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Physical and chemical characterization of tire-related particles: Comparison of particles generated using different methodologies

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Abstract

The purpose of this study was to characterize the physical and chemical properties of particles generated from the interaction of tires and road surfaces. Morphology, size distribution, and chemical composition were compared between particles generated using different methods, including on-road collection, laboratory generation under simulated driving conditions, and cryogenic breaking of tread rubber. Both on-road collected and laboratory generated particles exhibited the elongated shape typical of tire wear particles, whereas tread particles were more angular. Despite similar morphology for the on-road collected and the laboratory generated particles, the former were smaller on average. It is not clear at this stage if the difference is significant to the physical and chemical behavior of the particles. The chemical composition of the particles differed, with on-road generated particles containing chemical contributions from sources other than tires, such as pavement or particulates generated from other traffic-related sources. Understanding the differences between these particles is essential in apportioning contaminant contributions to the environment between tires, roadways, and other sources, and evaluating the representativeness of toxicity studies using different types of particulate generated.

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... 4 TRWP are heterogeneous particles composed of rubber polymer, minerals, bitumen, and various chemicals originating from the road environment or from the rubber itself. 5,6 They are susceptible to environmental weathering, leading to changes in physical properties and chemical composition of the particles. 4,7 For instance, metals, such as Pb, Mn, Co, Cr, Ba, and Ni, were measured as traces in the tire rubber and also in higher concentration in TRWP, revealing the contribution of the road constituents to the overall metal burden of TRWP. ...
... 4,7 For instance, metals, such as Pb, Mn, Co, Cr, Ba, and Ni, were measured as traces in the tire rubber and also in higher concentration in TRWP, revealing the contribution of the road constituents to the overall metal burden of TRWP. 5,6,8 Several organic chemicals are added to tire rubber to facilitate polymerization during manufacturing or to increase the performance and longevity of the tires during use. Among many other compounds, 2-mercaptobenzothiazole (MBT) and 1,3-diphenylguanidine (DPG) are intensively used as vulcanization agents; they can represent up to 0.5% of the tire rubber. ...
... It has been demonstrated that the chemical content of TRWP is not identical to that of pure tire tread due to encrustation of minerals and organic constituents originating from the road pavement. 5,8 The different surface areas of CMTT and TRWP could impact the solubilization kinetics of the associated compounds as well as their overall bioaccessibility. Furthermore, TRWP will undergo various types of weathering (thermooxidation, photodegradation, mechanical shear stress, biodegradation) once released in the environment that may affect its chemical and physical properties. ...
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Article
Tire and road wear particles (TRWP) account for an important part of the polymer particles released into the environment. There are scientific knowledge gaps as to the potential bioaccessibility of chemicals associated with TRWP to aquatic organisms. This study investigated the solubilization and bioaccessibility of seven of the most widely used tire-associated organic chemicals and four of their degradation products from cryogenically milled tire tread (CMTT) into fish digestive fluids using an in vitro digestion model based on Oncorhynchus mykiss. Our results showed that 0.06-44.1% of the selected compounds were rapidly solubilized into simulated gastric and intestinal fluids within a typical gut transit time for fish (3 h in gastric and 24 h in intestinal fluids). The environmentally realistic scenario of coingestion of CMTT and fish prey was explored using ground Gammarus pulex. Coingestion caused compound-specific changes in solubilization, either increasing or decreasing the compounds' bioaccessibility in simulated gut fluids compared to CMTT alone. Our results emphasize that tire-associated compounds become accessible in a digestive milieu and should be studied further with respect to their bioaccumulation and toxicological effects upon passage of intestinal epithelial cells.
... Tire wear particles (TWP) are a major source of microplastics in the environment [15,16] with potentially adverse effects on human health and aquatic and terrestrial ecosystems [17]. However, TWP are seldom found as pure tire particles in the environment because of mineral encrustations from the road surface during abrasion of tire treads; the resulting particles are therefore termed tire and road wear particles (TRWP) [18][19][20]. The primary entrance to the environment is runoff [15,21], which contains substantial amounts of TRWP [22]. ...
... The removal efficiency can be affected by TRWP size, as demonstrated by [9], who studied TRWP ≥ 125 µm and showed decreasing removal efficiency with decreasing size. This can be problematic for efficient TRWP retention by bioretention cells because significant amounts of smaller TWP (≤50 µm) have been found in road dust [18,24]. The effective removal of microplastics has also been reported in bioretention cells. ...
... These inlets are 70 m apart; they operate only during the warmer seasons and are closed during the cold winter season owing to icing (December-March) [27]. road dust [18,24]. The effective removal of microplastics has also been reported in bioretention cells. ...
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Article
Bioretention cells are popular stormwater management systems for controlling peak runoff and improving runoff water quality. A case study on a functional large-scale bioretention cell and a laboratory column experiment was conducted to evaluate the concentrations and retention efficiency of bioretention cells towards tire wear particles (TWP). The presence of TWP was observed in all soil fractions (<50 µm, 50–100 µm, 100–500 µm, and >500 µm) of the functional bioretention cell. TWP concentrations were higher (30.9 ± 4.1 mg/g) close to the inlet to the bioretention cell than 5 m away (19.8 ± 2.4 mg/g), demonstrating the influence of the bioretention cell design. The column experiment showed a high retention efficiency of TWP (99.6 ± 0.5%) in engineered soil consisting of sand, silty-sand, and garden waste compost. This study confirmed that bioretention cells built with engineered soil effectively retained TWP > 25 µm in size, demonstrating their potential as control measures along roads.
... Quite some studies refer to TWP, that is Tyre Wear Particles, though under real world conditions TWP is always associated with road wear. Figure 1 TRWP photo under the microscope (Kreider et al. 2010). Scanning electron microscope images of particles collected on the road (A, B) and particles collected in a laboratory road simulator (C, D). ...
... proactive, fuel efficient driving reduces tyre abrasion Kreider et al (2010) carried out an extensive study to characterize the physical and chemical properties of particles generated from the interaction of tires and road surfaces. They studied the morphology, size distribution, and chemical composition of generated particles and compared them using different methods, including on-road collection, laboratory generation under simulated driving conditions, and cryogenic breaking of tread rubber. ...
... Beji et al (2021) These data partly confirm other results obtained using road simulators that highlight a size distribution of TRWP frequently dominated by nanoparticles (20-90 nm) (Panko et al., 2009;JRC, 2014;Grigoratos et al., 2018). There are however also other findings that suggest that nanoparticles are not formed (Kreider et al, 2010) or only formed minimally when driving low speed with summer tyres (Gustafson 2010), for which the Kreider et al (2010) sampling methodology seems not to be suited for nanoparticles at all. The measurements of Beji et al (2021) further show that the nanoparticles dominated in number for 45-50% of the driving time. ...
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Technical Report
The rubber tyre case study (RTC) is one of the case studies within the European NMBP13 projects, that are active in 2019-2023 with the development and establishment of a solid, well-balanced nano risk governance approach for Europe. The RTC investigates what can be learned from applying this nano risk governance approach to the problem of tyre wear generated by car driving activities. Within the frame of the NMBP13 project there is a special focus on the nanomaterials. As part of the RTC, this paper collects available risk-related scientific information about environmental release of tyre wear particles (TWP), which generally associates with road wear to form TRWP (Tyre and Road Wear Particles). The particles’ size distribution concerns coarse, micro-sized and nano-sized particles and its associates. Key questions concerned in this study are: ‘What are the risks of nanoparticles released during the use of rubber tyres?’ And if there are risks, how could these be controlled?
... These tire wear particles had particle sizes smaller than 5 μm 7 . In contrast, tire abrasions from the environment have particle sizes up to 350 μm 8 . This can be due to the fact that they agglomerate fast after building. ...
... This can be due to the fact that they agglomerate fast after building. The particles produced by friction often take an elongated shape [7][8][9] . The chemical composition shows particularly high carbon and silicon contents as well as sulfur and heavy metals 7,10 . ...
... TWAP mostly form agglomerates from tire, pavement and brake wear. The morphology and chemical composition of the TWAP are consistent with the findings of other studies regarding TWRP [7][8][9][10] . With regard to use TWAP as a secondary raw material, separation-especially of the bigger particles (sand, glass beads)-might be favorable. ...
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Article
Tire wear is a main contributor to microplastics. As we cannot fully avoid tire wear, otherwise we could not brake and stop, new solutions are needed to address this problem. Not only on roads tire wear is released to the environment, even more can be found at airports. The advantage there is that the Tire Wear Airstrip Particles are gathered while cleaning the pavement. This collection is an opportunity to recycle and add new value to it. Whereas rubber powder is a common way to recycle and reuse end-of-life-tires as raw material in rubber compounds, the question is if TWAP is reusable in the same or similar way. In this study TWAP and rubber powder from truck tire treads are analyzed and compared with regard to their morphology, particle size distribution and composition. The particle size distribution of TWAP is broader than rubber powder containing also much smaller particles. The mineral content of TWAP is about 60%. These minerals can be residues of the pavement, brake wear but also rubber ingredients. In comparison to rubber powder, the impurities of TWAP are expected to have an impact with regard to potential applications and should be better separated.
... Furthermore, particles > 125 µm account for a low proportion (cumulative volume) of the sample (≈10%, Figure S6). Previous analyses of TRWP have also shown that the average particle size is < 125 µm (Kreider et al., 2010;Klöckner et al., 2021 andLundberg et al., 2020). The mesh sizes (125 and 20 µm) are commonly used for sieving analyses, and the use of those mesh sizes might enable a comparison with previous studies. ...
... Furthermore, the elements present in TWP (besides the ones stemming from the tread, i.e., C, O, and Si) coincide with the elements found in the mineral particles (see above). This is further evidence for the statement presented in several articles that environmental TWP occur as mixtures of tread and mineral encrustations (Halle et al., 2021;Kovochich et al., 2021;Kreider et al., 2010;Rausch et al., 2022;Sommer et al., 2018). In this case, the correlation between mineral encrustations and available minerals on the road is proved. ...
... Recently published studies have also observed that environmental TWP differ in chemical composition and morphology compared to pristine TWP (Halle et al., 2021;Kovochich et al., 2021;Sommer et al., 2018;Wagner et al., 2022). Several articles have described environmental TWP as elongated particles with mineral encrustations (Adachi & Tainosho, 2004;Kreider et al., 2010;Williams & Cadle, 1978). However, Kovochich et al. (2021) presented both elongated and near-spherical TWP. ...
