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Facemask pollution

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During the height of the Covid-19 pandemic, the global usage of disposable facemasks reached a staggering 129 billion per month. Most of these masks are manufactured from petroleum-based non-renewable plastics like polypropylene and the disposal of these masks results in serious pollution problems.  These include the loss of ecological integrity from buried waste in landfills, air pollution from increased waste incineration, and microplastic pollution. 

Recent research by engineers at Washington University in St. Louis investigated the multipronged pollution problem brought about by discarded facemasks.  The study in particular looked at the chemical changes that occur when facemasks are exposed to sunlight, water, and trace metal ions.

Masks littering the environment degrade into nanoplastics and produce reactive oxygen species.  These chemical agents interact with trace metal ions in the environment within hours.  The result is oxides of metals like manganese and iron, which can drive various biogeochemical reactions.

Abandoning and forgetting about plastics like facemasks is an unsustainable practice.  Plastics not only cause physical damage, but also introduce unpredictable and potentially dangerous chemical changes into environmental systems.

Plastic waste is a global problem that has continued to grow and become an increasingly serious threat over decades.  Understanding the nature of the effects of billions of facemasks in the environment is essential to efforts to address the challenges created by them.

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Sun exposure changes chemical fate of littered face masks

Photo, posted August 21, 2021, courtesy of Ivan Radic via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Sun powered carbon capture

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As the world struggles to implement technologies and find the political will to reduce carbon emissions, there are also ongoing efforts to find ways to capture carbon from emitting sources and from the atmosphere itself.  After capturing carbon dioxide, there is then the need to safely store it or make use of it.

Current methods for capturing and then releasing carbon dioxide are expensive and energy intensive.  In fact, some methods even require the use of fossil fuels.  Recently, researchers at Cornell University have developed a method for capturing carbon dioxide that is powered by sunlight.

The Cornell method mimics the mechanisms that plants use to store carbon which involves using sunlight to make a reactive enol molecule that grabs carbon dioxide.  

Existing chemical-based carbon capture techniques make use of amines, which are organic ammonia-derived compounds that react selectively with carbon dioxide.  But amines are not stable in the presence of oxygen and don’t last, which necessitates the energy-intensive production of more and more amines.

The Cornell method uses the same method that the plant enzyme RuBisCo uses in photosynthesis.  It is based on an inexpensive sorbent material that is capable of a high rate of carbon capture.

The researchers tested the system using flue samples from Cornell’s Combined Heat and Power Building, an on-campus power plant that burns natural gas.  The system was successful in isolating carbon dioxide.

Ultimately, they would like to stage the reaction on what looks like a solar panel, but one that would capture carbon instead of generating electricity.

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In a first, system uses sunlight to power carbon capture

Photo, posted August 8, 2015, courtesy of Holly Victoria Norval via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

A green battery from industrial waste

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Flow batteries are rechargeable batteries in which liquid electrolytes flow through one or more chemical cells from one or more tanks.  The electrolytes are redox pairs, that is, chemical compounds that can reversibly undergo reduction and oxidation reactions.  The most common redox electrolytes include elements like vanadium, chromium, iron, zinc, and bromine.  Flow batteries can provide large amounts of both electrical power and stored energy based on the size of the electrolyte tanks.  As a result, they can be scaled up far more readily than other battery technologies. 

Flow batteries are safe, stable, long-lasting, and their electrolytes can easily be refilled.  They have significant potential for use in utility-scale storage for renewable energy systems.

Researchers at Northwestern University have developed a redox flow battery based on an organic industrial-scale waste product.  The material – triphenylphosphine oxide or TPPO – is produced in the thousands of tons each year.  It is byproduct of producing a variety of substances including some vitamins, pharmaceuticals, agrochemicals, and other bulk chemicals.  For the most part, TPPO is of little use and must be carefully discarded.

The current market for redox flow batteries is very small but is expected to grow over time as the need for utility-scale energy storage continues to expand.  A battery technology based on a waste material that is already produced in high volume and that must otherwise be disposed of with caution would have significant advantages.

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Green battery discovery turns trash into treasure

Photo, posted January 12, 2015, courtesy of California Energy Commission via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Artificial intelligence and lost oil wells

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There have been commercial oil and gas wells across the United States for 170 years.  Researchers estimate that there are between two and three million wells that have been abandoned.  There are hundreds of thousands of them, across 27 states, that are “orphaned,” meaning that they are uncapped, unproductive, and nobody is responsible to manage their leakage or pollution.

