Retention Ponds May Help an Overlooked Source of Pollution – Automobile Tires

A new study has demonstrated that wetlands and retention ponds can actually help reduce the amount of tire particles entering the marine ecosystem by about 75%. 

This was found when analyzing the samples collected from some of the busiest routes in South West England and the Midlands. These routes are used by hundreds of thousands of vehicles every day, and the study found tire particles in each of the 70 samples taken.

It confirms what previous research revealed: that tires pose a big threat to the environment. Government-funded research in 2020 was one of the first to identify tire particles as a major source of microplastics. 

Microplastics are tiny particles of plastic that are less than 5 millimeters in diameter. These particles do not perish easily and remain active for a long time. Due to the persistence of microplastics and their contemporary nature, they have actually been proposed to be used as a global age marker, as we have noted previously.

Studies regarding microplastics have been ongoing for some time now, with research showing that they are found in the human body. In fact, carotid artery plaque patients with microplastics and nanoplastics are found to be at a higher risk of having a composite of myocardial infarction, stroke, or death from any cause in nearly three years of follow-up. 

Because of their small size, microplastics can be ingested by wildlife and then enter the food chain. Microplastics absorb toxic substances from the surrounding environment and then transfer to organisms, where they make their way into us. These tiny particles are even reported to be found in the human placenta.

Naturally occurring events like hurricanes may also contribute to their contamination. Besides all this, we also end up consuming these macroplastics through tap water. They also originate from microbeads in cosmetics and the degradation of larger plastic items like plastic bottles and bags.

Most of this plastic actually ends up in oceans with scientists discovering microplastics in marine environments worldwide. The study from four years ago suggested particles released from vehicle tires could be another source, previously largely unrecorded, of microplastics in the marine environment.

Led by the University of Plymouth, the Defra-funded study revealed that tire particles can be transported directly into the ocean through the atmosphere or by rainwater into sewers from where they pass through the water treatment process. 

The researchers estimated that 50 million m² of estuarine and coastal waters are at risk of being contaminated by tire particles. 

Taking Advantage of The Highway Road Network

Now, the latest study, also conducted by researchers from the University of Plymouth as well as Newcastle University, found that having retention ponds and wetlands can provide protection to rivers and oceans by reducing the discharge of tire wear particles into aquatic waters by nearly 75%.

As the paper notes, the collection of tiny plastic particles in the environment poses an alarming global challenge, especially with tire wear particles (TWPs) arising as potentially dangerous contributors to microplastic pollution. 

Road drainage, in particular, allows tire particles to enter marine environments. While drainage assets that control the removal of surface water are used globally, it is unknown just how useful they are in retaining microplastics of variable densities, i.e., TWP ~ 1–2.5 g cm3. 

As such, the study funded by UK National Highways investigated the ability of drainage assets to disrupt the movement of tire wear particles from the UK’s Strategic Road Network (SRN) to the marine environment.

The primary purpose of constructing wetlands and retention ponds alongside highways is to diminish the flow, prevent flooding, and remove pollutants.

As associate research fellow Florence Parker-Jurd noted, the aim of this study is to establish whether these drainage measures that are already in place along parts of the UK’s SRN have the potential to stop the spread of tire pollution as well. 

“Our results are positive in that regard and provide a much improved understanding on the extent and nature of tire pollution.” 

– Parker-Jurd

So, the team first collected samples from the “influent, effluent, and sediments” of different retention ponds and wetlands. 

Due to the pace of tire wear particle generation varying because of vehicle speed and direction, the study then compared the mass of these particles (TWPs) in drainage from both straight and curved sections of the SRN across eight drainage outfalls to determine the variability’s significance. 

As for quantifying tire wear, the study used pyrolysis gas chromatography-mass spectrometry (Py-GC–MS) and benzothiazole as a molecular marker with an internal standard benzothiazole-D4.

Py-GC–MS is a chemical analysis where a sample is introduced to an anaerobically heated environment and then broken down into smaller stable components through controlled thermal degradation. 

