Rising sea levels could lead to more methane emitted from wetlands

A low-salinity Bay Area estuary ecosystem is producing higher-than-expected levels of methane

Peer-Reviewed Publication

DOE/LAWRENCE BERKELEY NATIONAL LABORATORY

 

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ONE OF THE WETLAND SITES IN THE SAN FRANCISCO BAY AREA STUDIED BY TRINGE AND HER COLLEAGUES.

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CREDIT: DOE JOINT GENOME INSTITUTE

As sea levels rise due to global warming, ecosystems are being altered. One small silver lining, scientists believed, was that the tidal wetlands found in estuaries might produce less methane – a potent greenhouse gas – as the increasing influx of seawater makes these habitats less hospitable to methane-producing microbes.  

However, research from biologists at Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley indicates that these assumptions aren’t always true. After examining the microbial, chemical, and geological features of 11 wetland zones, the team found that a wetland region exposed to a slight amount of seawater was emitting surprisingly high levels of methane – far more than any of the freshwater sites.

Their results, now published in mSystems, indicate that the factors governing how much greenhouse gas is stored or emitted in natural landscapes are more complex and difficult to predict than we thought.

“We looked at how many methanogens, the organisms that make methane, are present in soils at these sites and it wasn't really well correlated with the amount of methane observed,” said senior author Susannah Tringe, director of Berkeley Lab’s Environmental Genomics & Systems Biology Division. “And even if you look at the amount of methanotrophs, organisms that eat methane, in combination with methanogens, that doesn’t seem to fully explain it.” 

Tringe and her colleagues took soil samples from the 11 sites and used high-throughput sequencing to analyze DNA from organisms found in the samples, including bacteria, viruses, and fungi. They examined what genes were present in the sequences and mapped them to known functions – for example, identifying genes known to be involved in metabolizing nitrogen or genes from bacteria that use sulfate during respiration. Then they worked to model how the genetic information they found, combined with chemical factors in the soil and water, could result in the methane emissions they observed.

Across most of the sites, which ranged from freshwater to full seawater salinities, the amount of methane emitted was inversely related to the amount of salt water that was flowing in and mingling with the river water. But at one site, which had been restored in 2010 from a seasonal grassy pasture for livestock grazing back to its original wetland habitat, the team saw high methane emissions despite the moderate amount of salt water.

Seawater contains more sulfate (an ion with sulfur and oxygen) than freshwater, leading to the assumption that increased influx of seawater in these environments would lead to less methane production as the methanogens that use CO2 to make cellular energy are outcompeted by the bacteria that use sulfate instead.

“Ultimately, we found that there were significant influences from other bacterial groups like the ones that break down carbon and even organisms that are better known as nitrogen cyclers, and we couldn’t readily explain the methane emissions by something as simple as, for example, how much sulfate is available or how many methanogens are there,” said Tringe.

Another concept in ecology is that restoring habitats to their native state can boost carbon storage, improve water quality, and increase wildlife populations. In recent decades, wetlands have been increasingly recognized as critical ecosystems for these environmental services, leading to widespread efforts to restore ecosystems by removing barriers, pollution, and non-native organisms. 

Modeling work by co-author Dennis D. Baldocchi, Executive Associate Dean and professor of Biometeorology at UC Berkeley, suggests that although the restored wetland is adding greenhouse gas to the atmosphere currently, the ecosystem will stabilize and begin to serve as a net carbon sink within 100 to 150 years. This may not be the timeline that stakeholders were hoping for when they restored the area with the goal of carbon sequestration. 

“We want to know if these systems will act as long-term carbon sinks,” said Baldocchi. “And these microbiological investigations can help refine our models and predictions.” 

Tringe noted that other labs have observed increased methane production from wetland soils with increased salinity. Scientists from Duke University took soil core samples from a coastal freshwater wetland and exposed them to artificial seawater, and artificial seawater lacking sulfate. In both cases, methane production went up. Tringe’s lab recently collaborated with Marcelo Ardón of North Carolina State University to analyze the microbial communities in those soils.