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Article
Tires, bitumen, and road markings are important sources of traffic-derived carbonaceous wear particles and microplastic (MP) pollution. In this study, we further developed a machine-learning algorithm coupled to an automated scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX) analytical approach to classify and quantify the relative number of the following subclasses contained in environmental road dust: tire wear particles (TWP), bitumen wear particles (BiWP), road markings, reflecting glass beads, metallics, minerals, and biogenic/organics. The method is non-destructive, rapid, repeatable, and enables information about the size, shape, and elemental composition of particles 2–125 µm. The results showed that the method enabled differentiation between TWP and BiWP for particles > 20 µm with satisfying results. Furthermore, the relative number concentration of the subclasses was similar in both analyzed size fractions (2–20 µm and 20–125 µm), with minerals as the most dominant subclass (2–20 µm x̄ = 78%, 20–125 µm x̄ = 74%) followed by tire and bitumen wear particles, TBiWP, (2–20 µm x̄ = 19%, 20–125 µm x̄ = 22%). Road marking wear, glass beads, and metal wear contributed to x̄ = 1%, x̄ = 0.1%, and x̄ = 1% in the 2–20-µm fraction and to x̄ = 0.5%, x̄ = 0.2%, and x̄ = 0.4% in the 20–125-µm fraction. The present results show that road dust appreciably consists of TWP and BiWP within both the coarse and the fine size fraction. The study delivers quantitative evidence of the importance of tires, bitumen, road marking, and glass beads besides minerals and metals to wear particles and MP pollution in traffic environments based on environmental (real-world) samples
... The shape of tire particles can vary, but most studies have reported them as elongated hetero-aggregates of TWP mixed together with mineral components from the road surface and environment, which are then reported as tire and road wear particles (TRWP). The percentage of minerals in the TRWP is variable according to current literature, with estimates of 6-53% (Klöckner et al., 2021b;Kreider et al., 2010;Sommer et al., 2018). The size of TRWP is expected to be in the range 50-350 μm (85% of particles) and <50 μm (15% of particles) (Kreider et al. 2010;Broeke et al. 2008), however it is suggested that most of TWP has sizes <50μm, which dominate in road tunnels (Klöckner et al., 2021b). ...
... The percentage of minerals in the TRWP is variable according to current literature, with estimates of 6-53% (Klöckner et al., 2021b;Kreider et al., 2010;Sommer et al., 2018). The size of TRWP is expected to be in the range 50-350 μm (85% of particles) and <50 μm (15% of particles) (Kreider et al. 2010;Broeke et al. 2008), however it is suggested that most of TWP has sizes <50μm, which dominate in road tunnels (Klöckner et al., 2021b). Asphalt and minerals such as quartz, have high densities (2.4 g/cm 3 , 2.7 g/cm 3 , respectively), whereas the density of pure TWP is 1.2 g/cm 3 (Degaffe and Turner, 2011). ...
... Road wear particles (RWP) in general are reported to include particles with similar size range and shape as TWP/TRWP, although a variation in different shapes were reported (Kreider et al., 2010;Sommer et al., 2018). Studies also report a variation in composition for RWP, including 94-95% minerals (quartz, feldspar, pyroxene, amphibole, mica) and different elements (Si, Al, Ca, Na, K, Mg; Fe, S), held together as aggregated particles by the bitumen (5-6%) from the road asphalt (Sommer et al., 2018). ...
... 12 As a result of the friction of tires with the road, tire tread wears off and subsequently combines with road pavement particles to form TRWPs, leading to about 1 000 000 ton/year of TRWPs in the U.S. alone. 13,14 Similar to the general microplastics, the effects of TRWPs on water bodies and air have been reported by many researchers 15−20 with benzothiazole, a curing accelerator, posing a 0.003% health risk studied during three exposure scenarios and four subpopulation groups. 21 TRWPs are also reported to cause acute toxicity of several aquatic lifeforms. ...
... 12,32 However, tire wear particles obtained from road simulators are smaller and range in size between 100 and 400 μm. 13,19 The next stage is the removal of organic matter from the soil since it can interfere with the TRWP identification. 33 Among the various digestion methods specific to the organic matter in soil, strong acids, 34 potassium hydroxide, enzymatic treatments, hydrogen peroxide, and Fenton's reagent are the most common. ...
... 7,47 However, most of the literature assessed the environmental impact of the tire particles using column leaching tests, accelerated weathering tests, 41,48 extractions, and aerobic incubators. 13,49 Although these studies did not separate TRWPs from soil, they do provide a database of possible transformation products. ...
Article
A comprehensive understanding of tire and road wear particles (TRWPs) and their detection and quantification in soils is still challenged by the lack of well-set standardized methods, inherent technological inconsistencies, and generalized protocols. Our protocol includes soil sampling, size separation, and organic matter removal by using hydrogen peroxide followed by density separation and analysis. In this context, roadside soil samples from different sites in Kansas and Ohio, USA, were collected and analyzed. Tire cryogrinds analogous to TRWPs were used to evaluate various density separation media, and collected particles more than 1 mm in size were then subjected to infrared spectroscopy (IR), thermogravimetric analysis (TGA), and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX) to confirm TRWP presence. Particles smaller than 1 mm were Soxhlet extracted, followed by gas chromatography–mass spectrometry (GC–MS) to validate the presence of tire-related intermediates. SEM-EDX validated the presence of elemental combinations (S + Zn/Na) ± (Al, Ca, Mg, K, Si) attributed to tires. Ketones, carboxylic acids, epoxies, cyclohexane, and benzothiazole sulfenamide (BTS) intermediates were the most probable tire-related intermediates observed in the roadside soil samples. Thus, this simple, widely applicable, cost-effective sample preparation protocol for TRWP analysis can assist TRWP research advancement in terrestrial environments.
... Grigoratos and Martini (2014) revealed that the maximum contribution of tyre wear particles to non-exhaust air particles in traffic by mass was up to 30 %. Harrison et al. (2012) evaluated the tyre wear particle emissions at the sampling site of the Marylebone Road in central London and found that tyre dust accounted for 10.7 % of total PM 10 mass. Tyre wear particles are predominantly generated through the following two mechanisms: (1) shearing forces between the tyre tread and road surface would primarily produce large and coarse size particles (Kim and Lee, 2018;Kreider et al., 2010); (2) localized high-temperature hot spots on the tyre tread causes the volatilisation and condensation of organic compounds in the tyre tread, emitting fine-sized particles (Kreider et al., 2010;Mathissen et al., 2011;Park et al., 2017;Pohrt, 2019). In the studies by Baensch-Baltruschat et al. (2020) and Oroumiyeh and Zhu (2021), it was found that tyre wear particles accounted for 11 % of the traffic-related particles referring to PM 10 . ...
... Grigoratos and Martini (2014) revealed that the maximum contribution of tyre wear particles to non-exhaust air particles in traffic by mass was up to 30 %. Harrison et al. (2012) evaluated the tyre wear particle emissions at the sampling site of the Marylebone Road in central London and found that tyre dust accounted for 10.7 % of total PM 10 mass. Tyre wear particles are predominantly generated through the following two mechanisms: (1) shearing forces between the tyre tread and road surface would primarily produce large and coarse size particles (Kim and Lee, 2018;Kreider et al., 2010); (2) localized high-temperature hot spots on the tyre tread causes the volatilisation and condensation of organic compounds in the tyre tread, emitting fine-sized particles (Kreider et al., 2010;Mathissen et al., 2011;Park et al., 2017;Pohrt, 2019). In the studies by Baensch-Baltruschat et al. (2020) and Oroumiyeh and Zhu (2021), it was found that tyre wear particles accounted for 11 % of the traffic-related particles referring to PM 10 . ...
... It meant that the driver who had a high frequency of harsh braking and accelerating would generate more tyre wear. It has been confirmed that both shearing force and friction heat between the tyre tread and the road pavement would increase tyre wear (Kreider et al., 2010;Mathissen et al., 2011;Piscitello et al., 2021). As a result, the shear force is increased when harsh braking or acceleration occurs, increasing the tyre's mechanical wear and thus generating coarse and even larger particles. ...
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Article
Tyre wear generates not only large pieces of microplastics but also airborne particle emissions, which have attracted considerable attention due to their adverse impacts on the environment, human health, and the water system. However, the study on tyre wear is scarce in real-world driving conditions. In the present study, the left-front and left-rear tyre wear in terms of volume lost in mm3 of 76 taxi cars was measured about every three months. This study covered 22 months from September 2019 to June 2021 and included more than 500 measurements in total. Some of the data was used to evaluate the effects of vehicle type and tyre type on tyre wear. In addition, a machine learning method (i.e., Extreme gradient boosting (XGBoost)) was used to probe the effect of driving behaviour on tyre wear by monitoring real-time driving behaviour. The current statistical results showed that, on average, the tyre wear was 72 mg veh-1 km-1 for a hybrid car and 53 mg veh-1 km-1 for a conventional internal combustion engine car. The average tyre wear measured for a taxi vehicle configuration featuring winter tyres was 160 mg veh-1 km-1, which was 1.4 and 3.0 times as much as those with all-season tyres and summer tyres, respectively. The wear rate of left-front tyres was 1.7 times higher than that of left-rear tyres. The XGBoost results indicated that compared to driving behaviour, tyre type and tyre position had more important effects on tyre wear. Among driving behaviours, braking and accelerating events presented the most considerable impact on tyre wear, followed by cornering manoeuvres and driving speed. Thus, it seems that limiting harsh braking and acceleration has the potential to reduce tyre wear significantly.
... 72−74 Kreider et al. developed a nomenclature describing whether particles were generated from the original tread (TP), laboratory-generated tire wear particles (WP) or on-road collected particles (RP). 73 The abbreviation TRWP (tire-and road wear particles) also encompasses the combination of these sources from a range of urban environments. 75 A broad size range (10 nm to 10 μm) of laboratory generated TRWP has been measured ( Figure 1c,d), 76−82 with a unimodal mass distribution in the 1−7 μm range and number size distribution of 10−200 nm. ...
... 25 Studded tires, used in cold climates to improve grip, generate ultrafine particles (<100 nm) (Figure 1c,d), that is speculated to originate from evaporation and subsequent condensation of softening oils in the rubber mix. 87 Only 1% of tire wear is estimated to be released into the PM 10 fraction, 73 with varying contribution to atmospheric PM 10 : <1% using tire tread polymers as tracers, 75 0.1−3.9% 81 and 1.0−7.5% 88 using source receptor techniques, and 3−4% using simultaneous measurements of mass behind the front wheel and in the surrounding atmosphere. ...
... 94 Compared to TP, TRWP are enriched in metals from brake linings and pavement materials and contain a lower concentration of polymers. 72,73 Zn is a notable exception, which is enriched in TP relative to TRWP, despite being emitted by other sources such as industrial processes 70 and brake pads. 50 2.1.3. ...
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Article
Implementation of regulatory standards has reduced exhaust emissions of particulate matter from road traffic substantially in the developed world. However, nonexhaust particle emissions arising from the wear of brakes, tires, and the road surface, together with the resuspension of road dust, are unregulated and exceed exhaust emissions in many jurisdictions. While knowledge of the sources of nonexhaust particles is fairly good, source-specific measurements of airborne concentrations are few, and studies of the toxicology and epidemiology do not give a clear picture of the health risk posed. This paper reviews the current state of knowledge, with a strong focus on health-related research, highlighting areas where further research is an essential prerequisite for developing focused policy responses to nonexhaust particles.
... There is some debate over the actual contribution of TWPs to PM. Tappe and Null (2002) reported that 5-7% of PM10 originates from TWP [11]. In contrast, Kreider et al. (2010) found that TWP makes a negligible contribution to PM because most TWPs have a diameter greater than 10 µm [12]. ...