Many are undocumented orphaned wells – UOWs – that are not listed in formal records and are basically out of sight and out of mind.  Besides having nobody responsible for them, nobody even knows where they are.  But they are potential sources of oil and chemical leaks into nearby water sources and can send toxic substances like benzene and hydrogen sulfide into the air. 

Researchers are using modern tools like drones, laser imaging, and advanced sensors to try to locate UOWs.  But these wells are scattered over an area of more than three million square miles.

To better predict where to look for undocumented wells, researchers are combining historical topographic maps with artificial intelligence. The US Geological Survey has scanned 190,000 topographic maps made between 1884 and 2006.  AI is being used to find the symbols for oil and gas wells on the maps.  People can recognize these symbols easily, but there are just too many maps to look at.  The problem is equivalent to finding a needle in a haystack; there is just an awful lot of hay to look through.

Abandoned wells are a big problem and it will take lots of modern technology to try to solve it.

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AI Helps Researchers Dig Through Old Maps to Find Lost Oil and Gas Wells

Photo, posted August 16, 2022, courtesy of Larry Syverson via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Geological thermal energy storage

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The electricity grid is increasingly using solar and wind power.  Depending on those two sources requires the ability to store energy to have on hand when the sun isn’t shining and the wind isn’t blowing.   Energy needs to be stored away to be used hours, days, or even weeks after it is produced.

Energy storage is booming.  California has increased its energy storage capacity tenfold in recent times.  One day in April, storage batteries were the largest source of electricity in the state for a period of two hours.  But batteries are not the only way to store energy.  There are chemical, electrochemical, mechanical, and thermal methods that each has potential advantages and unique features.

A project in Kern County, California, is making use of an abandoned oil field to create a long-term energy storage installation.  The plan is to retrofit depleted oil wells to store concentrated solar energy in superheated groundwater for long periods of time.  The stored heat can then be used to drive turbines when electricity is needed.

Some 1,200 feet below the surface of the oil field are pockets of permeable sandstone that have been emptied of the oil they previously contained.   An array of parabolic mirrors will gather solar energy that will heat silicon oil in an underground loop to 700 degrees Fahrenheit.  The oil pipeline will heat up groundwater down below.  When electricity is needed, the heated groundwater will be brought to the surface to operate turbines.

There is no new technology involved.  The individual aspects have never all been combined before, but the likelihood of success is high.  There are lots of depleted oil fields that could be used this way in the future.

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Can a California Oilfield Be Retrofitted to Store Solar Energy?

Photo, posted July 18, 2017, courtesy of John Ciccarelli / BLM via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Action on the toxic chemical from tires

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Since the 1990s, populations of coho salmon in streams and urban creeks up and down the West Coast have been dying in large numbers.  Scientists at the University of Washington began studying the mysterious deaths and it took years to figure out what was going on.  They analyzed water samples from urban creeks and found that chemicals from vehicle tires were present.  By soaking tires in water, they found that more than 2,000 chemicals were present.  It took three years to narrow down the suspect list to one chemical:  a toxin called 6PPD-quinone, which is produced when the common tire preservative 6PPD mixes with oxygen.  It is that chemical that was responsible for the salmon die-off.

6PPD-quinone is toxic enough to quickly kill some fish.  Studies showed that concentrations of the chemical in stormwater were found to be lethal for coho salmon following exposures lasting only a few hours.

Despite the discovery, the tire industry has continued to use the chemical in its products.  The industry says 6PPD is an antioxidant and antiozonant that helps prevent degradation and cracking of tires in the environment and is essential for the performance and safety of vehicles.

Last year, California regulators directed the tire industry to seek out substitutes for 6PPD.  The U.S. Tire Manufacturers Association pledged to investigate possible safer alternatives to the chemical.

In November, spurred by a petition by West Coast tribes whose lifeways depend on coho salmon, the EPA said it will study the impact of 6PPD with an eye to potentially banning its use. 