“There was this expectation that sulfate would be the most important thing. And in those studies, not only did salt water stimulate methane production, which again is kind of counter to the dogma that sulfate is important, it happened whether you had sulfate there or not; in fact the sulfate didn't have a big effect on the methane emissions,” said Tringe. “So I think these experimental manipulations are reconfirming the story that there's more nuanced effects of seawater intrusion than just a sulfate addition, and also more nuanced factors behind ecosystem restoration.”

This work was supported by the Department of Energy (DOE) Early Career Research Program award to Tringe and the DOE Joint Genome Institute.

Susannah Tringe preparing samples at one of the sites.

CREDIT

DOE Joint Genome Institute

Lawrence Berkeley National Laboratory (Berkeley Lab) is committed to delivering solutions for humankind through research in clean energy, a healthy planet, and discovery science. Founded in 1931 on the belief that the biggest problems are best addressed by teams, Berkeley Lab and its scientists have been recognized with 16 Nobel Prizes. Researchers from around the world rely on the Lab’s world-class scientific facilities for their own pioneering research. Berkeley Lab is a multiprogram national laboratory managed by the University of California for the U.S. Department of Energy’s Office of Science.

DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science.

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JOURNAL

mSystems

DOI

10.1128/msystems.00936-23 

ARTICLE TITLE

Multiple microbial guilds mediate soil methane cycling along a wetland salinity gradient

ARTICLE PUBLICATION DATE

30-Jan-2024

 

Researchers map genome for cats, dolphins, birds, and dozens of other animals

Data will have ‘huge implications’ for understanding human health and evolution

Peer-Reviewed Publication

JOHNS HOPKINS UNIVERSITY

 

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SILHOUETTES OF THE 51 VERTEBRATE SPECIES SELECTED FOR COMPLETE GENOME SEQUENCING BY JOHNS HOPKINS, PENNS STATE, AND ROCKEFELLER UNIVERSITY RESEARCHERS AS PART OF A STUDY PUBLISHED IN 2024. 

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CREDIT: DELPHINE LARIVIÈRE, PENN STATE UNIVERSITY.

Researchers mapped genetic blueprints for 51 species including cats, dolphins, kangaroos, penguins, sharks, and turtles, a discovery that deepens our understanding of evolution and the links between humans and animals. 

“Being able to access that genetic information will have huge implications for understanding human health and evolution,” said lead author Michael Schatz, a Bloomberg Distinguished Professor of computer science and biology at Johns Hopkins University. “A lot of work on drug compounds starts in mice and other animal models, so understanding their genomes and the genomes of other animals directly benefits us.”

The team, working with the Vertebrate Genomes Project, sequenced the genomes of 51 vertebrate species, prioritizing those that are useful models for understanding human evolution. The researchers developed novel algorithms and computer software that cut the sequencing time from months—or decades in the case of the human genome—to a matter of days.  

The findings are newly published today in the journal Nature Biotechnology.

Mammals, a subset of vertebrates that includes primates, dogs, cats, mice, and humans, share 50% to 99% of the same DNA and nearly all the genes from a common ancestor that lived roughly 200 million years ago. By comparing the complete genomes of these species, researchers can start to identify when and where DNA sequences diverged and the implications of those differences for humans. But, researchers say, this work has been limited by the number and quality of vertebrate genomes available, which has focused on a few key species.

Vertebrate genomes are billions of characters long, too long for any gene sequencing technology to read in one complete pass. Researchers must rely on tools that break down the genome into smaller, easier to read segments. Computer programs then take those segments and determine how they fit together, like pieces of a jigsaw puzzle.  

But traditional technology was not able to finish the puzzle. 

“Have you ever done a massive jigsaw puzzle where at some point all that’s left is blue sky, and you don’t think you’ll ever be able to fit the right pieces together? The old software would basically give up on these hard parts of the genome. That’s the problem with genome assembly,” Schatz said. “Our new program, using the latest sequencing data and the latest assembly algorithms, knows how to work through those parts to get a more complete picture.”

