Twist of groundwater contaminants

Synergistic effect of nitrate on natural purification of groundwater discovered. New water quality management paradigm for Aquifer Storage Recovery (ASR) techniques to secure stable water resources

NATIONAL RESEARCH COUNCIL OF SCIENCE & TECHNOLOGY

 

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AQUIFER STORAGE RECOVERY (ASR) OVERVIEW

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CREDIT: KOREA INSTITUTE OF SCIENCE AND TECHNOLOGY

In recent years, the world has been experiencing floods and droughts as extreme rainfall events have become more frequent due to climate change. For this reason, securing stable water resources throughout the year has become a national responsibility called 'water security', and 'Aquifer Storage Recovery (ASR)', which stores water in the form of groundwater in the ground when water resources are available and withdraws it when needed, is attracting attention as an effective water resource management technique.

The Korea Institute of Science and Technology (KIST) announced that a team of Dr. Seunghak Lee, Jaeshik Chung, and Sang Hyun Kim from the Water Resources Cycle Research Center has discovered that the natural purification of groundwater is enhanced by nitrate, a known pollutant. In order to apply ASR techniques in practice, it is very important to predict and manage the quality of recharged water, and this research is expected to mark a turning point in the water quality management strategy of ASR systems.

In addition to storing water resources, ASR techniques have the added benefit of improving water quality through various reactions in the ground. The organic pollutants in the recharged water are degraded by the interaction of microorganisms in the aquifer soil with the iron oxide minerals, and in general, the iron oxide minerals are gradually transformed and the effective surface area is reduced, causing the natural attenuation of organic pollutants to stop.

The KIST researchers found that the coexistence of nitrate in the recharged water leads to the formation of a new type of iron oxide, which results in a much higher removal efficiency than the stoichiometrically predicted organic pollutant removal efficiency. The coexistence of nitrate increases the duration of natural attenuation because it creates new species of iron oxides that can sustain the degradation of organic contaminants. Furthermore, the researchers found that the pollutant nitrate is removed during the overall reaction.

"This is the first study to confirm the positive role of nitrate in groundwater, which is known only as a water pollutant," said Dr. Seunghak Lee of KIST. "Based on this, we are promoting the development of ASR water quality management protocols that dramatically change the existing water quality management paradigm, such as introducing allowable standards for nitrate residue in the pretreatment process of the recharging water."

  

Natural attenuation of organic pollutants by iron oxide reductive dissolution in aquifers during ASR

Increased removal efficiency of organic pollutants due to the generation of new type of iron oxide minerals in the presence of nitrate

CREDIT

Korea Institute of Science and Technology

KIST was established in 1966 as the first government-funded research institute in Korea. KIST now strives to solve national and social challenges and secure growth engines through leading and innovative research. For more information, please visit KIST’s website at https://eng.kist.re.kr/

The results of the research, which was funded by the Ministry of Science and ICT (Minister Jong-ho Lee) through the Climate Change Impact Minimization Technology Development Project (2020M3H5A1080712) and the KIST K-Lab Program (2E33084), were published in the February issue of the international journal Water Research.

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JOURNAL

Water Research

DOI

10.1016/j.watres.2023.120954 

ARTICLE TITLE

Synergetic effect of nitrate on dissolved organic carbon attenuation through dissimilatory iron reduction during aquifer storage and recovery

 

Researchers obtain promising results for control of pollutants in water

Brazilian scientists tested a simple and sustainable method for monitoring and degrading a mixture of polycyclic aromatic hydrocarbons, compounds present in fossil fuels and industrial waste

FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO

 

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THE MIXTURE OF POLLUTANTS WAS DEGRADED BY MEANS OF A PHOTOCHEMICAL SYSTEM IN WHICH A LIGHT SOURCE IS ACTIVATED BY MICROWAVE RADIATION 

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CREDIT: CDMF

An article published in the journal Catalysis Communications describes a simple, efficient and sustainable approach to the degradation and quantitative monitoring of a mixture of polycyclic aromatic hydrocarbons (PAHs), emerging pollutants that contaminate various ecosystems owing to oil and other fossil fuel spills and improper disposal of industrial waste.