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After Salmon Deaths, EPA Takes Aim at Toxic Chemical Issuing from Car Tires

Photo, posted May 31, 2021, courtesy of Chris Yarzab via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Protecting berries with sunflower extract

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Many of us buy blueberries, raspberries, blackberries, and more in those little clear plastic clamshell boxes.  We try to check them out at the store to make sure they are ok and even if are, many soon end up coated with gray mold and other fungi.  It is a problem that is both disappointing and expensive.

Researchers from several Chinese Universities recently reported that compounds extracted from sunflower crop waste are quite effective at preventing rotting in blueberries.  They suggest that the food industry could use these natural compounds to protect berries from postharvest diseases.

Sunflowers are grown globally for their seeds and oil.  The flower stems themselves are generally considered to be a waste product.  Sunflowers are known to be particularly resistant to many plant diseases so the researchers decided to investigate whether there might be chemical constituents within the plants that are responsible for the protective property.

Their research led to the isolation of 17 different compounds known as diterpenoids, including four that have never been identified before.  They found that 4 of the compounds, including 2 of the newly discovered ones, were effective at preventing the growth of fungus on the blueberries. 

Berries were wetted with the compounds and then dried off and injected with mold spores.  Half of the treated berries were protected from the mold.

There is no reason that the method couldn’t be applied to a variety of crops.  There is great appeal in the concept of using a harmless extract from a plant to render a food crop safe from fungal infestation.  The technique holds great promise in preventing postharvest disease in fruit.

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Sunflower extract fights fungi to keep blueberries fresh

Photo, posted August 26, 2006, courtesy of Liz West via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Banning Neonicotinoid Pesticides | Earth Wise

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New York’s Birds and Bees Protection Act contains a targeted restriction on neonicotinoid pesticides. These widely-used insecticides are absorbed by plants and can be present in pollen and nectar, making them toxic to bees and other pollinators.

Among the largest applications of neonics (as they are called) has been in the form of coatings on crop seeds, such as corn and soybeans.  In 2019, Canada’s Quebec province strongly limited neonic use to protect pollinators and the environment.  The chemical industry vigorously protested the regulations and claimed that the restrictions would cause the collapse of the grain sector in Quebec.

Seed suppliers began supplying uncoated seeds in 2019 and now there is scarcely any use of coated seeds in the province.  Monitoring of over 1,000 agricultural sites has shown that there have been no crop failures related to the pesticide restrictions.  In fact, use of the neonics had no economic benefits. 

Naysayers warned that even more harmful pesticides or other farming practices would be used instead.  But that hasn’t happened either. Some farmers switched to much safer insecticides and others abandoned insecticide treatments altogether.

New York has faced similar opposition by farmers and chemical manufacturers to the Birds and Bees Protection Act and all of the same arguments that have been proven to be invalid in Quebec are being made in New York.  Most major environmental advocates in the state support the measures embodied in the legislation.  As usual, it boils down to a battle between economic interests and the health of the environment.

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Québec’s experience with pesticide ban offers a glimpse of what New York can expect

Photo, posted August 29, 2013, courtesy of the United Soybean Board / the Soybean Checkoff via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Pollution From Tires | Earth Wise

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A few years ago, researchers investigating massive deaths of coho salmon in West Coast streams discovered that the water contained particles from vehicle tires.  The cause of the fish mortality turned out to be a chemical called 6PPD that is added to tires to prevent cracking and degradation.  The mystery was solved, but so far, the chemical continues to be used by all major tire manufacturers and is found on roads and in waterways around the world.

Worse still, the acute toxicity of 6PPD and the chemicals that it transforms into when exposed to ground-level ozone is only the tip of the tire pollution iceberg.  Tire rubber contains more than 400 chemicals and compounds, many of which are carcinogenic. 

About 2 billion tires are sold across the globe each year and that number is expected to reach 3.4 billion by 2030.  Tires are made from about 20% natural rubber and 24% synthetic rubber, which requires about 4 gallons of petroleum per tire.  Hundreds of other ingredients – including steel, fillers, heavy metals like copper, cadmium, lead, and zinc – make up the rest.

Tire wear particles are emitted continually as vehicles travel.  They range in size from visible pieces of rubber or plastic to microparticles.  Research has shown that a car’s four tires collectively emit half a trillion ultrafine particles per mile driven.  These particles are small enough to be breathed into the lungs and can travel throughout the body and even cross the blood-brain barrier.  Particle pollution from tires exceeds that from tailpipes.

