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.

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Logging burns conceal industrial pollution in the name of ‘community safety’



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High intensity logging burns and the resulting smoke plume near Mount Baw Baw, April 2018
Photo Chris Taylor., Author provided

Chris Taylor, University of Melbourne and David Lindenmayer, Australian National University

Earlier this year, Melbourne and large areas of Central Victoria, experienced days of smoke haze and poor air quality warnings as a result of planned burns. It’s a regular event occurring every autumn.

This smoke has been reported by both government and media outlets as largely the result of planned burns to reduce bushfire risk, along with agricultural burn-offs and increased use of wood heaters.




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But this is only part of the story. A good proportion of the smoke this autumn has actually come from the intensive burning of debris left behind after clearfell logging. This is essentially industrial pollution.

Smoke Haze over Mooroolbark and Melbourne’s eastern suburbs on Tuesday 1 May 2018, shortly after the time when the Poor Air Quality Index reached 901.
Photo: Chris Taylor, Author provided

Industrial clearfell logging vs fuel reduction

To understand why clearfell logging burns are different compared with planned burns to reduce bushfire risk, we need to understand clearfell logging, which involves cutting most or all of the commercially valued trees in one single operation across a designated area (called a “coupe”).

Large volumes of forest biomass are left on the ground following clearfell logging in the Mount Disappointment State Forest with the Melbourne City Skyline in the background, August 2010.
Photo. Chris Taylor., Author provided

In the process of clearfell logging, understorey vegetation is usually pushed over. Along with tree heads and branches left behind after logging, large volumes of debris – known as “slash” – are created. This is partially removed by applying a high intensity burn across the coupe, which in turn establishes an ash seed bed for the next crop of trees to be established. Generally, around 90-100% of the coupe is burnt.

In contrast, planned burns to reduce bushfire risk (otherwise referred to as fuel reduction burns) are less intense. They mostly target “fine fuels” (vegetation less than 6mm in diameter) on the forest floor and in the understorey, which may average around 15 tonnes per hectare (t/ha). Burn coverage is usually 50-70% of the site.

Surface and understorey ‘fine fuels’ targeted in a recent low intensity burn near Mt Dandenong in April 2018.
Photo: Chris Taylor, Author provided

Clearfell logging burns consume much larger volumes of vegetation biomass in the form of tree heads, branches, bark and downed understorey vegetation. According to a report completed for the National Carbon Accounting System, clearfell logging burns consume, on average, 130 t/ha of slash in mixed-species forest and 140 t/ha of slash in Mountain Ash forests. This means that, while clearfell logging burns cover much less ground than fuel reduction burns, they burn far more biomass per hectare – generating far more smoke.

The list of planned burns on Forest Fire Management Victoria’s website showed that, at the beginning of May, 77 of the 119 burns either lit or planned to be lit across the Central Highlands of Victoria and surrounding areas were on logging coupes.




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These burns were individually lit over a period of weeks, with some days predominantly logging burns, others fuel reduction burns. An example when logging burns were prominent occurred on April 20 this year, where 10 out of 12 planned burns were observed as occurring on logging coupes. Using a simple calculation based on average biomass consumption, fuel loads and burn coverage for logging and fuel reduction burns, we estimate that up to 99% of biomass burnt most likely occurred on logging coupes. The following day, the Environmental Protection Authority observed “poor” air quality at multiple air monitoring stations across Melbourne due to smoke.

MODIS Rapid Response Terra Satellite image taken 20 April 2018 showing the smoke intensity of the logging burns.
NASA 2018

Even on days when the majority of burns lit were for fuel reduction, planned logging burns still contributed a proportion of biomass burned. For example, on April 30, only three out of 12 planned burns were observed as occurring on logging coupes, but they may have contributed to around one-third of the total biomass burned.




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Likewise, on the following day, the Environmental Protection Authority observed “very poor” air quality across multiple air monitoring stations. While multiple planned burns contributed to this pollution event, we contend that logging burns increased the levels of pollution in addition to the smoke originating from fuel reduction burns.

MODIS Rapid Response Terra Satellite image taken 30 April 2018 showing the smoke intensity of the planned burns.
NASA 2018

The key issue here is that not all “planned burns” are equivalent. Fuel reduction burns are intended to reduce the bushfire risk to lives and property. Indeed, work led by The Australian National University shows that regular fuel reduction burns can reduce risk to properties if carried out within close proximity.