According to Dr. Geoff Abbott from the School of Natural and Environmental Sciences (SNES) at Newcastle University, Py-GC-MS is a “really productive approach that can unravel and quantify the monomeric components of microplastics in the environment.”

Abbott, who has previously developed a breakthrough method using Py-GC-MS to detect tire-derived particles in the environment, said this method was used to “identify specific components” of nanoplastics and microplastics. These elements can be clearly associated with the tread of a vehicle tire. With the help of Py-GC-MS, the scientists were able to get “hard numbers on the total amount of tire wear particles,” he said.

Need for More Systemic Solutions

Upon examination, the study found tire wear within every sample. Moreover, the particles were present at concentrations of 2.86 ± 6 mg/L in drainage from the SRN. While it further found drainage from curved sections of the SRN containing, on average, a 40% greater tire wear particle mass than straight ones, this was ruled “not significant.” 

It was further found that in the collected samples, TWP considerably exceeded other forms of microplastics, such as plastic fragments and fibers, although they were removed in far greater quantities.

The study found that the presence of retention ponds and wetlands led to a 74.9% decrease in the mass of TWP. This reduction in tire wear particle mass was noteworthy for retention ponds, though that wasn’t the case for wetlands. However, the study noted that this could be because of the variability among sites and sampling occasions.

While the number of wetlands and retention ponds in the UK’s road network is rather small, similar drainage assets are used globally. The study says its results are relevant to the management of TWP pollution on a broader scale.

The study further recommended having the maintenance of wetlands and retention ponds as a major priority so that their apparent benefits continue to be realized. According to Richard Thompson OBE FRS, Director of the Marine Institute, who is also the senior author of the study and is also leading the ongoing project called “tire-LOSS: Lost at Sea – where are all the tire particles”:

“Tire particles are thought to be among the greatest sources of microplastic pollution worldwide.” 

The study aims to highlight the effects of tire pollution on the aquatic environment. Its findings suggest that the existing attributes of the road network can help stop the flow of TWP into rivers and seas. However, according to Thompson, these features are smaller in number compared to the total road network.

He further noted that previous studies have shown that substantial quantities of tire wear particles are actually distributed by wind instead of water. He added:

“Ultimately, we need to seek more systemic solutions, perhaps via improved vehicle tire design.” 

Environmental Initiatives Taken by Tire Manufacturers

Now, let’s look at the major tire manufacturers who have been taking responsibility and introducing environmental initiatives to reduce their negative impact on the surroundings and promote sustainability. 

#1. Michelin

The France-based Michelin is a $26.5 bln market cap company whose shares (ML-FR: Euronext Paris) are trading at 34.64, up 6.75% year-to-date (YTD). It has an EPS (TTM) of 2.78 and a P/E (TTM) of 12.47. Michelin pays a dividend yield of 3.90%.

The company operates in the automotive, road transportation, and specialty business sectors. It provides various kinds of tires and related products and services. 

While reporting its 2023 financial results, Michelin noted that “despite adverse market conditions and currencies,” it achieved “high segment operating income.” During the year, it recorded €28.3bn in sales while non-tire sales grew by 10%, €3.6bn in segment operating income, and €3.0bn in free cash flow. Michelin plans to initiate up to €1 billion share buyback program during 2024-2026.

According to the company, its achievement underscores the resilience of its business model and its commitment to advancing sustainability initiatives, which helped it reduce CO2 emissions by 6% and water consumption by 10%.

When it comes to environmental initiatives, Michelin has been working on creating innovative products with less impact, such as the “green” tire. It also uses an “All-Sustainable” approach to define its new objectives for 2030 and beyond.

At Michelin, an environmental footprint analysis of its products and services is carried out through life cycle assessment (LCA), which covers health, climate change, use of fossil-derived resources, and biodiversity. This approach will be rolled out across all of its solutions by 2030. 

By the end of this decade, the company plans to have 100% of its products and services eco-designed, over 80% of the tire environmental impact be linked to its usage phase, and more than 13% of the environmental impact relating to the use of fossil-derived raw materials.