Tire pollution is a huge problem that is just starting to receive the attention it deserves.

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Road Hazard: Evidence Mounts on Toxic Pollution from Tires

Photo, posted June 22, 2018, courtesy of Tony Webster via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Biosurfactants And Oil Spills | Earth Wise

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About 400 million gallons of oil leaks into the ocean every year.  This is a major source of environmental pollution.  Oil contains many hazardous compounds that are toxic or mutagenic for marine organisms. 

When oil spill incidents occur, large quantities of chemical dispersants, sometimes as much as millions of gallons, are applied to dissolve oil slicks, prevent oil from reaching coastlines, and enhance the dispersion of the oil in the water.  The hope for doing this is that microbial oil degradation will be enhanced as a result.  Certain microorganisms present in the water can feed on crude oil components and break them down into harmless substances.

A study at the University of Stuttgart in Germany in 2015 showed that chemical dispersants in fact can slow down microbial oil degradation and therefore inhibit water purification.  The oil components need to be broken down sufficiently for them to be bioavailable to microorganisms.  The study found that dispersants were not accomplishing this.

A new study by the same group along with researchers from the University of Tubingen in Germany and the University of Georgia has found that using biosurfactants rather than chemical dispersants stimulates different microbial oil degraders with respect to their growth and activity and can enhance our ability to deal with oil spills.   Treating the water with the biosurfactant rhamnolipid rather than any of the generally-used dispersants provided much higher rates of microbial breakdown of oil components.

The hope is that this work can lead to the development of effective and environmentally friendly approaches to combatting oil spills.

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Biosurfactants might offer an environmentally friendly solution for tackling oil spills

Photo, posted June 11, 2010, courtesy of Deepwater Horizon Response via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Spiders And Pest Control | Earth Wise

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Climate change facilitates the spread of invasive pest species by expanding their habitable environment ranges.  In conventional agriculture, farmers depend on chemical pesticides to control agricultural pests.  But 99% of all synthetic chemicals, including pesticides, are made from fossil fuels, and turning petrochemicals into pesticides requires massive amounts of energy.  These chemical pesticides also pollute the air and water, and destroy biodiversity by killing many non-target species as well.  

According to new research led by scientists from the University of Portsmouth in the U.K., groups of spiders could be used as an environmentally-friendly way to protect crops against agricultural pests.  The study, which was recently published in the journal Insects, suggests that web-building groups of spiders can be used to control populations of the tomato leafminer moth, a devastating pest of commercially important crops like tomatoes and potatoes.

The research team explored the use of tropical tent spiders for this pest control.  They are found in colonies around the world, and their range overlaps with regions of moth infestations, including Mediterranean Europe, Africa, Asia, and the Middle East.

In lab settings, different types of prey were introduced to colonies of spiders of varying body sizes.  The research team found that the larger spiders built larger webs and caught more prey, including tomato leafminer moths and fruit flies.   

Tropical tent spiders could be an effective and climate-friendly way to control flying insect pests.  However, more research is needed to ensure that these spiders don’t negatively impact crop pollination by also catching pollinators.

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Using spiders as environmentally-friendly pest control

Photo, posted June 10, 2018, courtesy of Lies Van Rompaey via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Cheaper Carbon Capture | Earth Wise

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As the years roll by without sufficient progress in reducing carbon dioxide emissions, the need for technologies that can capture CO2 from its sources or remove it from the air becomes stronger and stronger.  People have developed various ways to capture carbon dioxide, but to date, they generally suffer from some combination of being too costly or not being able to scale up to the necessary magnitude.

Scientists at the Pacific Northwest National Laboratory in Richland, Washington recently announced the creation of a new system that they claim is the least costly to date that captures carbon dioxide and turns it into a widely-used chemical: methanol.

Technologies that simply capture carbon dioxide that then needs to be stored in some secure location are difficult to implement from a cost perspective.  The PNNL researchers believe that turning CO2 into methanol can provide the financial incentive for widespread implementation.   Methanol can be used as a fuel, a solvent, or an important ingredient in plastics, paint, construction materials, and car parts.

The system is designed to be installed in fossil fuel-fired power plants as well as cement and steel plants.  Using a capture solvent developed by PNNL, the system grabs carbon dioxide molecules before they are emitted and converts them into methanol. Creating methanol from CO2 is nothing new, but capturing the carbon dioxide and converting into methanol in one continuously flowing system is new.

