Scientists are developing greener plastics – the bigger challenge is moving them from lab to market



File 20180813 2915 3vl524.jpg?ixlib=rb 1.1
Used once and done.
Michael Coghlan, CC BY-SA

Richard Gross, Rensselaer Polytechnic Institute

Synthetic plastics have made many aspect of modern life cheaper, safer and more convenient. However, we have failed to figure out how to get rid of them after we use them.

Unlike other forms of trash, such as food and paper, most synthetic plastics cannot be easily degraded by live microorganisms or through chemical processes. As a result, a growing plastic waste crisis threatens the health of our planet. It is embodied by the Great Pacific Garbage Patch – a massive zone of floating plastic trash, three times the size of France, stretching between California and Hawaii. Scientists have estimated that if current trends continue, the mass of plastics in the ocean will equal the mass of fish by 2050. Making plastics from petroleum also increases carbon dioxide levels in the atmosphere, contributing to climate change.

Much of my work has been dedicated to finding sustainable ways to make and break down plastics. My lab and others are making progress on both fronts. But these new alternatives have to compete with synthetic plastics that have established infrastructures and optimized processes. Without supportive government policies, innovative plastic alternatives will have trouble crossing the so-called “valley of death” from the lab to the market.

From wood and silk to nylon and plexiglass

All plastics consist of polymers – large molecules that contain many small units, or monomers, joined together to form long chains, much like strings of beads. The chemical structure of the beads and the bonds that join them together determine polymers’ properties. Some polymers form materials that are hard and tough, like glass and epoxies. Others, such as rubber, can bend and stretch.

A monomer of Teflon, a nonstick synthetic resin (top), and a chain of monomers (bottom).
Chromatos

For centuries humans have made products out of polymers from natural sources, such as silk, cotton, wood and wool. After use, these natural plastics are easily degraded by microorganisms.

Synthetic polymers derived from oil were developed starting in the 1930s, when new material innovations were desperately needed to support Allied troops in World War II. For example, nylon, invented in 1935, replaced silk in parachutes and other gear. And poly(methyl methacrylate), known as Plexiglas, substituted for glass in aircraft windows. At that time, there was little consideration of whether or how these materials would be reused.

Modern synthetic plastics can be grouped into two main families: Thermoplastics, which soften on heating and then harden again on cooling, and thermosets, which never soften once they have been molded. Some of the most common high-volume synthetic polymers include polyethylene, used to make film wraps and plastic bags; polypropylene, used to form reusable containers and packaging; and polyethylene terephthalate, or PET, used in clothes, carpets and clear plastic beverage bottles.

Recycling challenges

Today only about 10 percent of discarded plastic in the United States is recycled. Processors need an input stream of non-contaminated or pure plastic, but waste plastic often contains impurities, such as residual food.

Batches of disposed plastic products also may include multiple resin types, and often are not consistent in color, shape, transparency, weight, density or size. This makes it hard for recycling facilities to sort them by type.

Melting down and reforming mixed plastic wastes creates recycled materials that are inferior in performance to virgin material. For this reason, many people refer to plastic recycling as “downcycling.”

As most consumers know, many plastic goods are stamped with a code that indicates the type of resin they are made from, numbered one through seven, inside a triangle formed by three arrows. These codes were developed in the 1980s by the Society of the Plastics Industry, and are intended to indicate whether and how to recycle those products.


Filtre

However, these logos are highly misleading, since they suggest that all of these goods can be recycled an infinite number of times. In fact, according to the Environmental Protection Agency, recycling rates in 2015 ranged from a high of 31 percent for PET (SPI code 1) to 10 percent for high-density polyethylene (SPI code 2) and a few percent at best for other groups.

In my view, single-use plastics should eventually be required to be biodegradable. To make this work, households should have biowaste bins to collect food, paper and biodegradable polymer waste for composting. Germany has such a system in place, and San Francisco composts organic wastes from homes and businesses.

