Mercury pollution from decades past may have been re-released by Tasmania’s bushfires



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Tasmania’s fires may have released mercury previously absorbed by trees.
AAP Image

Larissa Schneider, Australian National University; Kathryn Allen, University of Melbourne, and Simon Haberle, Australian National University

Tasmania’s bushfires may have resulted in the release of significant amounts of mercury from burnt trees into the atmosphere. Our research shows that industrial mercury pollution from decades past has been locked up in west Tasmanian trees.

Mercury occurs naturally in Earth’s crust. Over the past 200 years, industrial activities have mobilised mercury from the crust and released it into the atmosphere. As a consequence, atmospheric mercury concentrations are now three to four times higher than in the pre-industrialisation era.

Mining is the largest source of the global atmospheric mercury, accounting for 37% of mercury emissions. When Europeans first arrived in Australia, there was, of course, no Environmental Protection Act in place to limit emissions from industrial activities. In western Tasmania, where mining has occurred for more than a century, this meant mercury was being released without control into the local atmosphere until changes in technology, market conditions, and later, regulation, conspired to reduce emissions.




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Australia emits mercury at double the global average


Because mercury is also very persistent in the environment, past mining activity has generated a reservoir of mercury that could be released to the atmosphere under certain conditions. This is a concern because even small amounts of mercury may be toxic and may cause serious health problems. In particular, mercury can threaten the normal development of a child in utero and early in its life.

Tree rings can reveal past mercury contamination

How much mercury has been released into the Australian environment and when has remained largely unknown. However, in a new study we show how mercury levels in Tasmania have dramatically changed over the past 150 years due to mining practices. Long-lived Huon pine, endemic to western Tasmania, is one of the most efficient bioaccumulators of mercury in the world. This makes it a good proxy for tracking mercury emissions in western Tasmania. If concentrations of mercury in the atmosphere are high in a given year, this can be detected in the annual ring of Huon pine for that year.

Mercury pollution from past mining practices in western Tasmania has left a lasting environmental legacy. The sampled trees contained a significant reservoir of mercury that was taken up during the peak mining period in Queenstown. Changes in mercury concentrations in the annual rings of Huon pine are closely aligned with changes in mining practices in the region.

Increased concentrations coincide with the commencement of pyritic copper smelting in Queenstown in 1896. They peak between 1910 and 1920 when smelting was at its height. In 1922, concentrations begin to decline in parallel with the introduction of a new method to separate and concentrate ores. This method required only one small furnace instead of 11 large ones. In 1934, a new dust-collection apparatus was installed in the smelter’s chimney, coinciding with the further decrease in mercury concentrations in nearby Huon pine.

Temporal tree rings of Huon pine, revealing historical mercury pollution.
Author provided

Toxic elements or compounds taken up by vegetation can also be released back into the local environment. Bushfires that burn trees that have accumulated mercury may release this mercury as vapour, dust or fine ash, potentially exposing people and wildlife to the adverse effects of mercury. It is estimated that bushfires release 210,000kg of mercury into the global atmosphere each year. As these fires become more frequent and ferocious in Australia, mercury concentrations in the atmosphere are likely to increase. Mercury released by bushfires can persist in the atmosphere for a year, allowing for long-distance transportation depending on wind strength and direction. This means that mining activity from over a century ago may have regional implications in the near future. The Tasmanian fires in December-February burned almost 200,000 hectares, including areas around Queenstown.

It is not currently possible to know how much mercury has been released by these recent fires. Our results simply highlight the potential risk and the need to better understand the amount of mercury taken up by vegetation that may one day be released back to the atmosphere via bushfires.

Re-release of historical mercury emissions by bushfires.
Author provided



Read more:
Dry lightning has set Tasmania ablaze, and climate change makes it more likely to happen again


Although there is no simple way to remove bio-accumulated mercury from trees, the history of mercury contamination recorded in tree rings provides important lessons. Decreased uptake of mercury after upgrades to the Queenstown copper smelter operations demonstrates the positive impact that good management decisions can have on the amount of mercury released into the environment.