... There is some debate over the actual contribution of TWPs to PM. Tappe and Null (2002) reported that 5-7% of PM10 originates from TWP [11]. In contrast, Kreider et al. (2010) found that TWP makes a negligible contribution to PM because most TWPs have a diameter greater than 10 µm [12]. ...
... The amount of TWPs released and their physicochemical properties depend on factors such as the road status (e.g., material, texture, and wetness), tire properties (e.g., composition, tire pressure, and accumulated mileage), and intensity of friction (e.g., speed, acceleration, and weight of vehicle). Even under the same conditions in a road simulator, tires from different manufacturers exhibited distinctive characteristics in terms of the average size, size distribution, and chemical composition of their TWPs [12]. ...
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Article
Physical friction between a tire and the road surface generates tire wear particles (TWPs), which are a source of microplastics and particulate matter. This study investigated the trends of chemical leaching from TWPs depending on the treadwear rating of the tire. A road simulator was used to produce TWPs from tires with various treadwear ratings. Liquid chromatography–tandem mass spectrometry was used to analyze the chemical leaching from TWPs, with a particular focus on benzothiazole and its derivative 2-hydroxy benzothiazole. However, chemical mapping via high-resolution tandem mass spectrometry detected another derivative: 2-mercaptobenzothiazole. The benzothiazole groups were observed to have different leaching tendencies, implying that using benzothiazole as a marker compound may lead to incorrect TWP quantitation. The results of this research also suggest that the ecotoxicological influence of TWPs can vary with the treadwear rating of a tire.
... Recently, attention has been given to microplastic particles associated with roads and traffic, as tire wear particles and road wear particles contain synthetic rubbers, and contribute a substantial amount of rubbers to the overall microplastic particle release into the environment (Boucher et al., 2020;Knight et al., 2020;Sundt et al., 2021). Previous studies have defined particles released from tire wear and subsequently mixed with road wear mineral particles as the hetero-aggregated tire and road wear particle (TRWP) (Kreider et al., 2010). These are estimated to contain 50% tire tread and 50% road wear (Kreider et al., 2010), in which the rubber concentration (SBR+BR) in the tire is estimated at 50% (Unice et al., 2012(Unice et al., , 2013. ...
... Previous studies have defined particles released from tire wear and subsequently mixed with road wear mineral particles as the hetero-aggregated tire and road wear particle (TRWP) (Kreider et al., 2010). These are estimated to contain 50% tire tread and 50% road wear (Kreider et al., 2010), in which the rubber concentration (SBR+BR) in the tire is estimated at 50% (Unice et al., 2012(Unice et al., , 2013. However, the assumption of road wear content in TRWP is based on a small number of studies and the use of a fixed percentage estimation of 50% road wear in TRWP has been questioned by a recent study (Klöckner et al., 2021). ...
... Fraunhofer's optical model was applied for the analysis (refraction index 1.333 and absorbation index 0.1). The size distribution was calculated on a volume percentage, and classification was based on a previous size distribution of TRWP (Kreider et al., 2010). ...
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Article
Road pollution is one of the major sources of microplastic particles to the environment. The distribution of tire, polymer-modified bitumen (PMB) and tire and road wear particles (TRWP) in different tunnel compartments were explored: road surface, gully-pots and tunnel wash water. A new method for calculating TRWP using Monte Carlo simulation is presented. The highest concentrations on the surface were in the side bank (tire:13.4±5.67;PMB:9.39±3.96; TRWP:22.9±8.19 mg/m²), comparable to previous studies, and at the tunnel outlet (tire:7.72±11.2; PMB:5.40±7.84; TRWP:11.2±16.2 mg/m²). The concentrations in gully-pots were highest at the inlet (tire:24.7±26.9; PMB:17.3±48.8; TRWP:35.8±38.9 mg/g) and comparable to values previously reported for sedimentation basins. Untreated wash water was comparable to road runoff (tire:38.3±10.5; PMB:26.8±7.33; TRWP:55.3±15.2 mg/L). Sedimentation treatment retained 63% of tire and road wear particles, indicating a need to increase the removal efficiency to prevent these from entering the environment. A strong linear relationship (R2-adj=0.88, p<0.0001) between total suspended solids (TSS) and tire and road wear rubber was established, suggesting a potential for using TSS as a proxy for estimating rubber loads for monitoring purposes. Future research should focus on a common approach to analysis and calculation of tire, PMB and TRWP and address the uncertainties related to these calculations.
... In the first two cases, the content of metals and other elements was examined. PAH concentrations in the field tyre and road wear particles were 19 times higher than in the tyre tread particles and 24 times higher than in the tyre and road wear particles produced in the laboratory [22]. ...
... The fractions mainly contained PE, 88%; PP, <1%; PS, 3%; PVC, 2%; and others, 7.5% [25]. Half of them consist of an elastomer tread containing a polymer with a mineral surface and the other half of binder encrustations [22,23,26]. These components are introduced into the environment in which they will be released. ...
... The emitted particles can be in the form of both fragments and fibres. Scientific studies showed longitudinal fractions that had mineral particles out of the way in their structure [22]. Scientific research shows that the particles can also be irregularly shaped fragments [31]. ...
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Article
Transport is one of the most important sources of environmental pollution. More and more information has shown that one of the greatest sources of emissions from transport are emissions related to the release of microplastics from tyres. This is one of the most underestimated sources of emissions into the environment. In this study, environmental samples are analysed for the presence of these particles. For this purpose, optical methods and spectroscopic methods are used. Fourier transform infrared (FTIR) spectroscopy is used to identify synthetic rubber, most likely derived from car tyres. A complementary confocal microscopy method is used to confirm the FTIR results. The soil samples and road dust from the areas with heavy traffic are tested. An average of 372 ± 50 fragments per kilogram dry weight are detected in the soil samples. In the case of samples from the road, this number is 515 ± 20 fragments per kilogram of dry matter. In the samples, most of the microplastics come from tyres, which confirms the scientists’ assumptions about the amount of emissions in the environment. More than 90% of the black fragments later identified as tyre-derived synthetic rubber are found in the samples. A greater number of microplastics are found in road dust samples than in the soil. This may be due to the direct influence of braking, which causes greater accumulation of samples at the emission source than at a short distance into the soil. There is also a noticeable difference in the size of the fraction. In the case of soils, a fraction below 50 µm accounts for the majority of cases. When one analyses road dust samples, one may observe that most of the fractions are between 50 and 200 µm. This may be due to the possibility of smaller emission particles over longer distances and the greater degradation process that occurs in soils. The microplastics from the road dust are less degraded than the microplastics from the soil.
... TWP found in environmental samples consists of a higher content of traffic-derived minerals (silica) and metals (aluminum, iron, titanium, or magnesium) than TWP from wear produced in controlled laboratory environments (such as the VTI road simulator) (Mattsson et al., submitted). TWP in field samples are commonly known as elongated black particles, and recent publications have shown that most particles are 20-200 µm (Figure 3) e.g., Kreider et al. (2010) and Sommer et al. (2018). However, other shapes and sizes have been reported, e.g., fragments with a more angular shape (Hassellöv et al., 2018;Kovochich et al., 2021;Rausch et al., 2022). ...
... In Paper I and II, particles <20 µm were not analysed due to analytical challenges. Kreider (2010) reported that less than 1% (volume) were <10 µm and it has previously been discussed that the fine fraction probably accounts for a negligible part of the total particle mass or volume even though the total number of particles are higher for fine particles. However, Figure 18 shows that the fine fraction (2-20 µm) stands for a considerable part of the sample (≈45% by volume) and should definitely not be excluded from the analyses. ...
... TWPs are generated by friction between tires and roads resulting in particles that are a combination of fragments of tire tread encrusted with pavement and road related particles (Panko et al., 2018;Baensch-Baltruschat et al., 2020;Rausch et al., 2022). TWPs are typically described as dark/black, elongated, cylindrical-shaped particles, ranging in size from~1 µm to >100 µm (Kreider et al., 2009;Sommer et al., 2018). Because of the aforementioned incorporation of environmental particles (e.g., pavement, road dust), the chemical composition of TWPs varies from that of pure tire tread and tire wear debris (Kreider et al., 2009). ...
... TWPs are typically described as dark/black, elongated, cylindrical-shaped particles, ranging in size from~1 µm to >100 µm (Kreider et al., 2009;Sommer et al., 2018). Because of the aforementioned incorporation of environmental particles (e.g., pavement, road dust), the chemical composition of TWPs varies from that of pure tire tread and tire wear debris (Kreider et al., 2009). A recent review on their generation, properties, emissions, human health risk, ecotoxicity, and fate in the environment, revealed that 1) contribution of TWPs to PM10 accounts for up to~11% by mass, 2) annual emissions of TWPs for numerous countries show per-capita-masses ranging from 0.2 to 5.5 kg/(cap*a), 3) ecotoxicological studies show effects of TWPs on aquatic organisms, but the test concentrations and materials do not reflect environmental conditions, and 4) further research is needed with regard to emission factors, development of analytical methods for environmental matrices, and longperiod monitoring (Baensch-Baltruschat et al., 2020). ...
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Article
Tire wear particles (TWPs) are a major category of microplastic pollution produced by friction between tires and road surfaces. This non-exhaust particulate matter (PM) is transported through the air and with runoff leading to environmental pollution and health concerns. Here, we collected airborne PM along paved roads with different traffic volumes and speeds using Sigma-2 passive samplers. Particles entering the samplers deposit onto substrates for analysis, or, as we modified it, directly into small (60 ml) separatory funnels, which is particularly useful with high particle loads, where a density separation aids in isolating the microplastics. We quantified putative TWPs (∼10–80 µm) deposited on the substrates (primarily adhesive tape on glass slides) and in the funnels using stereomicroscopy. Putative TWP deposition rates (particles/cm2/day ± SD) at 5 m from the road were highest near a busy highway (324 ± 129), followed by a boulevard with moderate traffic (184 ± 93), and a slow traffic avenue (29 ± 7). We observed that deposition rates increased within proximity to the highway: 99 ± 54, 180 ± 88, and 340 ± 145 at 30, 15, and 5 m, respectively. We show that TWP abundances (i.e., deposition and mass concentration) increase with vehicle braking (driving behavior). We observed no differences (p > 0.05) between the separatory funnel and adhesive tape collection methods. In addition, we were able to obtain FTIR spectra of TWPs (>10 µm) using µ-ATR-FTIR. Both deserve further scrutiny as novel sampling and analytical approaches. In a separate sampling campaign, we differentiated 1438 particles (∼1–80 µm) deposited on boron substrates into TWP, metal, mineral, and biogenic/organic classes with single particle SEM/EDX analysis based on morpho-textural-chemical classification and machine learning. The results revealed similar concentration trends with traffic (high > moderate > low), with the distribution of particle sources alike for the highway and the moderate road: TWPs (∼38–39%) > biogenic (∼34–35%) > minerals (∼23–26%), and metallic particles (∼2–3%). The low traffic road yielded a much different distribution: biogenic (65%) > minerals (27%) > TWPs (7%) > metallic particles (1%). Overall, this work provides much-needed empirical data on airborne TWPs along different types of roads.