To test their technology, researchers mapped the genome of the zebra finch, a songbird that had already been sequenced to study brain development. The new technology was far better at reassembling segments of the genome, creating a more accurate and complete map.

The open-source software is available online via Galaxy, a web-based platform, based at Johns Hopkins and Penn State, that offers scientific software for free to the public and supports half a million scientists and educators worldwide.

“In the past, only a handful of elite research groups would have had access to the resources needed to assemble these genomes. Now, anyone on the planet with access to the internet can visit the website and, with a few clicks of the button, run multiple scientific tools,” said Alex Ostrovsky, a Johns Hopkins software engineer on the Galaxy team who was responsible for making the tools easy to use for noncoders.

The team will continue working with the Vertebrate Genomes Project to sequence the genomes of at least one species across all 275 vertebrate orders. 

“In some ways, we’re building an evolutionary time machine,” Schatz said. “We can trace how vertebrates evolved over time and eventually gave rise to genes and sequences that are uniquely found in humans. 

“Having the genes of our evolutionary cousins mapped out will help us better understand ourselves.” 

 

This work was performed in collaboration with researchers at Pennsylvania State University, Rockefeller University, and several other institutions. Computational resources were provided by the Advanced Cyberinfrastructure Coordination Ecosystem (ACCESS-CI), the Texas Advanced Computing Center, the JetStream2 scientific cloud, and the Rockfish data center at Johns Hopkins University.

 

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JOURNAL

Nature Biotechnology

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Scalable, accessible and reproducible reference genome assembly and evaluation in Galaxy

ARTICLE PUBLICATION DATE

26-Jan-2024

 

Structural color ink: Printable, non-iridescent and lightweight

Peer-Reviewed Publication

KOBE UNIVERSITY

 

VIDEO: 

A SINGLE LAYER OF SILICON NANOSPHERES PRODUCES BRIGHT STRUCTURAL COLORS THAT ARE INDEPENDENT OF THE VIEWING ANGLE. THE COLOR CAN BE CONTROLLED BY THE DIAMETER OF THE SPHERES, WHERE SMALLER PARTICLES ARE BLUER AND LARGER ONES REDDER.

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CREDIT: FUJII MINORU

A new way of creating color uses the scattering of light of specific wavelengths around tiny, almost perfectly round silicon crystals. This Kobe University development enables non-fading structural colors that do not depend on the viewing angle and can be printed. The material has a low environmental and biological impact and can be applied extremely thinly, promising significant weight improvements over conventional paints.

An object has color when light of a specific wavelength is reflected. With traditional pigments, this happens by molecules absorbing other colors from white light, but over time this interaction makes the molecules degrade and the color fades. Structural colors, on the other hand, usually arise when light is reflected from parallel nanostructures set apart at just the right distance so that only light of certain wavelengths will survive while others are cancelled out, reflecting only the color we see. This phenomenon can be seen in wings of butterflies or feathers of peacocks, and has the advantage that the colors don't degrade. But from an industrial point of view, neatly arranged nanostructures cannot be painted or printed easily, and the color depends on the viewing angle, making the material iridescent.

Kobe University material engineers FUJII Minoru and SUGIMOTO Hiroshi have been developing an entirely new approach to producing colors. They explain, “In previous work since 2020, we were the first to achieve precise particle size control and develop colloidal suspensions of spherical and crystalline silicon nanoparticles. These single silicon nanoparticles scatter light in bright colors by the phenomenon of ‘Mie resonance,’ which allows us to develop structural color inks.” With Mie resonance, spherical particles of a size comparable to the wavelength of light reflect specific wavelengths particularly strongly. This means that the color that mainly comes back from the suspension can be controlled simply by varying the size of the particles.