Emerging pollutants are chemical compounds that have recently been identified as harmful to human health and the environment but are not regularly monitored and cannot be removed by conventional wastewater treatment methods. Examples include bisphenol (used in certain types of plastic), some pesticides, and substances found in personal care products and medications.

In pursuit of solutions to this problem, researchers in Brazil affiliated with the Federal University of São Carlos (UFSCar), São Paulo State University (UNESP) and the Federal University of Paraíba (UFPB) prepared a mixture containing low levels of naphthalene, anthracene and dibenzothiophene in surface water, simulating the natural environment. They used excitation-emission matrix (EEM) fluorescence spectroscopy as a higher-order method of analysis and calibration coupled with parallel factor analysis for data processing, whereby they separated the spectral components of the mixture in order to identify and quantify each pollutant, as well as other potential compounds present in natural water.

This methodology enabled each analysis to be completed in less than two minutes, without production of any residue or the need for more costly and sophisticated techniques, such as chromatography.

The mixture was then degraded using a photochemical system in which a lamp is activated by microwave radiation. The system degraded between 88% and 100% of the organic pollutants in only a minute. This high performance was associated with water photolysis that effectively generated hydroxyl radicals (oxidizing species capable of degrading organic pollutants at high speed).

According to Kelvin C. Araújo, first author of the article and a researcher at the Center for Development of Functional Materials (CDMF), a Research, Innovation and Dissemination Center (RIDC) funded by FAPESP and hosted by UFSCar, one of the highlights of the study was the choice of PAH monitoring method. Chromatography, the usual method, limits progress in this type of research in many parts of the world because the equipment is expensive and the technique requires more sophisticated training, he explained.

In this study, the researchers used a spectrofluorometer, which is more affordable for many laboratories. The analysis is up to five times faster than in chromatography, and no residue is produced after the process. Moreover, Araújo noted, demand for more accessible methods was detected by the group, which has long studied water treatment using chromatography as its main analytical technique.

Photochemical system

Another significant aspect of the study was the use of a microwave-activated photochemical system to degrade the PAHs. According to Ailton Moreira, currently a researcher at UNESP Institute of Chemistry in Araraquara and a co-author of the article, efficiently and quickly degrading emerging pollutants without the use of catalysts is a major challenge.

“The challenge is even more daunting when you’re working with mixtures of pollutants in natural water because of the many potential inhibitors of the degradation process, but the photochemical system performed outstandingly,” Moreira said, adding that the same system had already proved effective in studies involving degradation of agricultural and pharmaceutical waste. Based on the findings described in the article, the photochemical system could be used on a far larger scale – in wastewater treatment plants, for example.

The authors confirm that both the analytical method and the degradation process will be the focus of future studies in different projects led by members of the group. Next steps will include application of these technologies at a wastewater treatment plant in Gavião Peixoto, a city in São Paulo state, to monitor and degrade emerging pollutants.

About São Paulo Research Foundation (FAPESP)

The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at www.fapesp.br/en and visit FAPESP news agency at www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe.

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JOURNAL

Catalysis Communications

DOI

10.1016/j.catcom.2023.106834 

ARTICLE TITLE

Fast and efficient processes for oxidation and monitoring of polycyclic aromatic hydrocarbons in environmental matrices

 

Silicon spikes take out 96% of virus particles

An international research team led by RMIT University has designed and manufactured a virus-killing surface that could help control disease spread in hospitals, labs and other high-risk environments.

RMIT UNIVERSITY

 

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A VIRUS CELL ON THE NANO SPIKED SILICON SURFACE, MAGNIFIED 65,000 TIMES. AFTER 1 HOUR IT HAS ALREADY BEGUN TO LEAK MATERIAL.

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CREDIT: RMIT

An international research team led by RMIT University has designed and manufactured a virus-killing surface that could help control disease spread in hospitals, labs and other high-risk environments. 

The surface made of silicon is covered in tiny nanospikes that skewer viruses on contact. 

Lab tests with the hPIV-3 virus – which causes bronchitis, pneumonia and croup – showed 96% of the viruses were either ripped apart or damaged to the point where they could no longer replicate to cause infection. 