To control mercury emissions globally, the United Nations Environment Programme (UNEP) has developed the Minamata Convention on Mercury. Its primary goal is to protect human health and the environment from the negative effects of mercury. Australia has signed the convention and but has yet to ratify it. Once ratified, Australia would be required to record sources of mercury and quantify emissions, including those from bushfires.

But to do this, the government must first be able to identify environmental reservoirs of mercury. Our study, the first of its kind in the Southern Hemisphere, shows that the long-lived Huon pine can be used to for this purpose. Further work to determine what other tree species record atmospheric emissions of mercury and other toxic elements in other regions of Australia is required.The Conversation

Larissa Schneider, DECRA fellow, Australian National University; Kathryn Allen, Academic, Ecosystem and Forest Sciences, University of Melbourne, and Simon Haberle, Professor, Australian National University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

We need a legally binding treaty to make plastic pollution history



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The world urgently needs to move past plastic.
Veronika Meduna

Trisia Farrelly, Massey University

A powerful marriage between the fossil fuel and plastic industries threatens to exacerbate the global plastic pollution crisis. The Center for International Environmental Law (CIEL) estimates the next five years will see a 33-36% surge in global plastics production.

This will undermine all current efforts to manage plastic waste. It is time to stop trying (and failing) to bail out the bathtub. Instead, we need to turn off the tap.




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The United Nations Environment Assembly (UNEA) has recognised plastic pollution as a “rapidly increasing serious issue of global concern that needs an urgent global response”. An expert group formed last year proposed an international treaty on plastic pollution as the most effective response.

Together with Giulia Carlini, at CIEL, I was part of a 30-strong group of non-governmental organisations within this expert group attending the UNEA summit this week to discuss how we can start making plastic pollution history.

Unfortunately, despite strong statements from developing countries, including the Pacific Island states, a small group of countries stalled negotiations. This effectively turns back the clock on ambitious global action, and leaves us more desperate than ever for a real solution to our plastic problem.

Why we need a treaty

The first step is to reject the many false solutions that pop up in our news feeds.

Recycling is one of those false solutions. The scale of plastic production is too big for recycling alone. Of all the plastics produced between 1950 and 2015, only 9% have been recycled. This figure is set to plummet as China and a growing number of developing countries are rejecting plastic waste from Australia, New Zealand and the rest of the world.

China had been a major destination for Australia and New Zealand’s recyclable waste. China’s shutdown meant Australia lost the market for a third of its plastic waste. It also left New Zealand with 400 tonnes of stockpiled plastic waste last year.

With limited domestic recycling facilities, Australia and New Zealand are seeking new markets. Last year, New Zealand sent about 250,000 tonnes of plastic to landfill, and a further 6,300 tonnes to Malaysia for recycling. But now Malaysia is also rejecting other countries’ hazardous plastic waste.

Sending our platic to Asia is not a solution.
EPA/Diego Azubel, CC BY-SA

Even if we manage to find new plastic recycling markets, there is another problem. Recycling is not as safe as you might think. Flame retardants and other toxins are added to many plastics, and these compounds find a second life when plastics are recycled into new products, including children’s toys.

Plastic-to-energy is a false solution

What about burning plastic waste to generate energy? Think again. Incineration is expensive, can take decades for investors to break even. It is the opposite of a “zero waste” approach and locks countries into a perpetual cycle of producing and importing waste to “feed the beast”. And incineration leaves a legacy of contaminated air, soil, and water.

Producing lower-grade materials from plastic waste (such as roads, fenceposts and park benches) is not the solution either. No matter where we put it, plastic doesn’t go away. It just breaks into ever smaller pieces with a greater potential for harm in air, water, soil and marine and freshwater ecosystems.

This is why researchers are paying more attention to the less visible hazards posed when micro (less than 5mm long) and nano (less than 100 nanometres long) sized plastics carry pathogens, invasive species and persistent organic pollutants. They have found that plastics can emit methane contributing to greenhouse gas emissions.

