After a storm, microplastics in Sydney’s Cooks River increased 40 fold



A litter trap in Cook’s River.
James HItchcock, Author provided

James Hitchcock, University of Canberra

Each year the ocean is inundated with 4.8 to 12.7 million tonnes of plastic washed in from land. A big proportion of this plastic is between 0.001 to 5 millimetres, and called “microplastic”.

But what happens during a storm, when lashings of rain funnel even more water from urban land into waterways? To date, no one has studied just how important storm events may be in polluting waterways with microplastics.




Read more:
Microplastic pollution is everywhere, but scientists are still learning how it harms wildlife


So to find out, I studied my local waterway in Sydney, the Cooks River estuary. I headed out daily to measure how many microplastics were in the water, before, during, and after a major storm event in October, 2018.

The results, published on Wednesday, were startling. Microplastic particles in the river had increased more than 40 fold from the storm.

Particles of plastic found in rivers. They may be tiny, but they’re devastating to wildlife in waterways.
Author provided

To inner west Sydneysiders, the Cooks River is known to be particularly polluted. But it’s largely similar to many urban catchments around the world.

If the relationship between storm events and microplastic I found in the Cooks River holds for other urban rivers, then the concentrations of microplastics we’re exposing aquatic animals to is far higher than previously thought.

14 million plastic particles

They may be tiny, but microplastics are a major concern for aquatic life and food webs. Animals such as small fish and zooplankton directly consume the particles, and ingesting microplastics has the potential to slow growth, interfere with reproduction, and cause death.

Determining exactly how much microplastic enters rivers during storms required the rather unglamorous task of standing in the rain to collect water samples, while watching streams of unwanted debris float by (highlights included a fire extinguisher, a two-piece suit, and a litany of tennis balls).

Back in the laboratory, a multi-stage process is used to separate microplastics. This includes floating, filtering, and using strong chemical solutions to dissolve non-plastic items, before identification and counting with specialised microscopes.

Litter caught in a trap in Cooks River. These traps aren’t effective at catching microplastic.
Author provided

In the days before the October 2018 storm, there were 0.4 particles of microplastic per litre of water in the Cooks River. That jumped to 17.4 microplastics per litre after the storm.

Overall, that number averages to a total of 13.8 million microplastic particles floating around in the Cooks River estuary in the days after the storm.




Read more:
Seafloor currents sweep microplastics into deep-sea hotspots of ocean life


In other urban waterways around the world scientists have found similarly high numbers of microplastic.

For example in China’s Pearl River, microplastic averages 19.9 particles per litre. In the Mississippi River in the US, microplastic ranges from 28 to 60 particles per litre.

Where do microplastics come from?

We know runoff during storms is one of the main ways pollutants such as sediments and heavy metals end up in waterways. But not much is known about how microplastic gets there.

However think about your street. Wherever you see litter, there are also probably microplastics you cannot see that will eventually work their way into waterways when it rains.




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Many other sources of microplastics are less obvious. Car tyres, for example, which typically contain more plastic than rubber, are a major source of microplastics in our waterways. When your tyres lose tread over time, microscopic tyre fragments are left on roads.

Did you know your car tyres can be a major source of microplastic pollution?
Shutterstock

Microplastics may even build up on roads and rooftops from atmospheric deposition. Everyday, lightweight microplastics such as microfibres from synthetic clothing are carried in the wind, settling and accumulating before they’re washed into rivers and streams.

What’s more, during storms wastewater systems may overflow, contaminating waterways. Along with sewage, this can include high concentrations of synthetic microfibers from household washing machines.

And in regional areas, microplastics may be washing in from agricultural soils. Sewage sludge is often applied to soils as it is rich in nutrients, but the same sludge is also rich in microplastics.

What can be done?

There are many ways to mitigate the negative effects of stormwater on waterways.

Screens, traps, and booms can be fitted to outlets and rivers and catch large pieces of litter such as bottles and packaging. But how useful these approaches are for microplastics is unknown.

Raingardens and retention ponds are used to catch and slow stormwater down, allowing pollutants to drop to bottom rather than being transported into rivers. Artificial wetlands work in similar ways, diverting stormwater to allow natural processes to remove toxins from the water.

Almost 14 million plastic particles were floating in Cooks River after a storm two years ago.
Shutterstock

But while mitigating the effects of stormwater carrying microplastics is important, the only way we’ll truly stop this pollution is to reduce our reliance on plastic. We must develop policies to reduce and regulate how much plastic material is produced and sold.

Plastic is ubiquitous, and its production around the world hasn’t slowed, reaching 359 million tonnes each year. Many countries now have or plan to introduce laws regulating the sale or production of some items such as plastic bags, single-use plastics and microbeads in cleaning products.




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


In Australia, most state governments have committed to banning plastic bags, but there are still no laws banning the use of microplastics in cleaning or cosmetic products, or single-use plastics.

We’ve made a good start, but we’ll need deeper changes to what we produce and consume to stem the tide of microplastics in our waterways.The Conversation

James Hitchcock, Post-Doctoral Research Fellow, University of Canberra

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

NSW has approved Snowy 2.0. Here are six reasons why that’s a bad move



Lucas Coch/AAP

Bruce Mountain, Victoria University and Mark Lintermans, University of Canberra

The controversial Snowy 2.0 project has mounted a major hurdle after the New South Wales government today announced approval for its main works.

The pumped hydro venture in southern NSW will pump water uphill into dams and release it when electricity demand is high. The federal government says it will act as a giant battery, backing up intermittent energy from by wind and solar.

We and others have criticised the project on several grounds. Here are six reasons we think Snowy 2.0 should be shelved.

1. It’s really expensive

The federal government announced the Snowy 2.0 project without a market assessment, cost-benefit analysis or indeed even a feasibility study.

When former Prime Minister Malcolm Turnbull unveiled the Snowy expansion in March 2017, he said it would cost A$2 billion and be commissioned by 2021. This was revised upwards several times and in April last year, Snowy Hydro awarded a A$5.1 billion contract for partial construction.

Snowy Hydro has not costed the transmission upgrades on which the project depends. TransGrid, owner of the grid in NSW, has identified options including extensions to Sydney with indicative costs up to A$1.9 billion. Massive extensions south, to Melbourne, will also be required but this has not been costed.