More work is needed to optimize and scale the process and it may be several years before it is ready for commercial deployment.

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Scientists Unveil Least Costly Carbon Capture System to Date

Photo, posted November 25, 2022, courtesy of Massachusetts Department of Environmental Conservation via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The U.S. Ratifies A Climate Treaty | Earth Wise

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In a rare display of bipartisanship, the U.S. Senate voted 69-27 in favor of ratifying a key international climate agreement aimed at curbing global warming.  The Kigali Amendment to the Montreal Protocol, which has been ratified by 137 other countries so far, ends the use of climate-warming hydrofluorocarbons that are 1,000 times more potent than carbon dioxide in warming the atmosphere.   This is the first international climate treaty that the U.S. has joined in 30 years.

The Kigali Agreement was established in Kigali, Rwanda in 2016 to phase out HFCs, which have been the replacements for CFCs (chlorofluorocarbons) in air conditioners and refrigerators.  CFCs were found to be depleting the ozone layers that protects the earth from harmful ultraviolet rays.  HFCs do not deplete the ozone layer, but they have been a significant contributor to global warming.

The U.S. ratification of the treaty is largely symbolic.  The American Innovation and Manufacturing Act, passed by Congress in 2020, gave the EPA authority to regulate HFCs and the agency has already been doing so.  However, the Senate action shows that the U.S. is back on the international climate bandwagon. 

Failure to ratify the Kigali Amendment would have closed segments of the chemical and manufacturing industries to U.S. producers after 2023 because the Montreal Protocol prohibits trade with countries not party to it or its amendments.

Environmental advocates are hopeful that the U.S. can move forward on other climate actions.  A next step would be to focus on methane, the second leading driver of climate change after carbon dioxide.

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Senate Votes to Ratify the Kigali Amendment, Joining 137 Nations in an Effort to Curb Global Warming

Photo, posted June 13, 2017, courtesy of UNIDO via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Electricity From Bacteria | Earth Wise

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Microbiologists at Radboud University in the Netherlands have demonstrated in the laboratory that methane-consuming bacteria can generate electrical power.  Their study was recently published in the journal Frontiers in Microbiology.

The bacteria studied is called Candidatus Methanoperedens and in the natural environment it consumes methane in water sources that are contaminated with nitrogen including places like water-filled ditches and some lakes. The bacteria in the study make use of the nitrates in the water to break down and digest the methane. Methanogens, which are bacteria that reduce carbon dioxide to form methane, are the source of the methane in these places. 

The researchers exploited these complex interactions of bacteria to create a source of electrical power that is essentially a kind of battery with two terminals.  One of the terminals is a chemical terminal and one is a biological terminal.  They grew the bacteria on one of the electrodes where the bacteria donate electrons that result from its conversion of methane.  (Other microbiologists at the same institution had previously demonstrated electrical generation from a similar battery containing anammox bacteria that use ammonium rather than methane in their metabolic processing).

In the study, the Radboud scientists managed to convert 31% of the methane in the water into electricity but they are aiming at higher efficiencies. 

This approach represents a potential alternative to conventional biogas electricity generation.  In those installations, methane is produced by microorganisms digesting plant materials and the methane is subsequently burned to drive a turbine to generate power.  Those systems in fact have an efficiency of less than 50%.  The researchers want to determine whether microorganisms can do a better job of generating electricity from biological sources than combustion and turbines can do.

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Bacteria generate electricity from methane

Photo, posted December 3, 2008, courtesy of Martin Sutherland via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Turning Pollution Into Cash | Earth Wise     

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Power plants and other industrial facilities are a major source of carbon emissions.  There are a variety of techniques under development to prevent those emissions by capturing them rather than releasing them into the atmosphere.  All of them add costs to the functioning of the facility.  A good way to offset those costs is to convert the emissions into useful products, ideally making it profitable to capture emissions.

Engineers at the University of Cincinnati have developed an electrochemical system that converts carbon dioxide into ethylene, which is a chemical used in a wide range of manufacturing.  Ethylene has sometimes been called “the world’s most important chemical”.  It is used in many kinds of plastics, textiles, and the rubber found in tires and insulation. It is also used in heavy industry such as steel and cement plants as well as in the oil and gas industry.