... Whilst particles were sieved through a 250 μm mesh, the Mastersizer measures the longest length, and some particles fell into the 250-500 μm size category. This is comparable to tyre wear particles produced under realistic conditions in a road simulator laboratory, which have a size of 4-350 μm with a mode of 100 μm (Kreider et al., 2010). Based on calculating particle volume (mL) and mass (g.mL-1), the average number of tyre particles per gram was 4.0 (±1.2) million. ...
... This was the case in this study, with S. plana ingesting more than 25x the number of tyre particles compared to H. diversicolor. The size of the tested tyre particles overlapped with natural sediment sizes and was similar in size to tyre particles produced in a road simulator laboratory (4-350 μm; Kreider et al., 2010). The number of particles in the intestine of S. plana suggests that these manufactured particles also overlap with the size of sediment that this species ingests. ...
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Article
Tyre wear particles may be the largest source of microplastic to the natural environment, yet information on their biological impacts is inadequate. Two key estuarine invertebrates; the clam Scrobicularia plana and the ragworm Hediste diversicolor were exposed to 10% tyre particles in sediment for three days. Both species consumed the particles, although S. plana consumed 25x more than H. diversicolor (967 compared with 35 particles.g-1 wet weight, respectively). We then investigated the impact of 21 days exposure to different concentrations of tyre particles in estuarine sediments (0.2, 1, and 5% dry weight sediment) on aspects of the health of S. plana and H. diversicolor. Reductions in feeding and burial rates were observed for S. plana but not H. diversicolor, whilst both species showed a decrease in protein content in response to the greatest tyre particle concentration (5%), linked to an 18% decrease in energy reserves for H. diversicolor. Five percent tyre particle exposure led to an increase in total glutathione in the tissues of H. diversicolor, whilst lipid peroxidation decreased in the digestive glands of S. plana, possibly due to an increase in cell turnover. This study found that S. plana's health was impacted at lower concentrations than H. diversicolor, likely due to its consumption of large quantities of sediment. At the high exposure concentration (5%), the health of both invertebrates was impacted. This study did not separate the effects caused by the microplastic particles versus the effects of the chemical additives leaching from these particles, but our results do indicate that future studies should investigate effects in isolation and in combination, to determine the main drivers of toxicity.
... The circularity of all three TPs was estimated as 0.34-0.61. Compared to the TWP found in actual environmental media, the average size of TWP collected from the highway was measured as 5-220 µm with an irregular shape (Kreider et al., 2010;Kovochich et al., 2021). Although not intended, it was confirmed that laboratory-generated TPs in this study had physical characteristics like the TWP found in real-environment (in the aspect of particle size and shape). ...
... Compared to TWP, TPs used in this study were laboratory-generated; therefore, the natural aging process was excluded. Generated TWP detected in the environmental media accounts for more than 60 % mineral composition of a particle with various minerals such as Si, Al, and Ca, while virgin TPs contain 46 % polymer with high contents of polycyclic aromatic hydrocarbon (Kreider et al., 2010). In addition, when the aging process continues, the emission of 6-PDD from TPs decreases (Unice et al., 2015). ...
Article
Tire particles are generated by the abrasion of tire treads on roads and are major contributors to microplastics in soil environments. Contamination by tire wear particles worsens annually as the use of personal mobilities increases. Tire particles (112-541 µm) were obtained from three types of personal mobility tires (bicycle, car, and electric scooter) and exposed to plants (Vigna radiata) and springtails (Folsomia candida) for 28 d to assess the toxicity of each tire-particle type. The laboratory-generated tire particles exhibit adverse effects depending on the origin of the tire or test species. Particles from bicycle or electric-scooter tires changed the soil's bulk density and water holding capacity and adversely affected plant growth. Car tire particles had leached various organic compounds and induced detrimental effects on springtails (adult and offspring growth). We concluded that laboratory-generated tire particles (frow new tires) can affect the soil environment by changing soil properties and leaching chemicals; thus, causing adverse effects on soil organisms. Since this study found tire particle toxicity on soil organisms, it would be possible to compare the various contamination levels in areas near road soil and other clean soils.
... Tiny particles generated from the abrasion of car tires against the road surface are widely available in the environment but still rarely reported as microplastic contaminants in environmental studies (Arias et al., 2022;Knight et al., 2020;Kreider et al., 2010). Tire wear particles (TWP) could be one of the likely sources of SBR particles in the marine environment. ...
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Thesis
Worldwide, microplastics (MPs; 5 < mm) have been identified in most marine ecosystems and organisms. The large availability of this contaminant has raised the concern of scientists about the impacts on biodiversity and ecosystems. However, despite being frequently reported, some regions still lack studies on the characterisation of MPs contamination. This is the case in the Southwestern Tropical Atlantic (SWTA) region. To fill this gap, this thesis aims to provide a general understanding of the distribution and patterns of MP contamination in the ichthyofauna inhabiting the SWTA region along the estuarine-oceanic gradient. Thus, a protocol for extraction of MPs for marine organisms was adapted to diminish the probability of airborne contamination in the samples, which would be practical and of low operational cost. The thesis is structured in four chapters presented as articles and a general conclusion. The first chapter explored an estuarine trophic chain, comprising a commercially important top predatory fish and two of its main prey. Both species have different feeding habits, which was also observed in the frequency of MP ingestion, which varied with feeding strategies. In the second chapter, four coastal demersal fish species were used to characterise the ingestion of MPs in reef fishes from the SWTA region. No differences were observed between the ingestion rate of MPs by coastal species; however, a wide range of polymers was identified. The ocean ecosystem is discussed in the last two chapters of the thesis, focusing on pelagic and mesopelagic oceanic species. The third chapter characterises the contamination of two abundant mesopelagic fish families in the SWTA and addresses the influence of these species on the transport of MPs in the deep ocean. In this chapter, MP contamination in deep-sea fishes in the region was identified for the first time and areas of possible accumulation of particles were discussed. Finally, in the fourth chapter, pelagic predators important for industrial and artisanal fisheries were evaluated for the presence of MPs. In addition to the characterisation of contamination, evidence of trophic transfer of MPs from prey to predators was observed. Furthermore, this chapter discusses the ingestion of larger particles (macroplastics > 5 mm) derived from the intense ocean fishing and tourism activity in the Fernando de Noronha Archipelago (FNA). Overall, it was possible through this thesis to confirm the contamination by MPs in fish from the SWTA region. The ecological patterns, such as feeding strategies and trophic level, increased MP contamination probability. Furthermore, the influence of the species’ behaviour in the water column in areas with an accumulation of MPs. In addition, it was also possible to observe that, in general, the most frequent shape of MPs ingested by fishes are fibres. However, large oceanic pelagic predators (tunas) tended to ingest pellets and foams, which was also observed in their primary prey, indicating trophic transfer. Moreover, a variety of polymers were identified, but the most frequent polymers in the coastal region were polyethylene (PE), Alkyd Varnish and styrene-butadiene rubber (SBR); for the mesopelagic fishes in the oceanic region were polyamide (PA), PE and polyethylene terephthalate (PET). However, the most frequent polymers for tuna and prey were SBR, PA, and PET. The availability of these polymers in the SWTA region indicates intense pressure from fisheries (e.g., fishing nets and ship paint) and high tourist activity. The information available here can serve as a baseline to discuss and develop measures to mitigate the impacts caused by MPs contamination and plastic pollution in the SWTA region, thus contributing to the conservation of biodiversity and marine ecosystems.
... For a polymer of density 1500 kg m − 3 , more representative of PET and PVC (Table 3), v s is about 0.004 m s − 1 according to equation (3). By comparison, the settling velocities of fragments of MR of densities, ρ MR , 840 kg m − 3 and 1200 kg m − 3 , and d = 100 μm can be modelled as quasispheres (the mode of distribution of circularity of tire wear particles is 0.83; Kreider et al., 2010): ...
Article
Although airborne urban particles are a concern for air quality and human health, little information exists on the levels and characteristics of microplastics (MPs) and microrubbers (MRs) in this setting. In the present study, MPs and MRs are quantified and characterised in road dusts and accumulations captured passively (and up to elevations of 177 cm above road level) in the steps of utility poles at 18 locations throughout the city of Shiraz, southwest Iran. Dust accumulation rates were greatest at road level (median = 45 g m−2 month−1) and declined with elevation (median = 2.0 g m−2 month−1 at 177 cm). The accumulation rates and concentrations (per g of dust) of MPs and MRs were more variable between locations but accumulation declined with elevation for both particle types and MR concentration (up to ∼27,000 MR g−1) was always greater than corresponding MP concentration (up to ∼3300 MP g−1). Increasing elevation was also accompanied by an increasing proportion of fine (≤100 μm) and fibrous particles, and in particular for MPs. Fractionation in the quantities and characteristics with elevation above road level are attributed to the extent of resuspension of MPs and MRs from the road surface by wind and passing traffic, with aerodynamic considerations predicting the greatest and most widespread resuspension of fibrous MPs. The fractionation of MPs and MRs with elevation above road level also results in different exposures for adults and children.
... Tire and road wear particles (TRWP) arise from the tire wear fusing with the mineral encrustations of the road payments and are usually deposited in the soil beside the roadways (Jekel, 2019;Kreider et al., 2010). A recent study estimated that global tire debris (TRWP and larger tread pieces) was 0.2-5.5 kg/person (Baensch-Baltruschat et al., 2020). ...
Article
Tire and road wear particles (TRWP) are becoming an important research question with potential risks on ecological system. A comprehensive understanding of their detection and quantification in soils are challenged by the inherent technological inconsistencies, lack of well-set standardized methods, and generalized protocols. Reference tire cryogrinds were subjected to abiotic weathering. Next, the total environmental availability from parent elastomers and the release of additives from tire tread compounds were evaluated using mass concentration factors obtained from abiotic weathered tire cryogrinds. Headspace Gas chromatography-mass spectroscopy (HS-GC-MS) was employed as a nontargeted, suspect screening analysis technique to identify the tire related intermediates. Benzothiazole, 1,2-dihydro-2,2,4-trimethylquinoline (TMQ), aniline, phenol and benzoic acid were detected as tire tetrahydrofuran leachates. Total environmental availability of TMQ and benzothiazole were in the range of 1.7 × 10⁻³ and 0.11, respectively. Benzene and benzoic acid derivatives were identified as marker compounds for environmental samples. A TRWP content evaluation was made possible by quantifying marker concentrations and reference tire cryogrind formulation. TRWP content in the size range of 1–5 mm was between 800 and 1300 μg/g and 1200–3100 μg/g TRWP in Ohio and Kansas soil. For TRWP less than 1 mm, 0.15–2.1 wt% content was observed in Kansas and Ohio samples and were seemingly dependent on the locations and the traffic. This simple, widely applicable quantification method for TRWP analysis provides a database of tire degradation and TRWP intermediates. The TRWP content research is critical for further TRWP research development in terrestrial environment.