Tyres wear down into microplastics which find their way into the ocean. When plastics break down to nanoparticles, they are small enough to pass through cell walls. Our clothes release plastic microfibres into water from washing machines.

Plastic is truly global

Plastic pollution moves readily around the globe. It travels through trade, on winds, river and tidal flows, and in the guts of migrating birds and mammals. We don’t always know which toxic chemicals are in them, nor their recycled content. Plastic pollution can end up thousands of kilometres from the source.

This makes plastic pollution a matter of international concern. It cannot be solved solely within national borders or regions. A global, legally binding treaty with clear targets and standards is the real game-changer we urgently need.

The NGO component of UNEA’s expert group recognised an international treaty as the most effective response. The proposed treaty has the potential to capture the full life cycle of plastics by focusing on prevention, right at the top of the waste hierarchy.

The Zero Waste hierarchy.
Zero Waste Europe

These solutions could include restricting the volume of new or “virgin” plastics in products, banning avoidable plastics (such as single-use plastic bags and straws), and curbing the use of toxic additives.




Read more:
We can’t recycle our way to ‘zero waste’


More than 90 civil society organisations around the world and a growing number of countries have indicated early support for a treaty. Australia and New Zealand have not.The Conversation

Trisia Farrelly, Senior Lecturer, Massey University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

How much plastic does it take to kill a turtle? Typically just 14 pieces



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Plastic bags, balloons, and rope fragments were among more than 100 pieces of plastic in the gut of a single turtle.
Qamar Schuyler, Author provided

Britta Denise Hardesty, CSIRO; Chris Wilcox, CSIRO; Kathy Ann Townsend, University of the Sunshine Coast, and Qamar Schuyler, CSIRO

We know there is a lot of plastic in the ocean, and that turtles (and other endangered species) are eating it. It is not uncommon to find stranded dead turtles with guts full of plastic.

But we weren’t really sure whether plastic eaten by turtles actually kills them, or if they just happen to have plastic inside them when they die. Another way to look at it would be to ask: how much is too much plastic for turtles?

This is a really important question. Just because there’s a lot of plastic in the ocean, we can’t necessarily presume that animals are dying from eating it. Even if a few animals do, that doesn’t mean that every animal that eats plastic is going to die. If we can estimate how much plastic it takes to kill a turtle, we can start to answer the question of exactly how turtle populations are affected by eating plastic debris.




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Eight million tonnes of plastic are going into the ocean each year


In our research, published today in Nature Scientific Reports, we looked at nearly 1,000 turtles that had died and washed up on beaches around Australia or were found in nets. About 260 of them we examined ourselves; the others were reported to the Queensland Turtle Stranding Database. We carefully investigated why the turtles died, and for the ones we examined, we counted how many pieces of plastic they had eaten.

Some turtles died of causes that were nothing to do with plastic. They may have been killed by a boat strike, or become entangled in fishing lines or derelict nets. Turtles have even been known to die after accidentally eating a blue-ringed octopus. Others definitely died from eating plastic, with the plastic either puncturing or blocking their gut.

One of the first meals eaten by this sea turtle post-hatchling turned out to be deadly. It died from consuming more than 20 tiny pieces of plastic, many of which were about the same size as a grain of rice.
Kathy Townsend, Author provided

Some turtles that were killed by things like boat strikes or fishing nets nevertheless had large amounts of plastic in their guts, despite not having been killed by eating plastic. These turtles allow us to see how much plastic an animal can eat and still be alive and functioning.

The chart below sets out this idea. If an animal drowned in a fishing net, its chance of being killed by plastic is zero – and it falls in the lower left of the graph. If a turtle’s gut was blocked by a plastic bag, its chance of being killed by plastic is 100%, and it’s in the upper right.

The animals that were dead with plastic in their gut, but had other possible causes of death have a chance of death due to plastic somewhere between 0 and 100% – we just don’t know, and they can fall anywhere in the graph. Once we have all the animals in the plot, then we can ask whether we see an increase in the chance of death due to plastic as the amount of plastic in an animal goes up.

