Airborne microplastics found in cloud water influence cloud formation
By Cody Stark-Vernier
News Article Link: News Article
Journal Article Link: Journal Link
Background
Microplastic pollution is occurring in most of the ecosystems on Earth, from sources like personal care products, paints, plastic bottles and containers, synthetic textiles, and even from tires (1). Microplastics (MP's) are defined as tiny plastic particles less than 5mm in size, which can be released and mixed around the globe from water and winds (1). This pollution has increased steadily since about 1950 when society ramped up commercial products with various plastics (2).
These microplastics can exist in many forms like fibers and fragments (2). MP's can also be classified as primary and secondary. The primary MP's include microbeads and abrasives whereas secondary MP's are formed from fragmentation of larger plastics (2). Usually in the oceans there is a higher concentration of secondary MP's (3). The future of MP's that pollute the ocean largely depend on their density relative to sea water, as their buoyancy in sea water determines where the MP is likely to initially reside (3).
The free troposphere serves as a key route for long-distance transport of air pollutants due to its strong wind currents; studies have shown that airborne microplastics are carried within this layer as well, adding to global pollution (4). In addition, airborne microplastics can also serve as cloud condensation nuclei and ice-nucleating particles while moving through the free troposphere and boundary layer, potentially influencing cloud development (4).
News Article
In the article Japanese scientists find microplastics are present in clouds, the author(s) reflect on the findings of Wang et al. This article does a good job starting out by stating the ultimate conclusion of microplastics (MP's) existing in cloud water (as well as how much) and pulling the reader in by stating that the way in which these MP's effect the climate is still largely a mystery.
Compared to the plethora of data in the peer-reviewed article, the author(s) do a nice job summarizing the results succinctly and include the size ands type of MP found. I especially like how the author follows up the results with a quote from Hiroshi Okochi of Waseda University saying that "If the issue of ‘plastic air pollution’ is not addressed proactively, climate change and ecological risks may become a reality, causing irreversible and serious environmental damage in the future". This gives more weight to the results when followed by the potential hazards associated with MP's in clouds, which I believe is great organization.
However, there is a lack of organization in this article as MP's and their sources are not explicitly defined until the mid-section. I think it would be beneficial to define these terms in the beginning. I do like how the gaps in knowledge are defined, from the effects on climate to mechanisms of transport. This gives a reason for why the research is being done. A very important point is also mentioned, in that “'To the best of our knowledge, this is the first report on airborne microplastics in cloud water,' the authors wrote in their paper".
This article was also lacking key information from the peer-reviewed article that is tactically relevant, Mt Fuji's samples were collected at the summit and the foot (in the free troposphere and atmospheric boundary layer, respectfully) and Mt Oyama at the summit (atmospheric boundary layer, or ABL). Overall I would give this article a 7.0/10.
Peer Reviewed Article
The paper titled Airborne hydrophilic microplastics in cloud water at high altitudes and their role in cloud formation by Wang et al was published in the Journal of Environmental Chemistry Letters. This article analyzes MP's in cloud water sampled at the summits of Mt Fuji and Mt Oyama with an altitude range of 1300-3776 m with the main analytical technique used to characterize MP's being Fourier transform infrared spectroscopy (FTIR). Wang et al emphasizes that this paper is the first of its kind, as research on airborne MP's is very limited. Wang et al set out to determine which and how much MP's were present in cloud water in the free troposphere and ABL, as well as their properties like concentration and polymer type. The authors also set out to determine the origin of airborne MP's they collected.
Prior research has shown that airborne MP's had the capacity to act as cloud condensation nuclei (CCN) during transport in the free troposphere and the ABL. The researchers used a string-type passive cloud collector at the summits of the 2 mountains and a string-type automatic collector at the foot of Mt Fuji. In order to collect airborne MP's, 1.0-μm pore size polytetrafluoroethylene hydrophilic membrane filter (H100A047A; Advantec, Co.) was installed in the filter holder of each collector for sampling. In total, 70 pieces of MP were collected; 20 at Mt Oyama, 13 at Mt Fuji summit, and 37 at the foot of Mt Fuji. The Mt Fuji summit had the highest altitude of 3776 m, while the foot was 1300 m. The lowest point is Mt oyama with an altitude of 1252 m. The cloud water was analyzed using ion-chromatography and the airborne MP's within the cloud water were identified by FTIR, as shown in Figure 1.