... During their separation from tires, TWPs are exposed to friction and heat that causes them to metamorphose. This alters their physical and chemical properties (Kreider et al., 2010;Sommer et al., 2018) and causes them to be encapsulated in road surface materials, formed by road dust and asphalt bitumen particles (Adachi and Tainosho, 2004;Panko et al., 2013). The aggregates formed by the encapsulation of such core rubber particles were defined as TRWP. ...
Full-text available
Article
Urban areas play a key role in the production of microplastics (MPs) and their entry into water bodies. This article reviews the literature on the sources, transport, and control of MPs in urban environments with the aim of clarifying the mechanisms underlying these processes. Major MP sources include atmospheric deposition, micro-litter, and tire and road wear particles (TRWPs). MPs deposited from the atmosphere are mostly fibers and may be particularly important in catchments without traffic. Littering and attrition of textiles and plastic products is another important MP source. However, the quantities of MPs originating from this source may be hard to estimate. TRWPs are a significant source of MPs in urban areas and are arguably the best quantified source. The mobilization of MPs in urban catchments is poorly understood but it appears that dry unconsolidated sediments and MP deposits are most readily mobilized. Sequestration of MPs occurs in green areas and is poorly understood. Consequently, some authors consider green/pervious parts of urban catchments to be MP sinks. Field studies have shown that appreciable MP removal occurs in stormwater quality control facilities. Street cleaning and snow removal also remove MPs (particularly TRWPs), but the efficacy of these measures is unknown. Among stormwater management facilities, biofiltration/retention units seem to remove MPs more effectively than facilities relying on stormwater settling. However, knowledge of MP removal in stormwater facilities remains incomplete. Finally, although 13 research papers reported MP concentrations in stormwater, the total number of field samples examined in these studies was only 189. Moreover, the results of these studies are not necessarily comparable because they are based on relatively small numbers of samples and differ widely in terms of their objectives, sites, analytical methods, size fractions, examined polymers, and even terminology. This area of research can thus be considered “data-poor” and offers great opportunities for further research in many areas.
... Tires are made from rubber compounds consisting of a vast number of components, including natural and synthetic rubber, plasticizer oils, amorphous silica, and carbon black as filler and pigment as well as a variety of other additives and auxiliary materials of lesser quantity [1]. Among this complex mixture of components both plasticizer oils and carbon black are a source of polycyclic aromatic hydrocarbons (PAH) [2], a group of toxic compounds known to pose a risk to human health [3]. ...
Full-text available
Article
At the European level, limits have been set (REACH) for the content of polycyclic aromatic hydrocarbons (PAH) in products with rubber and plastic components that come into contact with human skin or the oral cavity. These limit values reported in Commission Regulation (EU) 1272/2013 are of particular importance for the utilization of end-of-life tires (ELT) as recycled rubber materials for consumer applications, but a suitable analytical method has not yet been specified. On the other hand, comprehensive measurement series of the PAH content of ELT materials are scarce in the context of compliance testing against this regulation and general published PAH levels in ELT materials are often based on very different analytical methods. In the present work, the PAH content of three different rubber granulates from ELT (obtained from whole truck and passenger car tires and truck tire treads) were investigated over a period of two years. The Grimmer method was used for PAH profile analysis, which in terms of extraction intensity and sample preparation not only meets the requirements for a reliable determination of the EU priority PAH, but in addition covers a more comprehensive PAH profile. A total of 26 different PAH compounds, including the 8 EU priority PAH (REACH) and the 16 U.S. EPA priority PAH, were analyzed and their variations over time were examined to obtain reliable current data for PAH content in rubber granulates produced from ELT
... За 100 километров езды на автомобиле с шин стирается примерно 20 граммов пластиковой пыли [3]. Микрочастицы, возникающие в результате истирания шин и дорожного покрытия, состоящие преимущественно из синтетического каучука, могут попадать в почву вблизи дорог с пылью или смывом и вносить значительный вклад в загрязнение придорожных территорий [16,36,[76][77][78]. Существуют данные об ежегодном уровне выбросов шинной пыли в размере около 10 тысяч тонн в Швеции, а в Германии -до 110 тысяч тонн [38]. ...
Article
Повсеместное использование пластмассы привело к увеличению количества пластикового мусора, накапливающегося в окружающей среде и разрушающегося на мелкие фрагменты, в том числе размером <5 мм – микропластик. За последнее десятилетие все большее количество исследований посвящается потенциальной опасности и методам анализа пластиковых частиц в водной среде. Однако, почвы могут быть загрязнены намного сильнее, при этом мало известно о накоплении микропластика в почве, возможных источниках, последствиях, взаимодействии пластиковых частиц с почвенными организмами и эффективных методах анализа. В данной статье представлен обзор, направленный на представление имеющейся информации о потенциальном экологическом воздействии микрочастиц пластика, возможных источниках и путях попадания в почвы, а также о предлагаемых методах аналитического контроля данного загрязнителя. Обзор позволяет наметить основные методологические проблемы, задачи и перспективы исследований в данной области. The ubiquitous use of plastics has led to an increase in the amount of plastic debris that accumulates in the environment and breaks down into small fragments, including <5 mm microplastics. Over the past decade, an increasing amount of research has focused on the potential hazards and methods for analyzing plastic particles in the aquatic environment. However, soils can be much more heavily contaminated, and little is known about the accumulation of microplastics in soil, possible sources, consequences, interactions of plastic particles with soil organisms, and effective methods of analysis. This article provides an overview aimed at presenting the available information on the potential environmental impacts of microplastics, possible sources and routes of entry into soils, and proposed methods for the analytical control of this pollutant. The review allows to outline the main methodological problems, tasks and prospects for research in this area.
... Abrasion of road markings may also contribute significant MPs to the urban environment (NIPHE 2016). Tire and road wear particles typically consist of ~25% synthetic polymers by mass (Kreider et al., 2010;Unice et al., 2019), and are considered MPs because their physicochemical properties and size range meet the definition of MPs (Campanale et al., 2022). In the EU, tire and road wear particles are reported to form at a rate of ~1 kg per person per year (Kole et al., 2017). ...
Article
Public concerns on microplastic (MP) pollution and its prevalence in urban runoff have grown exponentially. Huge amounts of MPs are transported from urban environments via surface runoff to different environment compartments, including rivers, lakes, reservoirs, estuaries, and oceans. The global concentrations of MPs in urban runoff range from 0-8580 particles/L. Understanding the sources, abundance, composition and characteristics of MPs in urban runoff on a global scale is a critical challenge because of the existence of multiple sources and spatiotemporal heterogeneity. Additionally, dynamic processes in the mobilization, aging, fragmentation, transport, and retention of MPs in urban runoff have been largely overlooked. Furthermore, the MP flux through urban runoff into rivers, lakes and even oceans is largely unknown, which is very important for better understanding the fate and transport of MPs in urban environments. Here, we provide a critical review of the global occurrence, transport, retention process, and sinks of MPs in urban runoff. Relevant policies, regulations and measures are put forward. Future global investigations and mitigation efforts will require us to address this issue cautiously, cooperating globally, nationally and regionally, and acting locally.
... Tyre and road wear particles can be mainly found in road runoff, roadside soils and river sediments; only a minor fraction is emitted in the atmosphere but it can reach a very high concentration in tunnel dust. It is estimated that around 90% of the material emitted consists of particles with dimension >10 mm and its contribution to ambient PM 10 and PM 2.5 ranges from 0.25 to 7 wt% [55,58,59]. Only few information can be found on the terrestrial toxicity of TRWP and on the entry paths of TRWP in the aquatic environment. ...
Article
The increasing motorisation rate worldwide is responsible for the demand of huge quantities of tyres that, after their useful service life, become waste and should be properly managed. Due to the relative low cost of tyres and the complexity related to recycling, worldwide around 41 % of the total amount of end-of-life tyres are discarded into landfills or stockpiles without any recovery of the material or of the energy. Moreover, the chemical composition of tyres makes them extremely resistant to degradation phenomena with a potential long-term permanence in the environment. The high energy amount required for the production of tyres and the related environmental impact should encourage the recycling of tyres and also promote the adoption of maintenance activities, such as retreading, that allow a considerable increase in the useful service life of tyres with consequent reduction in GHG emissions. In this article the relevant literature describing the current status of end-of-life options worldwide, the European legislation regarding tyre waste, their possible uses and the related environmental aspects are presented.
... During the tire use on the road, it will generate micronized rubber particles from abrasion, where they will mix with other materials and particulates deposited on the road (e.g. minerals, metals and salts) (Kreider et al., 2010;Unice et al., 2013;Kovochich et al., 2021). Estimates suggest that 10-17% of a tire is transferred into the environment as TWPs due to abrasion (Lassen et al., 2015;Unice et al., 2019aUnice et al., , 2019b. ...
Full-text available
Article
The interest in tire wear particles (TWPs), generated from abrasion of tires, have gained traction over the past few years, both in regards to quantifying particulate emissions, leaching of different compounds, toxicity, and analytical methods. The life of a tire, from cradle to end-of-life, crosses over different scenarios during its lifetime and transcends environmental compartments and legislative areas, underlining the need for a collective approach. Sustainability for a tire encompasses the use of raw materials, recycling of raw materials, circular economy and material sourcing. The tire industry is currently making significant efforts towards a greener and more sustainable production considering reduction of CO2-emissions, recycling, material sources and implementing the use of biomass from plants rather than oil-derived alternatives. In this paper, we aim to analyze and discuss the need for environmental regulation of tires in order to provide a series of targeted recommendations for future legislation. Our study shows that the numerous regulations related to tires focus on chemicals, manufacturing, raw materials, use of tires on roads, waste handling, safety and polycyclic aromatic hydrocarbons (PAHs) in different life cycle stages of a tire. However, none directly addresses the contribution of TWPs to the environment. Despite the overall good intentions of the existing regulations, there is a lack of focus on the compounds that partition from the tire and disperse in the environment, their mixture effects, and the transformative products from the parent compounds in the environment. Therefore, a renewed focus is needed on risk assessment of complex mixtures like TWPs. Thus, transparency in regard to use of chemicals in TWP, mixtures, minimization of emissions, and capture of particulate pollution should be a priority.
... For example, using a road simulator, one study found that TWPs had a bimodal size distribution that peaked at 0.3 μm and 4-5 μm (Aatmeeyata et al., 2009). Kreider et al. (2010) reported the majority of TWPs generated by a road simulator (collecting particles >0.3 μm) to be 5 μm and 25 μm in size, while Kwak et al. (2013) reported sizes in the range of 2-3 μm. Smaller particles have also been detected. ...