In contrast, clearfell logging burns are part of an industrial process that extracts pulp logs and sawlogs for commercial sale to private enterprise. They play no part in reducing bushfire risk to life and property. Actually, the reverse is true: logging makes forests more prone to subsequent high-severity crown-consuming fires with associated risks to communities.




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Victoria’s logged landscapes are at increased risk of bushfire


Given that a substantial proportion of the recent smoke over Melbourne and surrounding regional Victoria likely originated from logging burns, could that smoke be deemed industrial pollution? This is a valid question, given the serious health impacts associated with smoke pollution.

The ConversationLogging burns would not be needed (and a substantial amount of associated smoke not generated) if the forest had not been logged in the first place. It is imperative that government departments inform the public about the smoke pollution coming from logging operations, whose purpose is for private commercial gain.

Chris Taylor, Researcher, University of Melbourne and David Lindenmayer, Professor, The Fenner School of Environment and Society, Australian National University

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

Don’t believe the label: ‘flushable wipes’ clog our sewers



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Don’t believe the wipe hype: they can’t be flushed down toilets, not matter what the label says.
SIM Central and South East Asia Follow/Flickr, CC BY-NC

Ian Wright, Western Sydney University

The manufacturer of White King “flushable” wipes has been fined A$700,000 because these are not, in fact, flushable. The wipes, advertised as “just like toilet paper”, cannot disintegrate in the sewerage system, and cause major blockages.

The Federal Court found Pental Products and Pental Limited, which manufacture the wipes, guilty of making false and misleading representations. In particular, Pental claimed that the wipes would break down in the sewerage system, like toilet paper does.




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So-called flushable wipes, now sold for everything from make-up removal to luxury toilet paper, are a growing hazard to public health. Sydney Water says 75% of all sewer blockages in the city’s waste-water system involve wipes.

Don’t trust the label

While wipes might look a bit like toilet paper, there are major differences. Wipes are made from a very tough material called “air-laid paper”, and are often impregnated with cleansing chemicals, disinfectants and cosmetic scents.

Air-laid paper behaves very differently in sewers to toilet paper and does not readily disintegrate in water.

A CHOICE demonstration comparing wipes with toilet paper over 20 hours.

When in sewer pipes the resilient wipes have a tendency to entangle with other wipes and create blockages. This is a bit like the knot of tangled clothing sometimes found in the washing machine. Sewerage system managers around the globe seem powerless to prevent the problem.

Sewer blockages caused by wipes look grotesque. Unpleasant work in confined places is required to remove the blockages (some of which is done by hand!). In 2016 Newcastle’s Hunter Water removed an ugly seven-metre snake of wipes and assorted sewage debris, weighing roughly a tonne, from its sewers.

Wither do you wipe?

Wipes become very popular in the 1990s to help in cleaning babies’ bottoms while changing nappies. Since then, many similar products (“wet wipes”, “baby wipes” and “face wipes”) have proliferated well beyond the baby aisle.

Wipes may be advertised for personal hygiene, removing makeup and cleaning hands. Others are marketed for cleaning bathroom surfaces, toilets and other household areas. The marketing of wipes often boasts how easy they are to dispose by simply flushing them down the toilet.

More recently, a booming adult market is expanding their use as a luxury alternative to toilet paper, buoyed by endorsements from celebrities like Will Smith and Will.i.am. Research by Sydney Water found that males in the 15-44 bracket particularly preferred to use wipes rather than toilet paper. The same market survey estimated that a quarter of Sydney Water’s 4.6 million customers flush wipes down the toilet rather than putting them in a bin.

The three Ps

The fine imposed on Pental Products and Pental Limited for their “flushable” wipes is an important signal to others in this growing market.

However, wipes are not the only waste item that people should not flush down the toilet. This issue gained international notoriety in 2017 when Thames Water in London removed a 130-tonne monster sewer blockage, in a difficult and laborious three-week operation. The blockage was an accumulation of solids called a fatberg – a nightmarish combination of wipes, congealed fat, nappies, female sanitary products, and condoms.




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Have we forgotten what toilets are for? The Australia Water Association reminds us that they are for the three Ps: pee, poo and paper (toilet paper only).