The Tumut 3 scheme, with which Snowy 2.0 will share a dam.
Snowy Hydro Ltd

2. It will increase greenhouse gas emissions

Both Snowy Hydro Ltd and its owner, the federal government, say the project will help expand renewable electricity generation. But it won’t work that way. For at least the next couple of decades, analysis suggests Snowy 2.0 will store coal-fired electricity, not renewable electricity.

Snowy Hydro says it will pump the water when a lot of wind and solar energy is being produced (and therefore when wholesale electricity prices are low).




Read more:
Snowy 2.0 is a wolf in sheep’s clothing – it will push carbon emissions up, not down


But wind and solar farms produce electricity whenever the resource is available. This will happen irrespective of whether Snowy 2.0 is producing or consuming energy.

When Snowy 2.0 pumps water uphill to its upper reservoir, it adds to demand on the electricity system. For the next couple of decades at least, coal-fired electricity generators – the next cheapest form of electricity after renewables – will provide Snowy 2.0’s power. Snowy Hydro has denied these claims.

Khancoban Dam, part of the soon-to-be expanded Snowy Hydro scheme.
Snowy Hydro Ltd

3. It will deliver a fraction of the energy benefits promised

Snowy 2.0 is supposed to store renewable energy for when it is needed. Snowy Hydro says the project could generate electricity at its full 2,000 megawatt capacity for 175 hours – or about a week.

But the maximum additional pumped hydro capacity Snowy 2.0 can create, in theory, is less than half this. The reasons are technical, and you can read more here.

It comes down to a) the amount of time and electricity required to replenish the dam at the top of the system, and b) the fact that for Snowy 2.0 to operate at full capacity, dams used by the existing hydro project will have to be emptied. This will result in “lost” water and by extension, lost electricity production.



The Conversation, CC BY-ND

4. Native fish may be pushed to extinction

Snowy 2.0 involves building a giant tunnel to connect two water storages – the Tantangara and Talbingo reservoirs. By extension, the project will also connect the rivers and creeks connected to these reservoirs.

A small, critically endangered native fish, the stocky galaxias, lives in a creek upstream of Tantangara. This is the last known population of the species.

The stocky galaxias.
Hugh Allan

An invasive native fish, the climbing galaxias, lives in the Talbingo reservoir. Water pumped from Talbingo will likely transfer this fish to Tantangara.

From here, the climbing galaxias’ capacity to climb wet vertical surfaces would enable it to reach upstream creeks and compete for food with, and prey on, stocky galaxias – probably pushing it into extinction.

Snowy 2.0 is also likely to spread two other problematic species – redfin perch and eastern gambusia – through the headwaters of the Murrumbidgee, Snowy and Murray rivers.




Read more:
Snowy 2.0 threatens to pollute our rivers and wipe out native fish


5. It’s a pollution risk

Snowy Hydro says its environmental impact statement addresses fish transfer impacts, and potentially serious water quality issues.

Four million tonnes of rock excavated to build Snowy 2.0 would be dumped into the two reservoirs. The rock will contain potential acid-forming minerals and other harmful substances, which threaten to pollute water storages and rivers downstream.

When the first stage of the Snowy Hydro project was built, comparable rocks were dumped in the Tooma River catchment. Research in 2006 suggested the dump was associated with eradication of almost all fish from the Tooma River downstream after rainfall.

Snowy 2.0 threatens to pollute pristine Snowy Mountains rivers.
Schopier/Wikimedia

6. Other options were not explored

Many competing alternatives can provide storage far more flexibly for a fraction of Snowy 2.0’s price tag. These alternatives would also have far fewer environmental impacts or development risks, in most cases none of the transmission costs and all could be built much more quickly.

Expert analysis in 2017 identified 22,000 potential pumped hydro energy storage sites across Australia.

Other alternatives include chemical batteries, encouraging demand to follow supply, gas or diesel generators, and re-orienting more solar capacity to capture the sun from the east or west, not just mainly the north.

Where to now?

The federal government, which owns Snowy Hydro, is yet to approve the main works.

Given the many objections to the project and how much has changed since it was proposed, we strongly believe it should be put on hold, and scrutinised by independent experts. There’s too much at stake to get this wrong.




Read more:
Five gifs that explain how pumped hydro actually works


The Conversation


Bruce Mountain, Director, Victoria Energy Policy Centre, Victoria University and Mark Lintermans, Associate professor, University of Canberra

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

Seafloor currents sweep microplastics into deep-sea hotspots of ocean life



A rockfish hides in a red tree coral in the deep sea.
Geofflos

Ian Kane, University of Manchester and Michael Clare, National Oceanography Centre

What if the “great ocean garbage patches” were just the tip of the iceberg? While more than ten million tonnes of plastic waste enters the sea each year, we actually see just 1% of it – the portion that floats on the ocean surface. What happens to the missing 99% has been unclear for a while.

Plastic debris is gradually broken down into smaller and smaller fragments in the ocean, until it forms particles smaller than 5mm, known as microplastics. Our new research shows that powerful currents sweep these microplastics along the seafloor into large “drifts”, which concentrate them in astounding quantities. We found up to 1.9 million pieces of microplastic in a 5cm-thick layer covering just one square metre – the highest levels of microplastics yet recorded on the ocean floor.

While microplastics have been found on the seafloor worldwide, scientists weren’t sure how they got there and how they spread. We thought that microplastics would separate out according to how big or dense they were, in a similar manner to natural sediment. But plastics are different – some float, but more than half of them sink.




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Plastics which once floated can sink as they become coated in algae, or if bound up with other sticky minerals and organic matter. Recent research has shown that rivers transport microplastics to the ocean too, and laboratory experiments revealed that giant underwater avalanches of sediment can transport these tiny particles along deep-sea canyons to greater depths.

We’ve now discovered how a global network of deep-sea currents transports microplastics, creating plastic hotspots within vast sediment drifts. By catching a ride on these currents, microplastics may be accumulating where deep-sea life is abundant.

Once plastic debris has broken down and sinks to the ocean floor, currents sweep the particles into vast drifts.
Ian Kane, Author provided

From bedroom floors to the seafloor

We surveyed an area of the Mediterranean off the western coast of Italy, known as the Tyrrhenian Sea, and studied the bottom currents that flow near the seafloor. These currents are driven by differences in water salinity and temperature as part of a system of ocean circulation that spans the globe. Seafloor drifts of sediment can be many kilometres across and hundreds of metres high, forming where these currents lose their strength.