In their work now published in the journal ACS Applied Nano Materials, Fujii and Sugimoto demonstrate that the suspension can be applied to surfaces and will thus coat the underlying material in a form of structural color that does not depend on the viewing angle. This is because the color is not produced by the interaction of light reflected from neighboring structures as with “traditional” structural colors, but by its highly efficient scattering around individual nanospheres. Sugimoto explains another advantage: “A single layer of sparsely distributed silicon nanoparticles with a thickness of only 100-200 nanometers shows bright colors but weighs less than half a gram per square meter. This makes our silicon nanospheres one of the lightest color coats in the world.”

The Kobe University team used computational simulations to explore the properties of the ink under different circumstances, such as by varying the size of the particles and the distance between them, and then confirmed their results experimentally. They found that, contrary to intuition, the reflectance was highest when the individual particles were separated instead of when tightly packed. The authors explain, “This high reflectance despite small coverage of the surface by the nanospheres is due to the very large scattering efficiency. The requirement of a very small amount of silicon crystals for coloration is an advantage in the application as a color pigment.”

After further development and refinements, they are expecting interesting applications of their technology. Sugimoto explains, “We can apply it to the coating of, for example, airplanes. The pigments and coatings on an airplane have a weight of several hundreds of kilograms. If we use our nanosphere-based ink, we might be able to reduce the weight to less than 10% of that.”

A single layer of silicon nanospheres produces bright structural colors that are independent of the viewing angle. The color can be controlled by the diameter of the spheres, where smaller particles are bluer and larger ones redder.

A scanning electron micrograph of the nanosphere monolayer shows almost perfectly round particles of uniform size and only small regions of voids or agglomerates.

The nanospheres in a methanol suspension have different colors than when applied to a surface as a monolayer. The Kobe University researchers explain, “This is due to the multiple scattering, i.e., blue light subsides during consecutive scattering by absorption, while red light survives.”

CREDIT

FUJII Minoru

This work was partially supported by JSPS KAKENHI grants 18KK0141, 21H01748, 21H01782 and 22K18949, the JST FOREST Program grant JPMJFR213L and the JST START University Promotion Type grant JPMJST2051 (Kobe University GAP fund).

Kobe University is a national university with roots dating back to the Kobe Commercial School founded in 1902. It is now one of Japan's leading comprehensive research universities with nearly 16,000 students and nearly 1,700 faculty in 10 faculties and schools and 15 graduate schools. Combining the social and natural sciences to cultivate leaders with an interdisciplinary perspective, Kobe University creates knowledge and fosters innovation to address society’s challenges.

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JOURNAL

ACS Applied Nano Materials

DOI

10.1021/acsanm.3c04689 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Monolayer of Mie-Resonant Silicon Nanospheres for Structural Coloration.

ARTICLE PUBLICATION DATE

30-Jan-2024

 

Joint efforts to ensure the sustainability of our one and only Earth

The 37th International Geological Congress (IGC 2024) in August 2024, Busan, Korea, will highlight a growing concern amid urgent threats posed by accelerated climate and environmental changes.

Meeting Announcement

NATIONAL RESEARCH COUNCIL OF SCIENCE & TECHNOLOGY

 

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IGC2024 OFFICIAL POSTER

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CREDIT: THE 37TH INTERNATIONAL GELOGICAL CONGRESS ORGANIZNIG COMMITTEE (IGC2024)

The 37th International Geological Congress (IGC 2024) in August 2024, Busan, Korea, will highlight a growing concern amid urgent threats posed by accelerated climate and environmental changes. This will prompt collaborative efforts towards ensuring the sustainability of our planet.

Abnormally high temperatures across the globe during the past year were expected to make 2023 the hottest year in Earth's history. This realization underscores the concept of climate change, which was once confined to academic desks but has since permeated into our daily existence.

Geologists now assert that the rapid climate and environmental changes necessitate a reconsideration of our geological period. Traditionally, the era spanning 10,000 years to the present has been labeled the 'Holocene.' However, Nobel Prize winner Paul Crutzen proposes a new era, the 'Anthropocene,' attributing geological changes to human activities. Although the exact starting timing of the era is still arguable, many stratigraphers predict eventual recognition of the Anthropocene as an independent geological era.