These impressive results, featured on the cover of top nanoscience journal ACS Nano, show the material’s promise for helping control the transmission of potentially dangerous biological material in laboratories and healthcare environments. 

Spike the viruses to kill them 

Corresponding author Dr Natalie Borg, from RMIT’s School of Health and Biomedical Sciences, said this seemingly unsophisticated concept of skewering the virus required considerable technical expertise.  

“Our virus-killing surface looks like a flat black mirror to the naked eye but actually has tiny spikes designed specifically to kill viruses,” she said.  

“This material can be incorporated into commonly touched devices and surfaces to prevent viral spread and reduce the use of disinfectants.” 

The nano spiked surfaces were manufactured at the Melbourne Centre for Nanofabrication, starting with a smooth silicon wafer, which is bombarded with ions to strategically remove material.  

The result is a surface full of needles that are 2 nanometers thick – 30,000 times thinner than a human hair – and 290 nanometers high.  

Specialists in antimicrobial surfaces 

The team led by RMIT Distinguished Professor Elena Ivanova has years of experience studying mechanical methods for controlling pathogenic microorganisms inspired by the world of nature: the wings of insects such as dragonflies or cicadas have a nanoscale spiked structure that can pierce bacteria and fungi. 

In this case, however, viruses are an order of magnitude smaller than bacteria so the needles must be correspondingly smaller if they are to have any effect on them.  

The process by which viruses lose their infectious ability when they contact the nanostructured surface was analysed in theoretical and practical terms by the research team.  

Researchers at Spain’s Universitat Rovira i Virgili (URV), Dr Vladimir Baulin and Dr Vassil Tzanov, computer simulated the interactions between the viruses and the needles. 

RMIT researchers carried out a practical experimental analysis, exposing the virus to the nanostructured surface and observing the results at RMIT’s Microscopy and Microanalysis Facility. 

The findings show the spike design to be extremely effective at damaging the virus’ external structure and piercing its membranes, incapacitating 96% of viruses that came into contact with the surface within six hours.  

Study first author, Samson Mah, who completed the work under an RMIT-CSIRO Masters by Research Scholarship and has now progressed to working on his PhD research with the team, said he was inspired by the practical potential of the research. 

“Implementing this cutting-edge technology in high-risk environments like laboratories or healthcare facilities, where exposure to hazardous biological materials is a concern, could significantly bolster containment measures against infectious diseases,” he said. 

“By doing so, we aim to create safer environments for researchers, healthcare professionals, and patients alike.”  

The project was a truly interdisciplinary and multi-institutional collaboration carried out over two years, involving researchers from RMIT, URV (Spain), CSIRO, Swinburne University, Monash University and the Kaiteki Institute (Japan). 

This study was supported by the ARC Research Hub for Australian Steel Manufacturing and by the ARC Industrial Transformational Training Centre in Surface Engineering for Advanced Materials. 

‘Piercing of the Human Parainfluenza Virus by Nanostructured Surfaces’ is published in ACS Nano. (DOI: 10.1021/acsnano.3c07099) 

A virus cell on the nano spiked silicon surface, magnified 65,000 times. After 6 hours it has been completely destroyed.

JOURNAL

ACS Nano

DOI

10.1021/acsnano.3c07099 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Cells

ARTICLE TITLE

Piercing of the Human Parainfluenza Virus by Nanostructured Surfaces

 

New testing approach improves detection of rare but emerging Powassan virus spread by deer ticks

UMass Amherst-based NEWVEC developed method to monitor and prevent potentially deadly infections

UNIVERSITY OF MASSACHUSETTS AMHERST

 

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VECTOR-BORNE DISEASE EXPERT STEPHEN RICH IS A PROFESSOR OF MICROBIOLOGY AT UMASS AMHERST.

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CREDIT: UMASS AMHERST

Researchers at the New England Regional Center of Vector-Borne Diseases at the University of Massachusetts Amherst have come up with a new, more accurate method for detecting in ticks the emerging Powassan virus, which can cause life-threatening neuroinvasive disease, including encephalitis and meningitis. 