Great work Cody! Very interesting article and the information it presents. The fact that they took measurements both at the summit and the foot of the mountain (although only for one of the mountains) to see the difference, that is great. Also, their analysis techniques are very common, and we use many of them for our data!
ReplyDeleteSome questions please:
1. For the back trajectory (HYSPLIT) analysis, do you know how far back they went? Since if we go too far back, the results can become less reliable.
2. Also, when they say that the MPs in cloud water were primarily of oceanic origin, wouldn’t that still be anthropogenic at the end of the day? If not, how would the ocean have plastic in the first place?
3. Additionally, Japan has many mountains. Is there a specific reason why they chose these two (Mt Fuji and Mt Oyama), both located approximately in southeast Japan?
Hi Frozan. Thank you for your questions! 1. For the back trajectory (HYSPLIT), yes it can be inaccurate the further back you go due to wind field uncertainties accumulating quickly. From what I could fined, this study went back around 5-7 days. 2. Yes, it would still be anthropogenic. In this study, they conduct backward trajectory analysis and classified them into 3 categories: northern (Continental), southwestern (Continental), and maritime (Pacific Ocean). They define oceanic origin as those MP's coming from the pacific ocean region, although the MP's likely got there through anthropogenic processes. 3. They chose Mt Fuji because it is the highest in Japan and has an isolated peak and the side of the mountain where the research center is located is an unobstructed cliff which allows cloud water collection that is not effected by climbers or other human activities.
DeleteThank you Cody for the responses! Those make sense and appreciate you taking the time!
DeleteHi Cody! Great post! I agree that the news article has some organizational issues, but overall, it does a good job conveying the main ideas of the journal article. One of the main findings that caught my attention was that atmospheric microplastics with hydrophilic functional groups could become cloud condensation nuclei (CCN). I am really interested in how clouds formed from naturally derived CCN compare to those formed from anthropogenic CCN, and how that impacts the climate. Like Frozan, I am also interested in the HYSPLIT4 analysis. This analysis traced air masses from two cities in China, so they had to cross the East China Sea and parts of Japan. Does the analysis account for the mixing of air masses, or does that matter? The article also highlights the prevalence of polypropylene (PE) microplastics in the ocean, but PE is one of the least abundant microplastics found in the cloud water samples at all sites. What factors do you think influenced the distribution of microplastics found at the sites? How does the degradation of microplastics impact what is found and how these degradation products impact the climate?
ReplyDeleteHi Shyleigh. Thank you for your comments. As far as the mixing of air masses, HYSPLIT can simulate a cloud of particles that spreads due to both mean winds and turbulent diffusion. This accounts for vertical and horizontal mixing more realistically, called Dispersion Mode. I am unsure whether or not this study utilized this. As far as the PE concentrations in the cloud water, the study reports that the sodium concentration was low due to a rainfall during the study. So this might be the factor that skewed PE numbers. From what I could gather, older/degraded plastics usually look smaller, more oxidized, and chemically more complex, with leached or transformed byproducts. These smaller particles are better suited for CCN, and the degradation of these from UV light on a alrge scale can produce an increased concentration of greenhouse gases.
DeleteHi Cody! Great job with writing your blog post! I liked the article you had chosen as it is timely with the topics currently being discussed in class. It is interesting to see the connections between water pollutants with the atmospheric chemical reactions in the clouds we have been learning about. As we are learning about the reactivity of pollutants in clouds, I wonder what reactivity and residency time that these nine observed microplastics may have in these clouds, especially considering the often stormy weather in Japan. For those fibrous microplastics, I wonder how they compare to the health hazards of other particulate matter, like asbestos since it is also fibrous. Additionally, was there any significance for having the smallest feret diameter microplastics in the troposphere? Since many of the microplastics promoted cloud formation by acting as condensation nuclei for cloud ice and water, I wondered what the implications of having more clouds was. I was curious as to the reason why techniques of attenuated total reflection imaging and micro-Fourier transform infrared spectroscopy were chosen and how we may interpret their data, given that the data was collected from different sites and with different techniques to other studies.
ReplyDeleteHi Cody! Great work on your blog post! You established a great foundation for understanding this topic with your background information. I like that you highlighted a quote from the article that put emphasis on the severity of this issue. I think that information presented like this communicates the effects very clearly to the reader. Are they continuing this study, or is there a new study that will eliminate some of the areas of variability that were introduced here? Also, are there major differentiable characteristics between the polymers found in the cloud water and their effects, or are they similar enough to just be grouped together? Additionally, I appreciate you pointing out key information that was left out of the article. Overall, I enjoyed reading about this!
