Effects of Weathering on Microplastic Dispersibility and Pollutant Uptake Capacity

Harraq, Ahmed Al; Brahana, Philip J.; Arcemont, Olivia; Zhang, Donghui; Valsaraj, Kalliat T.; Bharti, Bhuvnesh

doi:10.1021/acsenvironau.2c00036

Cited by 40 publications

(34 citation statements)

References 49 publications

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“…Note that in the absence of microorganisms, the particles float to the air–water interface due to their inherent hydrophobicities. These particles remain hydrophobic even after 10 days in water, indicating that the additives in the model microplastics do not leach into the water and result in less buoyant microplastics over time …”

Section: Methodsmentioning

confidence: 99%

“…These particles remain hydrophobic even after 10 days in water, indicating that the additives in the model microplastics do not leach into the water and result in less buoyant microplastics over time. 20 Microbial Incubation. Alcanivorax was cultured in a modified marine broth, 21 and Synechococcus and Anabaena were cultured in a modified BG-11 medium 22 (see SI for details).…”

Section: Microplastics Polyethylene Model Microplastics (Spheres)mentioning

confidence: 99%

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Biofilm Formation Influences the Wettability and Settling of Microplastics

Pete

Brahana

Bello

et al. 2022

Environ. Sci. Technol. Lett.

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The fate of 99% of the plastics present in oceans is unknown. It is presumed that biofilm formation on plastics leads to their sinking to the ocean floor, thus making them undetectable at the surface. While it is established that biofilms lead to sinking of plastics, it is the mechanism by which biofilms enhance the vertical transport of plastics that remains unknown. It is commonly assumed that biofilms increase the effective mass density of the plastics, which drives their sinking. Here, we show that such an assumption is not always true, and formation of biofilms alone is an insufficient criterion to predict the sinking or floating of plastics. We study the biofilm formation and vertical transport of polyethylene microplastics in the presence of Alcanivorax borkumensis, Anabaena sp., and Synechococcus elongatus. We find that while all three microorganisms formed biofilms on microplastics, only Alcanivorax led to their sinking. The sinking of microplastics is attributed to the production of highly active biosurfactants by Alcanivorax and its adsorption onto microplastics, which is not the case for Anabaena and Synechococcus. Our study highlights that it is not only the formation but the properties of the formed biofilms that govern the sinking or floating of plastics.

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Section: Methodsmentioning

confidence: 99%

Section: Microplastics Polyethylene Model Microplastics (Spheres)mentioning

confidence: 99%

Biofilm Formation Influences the Wettability and Settling of Microplastics

Pete

Brahana

Bello

et al. 2022

Environ. Sci. Technol. Lett.

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“…The aging process has a significant impact on the composition and concentration of chemical functional groups present on the surface of microplastics. [37][38][39] This factor plays a crucial role in determining the wettability of microplastics in the environment and becomes increasingly important as the size of the microplastics decreases.…”

Section: Introductionmentioning

confidence: 99%

“…This was a challenging task as the pellets are large, which renders them susceptible to buoyancy, and not spherical, making it challenging to measure the binding energy at a hydrophilic-hydrophobic interface, as is usually done with smaller spherical colloids. 37,38 To address this issue, we determined the contact angle of a sessile water droplet deposited on the surface of one plastic pellet with a quasi-flat surface as observed through microscopic examination. The results of the contact angle Θ measurements, shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Ageing Affects the Mechanical Interaction between Microplastics and Lipid Bilayers

Fleury

Baulin

2023

Preprint

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Plastic pellets are the building blocks and pre-production form of many plastic products. Exposure to oxygen and sunlight leads to oxidation and photodegradation of the pellets, which results in a visible change in color. We investigate the effect of pellet-derived microplastics' aging on their mechanical interaction with lipid bilayers. For that purpose, polyethylene pellets were collected at the beach La Pineda near Tarragona, Spain. Pellets were sorted by chemical composition and a yellowing index, which was used as an indicator of aging. The hydrophilicity of the pellets was estimated through contact angle measurements. We produced microplastics from these pellets by grinding and filtering. Then, microplastics were dispersed around a free-standing bilayer formed in a 3D microfluidic chip to study interactions between microplastics and lipid bilayers. Our findings indicate that as the microplastics aged, the bilayer was stretched more significantly due to its increased adhesive interaction with the lipid bilayer. Interestingly, our theoretical model shows that the extracted adhesive interaction increases linearly with the measured pellet contact angle (e.g., pellet hydrophilicity). These findings raise concerns about the toxic risks that aged microplastics may pose to living organisms.

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“…Studies of sorption by microplastics are common in the literature. − Many show that uptake of organic compounds changes as the plastics age. , Published work includes investigations of the sorption mechanism (i.e., isotherm), strength, and kinetics. ,,− Most such studies have been performed by bulk methods that provide only average results. As a result, much remains to be learned about how different organics interact with plastic surfaces.…”

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confidence: 99%

Fluorescence Correlation Spectroscopy Studies of Dye Diffusion on Fresh and Aged Polyethylene Terephthalate

Rashidi,

Shafiee,

Higgins

2023

Anal. Chem.

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Microplastics accumulate a wide variety of organic pollutants and thus may serve as efficient vectors for the transport of toxic substances. Much remains to be learned about how organic molecules interact with the surfaces of plastics and how these properties evolve as the microplastics are weathered. In this Letter, we report, for the first time, the application of confocal fluorescence correlation spectroscopy (FCS) to studies of organic molecules adsorbed from aqueous solution onto the surfaces of synthetic secondary microplastics. Both fresh and artificially aged poly(ethylene terephthalate) (PET) plastics are employed. The plastics are artificially aged in a UV-ozone chamber. Raman and infrared spectra confirm the composition of the PET microplastics. Water contact angle and surface roughness measurements reveal, respectively, an increase in wettability and a change in the nature of roughness with aging, consistent with surface oxidation. Rhodamine B (RhB) dye is used as a fluorescent probe in FCS studies and serves as an analogue for organic pollutants commonly found on microplastics. The FCS results reveal the accumulation of dye on the PET surfaces as they age. Dye motion is significantly slower on the plastics than in bulk aqueous solution and occurs by anomalous subdiffusion. The rate of diffusion becomes dramatically slower and more anomalous as the plastics are aged. Surface diffusion is likely slowed by either ionic interactions or hydrogen bonding between the dye and plastic. These results provide new insights critical to the understanding of how microplastics accumulate and transport organic pollutants as they weather in the environment.

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Effects of Weathering on Microplastic Dispersibility and Pollutant Uptake Capacity

Cited by 40 publications

References 49 publications

Biofilm Formation Influences the Wettability and Settling of Microplastics

Biofilm Formation Influences the Wettability and Settling of Microplastics

Ageing Affects the Mechanical Interaction between Microplastics and Lipid Bilayers

Fluorescence Correlation Spectroscopy Studies of Dye Diffusion on Fresh and Aged Polyethylene Terephthalate

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