#2. Goodyear

This tire company develops, manufactures, and sells numerous rubber tire lines for various applications, such as automobiles, buses, trucks, motorcycles, aircraft, mining equipment, industrial equipment, and farm implements. It also manufactures and sells rubber-related chemicals and operates a commercial truck service.

With a market cap of $3.45 bln, Goodyear’s shares (GT: NASDAQ) are trading at $12.18, down by almost 15% YTD. It has an EPS (TTM) of -2.42 and a P/E (TTM) of -5.04. 

Goodyear reported a year-over-year decrease of 4.8% in its Q4 net sales to over $5 bln and a net loss of $291 million. Tire unit volume decreased to 3.8% from the previous year to 45.4 million. Operating income meanwhile increased by 62.3% year-over-year to $383 million. For the quarter, the company’s operating cash flow came in at $1.2 billion, while total debt dropped to $7.6 billion.

In its forward plan, the company shares its focus on margin expansion, optimizing its portfolio, sustainable cash flow generation, and capturing incremental segment operating income.

Goodyear has undertaken various initiatives to improve sustainability, which it defines as a “key component of our business strategy and an integral part of our culture.” This includes a 100% sustainable material tire, with the company demonstrating a tire made of 90% sustainable materials. Furthermore, Goodyear continues to reduce its environmental impact and improve fuel efficiency.

Recently, the supply chain solution provider DP World announced that it has successfully planted 702 trees as part of an ongoing decarbonization project called ‘Off the Road’ with Goodyear. The goal of the project is to offset the impact of CO2 emissions by planting two trees for each tire that DP World buys from Goodyear. 

#3. Continental 

The Germany-based Continental is a $14 bln market company whose shares (CON-DE: XETRA) are trading just above 62, down 19.37% YTD. It has an EPS (TTM) of 5.77 and a P/E (TTM) of 10.72. Continental pays a dividend yield of 3.55%.

The company operates in four group sectors: automotive, which covers architecture, mobility, safety, and user experience; Tires, which covers digital monitoring and management systems; ContiTech, which manufactures intelligent and environmentally friendly products; and Contract Manufacturing.

While providing an outlook for the current year, the company reported higher costs and a flat car market. Continental said it expects group sales between 41-44 billion euros and 500 million euros in additional costs due to wages. For its full-year results for 2023, Continental reported achieving goals with net income surging by 1,635% to €1.2 billion. The company’s full-year adjusted operating profit came in at 2.5 billion euros, while sales increased 5.1% to 41.4 billion euros. 

Continental further stated that it is “going on the offensive” regarding humankind’s sustainability as its central theme. The company has set four focus areas, which include achieving 100% carbon neutrality throughout the value chain and 100% emission-free mobility in terms of harmful emissions. Moreover, the aim is to attain 100% closed resource and product cycles and 100% responsible sourcing and business partnerships.

While solutions have yet to be fully developed, Continental has established a framework for itself and its partners to lead a path towards a sustainable economy. Sustainability, the company said, is a “tremendous opportunity” with the entire world and the global economy finding themselves “at the start of a new era.”

Conclusion

Plastic is all around us, but a lot of it ends up in the ocean. It is actually the most prevalent marine debris found in the ocean. While plastic has long been considered a problem, small particles of plastic called microplastics are now being studied, as not much is known about them or their impact. 

Microplastics come from different sources, including microbeads and larger plastic pieces that break apart into smaller ones. While governments in the UK and US have banned the use of microbeads, microplastics are still a huge problem. 

This is especially because little is known about them, and studies like this one from the University of Plymouth are providing us with vital new information to improve our scientific understanding of these tiny particles, which are not restricted to just plastic straws, water bottles, or clothing but also tires. 

This increased insight will help companies, future research, the government, and users better understand the impact of plastic pollution and human activities on the marine environment. It will also help us identify potential solutions, which may include changes in behavior, product design, and waste management, and fight against “one of the greatest environmental challenges” more effectively.