The media and geologists around the world are focusing on the proposed Anthropocene epoch due to the urgent need for collaborative efforts to address the crisis posed by swift climate and environmental changes. Consequently, in IGC 2024 the International Commission on Stratigraphy (ICS) under the International Union of Geological Sciences (IUGS), responsible for determining and classifying geological periods, will continue comprehensive discussions with other geoscientists on the issue. This discourse aligns with the upcoming 37th IGC 2024 scheduled for Busan, garnering significant media attention in anticipation of a decision during the Congress. Consequently, the IGC 2024 organizing committee is gearing up for the inaugural Anthropocene special session, complete with presentations and discussions on related topics. Korea stands at the forefront of global attention as it spearheads the initiation of this new geological era.

The 'International Geological Congress (IGC),' also referred to as the Geological Olympics, stands as the foremost international academic event in the realm of geological science. The quadrennial congress, initiated with the inaugural general meeting in Paris, 1878, operates on a rotating basis, maintaining its stature as the largest gathering in the field.

The 37th International Geological Congress (IGC 2024) is hosted by the International Union of Geological Sciences (IUGS) and organized by the 'Organizing Committee of IGC 2024' and will be held in Busan from August 25 to 31, 2024 in Busan, Korea. In 2020, the 36th International Geological Congress was scheduled to be held in New Delhi, India. However, it was conducted online to ensure the health and safety of attendees due to the Covid-19 pandemic. Despite the adjustment, interest in the first general meeting held in eight years has grown exponentially. It is a large-scale event, averaging participation of 6,000 members from 120 countries. Due to the recent proliferation of K-culture, including K-POP and K-Dramas, this 2024 meeting is expected to attract up to 10,000 people.

Join Informative and Sustainable IGC ‘Field Trips’

Field work is very essential and important for most geologists and IGC traditionally has opened several field courses to discuss the current local and regional geological issues. Approximately 40 courses are in the planning stages across South Korea and neighboring countries. The 3nd Circular provides a brief introduction to over 30 domestic courses and two overseas courses.

Despite its modest size, the Korean Peninsula boasts a wealth of geological treasures formed over an extensive geologic timeline since the Late Archean. The domestic Field Trip courses are categorized into three themes: Geology of Korea, Geoparks, and Geohazards. Participants, including registrants and accompanying persons, have the opportunity to engage in Field Trips before and after the congress, spanning several days. Mid-congress Field Trip programs are also available, offering exploration of Busan and its surrounding attractions for a day or half. The Field Trips will provide very special experiences to the attending geologists not only on the geological issue but also on the cultural concern and experience. Refer to the list and map below for details on the planned courses:

Lifetime of ‘biodegradable’ straws in the ocean is 8-20 months, study finds

Peer-Reviewed Publication

AMERICAN CHEMICAL SOCIETY

 

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AFTER 16 WEEKS IN SEAWATER, BIOPLASTIC STRAWS MADE OF FOAM (TOP IMAGE) BROKE DOWN AT LEAST TWICE AS FAST AS THE SOLID VERSIONS (BOTTOM IMAGE).

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CREDIT: ADAPTED FROM ACS SUSTAINABLE CHEMISTRY & ENGINEERING 2024, DOI: 10.1021/ACSSUSCHEMENG.3C07391

Plastic drinking straws that get into marine ecosystems make beaches unsightly and pose problems for turtles and seabirds. So, people increasingly favor alternatives marketed as biodegradable or compostable. But do marine microorganisms break apart those straws? Researchers conducted experiments with seawater and report in ACS Sustainable Chemistry & Engineering that some commercial bioplastic or paper straws might disintegrate within eight to 20 months in coastal ocean systems and switching to foam makes a major difference.  