Designing greener polymers

Since modern plastics have many types and uses, multiple strategies are needed to replace them or make them more sustainable. One goal is making polymers from bio-based carbon sources instead of oil. The most readily implementable option is converting carbon from plant cell walls (lignocellulosics) into monomers.

As an example, my lab has developed a yeast catalyst that takes plant-derived oils and converts them to a polyester that has properties similar to polyethylene. But unlike a petroleum-based plastic, it can be fully degraded by microorganisms in composting systems.

It also is imperative to develop new cost-effective routes for decomposing plastics into high-value chemicals that can be reused. This could mean using biological as well as chemical catalysts. One intriguing example is a gut bacterium from mealworms that can digest polystyrene, converting it to carbon dioxide.

Other scientists are developing high-performance vitrimers – a type of thermoset plastic in which the bonds that cross-link chains can form and break, depending on built-in conditions such as temperature or pH. These vitrimers can be used to make hard, molded products that can be converted to flowable materials at the end of their lifetimes so they can be reformed into new products.

It took years of research, development and marketing to optimize synthetic plastics. New green polymers, such as polylactic acid, are just starting to enter the market, mainly in compost bags, food containers, cups and disposable tableware. Manufacturers need support while they work to reduce costs and improve performance. It also is crucial to link academic and industrial efforts, so that new discoveries can be commercialized more quickly.

The ConversationToday the European Union and Canada provides much more government support for discovery and development of bio-based and sustainable plastics than the United States. That must change if America wants to compete in the sustainable polymer revolution.

Richard Gross, Professor of Chemistry, Rensselaer Polytechnic Institute

This article was originally published on The Conversation. Read the original article.

Some tropical frogs may be developing resistance to a deadly fungal disease – but now salamanders are at risk



File 20180514 100700 1eavvgx.jpg?ixlib=rb 1.1
Panamanian golden frogs (Atelopus zeteki) are listed as critically endangered, and may be extinct in the wild.
Jeff Kubina, CC BY-SA

Louise Rollins-Smith, Vanderbilt University

My office is filled with colorful images of frogs, toads and salamanders from around the world, some of which I have collected over 40 years as an immunologist and microbiologist, studying amphibian immunity and diseases. These jewels of nature are mostly silent working members of many aquatic ecosystems.

The exception to the silence is when male frogs and toads call to entice females to mate. These noisy creatures are often wonderful little ventriloquists. They can be calling barely inches from your nose, and yet blend so completely into the environment that they are unseen. I have seen tropical frogs in Panama and native frogs of Tennessee perform this trick, seemingly mocking my attempts to capture them.

My current research is focused on interactions between amphibians and two novel chytrid pathogens that are linked to global amphibian declines. One, Batrachochytrium dendrobatidis ( abbreviated as Bd), has caused mass frog dieoffs around the world. Recently my lab group contributed to a study showing that some species of amphibians in Panama that had declined due to Bd infections are recovering. Although the pathogen has not changed, these species appear to have developed better skin defenses than members of the same species had when Bd first appeared.

This is very good news, but those who love amphibians need to remain vigilant and continue to monitor these recovering populations. A second reason for concern is the discovery of a closely related chytrid, Batrachochytrium salamandrivorans (Bsal), which seems to be more harmful to salamanders and newts.

Amphibian chytrid fungus has been detected in at least 52 countries and 516 species worldwide.
USDA Forest Service

Global frog decline

More than a decade ago, an epidemic of a deadly disease called chytridiomycosis swept through amphibian populations in Panama. The infection was caused by a chytrid fungus, Batrachochytrium dendrobatidis. Scientists from a number of universities, working with the Smithsonian Tropical Research Institute in Panama, reported that chytridiomycosis was moving predictably from west to east from Costa Rica across Panama toward Colombia.

I was part of an international group of scientists, funded by the National Science Foundation, who were trying to understand the disease and whether amphibians had effective immune defenses against the fungus. Two members of my lab group traveled to Panama yearly from 2004 through 2008, and were able to look at skin secretions from multiple frog species before and after the epidemic of chytridiomycosis hit.