Full-text available
Article
Pollution derived from car tires is of growing research interest due to its apparent omnipresence in the urban environment and its associated toxicity. Studies have focused largely on the occurrence of these tire materials, deemed tire wear particles (TWPs), and their associated chemicals in the aquatic environment. However, less attention has been paid to atmospheric TWPs, which can remain airborne and be transported over long distances. In addition, there are few studies pertaining to the gaseous contaminants originating from tire wear, creating a significant knowledge gap. This review aims to summarize the current state of knowledge surrounding atmospheric tire wear pollution by detailing relevant studies conducted under both laboratory and ambient environmental conditions. Organic chemicals that are associated with this form of pollution, including diphenylamine antioxidants, phthalates, benzothiazole, benzotriazoles, and alkylphenols were highlighted for their potential implications for air. While a number of studies have investigated oxidation in aquatic environments, the current review highlights a clear absence of oxidation product information relevant to air. There is also a critical research gap surrounding the physico-chemical properties of these potential atmospheric pollutants. As a result, the environmental behaviour and fate of these contaminants are largely unknown. Based on these knowledge gaps, we propse recommendations for future work to advance this area of research.
... Chemical analysis showed that the carcinogenicity of harmful substances from tire and roadway wear is not less than engine exhaust gases (Kreider et al., 2010). Harmful substances of non-exhaust origin are not highly volatile. ...
Article
The aim of the study was to assess the harmful emissions of non-exhaust origin in Chelyabinsk. On asphalt roads 75% of the harmful emissions were 0.3 µm particulate matter. Removing 30 m from the roadway reduced the concentration of harmful substances by 5-7 times. By 2030, the number of vehicles in Chelyabinsk will increase by 25%. This will increase the amount of harmful emissions from tire and roadway wear by 20 tons per year.
... Tyre wear particles (TWP) are generated during the interaction between road surface and tyre. The size range of TWP is between 4 μm to several 350 μm (Kreider et al., 2010). The size and shape of TWP depends on different parameters such as tyre compositions, vehicle characteristics, road surface condition, driving operation (Baensch-Baltruschat et al., 2020). ...
... Average concentrations of harmful substances in the air begin to exceed the Maximum Permissible Concentrations (MPC), with a traffic intensity of more than 500 vehicles per hour (Table 3). Chemical analysis has shown that the carcinogenicity of substances from tire and roadway wear is not less than engine exhaust gases [36]. Harmful substances of non-exhaust origin are not highly volatile. ...
Full-text available
Article
Harmful emissions from tire wear and roadway wear are released into the air during the operation of vehicles. Particulate road dust contains carcinogenic substances. The amount and dispersion of particulate matter in road dust was determined with a portable laser particle counter. On asphalt roads, 75% of the harmful emissions were 0.3 µm particulate matter. On dirt roads, 95% of emissions were from particles less than 1 µm. The amount of large fractions of harmful emissions did not exceed 1.5%, regardless of traffic intensity. 30 m from the roadway, the concentration of harmful substances reduced by five- to sevenfold. By 2030, the number of vehicles in Chelyabinsk will increase by 25%. This will increase the amount of harmful emissions from tire and roadway wear by 20 tons per year.
... Previous tests on test benches have shown that tire particles have larger particle sizes than brakes due to the material properties and friction contact. The majority of the emitted tire particles were measured in a size range of approximately 10 µm or larger [2,4]. The particles from the brake contact, on the other hand, were usually measured in a controlled test environment in a size range of fewer than 3 µm, which increases the health risk for humans [5,6]. ...
Conference Paper
In recent years, the improvement of air quality in Germany, but also worldwide, has increasingly moved into the public focus. Since the turn of the millennium, a significant aspect of improving air quality has been seen in the reduction of household emissions, for example, and in the adjustment of traffic-related emissions. Due to legal requirements, exhaust emissions have been significantly reduced as a result of technological innovations, whereby other emission sources have moved to the fore. In particular, non-exhaust emissions, such as tire abrasion, resuspension of fine dust and brake emissions are major sources of emissions that have a sustained impact on air quality. Air quality monitoring is carried out throughout Europe with high precision and very expensive measuring stations, which are distributed locally to individual locations in a city. Based on this data, measures such as driving bans or road closures are initiated. Due to the high price, a comprehensive and locally high-resolution measurement in a city is not feasible, which means that individual events such as acceleration and braking cannot be detected. In this work, swarm measurements are performed in a controlled environment with the help of low-cost fine dust sensors in order to be able to conclude about individual traffic events. Thereby a temporal and local dynamic of the emitted particles, for example during braking, will be investigated. The aim is to measure the distribution of particles around a vehicle during a specific driving event. A differentiation of the particle concentration will be investigated for different measurement scenarios.
... The results show that PM concentrations were positively correlated with the average vehicle speed. Particles occur through volatilization and by shearing Kreider et al. (2010) and friction forces. In fact, the shearing forces mechanism practically induces coarse particles, whereas the volatile mechanism produces smaller fine particles via evaporation . ...
... The coarse fraction had high contribution of Ca (with 62% loading) which is an element that is used during road construction and can be used as a tracer for paved road wear (Piscitello et al., 2021), however no clear road construction contribution or soil tilling could be identified ( Figure S4). The coarse fraction was also enriched in Sr (26.3%) and Mn (22.8%), which come from brake linings and asphalt pavement materials (Adachi and Tainosho, 2004;Kreider et al., 2010). Both coarse and fine fractions had high Zn (55.8% and 62.9%), respectively, which is used in tyre manufacturing in the form of ZnO and is widely considered a tracer for tyre wear in the near-road environment (Pant and Harrison, 2013; J o u r n a l P r e -p r o o f Harrison et al., 2012). ...
Article
Traffic-related particulate matter (PM) plays an important role in urban air pollution. However, sources of urban pollution are difficult to distinguish. This study utilises a mobile particle concentrator platform and statistical tools to investigate factors affecting roadway ambient coarse particle (PM10–2.5) and fine particle (PM2.5–0.2) concentrations in greater Boston, USA. Positive matrix factorization (PMF) identified six PM10–2.5 sources (exhaust, road salt, brake wear, regional pollution, road dust resuspension and tyre-road abrasion) and seven fine particle sources. The seven PM2.5–0.2 sources include the six PM10–2.5 sources and a source rich in Cr and Ni. Non- exhaust traffic-related sources together accounted for 65.6% and 29.1% of the PM10–2.5 and PM2.5–0.2 mass, respectively. While the respective contributions of exhaust sources were 10.4% and 20.7%. The biggest non-exhaust contributor in the PM10–2.5 was road dust resuspension, accounting for 29.6%, while for the PM2.5–0.2, the biggest non-exhaust source was road-tyre abrasion, accounting for 12.3%. We used stepwise general additive models (sGAMs) and found statistically significant (p < 0.05) effects of temperature, number of vehicles and rush hour periods on exhaust, brake wear, road dust resuspension and road-tyre abrasion with relative importance between 19.1 and 62.2%, 12.5–42.1% and 4.4–42.2% of the sGAM model's explained variability. Speed limit and road type were also important factors for exhaust, road-tyre and brake wear sources. Meteorological variables of wind speed and relative humidity were significantly associated with both coarse and fine road dust resuspension and had a combined relative importance of 38% and 48%. The quantifying results of the factors that influence traffic-related sources can offer key insights to policies aiming to improve near-road air quality.
... Approximately 30% of the weight of a tire is emitted to the environment from use to scrap materials [24]. Simulation studies show that microscale and nanoscale particles are derived from tires under constant friction [25][26][27]. In addition, an analysis of airborne particles near a road showed that the size of the particles ranged from 6 to 562 nm and from 30 to 60 nm when cars were braking [28]. ...
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Nanoplastics are associated with several risks to the ecology and toxicity to humans. Nanoplastics are synthetic polymers with dimensions ranging from 1 nm to 1 μm. They are directly released to the environment or secondarily derived from plastic disintegration in the environment. Nanoplastics are widely detected in environmental samples and the food chain; therefore, their potentially toxic effects have been widely explored. In the present review, an overview of another two potential sources of nanoplastics, exposure routes to illustrate hazard identification of nanoplastics, cell internalization, and effects on intracellular target organelles are presented. In addition, challenges on the study of nanoplastics and future research areas are summarized. This paper also summarizes some approaches to eliminate or minimize the levels of nanoplastics to ensure environmental safety and improve human health.
... Tire tread wear is one of principal non-exhaust dust sources produced from road traffic along with brake and pavement wear [1][2][3][4][5][6][7][8][9][10]. Abraded tire tread material without other particles is called tire tread wear particles or tire wear particles (TWP), and TWP combined with other particles including road wear materials deposited on the road is called tire-road wear particle (TRWP) [2,4,8,9,11]. Tire tread contacts with the road surface including lots of mineral particles (MPs) during driving and it is abraded by friction with the road surface. During the wear process, the tire tread interacts with many MPs and some MPs will be stuck into the rubber to produce TRWPs. ...
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Tire tread wear particles (TWPs) are one of major sources of microplastics in the environment. Tire–road wear particles (TRWPs) are mainly composed of TWPs and mineral particles (MPs), and many have long shapes. In the present work, a preparation method of model TRWPs similar to those found in the environment was developed. The model TRWPs were made of TWPs of 212–500 μm and MPs of 20–38 μm. Model TWPs were prepared using a model tire tread compound and indoor abrasion tester while model MPs were prepared by crushing granite rock. The TWPs and MPs were mixed and compressed using a stainless steel roller. The TWPs were treated with chloroform to make them stickier. Many MPs in the model TRWP were deeply stuck into the TWPs. The proper weight ratio of MP and TWP was MP:TWP = 10:1, and the double step pressing procedure was good for the preparation of model TRWPs. The model TRWPs were characterized using scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The model TRWPs had long shapes and the MP content was about 10%. The model TRWPs made of TWPs and asphalt pavement wear particles showed plate-type particles deeply stuck into the TWP. Characteristics of model TRWPs can be controlled by employing various kinds and sizes of TWPs and MPs. The well-defined model TRWPs can be used as the reference TRWPs for tracing the pollutants.
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Particulate Matter (PM) concentrations near highways are influenced by vehicle tailpipe and non-tailpipe emissions, other emission sources, and urban background aerosols. This study collected PM2.5 and PM10 filter samples near two southern California highways (I-5 and I-710) over two weeks in winter 2020. Samples were analyzed for chemical source markers. Mean PM2.5 and PM10 concentrations were approximately 10–15 and 30 μg/m³, respectively. Organic matter, mineral dust, and elemental carbon (EC) were the most abundant PM components. EC and polycyclic aromatic hydrocarbons at I-710 were 19–26% and 47% higher than those at the I-5 sites, respectively, likely due to a larger proportion of diesel vehicles. High correlations were found for elements with common sources, such as markers for brake wear (e.g., Fe, Ba, Cu, and Zr) and road dust (e.g., Al, Si, Ca, and Mn). Based on rubber abundances, the contributions of tire tread particles to PM2.5 and PM10 mass were approximately 8.0% at I-5 and 5.5% at I-710. Two different tire brands showed significantly different Si, Zn, carbon, and natural rubber abundances.