To combat plastic pollution, some regions in the U.S. have restricted traditional polymers, such as polypropylene (PP), in drinking straws. These policies have led to a growing market for single-use items made from paper or bioplastics. However, replacement materials need to retain functionality so they don’t flop over after the first sip but will fall apart later if they end up in soil, fresh water or salt water. While the next generation of bioplastics, such as cellulose diacetate (CDA) and polyhydroxyalkanoates (PHA), may be able to meet both requirements, little is known about how long products made of these materials last in the ocean before fully degrading compared to other materials. So, Bryan James, Collin Ward and colleagues conducted experiments using real seawater to investigate the environmental lifetimes of different straws and to find a way to accelerate the breakdown of next-generation bioplastics. 

In initial tests, the researchers cut inch-long pieces from commercially available straws made from either coated or uncoated paper, PP polymer, or CDA, PHA or polylactic acid (PLA) bioplastics. Then the pieces were suspended on wires in large tanks with room temperature seawater flowing through them. The team found that after 16 weeks, paper, CDA and PHA straws lost 25-50% of their initial weights. The researchers projected that these degradable straws should fully disintegrate in coastal oceans within 10 months for paper, 15 months for PHA and 20 months for CDA. Additionally, the biofilms on the disintegrating samples contained microbes known to metabolize diverse polymers. Conversely, PP and PLA straws didn’t have measurable weight changes, which suggests they could persist for years in ocean water.  

Using the same experimental conditions, the researchers next examined how changing the CDA material’s structure, from solid to a foam, impacted the bioplastic’s environmental lifetime. They observed that the CDA foam broke down at least twice as fast as the solid version, and they estimated that a straw made from the prototype foam would disintegrate in seawater in eight months — the shortest lifetime of any material tested. Having demonstrated that some bioplastic straws are unlikely to remain intact over a long period, the researchers recommend that simple changes, such as switching to foam materials, could further reduce that time frame.  

The authors acknowledge funding from Eastman. Some authors are employees of Eastman, a manufacturer of biodegradable plastics.  

Some authors have patents in the field of biodegradable plastics. 

### 

The American Chemical Society (ACS) is a nonprofit organization chartered by the U.S. Congress. ACS’ mission is to advance the broader chemistry enterprise and its practitioners for the benefit of Earth and all its people. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions, peer-reviewed journals, scientific conferences, eBooks and weekly news periodical Chemical & Engineering News. ACS journals are among the most cited, most trusted and most read within the scientific literature; however, ACS itself does not conduct chemical research. As a leader in scientific information solutions, its CAS division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. ACS’ main offices are in Washington, D.C., and Columbus, Ohio. 

To automatically receive news releases from the American Chemical Society, contact newsroom@acs.org. 

Note: ACS does not conduct research, but publishes and publicizes peer-reviewed scientific studies. 

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JOURNAL

ACS Sustainable Chemistry & Engineering

DOI

10.1021/acssuschemeng.3c07391 

ARTICLE TITLE

Strategies to Reduce the Environmental Lifetimes of Drinking Straws in the Coastal Ocean

ARTICLE PUBLICATION DATE

30-Jan-2024

Some plastic straws degrade quicker than others, new study shows

WHOI researchers determine lifetimes of commercial drinking straws in the coastal ocean and develop a prototype bioplastic straw that degrades even faster than paper

Peer-Reviewed Publication

WOODS HOLE OCEANOGRAPHIC INSTITUTION

 

IMAGE: 

STRAWS ARE ONE OF THE MOST COMMONLY FOUND SOURCES OF MARINE LITTER. RESEARCHERS SAY WE LACK A FIRM UNDERSTANDING OF HOW LONG PLASTICS LAST IN THE OCEAN, BUT THAT SCIENCE SUPPORTS MOVING AWAY FROM USING THE MATERIAL. 