We analysed sediment samples from the seafloor taken at depths of several hundred metres. To avoid disturbing the surface layer of sediment, we used samples taken with box-cores, which are like big cookie cutters. In the laboratory, we separated microplastics from the sediment and counted them under microscopes, analysing them using infra-red spectroscopy to find out what kinds of plastic polymer types were there.

A microplastic fibre seen under a microscope.
Ian Kane, Author provided

Most microplastics found on the seafloor are fibres from clothes and textiles. These are particularly insidious, as they can be eaten and absorbed by organisms. Although microplastics on their own are often non-toxic, studies show the build-up of toxins on their surfaces can harm organisms if ingested.

These deep ocean currents also carry oxygenated water and nutrients, meaning that the seafloor hotspots where microplastics accumulate may also be home to important ecosystems such as deep-sea coral reefs that have evolved to depend on these flows, but are now receiving huge quantities of microplastics instead.

What was once a hidden problem has now been uncovered – natural currents and the flow of plastic waste into the ocean are turning parts of the seafloor into repositories for microplastics. The cheap plastic goods we take for granted eventually end up somewhere. The clothes that may only last weeks in your wardrobe linger for decades to centuries on the seafloor, potentially harming the unique and poorly understood creatures that live there.The Conversation

Ian Kane, Reader in Geology, University of Manchester and Michael Clare, Principal Researcher in Marine Geoscience, National Oceanography Centre

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

Snowy 2.0 threatens to pollute our rivers and wipe out native fish



Schopier/Wikimedia

John Harris, UNSW and Mark Lintermans, University of Canberra

The federal government’s Snowy 2.0 energy venture is controversial for many reasons, but one has largely escaped public attention. The project threatens to devastate aquatic life by introducing predators and polluting important rivers. It may even push one fish species to extinction.

The environmental impact statement for the taxpayer-funded project is almost 10,000 pages long. Yet it fails to resolve critical problems, and in one case seeks legal exemptions to enable Snowy 2.0 to wreak environmental damage.

The New South Wales government is soon expected to grant the project environmental approval. This process should be suspended, and independent experts should urgently review the project’s environmental credentials.

Native fish extinctions

Snowy Hydro Limited, a Commonwealth-owned corporation, is behind the Snowy 2.0 project in the Kosciuszko National Park in southern NSW. It involves building a giant tunnel to connect two water storages – the Tantangara and Talbingo reservoirs. By extension, the project will also connect the rivers and creeks connected to these reservoirs.

A small, critically endangered native fish, the stocky galaxias, lives in a creek upstream of Tantangara. This is the last known population of the species.




Read more:
Snowy 2.0 is a wolf in sheep’s clothing – it will push carbon emissions up, not down


An invasive native fish, the climbing galaxias, lives in the Talbingo reservoir (it was introduced from coastal streams when the original Snowy project was built). Water pumped from Talbingo will likely transfer this fish to Tantangara.

From here, the climbing galaxias’ capacity to climb wet vertical surfaces would enable it to reach upstream creeks and compete for food with, and prey on, stocky galaxias – probably pushing it into extinction.

The stocky galaxias.
Hugh Allan

Snowy Hydro has applied for an exemption under NSW biosecurity legislation to permit the transfer of the climbing galaxias and two other fish species: the alien, noxious redfin perch and eastern gambusia.

Redfin perch compete for food with other species and produce many offspring. They are voracious, carnivorous predators, known to prey on smaller fish.

Redfin perch also allow the establishment of a fatal fish disease – epizootic haematopoietic necrosis virus – or EHN. This disease kills the endangered native Macquarie perch, the population of which below Tantangara is one of very few remaining.

If Snowy 2.0 is granted approval, it is likely to spread these problematic species through the headwaters of the Murrumbidgee, Snowy and Murray rivers.

The climbing galaxias, which threatens the native stocky galaxias.
Stella McQueen/Wikimedia

Acid and asbestos pollution

Four million tonnes of rock excavated to build Snowy 2.0 would be dumped into the two reservoirs. Snowy Hydro has not assessed the pollution risks this creates. The rock will contain potential acid-forming minerals and a form of asbestos, which threaten to pollute water storages and rivers downstream.

When the first stage of the Snowy Hydro project was built, comparable rocks were dumped in the Tooma River catchment. Research in 2006 suggested the dump was associated with eradication of almost all fish from the Tooma River downstream after rainfall.




Read more:
Snowy 2.0 will not produce nearly as much electricity as claimed. We must hit the pause button


Addressing the problems

The environmental impact statement either ignores, or pays inadequate attention to, these environmental problems.

For example, installing large-scale screens at water inlets would be the best way to prevent fish transfer from Talbingo Dam, but Snowy Hydro has dismissed it as too costly.

Snowy Hydro instead proposes a dubious second-rate measure: screens to filter pumped flows leaving Tantangara reservoir, and building a barrier in the stream below the stocky galaxias habitat.

The best and cheapest way to prevent damage from alien species is stopping the populations from establishing. Trying to control or eradicate pest species once they’re established is far more difficult and costly.



The Conversation, CC BY-ND

We believe the measures proposed by Snowy Hydro are impractical. It would be very difficult to maintain a screen fine and large enough to prevent fish eggs and larvae moving out of Tantangara reservoir and such screens would be totally ineffective at preventing the spread of EHN virus.

A six metre-high waterfall downstream of the stocky galaxias habitat currently protects the critically endangered species from other invasive species threats. But climbing galaxias have an extraordinary ability to ascend wet surfaces. They would easily climb the waterfall, and possibly the proposed creek barrier as well.

Such an engineered barrier has never been constructed in Australia. We are informed that in New Zealand, the barriers have not been fully effective and often require design adjustments.




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Even if the barrier protected the stocky galaxias at this location, efforts to establish populations in other unprotected regional streams would be severely hampered by the spread of climbing galaxias.

Preventing redfin and EHN from entering the Murrumbidgee River downstream of Tantangara depends on the reservoir never spilling. The reservoir has spilled twice since construction in the 1960s, and would operate at much higher water levels when Snowy 2.0 was operating. Despite this, Snowy Hydro says it has “high confidence in being able to avoid spill”.

If dumped spoil pollutes the two reservoirs and Murrumbidgee and Tumut rivers, this would also have potentially profound ecological impacts. These have not been critically assessed, nor effective prevention methods identified.