ReplyDeleteHi, Kristen. Thank you for commenting. As far as the researchers continuing to study the effects of plastics on cloud formation, the researchers do study different effects of air and climate in these same locations (Mt Fuji and Oyama), but have yet to public more specifically about more discoveries of plastics in this area. This article mainly focuses on size, concentration, and hydrophilicity as comparing between the polymers found. Therefore ones of similar size were groups together, similar concentration, and hydrophilicity. These were the main factors at hand :)
DeleteGreat job on this post! I agree with your evaluation of the news article’s clarity and impact, and your overall assessment, at a 7/10 seems fair, given that while the article does a good job introducing the discovery of microplastics in cloud water, it misses some key contextual details that would have made it easier to digest. Both the sampling locations and differences in atmospheric layers (free troposphere vs. boundary layer) would have helped readers better understand the environmental significance of the findings.I appreciate what you said about the novelty of the analytical techniques used in the experiment and how the researchers acknowledge the issues that may arise from that. I also agree with your point that the quote from Okochi adds important weight to the discussion, tying the scientific results to larger climate concerns. That’s where I think the article really begins to touch on a global issue, but like you mentioned, it stops short of fully developing it. This could be a great opportunity to open a deeper conversation around environmental justice. However my question for you is what do you believe is the next step in all this. How do we go beyond stating the global nature of the issue and begin to work towards a place to improve it.
ReplyDeleteGreat Analysis, Cody! This is such an interesting study, and I think you did a great job laying out the background on microplastics. You mention that they found plastics with hydrophilic groups acting as cloud condensing nuclei, and I was wondering about the impact that has on cloud formation or the surrounding climate. Do you know of the observable effects that would have in clouds? The researchers collected their samples during the summer season. Was there a reason for focusing on cloud formations during this specific season? I appreciated your pointing out the flaws in the researcher’s methodology. Consistency in method and instrumentation for analysis is crucial for presenting reliable and accurate results. I liked how you highlighted the author’s call for solutions to plastic air pollution because that is not something I hear discussed often.
ReplyDeleteHi Talia, thank you for commenting. This article does talk about how they found plastics with hydrophilic groups acting as CCN. The researchers present this in a way to suggest that due to this hydrophilic nature, the airborne particles are better suited to form clouds. In other words, an increased hydrophilicity leads to more affinity to water and ice in the air thus forming clouds. The researchers also add that the plastics with hydrophilic groups were found in abundance, so it is safe to assume that the particles discovered had a significant impact on cloud formation.
DeleteThis is a fascinating and well-reasoned analysis! I agree with your opinion that the article did a good job summarizing the findings from the paper in easy-to-understand language while still maintaining a good amount of detail and describing the study in depth. I also agree that the article could have been better organized. Furthermore, I think they could have gone into more detail in some areas, even though they are clear that there is still a lot of gaps in the research; I think the article would have possibly benefited from describing the specific microplastics in some detail, and also potentially describing what some sources of these microplastics are specifically. I think this research in general would benefit from multiple data points over many locations and over time to see how this issue differs with location, like how they studied different altitudes here, and to see how the issue changes over time. Do you know how easy this study would be to replicate, and do you think it would be reasonable to repeat it extensively?
ReplyDeleteHi Teresa, thank you for commenting. As far as replicating a study like this I believe it to be a good idea to pick a different location and still design the experiment in the way as to collect samples from different parts of the atmosphere (like in this study, Mt Fuji's summit was in the free troposphere where as the foot of it as well as Mt Oyama's summit peaked in the atmospheric boundary layer). Also, samples could be collected at different times throughout the year to account for seasons. I think it would be beneficial to try and repeat this study in key areas around the globe rather than be limited to 1 region :)
DeleteThis is a very interesting article on microplastics, as usually when I think about microplastics pollution I think about plastics in the ocean, but I never considered how they could be transported in the atmosphere and even have an impact on things like cloud development.It would definitely have been interesting to see what policies/alternatives need to be considered/implemented in the near future in order to prevent an increase in MPs that are harmful to living organism as well as have an impact on atmosphere/climate. I definitely would like to see this type of research to be expanded to different regions across the globe. Which regions are most impacted by these MPs? I think this is crucial in order to help prevent certain regions of people from being disproportionately affected if nothing is done to prevent this issue from worsening.
ReplyDelete