Conceptual framework for estimating the probability of death due to plastic debris ingestion. Figure provided by the authors.

We tested this idea using our turtle samples. We looked at the relationship between the likelihood of death due to plastic as determined by a turtle autopsy, and the number of pieces of plastic found inside the animals.

Unsurprisingly, we found that the more plastic pieces a turtle had inside it, the more likely it was to have been killed by plastic. We calculated that for an average-sized turtle (about 45cm long), eating 14 plastic items equates to a 50% chance of being fatal.




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That’s not to say that a turtle can eat 13 pieces of plastic without harm. Even a single piece can potentially kill a turtle. Two of the turtles we studied had eaten just one piece of plastic, which was enough to kill them. In one case, the gut was punctured, and in the other, the soft plastic had clogged the turtle’s gut. Our analyses suggest that a turtle has a 22% chance of dying if it eats just one piece of plastic.

A green sea turtle that died after consuming 13 pieces of soft plastic and balloons, which blocked its gastrointestinal system.
Kathy Townsend

A few other factors also affected the animals’ chance of being killed by plastic. Juveniles eat more debris than adults, and the rate also varies between different turtle species.

Now that we know how much is too much plastic, the next step is to apply this to global estimates of debris ingestion rates by turtles, and figure out just how much of a threat plastic is to endangered sea turtle populations.The Conversation

Britta Denise Hardesty, Principal Research Scientist, Oceans and Atmosphere Flagship, CSIRO; Chris Wilcox, Senior Research Scientist, CSIRO; Kathy Ann Townsend, Lecturer in Animal Ecology, University of the Sunshine Coast, and Qamar Schuyler, Research Scientist, Oceans and Atmospheres, CSIRO

This article is republished from The Conversation under a Creative Commons license. Read the original article.

How to break up with plastics (using behavioural science)



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Single-use plastics are convenient, but it’s time to phase them out.
Photo by Sander Wehkamp/Unsplash

Kim Borg, Monash University

Australia is responsible for over 13 thousand tonnes of plastic litter per year. At the end of June 2018, the Australian government released an inquiry report on the waste and recycling industry in Australia. One of the recommendations was that we should phase out petroleum-based single-use plastics by 2023.

This means a real social shift, because the convenient plastic products that we use once and throw away are ubiquitous in Australia.




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In banning plastic bags we need to make sure we’re not creating new problems


Bans, as Coles and Woolworths recently adopted for plastic bags, are one option – but are not suitable for every situation. They can also feel like an imposition, which can inspire backlash if the community is not on board. Behavioural science can offer a path to curb our plastic use.

Technology alone is not the solution

First off, plastic is not evil: it’s flexible, durable, waterproof and cheap. The issue is the way we dispose of it. Because plastic is so versatile it has been adopted across a range of single-use “throw away” consumer products.

Many people are working on technological solutions to our plastic problems. These range from better recycling techniques and biodegradable “plastics” made from algae or starch, to (my favourite) using the wax moth caterpillar or “mutant bacteria” to consume plastic waste.

But these options are slow and expensive. They can also have other environmental impacts such as greenhouse gas emissions and resource consumption.

There are lots of reusable alternatives to many single-use products. The challenge is getting people to use them.

Behavioural science to the rescue

My research involves applying insights from various disciplines (like economics, psychology, sociology or communication) to understand how governments and businesses can encourage people to change their behaviour for environmental, social and economic benefits.




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Plastic-free campaigns don’t have to shock or shame. Shoppers are already on board


Research has found that simply providing information through awareness campaigns is unlikely to change behaviour. What media attention and campaigning can do is increase the public visibility of an issue. This can indirectly influence our behaviour by making us more open to other interventions and by signalling social norms – the unwritten rules of acceptable behaviour.

Successful behaviour change campaigns must empower individuals. We should be left feeling capable of changing, that changing our behaviour will impact the problem, and that we are not alone. One positive example is modelling sustainable behaviours, like using KeepCups or beeswax wraps, in popular TV shows.