The Tumut 3 scheme, part of the existing Snowy Hydro scheme.
Snowy Hydro Ltd

Looking to the future

Snowy 2.0 will likely make one critically endangered species extinct and threaten an important remaining population of another, as well as pollute freshwater habitats. As others have noted, the project is also questionable on other environmental and economic grounds.

These potential failures underscore the need to immediately halt Snowy 2.0, and subject it to independent expert scrutiny.


In response to the issues raised in this article, a spokesperson for Snowy Hydro said:

“Snowy Hydro’s EIS, supported by numerous reports from independent scientific experts, extensively address potential water quality and fish transfer impacts and the risk mitigation measures to be put in place. As the EIS is currently being assessed by the NSW Government we have no further comment.”


A previous version of this article incorrectly stated that water pumped from Tantangara will likely transfer fish to Talbingo. It should have said water pumped from Talbingo will likely transfer fish to Tantangara.The Conversation

John Harris, Adjunct Associate Professor, Centre for Ecosystem Science, UNSW and Mark Lintermans, Associate professor, University of Canberra

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

Polluted, drained, and drying out: new warnings on New Zealand’s rivers and lakes



Shutterstock

Troy Baisden, University of Waikato

The latest environmental report on New Zealand’s lakes and rivers reiterates bleak news about the state of freshwater ecosystems, and warns that climate change will exacerbate existing threats.

Almost all New Zealand rivers running through urban and farming areas (95-99%) carry pollution above water quality guidelines, while most of the nation’s wetlands (90%) have been drained, and many freshwater fish species (76%) are threatened or at risk.

The most significant pressures on freshwater ecosystems fit into four issues:


Ministry for the Environment/Stats NZ, CC BY-SA

Climate change gets more attention than in earlier assessments, reflecting the fact that glaciers are already shrinking and soils are drying out.




Read more:
New Zealand’s urban freshwater is improving, but a major report reveals huge gaps in our knowledge


What whitebait tell us about freshwater fish under stress

The latest assessment is an update on a freshwater report in 2017 and the comprehensive Environment Aotearoa 2019. It reiterates issues we’ve seen before, but begins to implement recent recommendations by the Parliamentary Commissioner for the Environment (PCE) calling for a stronger link between data and environmental management.

Biological impacts are at the forefront of this latest assessment. It shows that a wide range of freshwater organisms are at risk. The statistics for freshwater fish are the most concerning, with three quarters of the 51 native species already either threatened or at risk of extinction.

The report uses a particular group of native fish (īnanga, or galaxids) to connect the multiple impacts humans have, across a range of habitats at different life stages.

Īnanga are better known as whitebait, a delicacy that is a mix of juveniles from six different species caught as they migrate from the sea to rivers.

Whitebait is considered a delicacy in New Zealand.
Shutterstock

Īnanga of different ages and species live in different habitats, so they can be used to represent the issues facing a range of freshwater fish across ecosystems. The main stress factors include altered habitat, pollution and excess nutrients, water use for irrigation and climate change.

Climate change is expected to exacerbate existing stresses native organisms like īnanga face and protecting their habitat means understanding how much it will reduce water flows and create hotter and drier conditions.

Filling gaps in understanding

The use of organisms to assess environmental change, including climate change impacts, is an obvious but important step. It makes it possible to consider climate change in a way that meets the Environmental Reporting Act’s requirement to report on a “body of evidence”.

This latest report responds to the PCE’s concerns about gaps in our knowledge, which were raised in the Environment Aotearoa 2019 assessment. The new strategy for filling large holes in our knowledge has three priorities: knowing and monitoring what we have, what we may lose, and where or how we can make changes.




Read more:
Six ways to improve water quality in New Zealand’s lakes and rivers


The report highlights that mātauranga Māori, the process of using indigenous knowledge about the environment, can fill some gaps in data or add insights. Other methods and models, such as nutrient budget scenarios, also deserve consideration.

There is some good news as well. Some pollution concerns may be minor or limited to very small areas. This includes several so-called emerging contaminants, such as fire retardants, which have been discovered in groundwater around airfields but are now banned or restricted.

The second piece of good news is that new ways of studying the environment can help fill major gaps. For example, lakes may be more stable indicators of freshwater health than rivers and streams, but only 4% (about 150) of New Zealand’s 3,820 larger lakes are regularly monitored by regional councils.

For almost 300 lakes, the report includes an index of the plants that live in them, and for more than 3000 there is now an established method of estimating lake water quality. Further information is becoming available, using updated estimations, satellite data for the last 20 years and sediment cores to reconstruct environmental conditions over the last few hundred years.

Unfortunately, the data from lakes confirms the general trend of freshwater decline, but at least the multiple forms of complementary information should help us to manage New Zealand’s freshwater ecosystems better.The Conversation

Troy Baisden, Professor and Chair in Lake and Freshwater Sciences, University of Waikato

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

For decades, scientists puzzled over the plastic ‘missing’ from our oceans – but now it’s been found


Britta Denise Hardesty, CSIRO and Chris Wilcox, CSIRO

You’ve probably heard that our oceans have become a plastic soup. But in fact, of all the plastic that enters Earth’s oceans each year, just 1% has been observed floating on the surface. So where is the rest of it?

This “missing” plastic has been a longstanding scientific question. To date, the search has focused on oceanic gyres such as the Great Pacific Garbage Patch, the water column (the part of the ocean between the surface and the sea bed), the bottom of the ocean, and the stomachs of marine wildlife.

But our new research suggests ocean plastic is being transported back onshore and pushed permanently onto land away from the water’s edge, where it often becomes trapped in vegetation.

Of course, plastic has been reported on beaches around the world for decades. But there has been little focus on why and how coastal environments are a sink for marine debris. Our findings have big implications for how we tackle ocean plastic.

New research shows a significant amount of plastic pollution from our oceans ends up back on land, where it gets trapped.

The hunt for marine pollution

Our separate, yet-to-be-published research has found around 90% of marine debris that enters the ocean remains in the “littoral zone” (the area of ocean within 8km of the coast). This new study set out to discover what happens to it.

We collected data on the amount and location of plastic pollution every 100 kilometres around the entire coast of Australia between 2011 and 2016. Debris was recorded at 188 locations along the Australian coastline. Of this, 56% was plastic, followed by glass (17%) and foam (10%).