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CREDIT: PHOTO BY: BRYAN JAMES/©WOODS HOLE OCEANOGRAPHIC INSTITUTION

Woods Hole, Mass. (January 30, 2024) — Straws are one of the most common plastic waste products found on coastlines. As more and more plastic products are being produced, consumed, and disposed of, scientists and manufacturers are developing alternative materials that work equally as well, and don’t contribute to persistent plastic pollution in the environment.

But not all plastics are created the same—different manufacturers have different formulations of base polymers—such as polylactic acid (PLA) and polypropylene (PP)—and chemical additives. That means different plastic formulations behave differently in the environment and break down in the ocean at different rates. There are new materials out in the market that move away from petroleum-derived products—like cellulose diacetate (CDA), a polymer derived from wood pulp that is widely used in consumer goods—and Woods Hole Oceanographic Institution (WHOI) scientists have been working to quantify the environmental lifetimes of a wide range of plastic goods to answer the unresolved question, how long do straws last in the ocean?

In a new paper published in ACS Sustainable Chemistry & Engineering, WHOI scientists Collin Ward, Bryan James, Chris Reddy, and Yanchen Sun put different types of plastics and paper drinking straws head-to-head to see which degrade the fastest in the coastal ocean. They partnered with scientists from bioplastic manufacturing company Eastman, who provided funding, contributed as coauthors, and supplied materials for the study.

“We lack a firm understanding of how long plastics last in the ocean, so we've been designing methods to measure how fast these materials degrade,” Ward said. “It turns out, in this case, there are some bioplastic straws that actually degrade fairly quickly, which is good news.” 

Their approach involved suspending eight different types of straws in a tank of continuously flowing seawater from Martha’s Vineyard Sound, Massachusetts. This method also controlled the temperature, light exposure, and other environmental variables to mimic the natural marine environment. All straws were monitored for signs of degradation over 16 weeks, and the microbial communities growing on the straws were characterized. 

“My interest has been to understand the fate, persistence, and toxicity of plastic and how we can use that information to design next-generation materials that are better for people and the planet,” James said. “We have the unique capability where we can bring the environment of the ocean on land in our tanks at the environmental systems laboratory. It gives us a very controlled environment with natural seawater.”

They tested straws made of CDA, polyhydroxyalkanoates (PHA), paper, PLA, and PP. In the weeks the straws were submerged in the tanks, the CDA, PHA, and paper straws degraded by up to 50%, projecting environmental lifetimes of 10-20 months in the coastal ocean. The PLA and PP straws showed no measurable signs of degradation. 

The scientists then compared two straws made from CDA—one a solid and the other a foam, both provided by Eastman. The straw made from foamed CDA was a prototype to see if increasing the surface area would accelerate break down. They found that the degradation rate of the foam straw was 184% faster than its solid counterpart, resulting in a shorter projected environmental lifetime than the paper straws.

“The unique aspects of this foam straw are that it's able to have a shorter expected lifetime than the paper straws but retain the properties that you enjoy of a plastic or a bioplastic straw,” James said, making it a promising alternative to conventional plastic straws compared to paper straws, which degrade quickly in the ocean but sour user experience by getting soggy, according to the authors.

“This study can be immensely valuable for straw manufacturers by providing informed and transparent data when selecting a material for straws. Even more, it provides reassurance that CDA-based straws won’t add to the persistent plastic pollution, while also demonstrating straw manufacturers’ commitment to offering a sustainable product that reduces risk to marine life,” said Jeff Carbeck, Eastman’s Vice President of Corporate Innovation. 

Science supports a push away from conventional plastic material. Plastic pollution causes harm to humans and ecosystems and the plastic industry is a large-scale contributor to climate change, accounting for roughly 4 to 5% of all greenhouse gas emissions across their lifecycle. With plastic waste becoming ubiquitous in the global ocean and marine food chain over the past 50 years, it’s important to identify new materials that are sustainably sourced, contribute to the shift from a linear to a circular economy, and break down if they incidentally leak into the environment.

“While some push to shift away from plastics, the reality is that plastics are here to stay. We're trying to accept the fact that these materials are going to be used by consumers, and then we can work with companies to minimize the impacts of them should they leak into the environment,” Ward said.  

