesta can capitalize on it, causing disruption in these ecosystems[32]. In Straffelini et al.'s paper, they touch on research about adverse effects on humans as this runoff finds its way into drinking water and also become airborne in particles PM10/PM2.5, potentially causing respiratory and cardiovascular issues when inhaled over time[32]. The European Union and United States of America have legislation to reduce runoff contamination in the environment, with California and Washington having policies to reduce copper use in breaks, hopefully to <0.5% in 2025 (see Figure 8)[32], though alternative materials having performance issues may hinder or slow this transition[32].


References

  1. ↑ Opher, Friedler, Tamar, Eran (September 2009). "Factors affecting highway runoff quality". Urban Water Journal. 3: 155–172 – via Taylor & Francis.
  2. ↑ "Runoff Water Quality". Southern California Coastal Water Research Project. 4/10/2025. Check date values in: |date= (help)
  3. ↑ Jump up to: 3.0 3.1 Baker, Tyler, Galloway, Tony J., Charles R., Tamara S. (March 2014). "Impacts of metal and metal oxide nanoparticles on marine organisms". Environmental Pollution. 186: 257–271 – via Elsevier Science Direct.CS1 maint: multiple names: authors list (link)
  4. ↑ Jump up to: 4.0 4.1 Han, Lau, Kayhanian, Stenstrom, Younghan, Sim-Lin, Masoud, Michael K. (November 2006). "Characteristics of Highway Stormwater Runoff". Water Environment Research. 78: 2377–2388 – via Wiley Online Library.CS1 maint: multiple names: authors list (link)
  5. ↑ Dwight, Semenza, Baker, Olson, Ryan H., Jan C., Dean B., Betty H. (January 2002). "Association of Urban Runoff with Coastal Water Quality in Orange County, California". Water Environment Research. 74: 82–90 – via Wiley Online Library.CS1 maint: multiple names: authors list (link)
  6. ↑ Lavers, Villarini, David A., Gabriele (March 2015). "The contribution of atmospheric rivers to precipitation in Europe and the United States". Journal of Hydrology. 522: 382–390 – via Elsevier Science Direct.
  7. ↑ Stull, Roland (2017). Practical Meteorology. Vancouver, BC, Canada: University of British Columbia. p. 472. ISBN 978-0-88865-283-6.
  8. ↑ Deletic, Maksimovic, Ana B., C. T. (September 1998). "Evaluation of Water Quality Factors in Storm Runoff from Paved Areas". Journal of Environmental Engineering. 124 – via ASCE Library.
  9. ↑ Röthig, T., Trevathan-Tackett, S. M., Voolstra, C. R., Ross, C., Chaffron, S., Durack, P. J., … Sweet, M. (2023). Human-induced salinity changes impact marine organisms and ecosystems. Global Change Biology, 29(17), 4731–4749. doi:10.1111/gcb.16859
  10. ↑ Lougee, L. A., Bollens, S. M., & Avent, S. R. (2002). The effects of haloclines on the vertical distribution and migration of zooplankton. Journal of Experimental Marine Biology and Ecology, 278(2), 111–134. doi:10.1016/S0022-0981(02)00326-X
  11. ↑ Gillis, P. L., Parrott, J. L., & Helm, P. (2022). Environmental Fate and Effects of Road Run-Off. Archives of environmental contamination and toxicology, 82(2), 159–161. https://doi.org/10.1007/s00244-021-00906-3
  12. ↑ Environmental Investigations and Laboratory Services Program, Kendra, W., & Willms, R., 90-e54 Recurrent Coho Salmon Mortality at Maritime Heritage Fish Hatchery, Bellingham: A Synthesis of Data Collected from 1987-1989. (1990).
  13. ↑ Oil in the Sea III: Inputs, fates, and effects. (2003). . National Academies Press.
  14. ↑ Jump up to: 14.0 14.1 NOAA. (n.d.). How oil harms animals and plants in marine environments. Office of Response and Restoration. https://response.restoration.noaa.gov/oil-and-chemical-spills/oil-spills/how-oil-harms-animals-and-plants-marine-environments.html
  15. ↑ NOAA. (n.d.). Oil Spill Science: Where did the oil go? Washington D.C.