Once we’re aware of an issue, we may need a little help to move from intention to action. One strategy for providing this push is a small financial disincentive, like Ireland’s famous “plastax” on single-use plastic bags. Many cafés also offer discount coffees to reward bringing reusable cups.

We can also encourage retailers to “change the default”. Japan increased the refusal rate of plastic bags to 40% after six months of cashiers simply asking people if they wanted a bag.

This approach could be used for other products too. For example, imagine your drink not coming with a straw unless you specifically ask for it. This would cut down on waste, while also avoiding the unintended consequences of banning a product that is important for people with a disability.

Given that there is already strong support for reducing our reliance on single-use plastics, another simple solution would be to provide prompts in key locations, like carparks and workplaces, to remind people to bring their reusables.

While we may have the best of intentions to carry reusables, our old habits can often get in the way. Defaults and prompts can help to bring our good intentions in line with our actual behaviours.

Consumer demand also encourages manufacturers to make more convenient reusable options, like collapsible coffee cups and metal keychain straws. Businesses can also make reusables more accessible by introducing product-sharing schemes like the Freiburg Cup in Germany or Boomerang Bags in Australia.

No ‘one size fits all’ solution

Different situations need different solutions. Product sharing or reusable coffee cups might work in an office or café where the same customers return regularly, but would be impractical at a gallery or museum where customers vary each day.

For societal-level change multiple approaches are more effective than any one initiative alone. For example, if we wanted to phase out plastic cutlery nationally, we could start with an awareness campaign that encourages people to carry reusable alternatives. Then, once the community is on board, implement a small fee with some reminder prompts, and finally move to a ban once the majority have already changed their behaviour.




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Ten ‘stealth microplastics’ to avoid if you want to save the oceans


The ConversationThe key to successfully phasing out our reliance on single-use plastic products is to change the norm. The more we talk about the problem and the solutions, the more businesses will seek out and offer alternatives, and the more likely we are to mobilise together.

Kim Borg, Doctoral Candidate & Research Officer at BehaviourWorks Australia, Monash Sustainable Development Institute, Monash University

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

We have no idea how much microplastic is in Australia’s soil (but it could be a lot)



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Microplastic in the soil is extremely difficult to track (or remove).
Florida Sea Grant, CC BY-NC-SA

Alisa Bryce, University of Sydney; Alex McBratney, University of Sydney; Budiman Minasny, University of Sydney; Damien Field, and Stephen Cattle, University of Sydney

Microplastics in the ocean, pieces of plastic less than 5mm in size, have shot to infamy in the last few years. Governments and businesses targeted microbeads in cosmetics, some were banned, and the world felt a little better.

Dealing with microbeads in cosmetics is a positive first step, but the reality is that they are just a drop in the ocean (less than a billionth of the world’s ocean).




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Microplastics in soil may be a far greater problem. Norwegian research estimates that in Europe and North America, between 110,000 and 730,000 tonnes of microplastic are transferred to agricultural soils each year.

Here lies the issue: we know almost nothing about microplastics in global soils, and even less in Australian soils. In this article we take a look at what we do know, and some questions we need to answer.

How microplastics get into agricultural soil

Sewage sludge and plastic mulch are the two biggest known contributors of microplastics to agricultural soil. Australia produces about 320,000 dry tonnes of biosolids each year, 55% of which is applied to agricultural land. Biosolids, while controversial, are an excellent source of nutrients for farmland. Of the essential plant nutrients, we can only manufacture nitrogen. The rest we must either mine or recycle.

Sewage treatment plants receive water from households, industry, and stormwater, each adding to the load of plastics. Technical clothing such as sportswear and quick-dry fabrics often contain polyesters and polyamides that break off when clothes are washed. Tyre debris and plastic films wash in with the stormwater. Treatment plants filter microplastics out of the water, retaining them in the sludge that is then trucked away and spread over agricultural land.




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In agriculture, plastic mulch suppresses weeds, keeps the soil warm and damp to assist germination, and improves yield. Over time, these mulches break down, and some fragment into smaller pieces.