Data was recorded approximately every 100 kilometres along the coast of Australia. Of the marine debris recorded, more than half was plastic.

The debris was a mix of litter from people and deposition from the ocean. The highest concentrations of plastic pollution were found along coastal backshores – areas towards the inland edge of the beach, where the vegetation begins. The further back from the water’s edge we went, the more debris we found.

The amount of marine debris, and where it ends up, is influenced by onshore wave activity and, to a lesser extent, wind activity. Densely populated areas and those where the coast was easily accessible were hotspots for trapped plastics.




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Think about what you see on your beach. Smaller debris is often found near the water’s edge, while larger items such as drink bottles, plastic bags and crisp packets are often found further back from the water, often trapped in vegetation.

We also found more debris near urban areas where rivers and creeks enter the ocean. It could be that our trash is being trapped by waterways before it gets to the sea. We’re finding similar patterns in other countries we’re surveying around the Asia Pacific and beyond.

This pollution kills and maims wildlife when they mistake it for food or get tangled in it. It can damage fragile marine ecosystems by smothering sensitive reefs and transporting invasive species and is potentially a threat to human health if toxins in plastics make their way through the food chain to humans.

It can also become an eyesore, damaging the economy of an area through reduced tourism revenue.

Onshore waves, wind and areas with denser human populations influences where and how much marine debris there is along our coastlines.
CSIRO

Talking rubbish

Our findings highlight the importance of studying the entire width of coastal areas to better understand how much, and where, debris gets trapped, to inform targeted approaches to managing all this waste.

Plastic pollution can be reduced through local changes such as water refill stations, rubbish bins, incentives and awareness campaigns. It can also be reduced through targeted waste management policies to reduce, reuse and recycle plastics. We found container deposit schemes to be a particularly effective incentive in reducing marine pollution.




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This discussion is particularly timely. The National Plastics Summit in Canberra last week brought together governments, industry and non-government organisations to identify new solutions to the plastic waste challenge, and discuss how to meet targets under the National Waste Policy Action Plan. Understanding that so much of our debris remains local, and trapped on land, provides real opportunities for successful management of our waste close to the source. This is particularly critical given the waste export ban starting July 1 at the latest.

Plastic in our oceans is increasing. It’s clear from our research that waste management strategies on land must accommodate much larger volumes of pollution than previously estimated. But the best way to keep plastic from our ocean and land is to stop putting it in.

Arianna Olivelli contributed to this article, and the research upon which it was based.




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The Conversation


Britta Denise Hardesty, Principal Research Scientist, Oceans and Atmosphere Flagship, CSIRO and Chris Wilcox, Senior Research Scientist, CSIRO

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

The sweet relief of rain after bushfires threatens disaster for our rivers



After heavy rainfall, debris could wash into our waterways and threaten fish, water bugs, and other aquatic species.
Jarod Lyon, Author provided

Paul McInerney, CSIRO; Gavin Rees, CSIRO, and Klaus Joehnk, CSIRO

When heavy rainfall eventually extinguishes the flames ravaging south-east Australia, another ecological threat will arise. Sediment, ash and debris washing into our waterways, particularly in the Murray-Darling Basin, may decimate aquatic life.

We’ve seen this before. Following 2003 bushfires in Victoria’s alpine region, water filled with sediment and debris (known as sediment slugs) flowed into rivers and lakes, heavily reducing fish populations. We’ll likely see it again after this season’s bushfire emergency.




Read more:
The bushfires are horrendous, but expect cyclones, floods and heatwaves too


Large areas of northeast Victoria have been burnt. While this region accounts only for 2% of Murray-Darling Basin’s entire land area, water flowing in from northeast Victorian streams (also known as in-flow) contributes 38% of overall in-flows into the Murray-Darling Basin.

Fire debris flowing into Murray-Darling Basin will exacerbate the risk of fish and other aquatic life dying en masse as witnessed in previous years..

What will flow into waterways?

Generally, bushfire ash comprises organic carbon and inorganic elements such as nitrogen, phosphorous and metals such as copper, mercury and zinc.

Sediment rushing into waterways can also contain large amounts of soil, since fire has consumed the vegetation that once bound the soil together and prevented erosion.

And carcinogenic chemicals – found in soil and ash in higher amounts following bushfires – can contaminate streams and reservoirs over the first year after the fire.

A 2014 post-fire flood in a Californian stream.

How they harm aquatic life

Immediately following the bushfires, we expect to see an increase in streamflow when it rains, because burnt soil repels, not absorbs, water.

When vast amounts of carbon are present in a waterway, such as when carbon-loaded sediments and debris wash in, bacteria rapidly consumes the water’s oxygen. The remaining oxygen levels can fall below what most invertebrates and fish can tolerate.

These high sediment loads can also suffocate aquatic animals with a fine layer of silt which coats their gills and other breathing structures.

Habitats are also at risk. When sediment is suspended in the river and light can’t penetrate, suitable fish habitat is diminished. The murkier water also means there’s less opportunity for aquatic plants and algae to photosynthesise (turn sunshine to energy).




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How wildfire smoke affects pets and other animals


What’s more, many of Australia’s waterbugs, the keystone of river food webs, need pools with litter and debris for cover. They rely on slime on the surface of rocks and snags that contain algae, fungi and bacteria for food.

But heavy rain following fire can lead to pools and the spaces between cobbles to fill with silt, causing the waterbugs to starve and lose their homes.

This is bad news for fish too. Any bug-eating fish that manage to avoid dying from a lack of oxygen can be faced with an immediate food shortage.

Many fish were killed in Ovens River after the 2003 bushfires from sediment slugs.
Arthur Rylah Institute, Author provided

We saw this in 2003 after the sediment slug penetrated the Ovens River in the north east Murray catchment. Researchers observed dead fish, stressed fish gulping at the water surface and freshwater crayfish walking out of the stream.

Long-term damage

Bushfires can increase the amount of nutrients in streams 100 fold. The effects can persist for several years before nutrient levels return to pre-fire conditions.

More nutrients in the water might sound like a good thing, but when there’s too much (especially nitrogen and phosphorous), coupled with warm temperatures, they can lead to excessive growth of blue-green algae. This algae can be toxic to both people and animals and often closes down recreational waters.