  16. ↑ Baker, T. J., Tyler, C. R., & Galloway, T. S. (2014). Impacts of metal and metal oxide nanoparticles on marine organisms. Environmental Pollution, 186, 257–271. doi:10.1016/j.envpol.2013.11.014
  17. ↑ Zheng, N., Wang, S., Dong, W., Hua, X., Li, Y., Song, X., Chu, Q., Hou, S., & Li, Y. (2019). The Toxicological Effects of Mercury Exposure in Marine Fish. Bulletin of environmental contamination and toxicology, 102(5), 714–720. https://doi.org/10.1007/s00128-019-02593-2
  18. ↑ Australian Institute of Marine Science. (n.d.). Backgrounder: Impact of land runoff. AIMS. https://www.aims.gov.au/impact-of-runoff
  19. ↑ Goodridge Gaines, L. A., Henderson, C. J., Olds, A. D., Ortodossi, N. L., Brook, T. W., Hourigan, B. J., & Gilby, B. L. (2024). Assessing the combined effects of catchment land use and runoff on estuarine fish assemblages. Estuarine, Coastal and Shelf Science, 305, 108873. doi:10.1016/j.ecss.2024.108873
  20. ↑ Environmental Protection Agency. (2025, February 5). The Effects: Dead Zones and Harmful Algal Blooms. EPA. https://www.epa.gov/nutrientpollution/effects-dead-zones-and-harmful-algal-blooms
  21. ↑ Environmental Protection Agency. (2025, February 17). Types of Green Infrastructure. EPA. https://www.epa.gov/green-infrastructure/types-green-infrastructure
  22. ↑ United States Environmental Protection Agency. (2021, December). Stormwater Best Management Practice: Bioretention Rain Gardens.
  23. ↑ United States Environmental Protection Agency. (2021, December). Stormwater Best Management Practice: Grassed Swales.
  24. ↑ Jump up to: 24.0 24.1 24.2 Burgis, C.; Hayes, G.; Zhang, W.; Henderson, D.; Macko, S.; Smith, J. (December 2020). "Tracking denitrification in green stormwater infrastructure with dual nitrate stable isotopes". Science of The Total Environment. 747 – via Elsevier Science Direct.
  25. ↑ Clary, J., Jones, J., Leisenring, M., Hobson, P., & Strecker, E. (2016, January 6). International Stormwater BMP Database: 2016 Summary Statistics. Denver; The Water Research Foundation.
  26. ↑ Clary, J., Jones , J., Leisenring, M., Hobson, P., & Strecker, E. (2020, November 6). International Stormwater BMP Database: 2020 Summary Statistics. Denver; The Water Research Foundation.
  27. ↑ Jump up to: 27.0 27.1 Burgis, C.; Hayes, G.; Henderson, D.; Zhang, W.; Smith, J. (August 2020). "Green stormwater infrastructure redirects deicing salt from surface water to groundwater". Science of The Total Environment. 729 – via Elsevier Science Direct.
  28. ↑ Jump up to: 28.0 28.1 28.2 28.3 28.4 28.5 Tian, Z., Zhao, H., Peter, K. T., Gonzalez, M., Wetzel, J., Wu, C., Hu, X., Prat, J., Mudrock, E., Hettinger, R., Cortina, A. E., Biswas, R. G., Kock, F. V., Soong, R., Jenne, A., Du, B., Hou, F., He, H., Lundeen, R., … Kolodziej, E. P. (2021). A ubiquitous tire rubber–derived chemical induces acute mortality in Coho Salmon. Science, 371(6525), 185–189. https://doi.org/10.1126/science.abd6951
  29. ↑ Jump up to: 29.0 29.1 29.2 29.3 Environmental Protection Agency. (2024, November 26). 6PPD-quinone. EPA. https://www.epa.gov/chemical-research/6ppd-quinone
  30. ↑ Lu, R. (2024, December 14). Science of science | science. A ubiquitous tire rubber–derived chemical induces acute mortality in coho salmon. https://www.science.org/doi/10.1126/science.aao0185
  31. ↑ Washington State Department of Ecology. (2024, October). 6PPD action plan and alternatives assessment. https://apps.ecology.wa.gov/publications/documents/2404053.pdf
  32. ↑ Jump up to: 32.0 32.1 32.2 32.3 32.4 32.5 32.6 32.7 32.8 32.9 Straffelini, G., Ciudin, R., Ciotti, A., & Gialanella, S. (2015). Present knowledge and perspectives on the role of copper in brake materials and related environmental issues: A critical assessment. Environmental Pollution, 207, 211–219. https://doi.org/10.1016/j.envpol.2015.09.024
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