Perhaps people should visit an Irish website called think before you flush. It lists other common waste objects that should not be flushed, such as cigarette butts, cotton buds, dental floss, hair and unwanted medication. It also advises that a bin be placed in each bathroom.

The ConversationHopefully, packets of wipes will now carry warning labels to advise users not to flush them down the toilet. Just because you can flush something down the toilet does not mean it is good for the environment or society to do so.

Ian Wright, Senior Lecturer in Environmental Science, Western Sydney University

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

Your drive to the shops makes life pretty noisy for whales



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Living alongside humans gets noisier all the time.
Katrina Burgers/Shutterstock.com

Andrew J. Wright, Fisheries and Oceans Canada

As unlikely as it may seem, your drive to the supermarket is responsible for a lot of noise pollution in our oceans – and a lot of stress to marine life as a result.

Of course, it’s not the specific sound of your car trundling along the street that the fish and whales hear. But many of the products that feature in your weekly shop – from the goods you buy, to the petrol you burn, to your car’s component parts – contribute to marine noise pollution.




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The fuel

Let’s start with the oil. Before we can drill the oil or turn it into fuel to drive our cars, oil companies have to discover it.

Companies look for oil using high-pressure airguns. These machines are towed across the surface of the ocean, firing off sounds to determine the make-up of sediment layers in the seafloor. These are some of the loudest human-created sounds – researchers working in the middle of the Atlantic Ocean have been able to record the sounds produced from coastal oil surveys.

Rex Virtual Drilling.
Chooywa/wikimedia, CC BY-SA

These sounds are problematic for marine life. Whales and other animals that rely heavily on sound for communicating and finding food are most affected. Hearing is to these animals much the same as vision is to humans. Unusually loud sounds can disturb whales’ behaviour and, if they are close enough, can damage their hearing. There is even some suggestion that the airguns can cause whale strandings, although this is not yet completely certain.

Currently, one-third of all oil comes from offshore sources and this proportion is expected to increase. This can only mean more bad news for our marine life.

The car

What about the metal box that consumes all the oil? Parts for the car are sourced from all over the world and have to be shipped across our oceans. In turn, the raw materials needed to make these parts are usually shipped in from yet more places. The commercial shipping needed for all this represents another problematic source of ocean noise.

The relative density of commercial shipping routes in our oceans.
B.S. Halpern/Wikimedia Commons, CC BY-SA

The contributions of individual ships may seem trivial in comparison to the loud noise from airguns. However, the world merchant fleet includes around 52,000 ships. Collectively, these increase the ambient noise levels in our oceans. In fact, the amount of low-frequency sound in some parts of our oceans has doubled each decade over the past 60 years.

Humans perceive only some of this sound, because of the very low pitches involved. But these sounds are well within the frequency range used by baleen whales. Recent work suggests that this constrains the communication ranges in whales, causing chronic stress and potentially interrupting mating behaviour.

Parts of the ocean are filling up with man-made noise, and that presents many dangers to marine life.
B. Southall/NMFS and NOAA

The groceries

Oh, and most of your groceries are shipped around the world at some point too, as are many other consumer items – including the battery in your hybrid car, if you have one. Around 90% of world trade is carried by commercial ships at some stage. Not all of this ends up in your shopping bag, but a large proportion enters the consumer market at some point.

Certain grocery items, such as fish, originate from the oceans themselves. Like cargo ships, fishing vessels produce noise from their engines and propellers, but they also have noisy fish-finding sonars and winches as well.




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The solutions

The good news is that noise pollution, unlike chemical pollution, dissipates quickly. This means that the future for underwater noise remains bright. If you want to give the whales a break, just drive a little less, or support higher efficiency standards for vehicles. This will not only reduce oil consumption, but also the wear and tear on your car, meaning that fewer replacement parts will need to be shipped in.

Time for a rethink?
Joe Goldberg/flickr, CC BY-SA

You can also buy locally produced items and support the local economy too. That way everyone wins.

The ConversationNo matter how connected we think everything is, the situation is generally even more complicated than we can imagine. So next time you walk to the shops and buy an apple grown in your state, you should allow yourself a moment to feel good about yourself, safe in the knowledge that you have helped to make the oceans a tiny bit quieter.

Andrew J. Wright, Marine Mammal Researcher, Fisheries and Oceans Canada

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