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Strength from perpetual grief: how Aboriginal people experience the bushfire crisis


Large parts of the upper Murray River catchment above Lake Hume has burnt, risking increases to nutrient loads within the lake and causing blue-green algae blooms which may flow downstream. This can impact communities from Albury all the way to the mouth of the Murray River in South Australia.

Some aquatic species are already teetering on the edge of their preferred temperature as stream temperatures rise from climate change. In places where bushfires have burnt all the way to the stream edge, decimating vegetation that provided shade, there’ll be less resistance to temperature changes, and fewer cold places for aquatic life to hide.

Cooler hide-outs are particularly important for popular angling species such as trout, which are highly sensitive to increased water temperature.

Ash blanketing the forest floor can end up in waterways when it rains.
Tarmo Raadik

But while we can expect an increase in stream flow from water-repellent burnt soil, we know from previous bushfires that, in the long-term, stream flow will drop.

This is because in the upper catchments, regenerating younger forests use more water than the older forests they replace from evapotranspiration (when plants release water vapour into the surrounding atmosphere, and evaporation from the surrounding land surface).

It’s particularly troubling for the Murray-Darling Basin, where large areas are already enduring ongoing drought. Bushfires may exacerbate existing dry conditions.

So what can we do?

We need to act as soon as possible. Understandably, priorities lie in removing the immediate and ongoing bushfire threat. But following that, we must improve sediment and erosion control to prevent debris being washed into water bodies in fire-affected areas.




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In fact, there’s plenty we can do to make future fires less likely


One of the first things we can do is to restore areas used for bushfire control lines and minimise the movement of soil along access tracks used for bushfire suppression. This can be achieved using sediment barriers and other erosion control measures in high risk areas.

Longer-term, we can re-establish vegetation along waterways to help buffer temperature extremes and sediment loads entering streams.

It’s also important to introduce strategic water quality monitoring programs that incorporate real-time sensing technology, providing an early warning system for poor water quality. This can help guide the management of our rivers and reservoirs in the years to come.

While our current focus is on putting the fires out, as it should be, it’s important to start thinking about the future and how to protect our waterways. Because inevitably, it will rain again.The Conversation

Paul McInerney, Research scientist, CSIRO; Gavin Rees, , CSIRO, and Klaus Joehnk, Senior research scientist, CSIRO

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

Australia’s pristine beaches have a poo problem



Raw sewage from 3,500 people in Sydney’s affluent eastern suburbs is discharged directly into the ocean.
Will Turner/Unsplash

Ian Wright, Western Sydney University; Andrew Fischer, University of Tasmania; Boyd Dirk Blackwell, University of Tasmania; Qurratu A’yunin Rohmana, University of Tasmania, and Simon Toze, CSIRO

Australians love our iconic coastal lifestyle. So many of our settlements are spread along our huge coastline. Real estate prices soar where we can catch a view of the water.

But where there are crowded communities, there is sewage. And along the coast it brings a suite of problems associated with managing waste, keeping the marine environment healthy, and keeping recreational swimmers safe.




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Sewage is not a sexy topic. People often have an “out of sight, out of mind” attitude. But where does sewage go, and is it treated and disposed of in the waters that we Australians love?

The bigger the coastal community, the bigger the volume of sewage. Disposal of human waste into the ocean might solve one problem, but we now realise that the “waste” is as precious as the ocean it pollutes.

We should be treating and recycling sewage to a drinkable level.
shutterstock

Understanding the problem from a national perspective

Such problems play out continuously along our coastline. Each isolated community and catchment issue arises and is resolved, often in ignorance of and isolation from similar issues somewhere else.

At present, places where sewage impacts are generating community concern include Merimbula, Warrnambool and, perhaps most bizarrely, Vaucluse and Diamond Bay in Sydney’s affluent eastern suburbs.

It’s hard to believe this location has raw and untreated sewage from 3,500 people discharged directly into the Tasman Sea. Sydney Water pledged in 2018 to fix this unsightly pollution by transferring the flow to the nearby Bondi sewage treatment plant.

Community group Clean Ocean Foundation has worked with the Marine Biodiversity Hub to start the process of viewing outfall pollution – where a drain or sewer empties into the sea – as part of a bigger picture. It’s a first step towards understanding from a national perspective.




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Together they have produced the National Outfall Database to provide the first Australia-wide comparison.

The best and worst offenders

Previously the information available to the public was sketchy and often not easily accessed. The database shows how differently Australia manages coastal sewage with information on the outfalls.

Clean Ocean Foundation CEO John Gemmill said:

Water authorities in the main do a great job with severe funding constraints. But they can be reticent to divulge information publicly.

One authority, suspicious of the research project, initially refused to give the location of the outfall, claiming it would be vandalised by enraged “surfies and fishermen”.

Sydney has Australia’s biggest outfall. It provides primary treatment at Malabar, New South Wales, and serves about 1.7 million people. The outfall releases about 499 megalitres (ML) per day of treated sewage, called “effluent”.

That’s about eight Olympic-sized swimming pools of effluent an hour. It is discharged to the Pacific Ocean 3.6 kilometres from the shoreline at a depth of 82 metres.

The cleanest outfall (after sustained advocacy over decades from the Clean Ocean Foundation) is Boags Rock, in southern Melbourne. It releases tertiary-treated sewage with Class A+ water. This means the quality is very suitable for reuse and has no faecal bacteria detected (Enterococci or E.coli).

Recycling sewage

Treated sewage is 99% water. The last 1% is what determines if the water will harm human and environmental health. Are we wasting a precious resource by disposing of it in the ocean?

As desalination plants are cranking up in Sydney and Melbourne to extract pure water from salty ocean, why shouldn’t we also recycle sewage?




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More of us are drinking recycled sewage water than most people realise


Clean Ocean Foundation has released a report showing it would pay to treat sewage more thoroughly and reuse it. This report finds upgrading coastal sewage outfalls to a higher level of treatment will provide tens of billions of dollars in benefits.

Industry analysis suggests that, for a cost outlay of between A$7.3 billion and A$10 billion, sewage treatment upgrades can deliver between A$12 billion and A$28 billion in net benefits – that is, the financial benefits above and beyond what it cost to put new infrastructure in place.

Then there are non-economic benefits such as improved ecological and human health, and improved recreational and tourism opportunities by use of suitable recycling processes.