This robust, real-time approach reduces the incidence of false positive test results, the NEWVEC researchers found. The team describes the study in a special issue of the journal Viruses, titled “Tick-borne Viruses: Transmission and Surveillance.” 

“Powassan has been a growing concern in New England for the past several years and false positives can confound efforts to surveil,” says vector-borne disease expert Stephen Rich, professor of microbiology at UMass Amherst and principal investigator and executive director of NEWVEC. “The development of sensitive detection methods for diagnostics and surveillance is critical.”

Named after the town in Ontario, Canada, where it was first identified in 1958 in a 5-year-old boy who died from encephalitis, Powassan virus is a flavivirus related to West Nile and other mosquito-borne viruses. 

Though still rare, Powassan virus is drastically increasing in incidence in the U.S., predominantly in the Northeast and Great Lakes region. More than 10% of the record 290 U.S. cases reported in 2022 (compared to only one case per year from 2004 to 2006) resulted in death, and half of the survivors suffered long-term neurological damage. The virus is transmitted to humans primarily by Ixodes scapularis, the same blood-sucking deer ticks that transmit Lyme disease, babesiosis and other tick-borne illnesses. 

The team at NEWVEC – which brings together academic communities, public health practitioners and residents and visitors across the Northeast in an effort to reduce diseases spread by ticks and mosquitoes – developed a triplex real-time PCR test for the simultaneous and quantitative detection of the Powassan virus and Powassan virus lineage II (deer tick virus) in Ixodes scapularis, or deer ticks. (The prototype Powassan virus is found mostly in Ixodes cookei and Ixodes marxi ticks that feed almost exclusively on woodchucks in their burrows and rarely bite humans or human pets.) 

The NEWVEC team conducted a tick survey in coastal and offshore Massachusetts, focusing on 13 sites from the highly endemic regions of tick-borne diseases in Cape Cod and Martha’s Vineyard. They tested the ticks for Powassan virus, comparing  their new triplex PCR method to the standard, commercially available Luminex xMap technology.

“The good news is that ours works as well as the other one. So, in other words, everything that the other one could detect, we could detect,” Rich explains. “The great news is that we also overcame the problem of false negatives, which is what happens when a sample is not of sufficient quality that any test would ever be able to detect the virus in it.”

The new triplex method accomplishes a reduction in false negatives by using a “clever” quality control. Both tests seek to detect the presence of Powassan virus RNA. “But we also had a paired search for the RNA from the tick, which is present in every tick regardless of whether it has the virus or not,” Rich says. “And what that tells us is, if we can amplify tick RNA, then we have some hope of being able to detect the virus RNA. If we don’t detect the tick DNA, then we have no hope of being able to detect the virus RNA.

“And before we developed that method, people would be left to wonder – if they were inquisitive – whether a negative result meant that the virus wasn’t there or that the sample wasn’t testable. So, we’ve ruled out that latter possibility. And now we know with some assurance that when a tick tests negative, it’s a true negative. It’s not that the sample just isn’t good enough.”

In the areas surveyed, “We found pockets of high incidence of this virus,” Rich says.

Powassan virus was detected at four of six sites in Cape Code and two of seven sites in Martha’s Vineyard. Of 819 ticks collected, 33 (4.03%) tested positive for Powassan virus and 752 tested as Powassan negative, using the new triplex method. Thirty-four ticks (4.15%) failed the quality control tick RNA test. That showed that the standard Luminex method underestimated the overall prevalence of Powassan virus because those 34 ticks were found Powassan negative. And only 30 ticks tested positive using the Luminex method, demonstrating that the triplex technique has a higher sensitivity to detect the virus RNA.

Infection rates reached as high as 10.43% at one site in Truro on Cape Cod, and were completely absent at seven other sites. All the ticks that tested positive for the Powassan virus also were positive for the lineage II deer tick virus. 

The researchers say they hope this improved triplex PCR test will be useful in transmission studies and as a tool to monitor and prevent Powassan virus infections in Massachusetts and other areas where the virus has been reported.