The Cincinnati process is a two-stage cascade reaction that converts carbon dioxide to carbon monoxide and then into ethylene.  It is based on the underlying principle of the plug-flow reactor that is used for variety of production applications.  The study, published in the journal Nature Catalysis, demonstrates that the process has high ethylene selectivity – meaning that it effectively isolates the desired compound – as well as high productivity – meaning that it makes a lot of it.  The system will take more time to become truly economical, but the researchers are continuing to make progress on that front with improved catalysts.

The researchers believe that this technique can reduce carbon emissions and make a profit doing it.  Power plants and other facilities emit a lot of carbon dioxide.  With this process, it may be possible to capture it and produce a valuable chemical.

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Conversion process turns pollution into cash

Photo, posted February 27, 2018, courtesy of Cyprien Hauser via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Wastewater And Ammonia | Earth Wise

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Ammonia is the second most produced chemical in the world.  More than half of it is used in agriculture to produce various kinds of fertilizer, to produce cotton defoliants that make cotton easier to pick, and to make antifungal agents for fruits.  Globally, ammonia represents more than a $50 billion a year market.

Current methods to make ammonia require enormous amounts of heat – generated by burning fossil fuels – to break apart nitrogen molecules so that they can bind to hydrogen to form the compound. Ammonia production accounts for about 2% of worldwide fossil energy use and generates over 400 million tons of CO2 annually.

Engineers at the University of Illinois Chicago have created a solar-powered electrochemical reaction that uses wastewater to make ammonia and does it with a solar-to-fuel efficiency that is 10 times better than previous comparable technologies.

The process uses nitrate – which is one of the most common groundwater contaminates – to supply nitrogen and uses sunlight to power the reaction.  The system produces nearly 100% ammonia with almost no hydrogen side reactions.  No fossil fuels are needed, and no carbon dioxide or other greenhouse gases are produced.  The new method makes use of a cobalt catalyst that selectively converts nitrate molecules into ammonia.

Not only is the reaction itself carbon-neutral, which is good for the environment, but if it is scaled up for industrial use, it will consume wastewater, thereby actually being good for the environment.  The new process is the subject of a patent filing and the researchers are already collaborating with municipal corporations, wastewater treatment centers, and others in industry to further develop the system.

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Combining sunlight and wastewater nitrate to make the world’s No. 2 chemical

Photo, posted August 29, 2018, courtesy of Montgomery County Planning Commission via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Sustainable Polymer From Wood | Earth Wise

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Scientists from the University of Bath in the UK have developed a sustainable polymer using xylose, a sugar found in wood.

The new polymer is a member of the polyether family.  It could be used in a variety of applications, including being a building block for polyurethane, used for example in mattresses and shoe soles. It could also be a bio-derived alternative to polyethylene glycol, a chemical widely used in biomedicine, or in polyethylene oxide, which is sometimes used as an electrolyte in batteries.

Xylose, also known as wood sugar, is one of the most abundant carbohydrates on earth, second only to glucose. Apart from comprising 5-20% of hardwoods, xylose is a major component of straw, corncobs, and many other plant materials.

The new polymer could reduce reliance on crude oil products and its properties can be easily controlled to make the material flexible or crystalline.  Added functionality could be added to it by binding other chemical groups such as fluorescent probes or dyes to the sugar molecule for biological or chemical sensing applications.

Tweaking the physical and chemical properties of bio-derived polymers has previously been a very difficult thing to do.  The Bath researchers discovered that combining two mirror-image chemical forms of xylose results in a stronger and more adaptable material.  They have filed a patent for their technology and are seeking industrial collaborators for further development.

The reliance of plastics and polymers on fossil fuels is a major problem.  Bio-derived polymers, such as this new one, are an important part of the effort to make plastics sustainable.

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Scientists make sustainable polymer from sugars in wood

Photo, posted January 25, 2017, courtesy of Keith Double via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

What’s Been Killing Salmon? | Earth Wise

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For decades, there have been mysterious deaths of Coho salmon.  The salmon return from the Pacific Ocean each year to spawn along the West Coast.   They can be found from Alaska all the way down into California.  After heavy rain events each fall, fish have been turning up dead in huge numbers before they spawn.  Normally, less than 1% of adult Coho die before spawning. In these mass death events, anywhere from 40% to 90% of fish can perish in affected streams.  The mysterious phenomenon has been the subject of intense research for years.