Many amphibians have granular glands in their skin that synthesize and sequester antimicrobial peptides (AMPs) and other defensive molecules. When the animal is alarmed or injured, the defensive molecules are released to cleanse and protect the skin.

Through mechanisms that remain a mystery, we observed that these skin defenses seemed to improve after the pathogen entered the amphibian communities. Still, many frog populations in this area suffered severe declines. A global assessment published in 2004 showed that 43 percent of amphibian species were declining and 32 percent of species were threatened.

In Panama, Smithsonian scientists operate the largest amphibian conservation facility of its kind in the world.

Signs of resistance

In 2012-2013, my colleagues ventured to some of the same sites in Panama at which amphibians had disappeared. To our great delight, some of the species were partially recovering, at least enough so that they could be found and sampled again.

We wanted to know whether this was happening because the pathogen had become less virulent, or for some other reason, including the possibility that the frogs were developing more effective responses. To find out, we analyzed multiple measures of Bd‘s virulence, including its ability to infect frogs that had never been exposed to it; its rate of growth in culture; whether it had undergone genetic changes that would show loss of some possible virulence characteristics; and its ability to inhibit frogs’ immune cells.

As our group recently reported, we found that the pathogen had not changed. However, we were able to show that for some species, frog skin secretions we collected from frogs in populations that had persisted were better able to inhibit the fungus in a culture system than those from frogs that had never been exposed to the fungus.

The prospect that some frog species in some places in Panama are recovering in spite of the continuing presence of this virulent pathogen is fantastic news, but it is too soon to celebrate. The recovery process is very slow, and scientists need to continue monitoring the frogs and learn more about their immune defenses. Protecting their habitat, which is threatened by deforestation and water pollution, will also be a key factor for the long-term survival of these unique amphibian species in Panama.

If Bsal fungus spreads to North America, it could wipe out species like this Northern Slimy Salamander (Plethodon glutinosus).
Marshal Hedin, CC BY

Salamanders (and frogs) at risk

On a global scale, Bd is not the only threat. A second pathogenic chytrid fungus called Batrachochytrium salamandrivorans (abbreviated as Bsal) was recently identified in Europe, and has decimated some salamander populations in the Netherlands and Belgium. This sister species probably was accidentally imported into Europe from Asia, and seems to be a greater threat to salamanders than to frogs or toads.

Bsal has not yet been detected in North America. I am part of a new consortium of scientists that has formed a Bsal task force to study whether it could become invasive here, and which species might be most adversely affected.

In January 2016 the U.S. Fish and Wildlife Service listed 201 salamander species as potentially injurious to wildlife because of their their potential to introduce Bsal into the United States. This step made it illegal to import or ship any of these species between the continental United States, the District of Columbia, Hawaii, the Commonwealth of Puerto Rico or any possession of the United States.

The Bsal task force is currently developing a strategic plan that lists the most urgent research needs to prevent accidental introduction and monitor vulnerable populations. In October 2017 a group of scientists and conservation organizations urged the U.S. government to suspend all imports of frogs and salamanders to the United States.

The ConversationIn short, it is too early to relax. There also are many other potential stressors of amphibian populations including climate change, decreasing habitats and disease. Those of us who cherish amphibian diversity will continue to worry for some time to come.

Louise Rollins-Smith, Associate Professor of Pathology, Microbiology and Immunology, Vanderbilt University

This article was originally published on The Conversation. Read the original article.

Developing countries can prosper without increasing emissions


Meg Argyriou, ClimateWorks Australia

One of the ironies of fighting climate change is that developed countries – which have benefited from decades or centuries of industrialisation – are now asking developing countries to abandon highly polluting technology.

But as developing countries work hard to grow their economies, there are real opportunities to leapfrog the significant investment in fossil fuel technology typically associated with economic development.

This week, researchers, practitioners and policy makers from around the world are gathered in New York city for the International Conference on Sustainable Development as part of Climate Week. We at ClimateWorks will be putting the spotlight on how developing countries can use low- or zero-emissions alternatives to traditional infrastructure and technology.