Article
Tire and road wear particles (TRWP) are polymer-based microparticles that are emitted into the environment during tire usage. Growing efforts are currently being made to quantify these emissions, characterize the leachates and assess their environmental impact. This study aimed to investigate the effect of aging on TRWP composition. Cryomilled tire tread particles (CMTTP) and TRWP were exposed for different durations to three aging conditions: accelerated thermal and photochemical aging and natural outdoor aging. Particles were then extracted with cyclohexane/ethanol. The time-concentration profiles of 23 additives and transformation products present in these extracts were determined by UHPLC-HRMS. Several chemicals, such as N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6-PPD) or 1,3-diphenylguanidine (DPG), decayed exponentially under all aging conditions, with half-lives of a few days under artificial photoaging versus dozens of days under pure thermal aging at 60 °C. The natural aging profiles lie between those 2 laboratory aging conditions. Other chemicals, such as 6PPD-quinone, presented bell-shaped concentration profiles within CMTTP when particles were exposed to UV light. 6PPD-quinone reached a maximal concentration within a month under natural aging. For TRWP, the initial load of 6PPD-quinone had already reached a maximum prior to the aging experiments and decreased exponentially under natural aging with a half-life below one month. Pure thermal aging induced a significantly slower decay of 6PPD-quinone within TRWP (half-life of half a year), emphasizing a greater stability and persistence in environmental compartments without light. This study highlighted that the more readily accessible CMTTP could be considered a reasonable proxy of TRWP to investigate the fate of chemicals within rubber particles, at least from a qualitative standpoint. Overall, the concentrations of 20 of the evaluated chemicals decreased by >50 % within 50 days under natural aging.
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Tire wear particles (TWP) are assumed to be one of the major sources of microplastic pollution to the environment. However, many of the previously published studies are based on theoretical estimations rather than field measurements. To increase the knowledge regarding actual environmental concentrations, samples were collected and analyzed from different matrices in a rural highway environment to characterize and quantify TWP and other traffic-derived non-exhaust particles. The sampled matrices included road dust (from kerb and in-between wheeltracks), runoff (water and sediment), and air. In addition, airborne deposition was determined in a transect with increasing distance from the road. Two sieved size fractions (2–20 µm and 20–125 µm) were analyzed by automated Scanning Electron Microscopy/Energy Dispersive X-ray spectroscopy (SEM/EDX) single particle analysis and classified with a machine learning algorithm into the following subclasses: TWP, bitumen wear particles (BiWP), road markings, reflecting glass beads, metals, minerals, and biogenic/organic particles. The relative particle number concentrations (%) showed that the runoff contained the highest proportion of TWP (up to 38 %). The share of TWP in kerb samples tended to be higher than BiWP. However, a seasonal increase of BiWP was observed in coarse (20–125 µm) kerb samples during winter, most likely reflecting studded tire use. The concentration of the particle subclasses within airborne PM80-1 decreases with increasing distance from the road, evidencing road traffic as the main emission source. The results confirm that road dust and the surrounding environment contain traffic-derived microplastics in both size fractions. The finer fraction (2–20 µm) dominated (by mass, volume, and number) in all sample matrices. These particles have a high potential to be transported in water and air far away from the source and can contribute to the inhalable particle fraction (PM10) in air. This highlights the importance of including also finer particle fractions in future investigations.
Chapter
Water treatment plants are capable of removing a fraction of micro and nanoplastics (MPs and NPs) in influents. It shows that the produced sludge through water treatment is highly contaminated by MPs and NPs. This pollution not only limits the conventional sludge treatment practice such as landfilling but also could highly affect the sludge treatment processes as well as sludge application for the agricultural sector. In this chapter, the accumulation of MPs and NPs in sludge was studied to evaluate the effects of these emerging contaminants on sludge management and application. In this way, composition of the sludge of water treatment plants as well as the abundance and potential sources of MPs and NPs in different sludge are first evaluated. Afterward, the influences of water treatment plant characteristics and sludge treatment processes on MP and NP removal are assessed. The effects of MPs and NPs on microbial community diversity in sludge are then studied to better understand the effect of these pollutions on activated sludge and sludge treatment processes. Finally, the implications of using sludge on agricultural soils are discussed.
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Microplastics (plastic particles <5 mm) are abundant in aquatic environments, particularly near urban areas. Little is known, however, about how variations in microplastic abundances within watersheds affect fishes. Microplastics were examined in demersal fishes—white sucker (Catostomus commersonii) and common carp (Cyprinus carpio)—across 11 sites in the Thames River, Ontario, Canada. Microplastics were found in 44% of white sucker, ranging from 0 to 14 particles per fish, and 31% of common carp, ranging from 0 to 128 particles per fish. Across both species, the number of microplastics was higher in urban sites than rural sites, and there was a positive relationship between the number of microplastics in the fish and the abundance of microplastics in the sediment. Body mass was also positively related to number of microplastics in fish. Together these results provide insight into environmental and biological factors that may be influencing microplastic ingestion in demersal fishes.
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The abrasion behavior of model tire tread compounds was characterized by the shapes and size distributions of their wear particles. Carbon black-filled NR/BR vulcanizates with varying compositions (NR/BR = 100/0, 80/20, and 60/40) were used. These were thermally aged at 80 °C for 30 days. The wear particles produced from the aged specimen had rougher shapes than those produced from the unaged specimen. The size distributions of wear particles for the aged specimen were smaller than those for the unaged specimen. The wear particles produced from the NR = 100 sample had a larger size distribution than those produced from the NR/BR blend samples. The size distributions of wear particles smaller than 500 μm were found to be closely related to the crosslink density irrespective of the rubber composition and thermal aging. The aged samples exhibited narrower abrasion patterns than their unaged samples. Furthermore, the spacing and depth decreased as the BR content increased. The abrasion patterns were closely related to the size distributions of wear particles. The abrasion rates and the number of wear particles significantly increased after the thermal aging. The abrasion behavior was mainly affected by the crosslink density, rubber composition, presence of antidegradants, and tensile strength. By analyzing the shapes and size distributions of the wear particles and the crosslink densities, the abrasion behavior could be further elucidated.
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Road pavements are exposed to traffic loading and external deterioration agents which both can compromise tire-pavement interactions, posing a threat to road safety. The surface wear generates crushed pavement materials or tire rubber wear particles which, combined with other contaminants, negatively impact the environment. In fact, these particles may remain on the road surface; adhere to tires; become airborne; or drain by rainfall to roadsides, waterways, lakes, and even open oceans. Therefore, the presence of road contaminants on road infrastructure pavements is a concern for both road safety and the environment. Although the condition of pavement, traffic intensity, airborne dust emissions, and roadside environments are significantly monitored by road practitioners, especially in urban areas, there is still a need to better evaluate the pollutants remaining on road surfaces. It is known that particles smaller than 40 μm can be trapped within micro-asperities and remain on road surfaces, while particles of larger sizes can be transported by rainfall. However, it is difficult to mobilize particles with sizes larger than 105 μm by storm water runoffs, which tend to remain on road surfaces. Hence, not only rainfall characteristics are responsible of particle’s kinetics, but also particle’s size and road surface roughness are important. Therefore, this paper presents an overview of road safety and environmental concerns around contaminants, highlighting the importance of the road surface characteristics in their behavior. Finally, the current methods to measure road surface characteristics and their application for environmental and safety issues are discussed.
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PM10 aerosol was measured during one semester, simultaneously, at a roadside (RS) and an urban background (UB) location in Coimbra, Portugal. On average, the mass concentrations were 36% higher at the RS, compared to UB. Application of Positive Matrix Factorisation (PMF) and Ionic Mass Balance (IMB) methodologies permitted to source apportion the aerosol mass. During the cold season, biomass burning was a prevalent particulate matter source at both urban locations, contributing with up to 30% of PM10. At the RS, vehicle non-exhaust emissions (brake, tyre and road dust) doubled exhaust emissions by combustion engines, accounting for 18–19% of PM10. Unreacted and reacted sea salt was an important fraction of PM10, principally during the warm season, when it composed approximately 25% of the aerosol. Secondary pollution by ammonium salts and carbonaceous matter was important across the seasons, especially at the UB location, where they dominated the particulate mass.
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Microrubber (MR) encompasses all tire-related particles in the micro-scale and has recently drawn increased attention as a subclass of the broader group of microplastics. While tire particles entered the environment since the introduction of rubber tires for vehicles, the concern regarding tire wear particles (TWP) as an environmental contaminant is relatively new. Recent studies have examined physical and chemical toxicity of MR particles and leachates to a variety of organisms. However, there is a lack of information on the long-term effects of tire particle exposure under environmentally realistic conditions. The current study examined the chronic toxicity of crumb rubber (CR) particles to the estuarine fish species, mummichog (Fundulus heteroclitus) under episodic exposures at environmentally relevant concentrations. Immunohistochemistry (IHC) of fish gill, intestine, and liver was performed to assess CYP1A induction in these organs. Bile fluorescence was measured as an indicator of exposure to polycyclic aromatic hydrocarbons (PAHs) from CR. DNA damage was measured through the formation of 8-hydroxy-2′-deoxyguanosine (8-OHdG) together with other oxidative stress measures as lipid peroxidation (TBARS assay), free glutathione (GSH), and oxidized glutathione (GSSG) concentrations. Upregulation of CYP1A in gill, intestine, and liver was observed especially in gill filaments and general vasculature. Increased bile fluorescence demonstrated exposure to aromatic compounds, especially pyrene-like PAHs. Data for DNA damage indicated greater plasma 8-OHdG concentrations as a result of increased DNA repair. There was a decrease in malondialdehyde (MDA) production and an increase in total GSH at higher concentrations of CR. It appeared that under long-term repeated dosing, antioxidant systems in mummichog were upregulated to deal with exogenous stressors released by the CR particles. Combined, these data demonstrate that fish exposed to tire crumb rubber particles illicit significant biomarker responses under environmentally relevant CR concentrations, but induced antioxidant and detoxification pathways may prevent mortality and serious physiological effects in F. heteroclitus when exposed to environmentally relevant concentrations of CR.
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As natural carbon sinks, coastal wetlands are of great significance to alleviate global climate change. However, due to environmental pollution, the soil carbon sequestration capacity of coastal wetlands is decreasing, and then the emission of CO 2 is accelerated. The Yellow River Delta is one of the largest deltas in China. Economic development and human activities have led to the input of large quantities of microplastics. Microplastics can alter soil properties, causing the emission of CO 2 to be affected. However, the impact of common microplastics in coastal wetlands on CO 2 generation and emission is not clear. In this study, tread particles (TP) and polypropylene (PP) particles were applied to coastal wetland soil to study their effects on greenhouse gas CO 2 emissions. The results showed that the cumulative emission of CO 2 increased by 32.7% - 49.5% and 13.9% - 24.6% respectively compared with CK 14 days after the addition of TP and PP. The promoting effect of TP was stronger than that of PP. The results provided theoretical and basic data support for the evaluation of greenhouse gas emissions and atmospheric environmental effects of Yellow River Delta wetlands under microplastics pollution.