“Powassan virus is only a threat to people through the bite of tick,” Rich says. “That’s why these highly accurate and sensitive tests of the tick are so valuable in assessing where and when risk of exposure is highest.”

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JOURNAL

Viruses

DOI

10.3390/v16020250 

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Active Surveillance of Powassan Virus in Massachusetts Ixodes scapularis Ticks, Comparing Detection Using a New Triplex Real-Time PCR Assay with a Luminex Vector-Borne Panel

 

Curbside collection improves organic waste composting, reduces methane emissions

UNIVERSITY OF ILLINOIS COLLEGE OF AGRICULTURAL, CONSUMER AND ENVIRONMENTAL SCIENCES

URBANA, Ill. – Most organic household waste ends up in landfills where it generates methane, a powerful greenhouse gas. Composting food and garden waste instead of sending it to landfills can significantly reduce methane emissions and help mitigate global warming. A new study from the University of Illinois Urbana-Champaign explores the effects of curbside compost collection programs in New South Wales, Australia.

“Governments around the world are interested in composting organic waste and reducing their methane emissions, and they are looking for ways to make waste collection more convenient for households. As municipal composting services were being rolled out in Australia, we wanted to measure how these policies affected household waste disposal behavior,” said Becca Taylor, assistant professor in the Department of Agricultural and Consumer Economics, part of the College of Agricultural, Consumer and Environmental Sciences (ACES) at Illinois.

Between 2009 and 2015, 24 local government councils in New South Wales, Australia’s most populous state, adopted curbside services to collect food and garden waste for recycling into compost. Households received a red bin for general waste, a yellow bin for recycling, and a green bin for organic waste. Information campaigns educated people on the types of waste allowed in the bins, and some councils provided small kitchen caddies to make waste sorting easier.

Taylor and coauthor Lihini de Silva, Monash Business School, Australia, analyzed household waste data from annual New South Wales government waste and resource recovery reports from 2008 to 2015.  

“We had access to data for all three curbside waste streams: landfill, recycling, and the newly added compost, so we could see spillover and linkages between them. We found the programs were very successful in getting organic waste out of the landfill. On average households redirected 4.2 kilograms of waste to composting, which represents 25% of the waste that previously went to landfills," Taylor stated.

In some areas, people could put both food scraps and garden waste in the green bins, while other areas only allowed for garden waste. When the researchers compared the two types, they did not find large differences in quantities, which suggests most of the compost came from garden waste.

“People were willing to compost garden waste if they were given the bins to do so. However, there is still room for improvement in getting food waste from landfill to compost, and additional interventions might be needed in addition to providing the bins,” Taylor said.

Based on the Australian data, Taylor and de Silva estimated that moving a ton of organic waste from landfill to compost would result in 6% to 26% reductions in methane emissions. They noted these results could vary for other locations because calculations are based on the specific compost and landfill technologies that are used.

”We also wanted to see if composting affected other recycling or waste amounts. It could go either way – people could be reminded to recycle other waste as well, or the additional time and effort could result in less general recycling. Another concern was whether giving people an extra bin would increase the total amount of waste,” Taylor said. “However, we did not find significant effects on recycling rates, so it’s not crowding out other recycling, but also not encouraging it. We also found no effects on the total amount of waste.”

​​Methane traps heat in the atmosphere around 30 times more effectively than carbon dioxide. It remains in the atmosphere for a much shorter amount of time, so reductions in methane emissions have a more immediate impact on reducing global warming. Landfills are the third largest source of human-related methane emissions, after fossil fuels and livestock. Composting organic waste instead of sending it to landfills provides an important and low-cost way to reduce methane emissions, the researchers explained.

“These compost collection programs facilitate methane emission reductions without reducing the amount of waste. This underscores that recycling is important, but generating less waste in the first place would result in even greater emission reductions. Both measures are important elements of sustainable practices,” Taylor concluded.

The paper, “If You Build It, Will They Compost? The Effects of Municipal Composting Services on Household Waste Disposal and Landfill Emissions,” is published in Environmental and Resource Economics [DOI: 10.1007/s10640-023-00834-x].