What the rest of Australia can learn from WA

Clean Ocean Foundation president Peter Smith said Australia’s key decision-makers now, more than before, have a “golden opportunity” to adopt a sea change in water reform around coastal Australia based on good science and sound economic analysis.

In the context of the drought of southeast Australia, recycling water from ocean outfalls is an option that demands further debate.




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As expensive desalination plants are switched on, Sydney proposes to double the size of its desalination plant – just a few kilometres from massive ocean outfalls that could provide so much recycled water. And to our shame, NSW ocean outfalls are among the lowest in standards of treatment.

Western Australia, on the other hand, leads the push to recycle wastewater as it continues to struggle with diminishing surface water from climate change.

In fact, in 2017 the Water Corporation announced massive investment in highly treated sewage being used to replenish groundwater supplies. Perth now sources 20% of its drinking water from groundwater, reducing its reliance on two desalination plants. A key factor was successful engagement with affected communities.

The discharge of poorly treated sewage to rivers, estuaries and oceans is a matter of national environmental significance and the Commonwealth should take a coordinating role.

Our oceans do not respect state boundaries. The time is ripe for a deliberate national approach to recycling sewage and improved systems to manage outfalls.The Conversation

Ian Wright, Senior Lecturer in Environmental Science, Western Sydney University; Andrew Fischer, Senior Lecturer, University of Tasmania; Boyd Dirk Blackwell, Adjunct Researcher, University of Tasmania; Qurratu A’yunin Rohmana, Research Analyst, University of Tasmania, and Simon Toze, Senior Principal Research Scientist, CSIRO

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

Will the discovery of another plastic-trashed island finally spark meaningful change?


Jennifer Lavers, University of Tasmania and Annett Finger, Victoria University

Today we learnt of yet another remote and formerly pristine location on our planet that’s become “trashed” by plastic debris.

Research published today in Scientific Reports shows some 238 tonnes of plastic have washed up on Australia’s remote Cocos (Keeling) Islands.

It’s not the first time the world has been confronted with an island drowning under debris. Perhaps it’s time to take stock of where we’re at, what we’ve learnt about plastic and figure out whether we can be bothered, or care enough, to do something meaningful.




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This South Pacific island of rubbish shows why we need to quit our plastic habit


Taking stock

In 2017, the world was introduced to Henderson Island, an exceptionally remote uninhabited island in the South Pacific. It has the dubious honour of being home to the beach with the highest ever recorded density of plastic debris (more than 4,400 pieces per metre squared).

What’s more, a single photo taken in 1992 showed Henderson Island had gone from pristine to trashed in only 23-years.

Now, the Cocos (Keeling) Islands off the coast of Australia are set to challenge that record, despite being sparsely populated and recognised for having one of Australia’s most beautiful beaches.

A recent, comprehensive survey of the Cocos (Keeling) Islands revealed mountains of plastic trash washed up on the beaches.




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While the density of debris on Cocos (a maximum of 2,506 items per square metre) was found to be less than that on Henderson Island, the total amount of debris Cocos must contend with is staggering: an estimated 414 million debris items weighing 238 tonnes.

A quarter of the identifiable items were found to be “single-use”, or disposable plastics, including straws, bags, bottles, and an estimated 373,000 toothbrushes.

At only 14 kilometres squared, the entire Cocos (Keeling) Island group is a little more than twice the size of the Melbourne CBD. So it’s hard to envision 414 million debris items in such a small area.

Lessons learned

Islands “filter” debris from the ocean. Items flow past and accumulate on beaches, providing valuable information about the quantity of plastic in the oceans.

So, what have these two studies of remote islands taught us?

South Island. A quarter of the identifiable items were found to be disposable plastics.
Cara Ratajczak, Author provided

On Cocos, the overwhelming quantity of debris you can see on the surface accounts for just 7% of the total debris present on the islands. The remaining 93% (approximately 383 million items) is buried below the sediment. Much like the proverbial iceberg, we’re only seeing the very tip of the problem.

Henderson Island, on the other hand, highlighted the terrifying pace of change, from pristine, tropical oasis to being inundated with 38 million plastic items in just two decades.

In the past 12 months alone, scientists have made other, ground-breaking discoveries that have emphasised how little we understand about the behaviour of plastic in the environment and the myriad consequences for species and habitats – including ourselves.




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


Here are a few of the shocking discoveries:

  • microplastics were reported in bottled water, salt and beer

  • chemicals from degrading plastic in the ocean were found to disrupt photosynthesis in marine bacteria that are important to the carbon cycle, including producing the oxygen for approximately every tenth breath we take

  • degrading plastic exposed to UV sunlight (such as those on beaches) was reported to produce greenhouse gas emissions, including methane. This is predicted to increase significantly over the next 20 years in line with plastic production trends

  • microplastic particles are ingested by krill at the base of the marine food web, then fragmented into nano-sized particles

  • plastic items recovered from the ocean were found to be reservoirs and potential vectors for microbial communities with antibiotic resistant genes

  • tiny nanoplastics are transported via wind in the atmosphere and deposited in cities and even remote areas, including mountain tops

Meaningful action

Clean-ups on near-shore islands and coastal areas around cities are fantastic.

The educational component is invaluable and they provide an important sense of community. They also prevent large items, like bottles, from breaking up into hundreds or thousands of bite-sized microplastics.

But large-scale clean-ups of the Cocos (Keeling) Islands, and most other remote islands, are challenging for a variety of reasons. Getting to these locations is expensive, as would be shipping the plastic off for recycling or disposal.

There are also serious biosecurity issues relating to moving plastic debris off islands. Even if we did somehow manage to clean these remote islands, it would not be long before the beaches are trashed again, as it was estimated on Henderson Island that more than 3,500 new pieces of plastic wash up every single day.

As Heidi Taylor from Tangaroa Blue, an Australian initiative tackling marine debris, puts so aptly:

if all we ever do is clean up, that is all we will ever do.

For our clean-up efforts to be effective, they must be paired with individual behaviour change, underpinned by legislation that mandates producers to take responsibility for the entire lifecycle of their products.

Single-use items, such as razors, cutlery, scoops for coffee or laundry powder and toothbrushes were very common on the beaches of Cocos. Clearly this is an area where extended product stewardship laws (following the principles of a circular economy), coupled with informed consumer choices can lead to better decisions about the types of products we use and how and when we dispose of them.




Read more:
There’s no ‘garbage patch’ in the Southern Indian Ocean, so where does all the rubbish go?