“We recognize the importance of testing, validating and understanding the marine degradation of our CDA based products, but lacked the necessary resources,” Carbeck said. “Knowing that WHOI possessed the expertise and facilities, we engaged in a collaborative effort to address this challenge. This partnership showcases the power of industry-academia collaboration in advancing shared goals and making a positive impact.”

The research team also found that the microbial communities of the straws that degraded were unique to each straw material. However, the microbial communities on both non-degrading straws were the same despite having vastly different chemical structures. This provided further evidence that the native microbes were degrading the biodegradable straws, whereas the non-biodegradable straws likely persist in the ocean.

“Our understanding of the impacts of plastic pollution on ocean health are really uncertain, and a lot of this boils down to not know the long-term fates of these materials,” Ward said. He and the rest of the research team plan to continue measuring the degradability of plastic materials, with the hope of guiding where the industry goes next. 

“There are a lot of advantages of partnering with material manufacturers, including access to analytical facilities, and knowledge about and access to their materials that you don't get if you work in your own silo,” Ward said. “We’re trying to optimize their products for degradation in the environment and ultimately the good of the planet.”

Degradation of straws made from different types of materials were observed for 16 weeks at WHOI's Environmental Systems Lab. The tanks the straws were kept in had a continuous flow of ocean water from Martha's Vineyard Sound.

CREDIT

Photo by: Rachel Mann/©Woods Hole Oceanographic Institution)

Key Takeaways 

• Not all plastics are created the same, and some last longer in the ocean than others. WHOI scientists have been working for years to quantify the environmental lifetimes of a wide range of plastic goods to see which have the shortest and longest lifespans in the ocean. To determine what plastics persist in the ocean, the team tests different products in large tanks that recreate the natural ocean environment. They focused on drinking straws first, as they are one of the most prevalent forms of plastic waste found in beach cleanups. 
• The authors found that straws made from cellulose diacetate (CDA), polyhydroxyalkanoates (PHA), and paper degraded by up to 50% in 16 weeks. They all had unique microbial communities that helped break down the material. 
• A prototype straw from Eastman, made of foamed CDA, degraded more quickly than the solid, meaning that altering the surface area of the straw can speed up the degradation process.
• Science supports a shift away from persistent plastics—making it even more important to ensure new materials break down if they leak into the environment and don’t further pollute the ocean.

 

Authors:

Bryan D. James,*,1 Yanchen Sun,1 Mounir Izallalen,2 Sharmistha Mazumder,2 Steve T. Perri,2 Brian Edwards,2 Jos de Wit,2 Christopher M. Reddy,1 Collin P. Ward*,1 

 

Affiliations:

 

1 Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA 02543

2 Eastman, Kingsport, TN, USA 37662

 

About Woods Hole Oceanographic Institution

 

The Woods Hole Oceanographic Institution (WHOI) is a private, non-profit organization on Cape Cod, Massachusetts, dedicated to marine research, engineering, and higher education. Established in 1930, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate an understanding of the ocean’s role in the changing global environment. WHOI’s pioneering discoveries stem from an ideal combination of science and engineering—one that has made it one of the most trusted and technically advanced leaders in basic and applied ocean research and exploration anywhere. WHOI is known for its multidisciplinary approach, superior ship operations, and unparalleled deep-sea robotics capabilities. We play a leading role in ocean observation and operate the most extensive suite of data-gathering platforms in the world. Top scientists, engineers, and students collaborate on more than 800 concurrent projects worldwide—both above and below the waves—pushing the boundaries of knowledge and possibility. For more information, please visit www.whoi.edu.

 

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JOURNAL

ACS Sustainable Chemistry & Engineering

DOI

10.1021/acssuschemeng.3c07391 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Strategies to Reduce the Environmental Lifetimes of Drinking Straws in the Coastal Ocean

ARTICLE PUBLICATION DATE

30-Jan-2024