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JOURNAL

Environmental and Resource Economics

DOI

10.1007/s10640-023-00834-x 

METHOD OF RESEARCH

Data/statistical analysis

ARTICLE TITLE

f You Build It, Will They Compost? The Effects of Municipal Composting Services on Household Waste Disposal and Landfill Emissions

 

Researchers find energy development and tree encroachment impact Wyoming pronghorn

UNIVERSITY OF WYOMING

 

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PRONGHORNS CONGREGATE IN THE ADOBE TOWN AREA OF WYOMING’S RED DESERT. A NEW ANALYSIS INVOLVING A UW RESEARCHER SHOWS THAT MANY PRONGHORN HERDS IN THE STATE ARE EXPERIENCING LONG-TERM DECLINES IN FAWN PRODUCTION, PRIMARILY A RESULT OF OIL AND GAS DEVELOPMENT AND ENCROACHMENT OF TREES.

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CREDIT: JACOB HENNIG

While Wyoming is home to some of North America’s most abundant populations of pronghorn that have largely been stable in recent years, a new analysis shows that many herds are experiencing long-term declines in fawn production.

Those declines are primarily a result of oil and gas development and encroachment of trees, according to researchers from the University of Wyoming, the University of Florida, the University of Nebraska-Lincoln, the University of Arkansas and the Northern Plains Agricultural Research Laboratory. Their findings have been published in the journal Global Ecology and Conservation.

The study included data collected by the Wyoming Game and Fish Department for 40 pronghorn herds covering much of Wyoming -- home to about half of North America’s population of the iconic animal -- over a 35-year period from 1984-2019. In addition to analyzing the Game and Fish Department’s extensive information from annual pronghorn population surveys, the researchers looked at region-specific data regarding oil and gas development, roads, fire, invasive plants, tree encroachment and precipitation patterns.

“Long-term declines in (pronghorn) productivity were associated with increases in oil and gas development and woody encroachment,” wrote the research team, led by former University of Nebraska researcher Victoria Donovan, now with the University of Florida, and Professor Jeff Beck, of UW’s Department of Ecosystem Science and Management. They found that “both tree cover and oil and gas development have increased substantially across most herd units in Wyoming over the last 40 years.”

“Other drivers of global change viewed as threats to pronghorn -- including nonnative annual grass invasions, wildfire, roads and increased winter precipitation -- were not prominent drivers of long-term declines in pronghorn productivity,” the scientists concluded.

While oil and gas development already is widely recognized as impacting Wyoming’s rangelands and the species on those lands, the researchers noted that tree encroachment is not generally viewed as a threat to the state’s sagebrush ecosystems. That’s likely because average tree cover ranged from less than 1 percent to 18 percent across the 40 pronghorn herd unit areas.

But even low levels of invading trees have been shown to have drastic impacts on sagebrush-dependent wildlife, the scientists wrote. For Wyoming’s pronghorn, the increase in trees could be providing cover for predators; driving loss of forage associated with sagebrush and grassland cover; and causing pronghorn to avoid those areas.

The researchers suggest that efforts to prevent and manage tree growth amid sagebrush ecosystems could be important for Wyoming pronghorn to maintain their numbers. This could include manual removal of trees and controlled burning.

“Our results contribute to the overwhelming evidence that early management of invading trees within sagebrush habitat will help protect iconic rangeland species like pronghorn,” they wrote. “Preventative management and management applied in the early phases of encroachment is, thus, the most impactful and cost-effective approach.”

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JOURNAL

Global Ecology and Conservation

DOI

10.1016/j.gecco.2024.e02848 

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Declining pronghorn (Antilocapra americana) population productivity caused by woody encroachment and oil and gas development

ARTICLE PUBLICATION DATE

26-Mar-2024

 

World's first demonstration that forests trap airborne microplastics

Peer-Reviewed Publication

JAPAN WOMEN'S UNIVERSITY

 

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DYNAMICS OF AMPS IN THE FOREST

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CREDIT: NONE IN PARTICULAR

A research group led by Japan Women’s University finds that airborne microplastics adsorb to the epicuticular wax on the surface of forest canopy leaves, and that forests may act as terrestrial sinks for airborne microplastics

Tokyo, Japan – Think of microplastics, and you might think of the ones accumulating in the world’s oceans. However, they are also filling the sky and the air we breathe. Now, it has been discovered that forests might be acting as a sink for these airborne microplastics, offering humanity yet another crucial service.