Biodegradable bioplastic mulches are designed to break down into carbon dioxide, water, and various “natural substances”. Environmentally friendly plastics are often more expensive, raising the question of whether businesses will be able to afford them.

Other potential sources of plastics in agricultural soil include polymer sealants on fertilisers and pesticides, and industrial compost. Unsold food is often sent to the composting facility still in plastic packaging, and with plastic stickers on every apple and kiwi fruit.

The Australian Standard for composts tacitly recognises that microplastics are likely to be present in these products by having acceptable levels of “visible contamination”. Anyone who has bought compost or garden loam from a landscaping supplier may have noticed pieces of plastic in the mix.

In horticulture, particularly as green walls and green roofs grace more buildings, polystyrenes are used deliberately to make lightweight ‘soil’.

There might be other pathways we don’t know about yet.

What happens once microplastics are in the soil?

Here we stand at the edge of the cavernous knowledge gap, because we don’t know the effect of microplastics in our soil. The overarching question, physically and biologically, is where do microplastics go?

How plastics fragment and degrade in the soil depends on the type of plastic and soil conditions. Compostable, PET, and various degradable plastics will behave differently, having different effects on soil physics and biology.

Fragments could move through soil cracks and pores. Larger soil fauna might disperse fragments vertically and laterally, while agricultural practices such as tillage could push plastics deeper into the soil. Some fragmented plastics can absorb agrochemicals.

Soil microbes can break down some plastics, but what are the byproducts and what are their effects? Newer, biodegradable bioplastics theoretically have limited impact as they break down into inert substances. But how long do they take to break down in different soil and climatic conditions, and what proportion in the soil are non-degradable PET plastics?

Both the main form of carbon in soil and polythene (the most common type of plastic) are carbon-based polymers. Could the two integrate? If they did, would this prevent plastics from moving deeper into the soil, but would it also stop them breaking down?

Could plastics be a hidden source of soil carbon storage?

Bioaccumulation

Bioaccumulation is when something builds up in a food chain.

Research into microplastic accumulation on land is sparse at best. A 2017 study in Mexico found microplastics in chicken gizzards. In the study area, waste management is poor and most plastics were ingested directly from the soil surface as opposed to having bioaccumulated.

Nematodes can take up polystyrene beads suggesting some potential for bioaccumulation, however earthworms have reduced growth rate and increased mortality when they ingest microbeads.

Larger microplastics are unlikely to cross plant cell membranes, but it’s possible that plants can absorb the chemicals formed when plastic degrades. Plants have natural mechanisms to keep contaminants out of their fruiting bodies – pieces of plastic in apples or berries is highly unlikely – but root vegetables and leafy greens are a different story.

Metals can accumulate in leafy greens and the skin of root vegetables – could plastics or their byproducts do the same?

This is before we even get to nanoplastics, which are 1-100 nanometres wide. Can plant roots can absorb nanoplastics, and can they pass through an animal’s gut membrane?

Where to now?

The first step is to quantify how much plastic is currently in the soil, where it is, and how much more to expect. This is more difficult in land than water, as it’s easier to filter plastics out the ocean than to separate them from soil samples. The smaller the plastics are, the harder they’ll be to track and identify – which is why research must start now.

Research needs to address the different types of plastics, including beads and other synthetic fibres. Each is likely to act differently in the soil and terrestrial ecosystems.

Understanding how these plastics react will inform the next obvious questions: at what quantity do they become hazardous to soil, plant and animal life, and how can we mitigate this impact?

The ConversationPlastics in soil represent artefacts of human civilisation. Soils are full of human artefacts; if this was not the case then there would be no field archaeology. However, the effects of microplastic may persist far longer than our own civilisation. We must fill in our knowledge gaps swiftly.

Alisa Bryce, Research Affiliate, University of Sydney; Alex McBratney, Professor of Digital Agriculture & Soil Science; Director, Sydney Institute of Agriculture, University of Sydney; Budiman Minasny, Professor in Soil-Landscape Modelling, University of Sydney; Damien Field, Associate professor, and Stephen Cattle, Associate professor, University of Sydney

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