The global plastic crisis requires immediate and wide-ranging actions that drastically reduce our plastic consumption. And large corporations and government need to adopt a leadership role.

In the EU, for instance, governments voted in March 2019 to implement a ban on the ten most prolific single-use plastic items by 2021. The rest of the world urgently needs to follow suit. Let’s stop arguing about how to clean up the mess, and start implementing meaningful preventative actions.The Conversation

Jennifer Lavers, Research Scientist, University of Tasmania and Annett Finger, Adjunct Research Fellow, Victoria University

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

There’s no ‘garbage patch’ in the Southern Indian Ocean, so where does all the rubbish go?


File 20190401 177175 1wvztzj.jpg?ixlib=rb 1.1
Plastic waste on a remote beach in Sri Lanka.
Author provided

Mirjam van der Mheen, University of Western Australia; Charitha Pattiaratchi, University of Western Australia, and Erik van Sebille, Utrecht University

Great areas of our rubbish are known to form in parts of the Pacific and Atlantic oceans. But no such “garbage patch” has been found in the Southern Indian Ocean.

Our research – published recently in Journal of Geophysical Research: Oceans – looked at why that’s the case, and what happens to the rubbish that gets dumped in this particular area.

Every year, up to 15 million tonnes of plastic waste is estimated to make its way into the ocean through coastlines (about 12.5 million tonnes) and rivers (about 2.5 million tonnes). This amount is expected to double by 2025.




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Some of this waste sinks in the ocean, some is washed up on beaches, and some floats on the ocean surface, transported by currents.

The garbage patches

As plastic materials are extremely durable, floating plastic waste can travel great distances in the ocean. Some floating plastics collect in the centre of subtropical circulating currents known as gyres, between 20 to 40 degrees north and south, to create these garbage patches.

The Great Pacific Garbage Patch.
National Oceanic and Atmospheric Administration

Here, the ocean currents converge at the centre of the gyre and sink. But the floating plastic material remains at the surface, allowing it to concentrate in these regions.

The best known of these garbage patches is the Great Pacific Garbage Patch, which contains about 80,000 tonnes of plastic waste. As the National Oceanic and Atmospheric Administration points out, the “patches” are not actually clumped collections of easy-to-see debris, but concentrations of litter (mostly small pieces of floating plastic).

Similar, but smaller, patches exist in the North and South Atlantic Oceans and the South Pacific Ocean. In total, it is estimated that only 1% of all plastic waste that enters the ocean is trapped in the garbage patches. It is still a mystery what happens to the remaining 99% of plastic waste that has entered the ocean.

Rubbish in the Indian Ocean

Even less is known about what happens to plastic in the Indian Ocean, although it receives the largest input of plastic material globally.

For example, it has been estimated that up to 90% of the global riverine input of plastic waste originates from Asia. The input of plastics to the Southern Indian Ocean is mainly through Indonesia. The Australian contribution is small.

The major sources of riverine input of plastic material into the Indian Ocean.
The Ocean Cleanup, CC BY-NC-ND

The Indian Ocean has many unique characteristics compared with the other ocean basins. The most striking factor is the presence of the Asian continental landmass, which results in the absence of a northern ocean basin and generates monsoon winds.

As a result of the former, there is no gyre in the Northern Indian Ocean, and so there is no garbage patch. The latter results in reversing ocean surface currents.

The Indian and Pacific Oceans are connected through the Indonesian Archipelago, which allows for warmer, less salty water to be transported from the Pacific to the Indian via a phenomenon called the Indonesian Throughflow (see graphic, below).

Schematic currents and location of a leaky garbage patch in the southern Indian Ocean: Indonesian Throughflow (ITF), Leeuwin Current (LC), South Indian Counter Current (SICC), Agulhas Current (AC).
Author provided

This connection also results in the formation of the Leeuwin Current, a poleward (towards the South Pole) current that flows alongside Australia’s west coast.

As a result, the Southern Indian Ocean has poleward currents on both eastern and western margins of the ocean basin.

Also, the South Indian Counter Current flows eastwards across the entire width of the Southern Indian Ocean, through the centre of the subtropical gyre, from the southern tip of Madagascar to Australia.

The African continent ends at around 35 degrees south, which provides a connection between the southern Indian and Atlantic Oceans.

How to follow that rubbish

In contrast to other ocean basins, the Indian Ocean is under-sampled, with only a few measurements of plastic material available. As technology to remotely track plastics does not yet exist, we need to use indirect ways to determine the fate of plastic in the Indian Ocean.

We used information from more than 22,000 satellite-tracked surface drifting buoys that have been released all over the world’s oceans since 1979. This allowed us to simulate pathways of plastic waste globally, with an emphasis on the Indian Ocean.

Global simulated concentration of floating waste after 50 years.
Mirjam van der Mheen, Author provided

We found that unique characteristics of the Southern Indian Ocean transport floating plastics towards the ocean’s western side, where it leaks past South Africa into the South Atlantic Ocean.

Because of the Asian monsoon system, the southeast trade winds in the Southern Indian Ocean are stronger than the trade winds in the Pacific and Atlantic Oceans. These strong winds push floating plastic material further to the west in the Southern Indian Ocean than they do in the other oceans.

So the rubbish goes where?

This allows the floating plastic to leak more readily from the Southern Indian Ocean into the South Atlantic Ocean. All these factors contribute to an ill-defined garbage patch in the Southern Indian Ocean.

Simulated concentration of floating waste over 50 years in the Indian Ocean.

In the Northern Indian Ocean our simulations showed there may be an accumulation of waste in the Bay of Bengal.




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‘Missing plastic’ in the oceans can be found below the surface


It is also likely that floating plastics will ultimately end up on beaches all around the Indian Ocean, transported by the reversing monsoon winds and currents. Which beaches will be most heavily affected is still unclear, and will probably depend on the monsoon season.

Our study shows that the atmospheric and oceanic attributes of the Indian Ocean are different to other ocean basins and that there may not be a concentrated garbage patch. Therefore the mystery of all the missing plastic is even greater in the Indian Ocean.The Conversation

Mirjam van der Mheen, PhD Candidate in Oceanography, University of Western Australia; Charitha Pattiaratchi, Professor of Coastal Oceanography, University of Western Australia, and Erik van Sebille, Associate Professor in Oceanography and Climate Change, Utrecht University

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