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Microplastic categorization schemes are diverse, thereby posing challenges for cross‐study comparisons. Further, categorization schemes are not necessarily aligned with, and thus useful for applications such as source reduction initiatives. To address these challenges, we propose a hierarchical categorization approach that is “fit for purpose” to enable the use of a scheme that is tailored to the study’s purpose and contains categories which, if adopted, would facilitate inter‐study comparison. The hierarchical categorization scheme is flexible to support various study purposes (e.g., to support regulation, toxicity assessment) and it aims to improve the consistency and comparability of microplastics categorization. Categorization is primarily based on morphology, supplemented by other identification methods as needed (e.g., spectroscopy). The use of the scheme was illustrated through a literature review aimed at critically evaluating the categories used for reporting microplastics morphologies in North American freshwater environments. Categorization and grouping schemes for microplastic particles were highly variable, with up to 19 different categories used across 68 studies, and nomenclature was inconsistent across particle morphologies. Our review demonstrates the necessity for a “fit for purpose” categorization scheme to guide the information needs of scientists and decision‐makers for various research and regulatory objectives across global, regional, and local scales. This article is protected by copyright. All rights reserved.
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Tires generally wear out due to the friction between the tire and the road surface. Minimizing tire wear could reduce the non-exhaust particulate matter (PM) emissions from tires. Typically, tire treadwear grade can be used as an indicator of PM emissions from tires. Tires that wear out quickly will produce higher PM emissions than more durable tires. In this study, the effect of treadwear grade on the generation of tire PM emissions was investigated through laboratory and on-road driving measurements. In the laboratory measurements, a tire wear simulator installed in an enclosed chamber was used to eliminate artifacts caused by interfering particles during the generation and measurement of tire wear particles. For realistic on-road driving measurements, a mobile sampling vehicle was employed to sample road dust. The road dust was chemically analyzed using pyrolysis gas chromatography–mass spectrometry (GC–MS) to characterize the tire-road wear particles. Both measurements showed that the higher treadwear grade generated lower tire PM emissions due to the high strength of the rubber, except for the UTQG 700 tire. The UTQG 700 tire, which had the highest treadwear grade, produced higher PM emissions than the UTQG 350 and 500 tires because it readily formed the fine particles due to lamellar peeling rather than tearing or curling of tire treads. Notably, tire nanoparticles were observed in laboratory measurements due to the volatilization and nucleation of the sulphur (S) and zinc (Zn) compounds in the tire tread due to the frictional heat between the tire and paved road surface.
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The environmental threat represented by tire and road wear particles (TRWPs) has highlighted the need for effective analytical strategies for their detection and quantitation in different matrices. To date, however, there is little consensus in the literature on how to obtain reliable data on TRWPs in environmental samples, which chemical marker should be used, and how analytical results can be correlated with the amount of particulate. This review compares the analytical strategies described in the literature from a critical point of view and outlines the most crucial aspects, giving an overview of the current knowledge and discussing the analytical challenges that need to be addressed. The literature highlights the critical role played by the selection of detection and quantitation markers, the variations in the formulation of the tires, the environmental degradation pathways of TRWPs components, and the effects of the sample matrix and composition on the analytical response.
Chapter
During normal driving conditions, wear particles are formed due to the friction between tire tread and road surface. To derive realistic particles for study purposes, basically, two approaches can be taken: Either collection outdoor under real usage conditions or indoor under very controlled conditions. The first approach is challenging due to many disturbing factors, while the second might be biased by choosing specific conditions. This article describes how both approaches are used in combination to ensure field relevance of high-quality characterization insights. Particle samples collected from the environment always contain material from both surfaces—the tire tread and the road, which is why in this context we refer to TRWP (Tire Road Wear Particles), which consist of combined material—roughly 50%/50% (by mass)—from both sources. To capture those TRWP outdoor under real usage conditions a special vehicle was used which is equipped with a vacuum cleaner system in the wheelhouse. For further evaluation the samples were further refined and analyzed. For better assignment of the collected material to the dedicated test tire a TiO2 marker was used. A trend between driving conditions and detected particle size was observed which must be further investigated. Under lab conditions the generated particles can be assigned explicitly to the specific compound and to the operation conditions. The particles are observed with optical methods direct at the sample wheel or separately offline after collection. The obtained images are processed applying methods from the field of “Particle Object Tracking”, such as Feature-Point-Detection and Blob-Analysis. As an outcome, individual rubber particles are identified, tracked and characterized. Finally, the size distribution of the particles can be concluded from the entity of all particles, whereby information about the shape of each individual particle is available. Through these insights on size and shape environmental impact of TRWP can be determined more accurately and—most importantly—suitable mitigation approaches can be derived.
Chapter
Microplastics (MPs), an emerging global pollutant, are widely present in different ecosystems due to the overuse of plastic worldwide, causing potential risks to the health of humans and other animals. Wastewater contains high levels of MPs, and most of them (≈99%) remain in sewage sludge even after highly efficient wastewater treatment processes. Part of these MPs finally enters the soil ecosystem as sludge is spread on soil. Many studies have focused on MPs in marine ecosystems or other aquatic environments, while limited research has focused on MPs in sewage sludge. Therefore, we strive to comprehensively describe the current and latest state of MPs in sewage sludge. Several main sources of MPs in sludge are summarized. The traditional pretreatment, extraction, and identification methods as well as some latest new methods are illustrated. The influence of MPs in sludge on sewage treatment, sludge digestion, and soil (including the effects on fauna, plants, and microorganisms in soil) are summarized. Based on this information, we also offer several proposals involving MPs in sewage sludge for future research.
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Pavement surface texture significantly contributes to tire wear and tire-pavement friction. Currently available relationships quantify tire wear and tire-pavement friction simply in terms of empirical pavement texture parameters. The objective of this paper is to present correlations with which the tire wear rate and tire-pavement friction on smooth concrete pavements can be predicted using actual texture properties. Using a laboratory tire wear simulator and an aircraft tread-rubber block, a number of wear and friction tests are performed on pavement samples having different fine aggregate sizes. Frequency characteristics of the texture of the pavements are achieved by decomposing the profilometer measurements using the fast Fourier transform technique and constructing power spectral density plots of texture over surface spatial frequency. Then the tire wear rates as well as dry friction and wet friction of the tire-pavement interface are correlated to microtexture and macrotexture components of the texture power spectral density. The developed correlations indicate that both tire wear and dry friction are significantly affected by pavement microtexture. The developed wear correlations can be also useful for predicting the wear index of a pavement based on conventional Mu-meter and grease patch test results. This is illustrated by an example in which the wear index for a concrete runway pavement at Luke Air Force Base, Ariz., is computed using the new relations.
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Samples of creek bed sediment collected near seal-coated parking lots in Austin, Texas, by the City of Austin during 2001-02 had unusually elevated concentrations of polycyclic aromatic hydrocarbons (PAHs). To investigate the possibility that PAHs from seal-coated parking lots might be transported to urban creeks, the U.S. Geological Survey, in cooperation with the City of Austin, sampled runoff and scrapings from four test plots and 13 urban parking lots. The surfaces sampled comprise coal-tar-emulsion-sealed, asphalt-emulsion-sealed, unsealed asphalt, and unsealed concrete. Particulates and filtered water in runoff and surface scrapings were analyzed for PAHs. In addition, particulates in runoff were analyzed for major and trace elements. Samples of all three media from coal-tar-sealed parking lots had concentrations of PAHs higher than those from any other types of surface. The average total PAH concentrations in particulates in runoff from parking lots in use were 3,500,000, 620,000, and 54,000 micrograms per kilogram from coal-tar-sealed, asphalt-sealed, and unsealed (asphalt and concrete combined) lots, respectively.
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In a road simulator study, a significant source of sub-micrometer fine particles produced by the road–tire interface was observed. Since the particle size distribution and source strength is dependent on the type of tire used, it is likely that these particles largely originate from the tires, and not the road pavement. The particles consisted most likely of mineral oils from the softening filler and fragments of the carbon-reinforcing filler material (soot agglomerates). This identification was based on transmission electron microscopy studies of collected ultrafine wear particles and on-line thermal treatment using a thermodesorber.The mean particle number diameters were between 15–50 nm, similar to those found in light duty vehicle (LDV) tail-pipe exhaust. A simple box model approach was used to estimate emission factors in the size interval 15–700 nm. The emission factors increased with increasing vehicle speed, and varied between 3.7×1011 and 3.2×1012 particles vehicle−1 km−1 at speeds of 50 and 70 km h−1. This corresponds to between 0.1–1% of tail-pipe emissions in real-world emission studies at similar speeds from a fleet of LDV with 95% gasoline and 5% diesel-fueled cars. The emission factors for particles originating from the road–tire interface were, however, similar in magnitude to particle number emission factors from liquefied petroleum gas-powered vehicles derived in test bench studies in Australia 2005. Thus the road–tire interface may be a significant contributor to particle emissions from ultraclean vehicles.
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Pulmonary responses in rats were compared after short-term inhalation exposure to polymorphs of silica dust. Groups of CD rats were exposed 6 h a day for 3 d to crystalline silica or amorphous silica. Another group was exposed to Ludox colloidal silica for 6 h a day, 5 d a week for two or four weeks. Thereafter the groups were killed, and the lungs washed at several postexposure times. The crystalline silica produced persistent pulmonary inflammatory responses characterized by neutrophil recruitment and consistently elevated biomarkers of cytotoxicity in bronchoalveolar lavage fluids, and progressive histopathological lesions were observed within one month of the exposure. Amorphous silica produced a transient pulmonary inflammatory response, and Ludox elicited transient pulmonary inflammatory responses at 50 or 150 mg center dot m-3 but not at 10 mg center dot m-3. After three months most of the biochemical values of the Ludox-exposed animals had returned to the control level. These results demonstrate that crystalline silica dust is more potent in producing pulmonary toxicity when compared with amorphous or colloidal silica particles.
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Tire dust is a significant pollutant, especially as a source of zinc in the urban environment. This study characterizes the morphology and chemical composition of heavy metal particles embedded in tire dust and traffic-related materials (brake dust, yellow paint, and tire tread) as measured by a field emission scanning electron microscope equipped with an energy dispersive X-ray spectrometer (FESEM/EDX). In 60 samples of tire dust, we detected 2288 heavy metal particles, which we classified into four groups using cluster analysis according to the following typical elements: cluster 1: Fe, cluster 2: Cr/Pb, cluster 3: multiple elements (Ti, Cr, Fe, Cu, Zn, Sr, Y, Zr, Sn, Sb, Ba, La, Ce, Pb), cluster 4: ZnO. According to their morphologies and chemical compositions, the possible sources of each cluster were as follows: (1) brake dust (particles rich in Fe and with trace Cu, Sb, and Ba), (2) yellow paint (CrPbO(4) particles), (3) brake dust (particulate Ti, Fe, Cu, Sb, Zr, and Ba) and heavy minerals (Y, Zr, La, and Ce), (4) tire tread (zinc oxide). When the chemical composition of tire dust was compared to that of tire tread, the tire dust was found to have greater concentrations of heavy metal elements as well as mineral or asphalt pavement material characterized by Al, Si, and Ca. We conclude that tire dust consists not only of the debris from tire wear but also of assimilated heavy metal particles emitted from road traffic materials such as brake lining and road paint.
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