Read more: How trade policies can support global efforts to curb climate change


Developing nations are part of climate change

According to recent analysis, six of the top 10 emitters of greenhouse gases are now developing countries (this includes China). Developing countries as a bloc already account for about 60% of global annual emissions.

//platform.twitter.com/widgets.js

If we are are to achieve the global climate targets of the Paris Agreement, these countries need an alternative path to prosperity. We must decouple economic growth from carbon emissions. In doing so, these nations may avoid many of the environmental, social and economic costs that are the hallmarks of dependence on fossil fuels.

This goal is not as far-fetched as it might seem. ClimateWorks has been working as part of the Deep Decarbonization Pathways Project, a global collaboration of researchers looking for practical ways countries can radically reduce their carbon emissions – while sustaining economic growth.

For example, in conjunction with the Australian National University, we have modelled a deep decarbonisation pathway that shows how Australia could achieve net zero emissions by 2050, while the economy grows by 150%.

Similarly, data compiled by the World Resources Institute shows that 21 countries have reduced annual greenhouse gas emissions while simultaneously growing their economies since 2000. This includes several eastern European countries that have experienced rapid economic growth in the past two decades.

PricewaterhouseCoopers’ Low Carbon Index also found that several G20 countries have reduced the carbon intensity of their economies while maintaining real GDP growth, including nations classified as “developing”, such as China, India, South Africa and Mexico.

‘Clean’ economic growth for sustainable development

If humankind is to live sustainably, future economic growth must minimise environmental impact and maximise social development and inclusion. That’s why in 2015, the UN adopted the Sustainable Development Goals: a set of common aims designed to balance human prosperity with protection of our planet by 2030.

These goals include a specific directive to “take urgent action to combat climate change and its impacts”. Likewise, language in the Paris Climate Agreement recognises the needs of developing countries in balancing economic growth and climate change.

The Sustainable Development Goals are interconnected, and drawing these links can provide a compelling rationale for strong climate action. For example, a focus on achieving Goal 7 (Affordable and Clean Energy) that also considers Goal 13 (Climate Action) will prioritise low or zero-emissions energy technologies. This in turn delivers health benefits and saves lives (Goal 3) through improved air quality, which also boosts economic productivity (Goal 8).


Read more: Climate change set to increase air pollution deaths by hundreds of thousands by 2100


Therefore efforts to limit global temperature rise to below 2℃ must be considered within the context of the Sustainable Development Goals. These global goals are intrinsically linked to solving climate change.

But significant barriers prevent developing countries from adopting low-emissions plans and ambitious climate action. Decarbonisation is often not a priority for less developed countries, compared to key issues such as economic growth and poverty alleviation. Many countries struggle with gaps in technical and financial expertise, a lack of resources and inconsistent energy data. More fundamentally, poor governance and highly complex or fragmented decision-making also halt progress.

The ConversationIt’s in the best interest of the entire world to help developing countries navigate these problems. Creating long-term, lowest-emissions strategies, shaped to each country’s unique circumstances, is crucial to maintaining growth while reducing emissions. Addressing these problems is the key to unlocking the financial flows required to move to a just, equitable and environmentally responsible future.

Meg Argyriou, Acting CEO of ClimateWorks, ClimateWorks Australia

This article was originally published on The Conversation. Read the original article.

Amazon: Deforestation Continuing to Fall


The link below is to an article that examines deforestation in the Amazon, with a trend now developing showing that deforestation is slowing, but more more needs to be done.

For more visit:
http://www.guardian.co.uk/environment/2012/aug/03/amazon-deforestation-falls-again

Antarctica: Massive Ice Shelf Crack


The link below is to an article reporting on a massive crack that is developing in an ice shelf in Antarctica. The article also includes a video of the developing crack.

For more visit:
http://www.canberratimes.com.au/environment/climate-change/gigantic-antarctic-crack-mapped-for-the-first-time-20120301-1u4bt.html