Recently, scientists announced that they may have solved the mystery.  There is a chemical antioxidant known as 6PPD that is used in the manufacture of tires around the world to make them last longer.  As tire treads break down over time, they leave behind bits of microplastics on roads.  The 6PPD in the plastic bits reacts with ozone to become another chemical:  a previously unreported substance called 6PPD-quinone.

That chemical turns out to be toxic to Coho salmon.  Researchers have found the presence of 6PPD-quinone in roadway water runoff samples taken from across the West Coast.  Based on these observations, they believe it is likely that exposure to this chemical is the main cause of the Coho salmon population decline.

Coho salmon are a favorite of sport fishermen and have great cultural significance to many Native American tribes on the West Coast.  The central California Coho population is classified as endangered and three other Coho populations are listed as threatened.

Tire industry representatives call the study results “preliminary” but say the industry is deeply committed to protecting the environment.  A safe chemical substitute for 6PPD is clearly needed.

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Salmon have been dying mysteriously on the West Coast for years. Scientists think a chemical in tires may be responsible

Photo, posted November 17, 2011, courtesy of Lynn Ketchum/Oregon State University via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Carnivores Eating Human Food | Earth Wise

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A recent study by ecologists at the University of Wisconsin-Madison has found that carnivores living near people often get more than half of their diets from human food sources rather than from their traditional prey.  This represents a major lifestyle disruption that puts North America’s carnivore-dominated ecosystems at risk.

The researchers studied the diets of seven predator species across the Great Lakes region using bone and fur samples taken from animals from areas as remote as national parks to metropolitan areas including Albany, New York.  What they found – unsurprisingly – is that the closer carnivores lived to cities and farms, the more human food they ate.  Dietary contributions of human food varied with species, but on average was more than 25% in most human-altered habitats.

The researchers studied the diets of carnivores like bobcats, coyotes, red and gray foxes, fishers, and American martens by chemical analysis of samples from Minnesota, Wisconsin, upstate New York, and the Upper Peninsula of Michigan.  The diets of the animals could be analyzed on the basis of the carbon content of bone and fur samples.  Human food, heavy in corn and sugar, lends these samples a distinctive carbon isotope signature.  In contrast, prey species confer their own carbon signatures.  The ratio of these isotope fingerprints provides information on the proportion of an animal’s diet that came from human sources.

Relying upon human food increases how much carnivores overlap one another in their competition for food.  Compared to when these predators vie for distinct prey, there can be more conflicts between animals.  Changing how a species gets their food can have far-ranging effects on ecosystems.

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Carnivores living near people feast on human food, threatening ecosystems

Photo, posted August 18, 2007, courtesy of Jitze Couperus via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Fuel From Lignin | Earth Wise

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Lignin is an organic polymer that provides the rigid structure of plants and is what gives wood and bark their characteristic properties.  Lignin typically comprises between 20 and 35% of the mass of wood.  The two major substances extracted from trees, grasses, and other biomass materials are cellulose and lignin.  Cellulose is used to make paper, bioethanol, and other products, but lignin is largely unused because it is difficult to break down into useful substances such as feedstocks for fuels.  As a result, lignin is largely wasted.  Worldwide, some 50 million tons of lignin are produced from paper and bioethanol manufacturing each year and almost all of that is simply burned to generate heat.

Lignin can be broken down using pyrolysis techniques at high temperatures to create bio-oils, but those oils lack sufficient hydrogen and contain too much oxygen to be useful as fuels.  There is a process called hydrodeoxygenation that adds hydrogen and removes oxygen, but it requires high temperatures and very high pressures as well as producing char and tar that reduces the efficiency of the process.

Researchers at Georgia Tech recently published work describing a new process for turning lignin into useful products.  They developed a dual catalyst system of super-acid and platinum particles that adds hydrogen and removes oxygen from lignin bio-oil and makes it useful as a fuel and source of chemical feedstocks. 

The new process could help meet the growing demand for bio-based oils as well as helping the forest product, paper, and bioethanol industries by providing an additional revenue stream from what previously was a waste product.

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New Process Boosts Lignin Bio-oil as a Next-Generation Fuel

Photo, posted August 16, 2017, courtesy of evcabartakova via Flickr.

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