 

In a recently published study, a multi-institutional research group led by Professor Miyazaki Akane of Japan Women’s University has used a new technique to measure the levels of microplastics adhering to the leaves of trees, revealing that forests are potentially acting as terrestrial sinks for these particles.

Microplastics have come into public focus within the last decade because of their effects on the environment and human health. Airborne microplastics are tiny plastic particulates(less than 100 µm) that become suspended in the atmosphere and dispersed throughout the environment, but it has been unclear where they end up. Forests have been known to accumulate airborne pollutants, but their ability to capture airborne microplastics has been poorly understood.

“We investigated airborne microplastics on konara oak tree leaves in a small forest in Tokyo,” says lead author of the study, Natsu Sunaga. “We wanted to determine a reliable method for analyzing levels of these microplastics on leaf surfaces, and how exactly airborne microplastics become trapped by leaves.”

The team examined the leaves of Quercus serrata, a species of oak representative of Japanese forests. To extract the plastics, the leaves were treated using three processes: washing with ultrapure water, simultaneous treatment with ultrasonic waves and washing with ultrapure water, and treatment with an alkaline solution of 10% potassium hydroxide.

“We found that airborne microplastics strongly adsorb to the epicuticular wax on the leaf surface,” explains Akane Miyazaki, senior author. “In other words, these particles accumulate when they stick to the waxy surface coating of leaves.”

The team discovered that the first two treatments – rinsing with ultrapure water alone or in combination with ultrasonic waves – were insufficient for accurately determining the levels of airborne microplastics on forest canopy leaves. Treatment with alkaline potassium hydroxide, however, removed both the epicuticular wax and the substances adhered to it, proving to be an effective method for detecting airborne microplastics stuck to leaf surfaces. Crucially, previous studies that used only the first two methods may have underestimated the number of plastics adhering to leaf surfaces.

“Based on our findings, we estimate that the Quercus serrata forests of Japan (~32,500 km2) trap approximately 420 trillion airborne microplastics per year in their canopies,” states Sunaga. “This indicates that forests may act as terrestrial sinks for airborne microplastics.”

How the accumulation of these microplastics will affect forest ecosystems, including ecosystem functions and soil health, is unknown, and this will undoubtedly be an area of further research. For now, we know that forests and even roadside canopies might reduce the amount of plastic entering our lungs, and for that we have yet another reason to thank trees.

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Reference
Title of original paper : “Alkaline extraction yields a higher number of microplastics in forest canopy leaves: implication for microplastic storage”
DOI : 10.1007/s10311-024-01725-3
Journal : Environmental Chemistry Letters
Article Publication Date : 20 March 2024
Authors :  Natsu Sunaga a, Hiroshi Okochi b, Yasuhiro Niida c, Akane Miyazaki a,＊
a Graduate School of Chemical and Biological Sciences, Japan Women's University
b Graduate School of Creative Science and Engineering, Waseda University
c PerkinElmer Japan G.K.
＊Corresponding author. Akane Miyazaki
 

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About Japan Women's University

Japan Women's University was founded as Japan's first organized institution of higher education for women, and celebrates its 120th anniversary in 2021. It is the only private women's university with a Faculty of science, and is a women's comprehensive university with an educational environment that integrates the humanities and sciences. The Faculty of Transcultural Studies opened last year, and new faculties are scheduled to open in 2024 (Faculty of Architecture and Design) and 2025 (Faculty of Food Science (tentative name, under planning)). Under the tagline of "I move, and the world opens up," we are fostering human resources who can learn and act on their own initiative and create new value. For more information, please visit https://www.jwu.ac.jp.

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JOURNAL

Environmental Chemistry Letters

DOI

10.1007/s10311-024-01725-3 

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

“Alkaline extraction yields a higher number of microplastics in forest canopy leaves: implication for microplastic storage”

ARTICLE PUBLICATION DATE

20-Mar-2024