Japan plans to dump a million tonnes of radioactive water into the Pacific. But Australia has nuclear waste problems, too


Tilman Ruff, University of Melbourne and Margaret Beavis

The Japanese government recently announced plans to release into the sea more than 1 million tonnes of radioactive water from the severely damaged Fukushima Daiichi nuclear plant.

The move has sparked global outrage, including from UN Special Rapporteur Baskut Tuncak who recently wrote,

I urge the Japanese government to think twice about its legacy: as a true champion of human rights and the environment, or not.

Alongside our Nobel Peace Prize-winning work promoting nuclear disarmament, we have worked for decades to minimise the health harms of nuclear technology, including site visits to Fukushima since 2011. We’ve concluded Japan’s plan is unsafe, and not based on evidence.

Japan isn’t the only country with a nuclear waste problem. The Australian government wants to send nuclear waste to a site in regional South Australia — a risky plan that has been widely criticised.

Contaminated water in leaking tanks

In 2011, a massive earthquake and tsunami resulted in the meltdown of four large nuclear reactors, and extensive damage to the reactor containment structures and the buildings which house them.

Water must be poured on top of the damaged reactors to keep them cool, but in the process, it becomes highly contaminated. Every day, 170 tonnes of highly contaminated water are added to storage on site.

As of last month, this totalled 1.23 million tonnes. Currently, this water is stored in more than 1,000 tanks, many hastily and poorly constructed, with a history of leaks.

How does radiation harm marine life?

If radioactive material leaks into the sea, ocean currents can disperse it widely. The radioactivity from Fukushima has already caused widespread contamination of fish caught off the coast, and was even detected in tuna caught off California.




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Ionising radiation harms all organisms, causing genetic damage, developmental abnormalities, tumours and reduced fertility and fitness. For tens of kilometres along the coast from the damaged nuclear plant, the diversity and number of organisms have been depleted.

Of particular concern are long-lived radioisotopes (unstable chemical elements) and those which concentrate up the food chain, such as cesium-137 and strontium-90. This can lead to fish being thousands of times more radioactive than the water they swim in.

Failing attempts to de-contaminate the water

In recent years, a water purification system — known as advanced liquid processing — has been used to treat the contaminated water accumulating in Fukushima to try to reduce the 62 most important contaminating radioisotopes.

But it hasn’t been very effective. To date, 72% of the treated water exceeds the regulatory standards. Some treated water has been shown to be almost 20,000 times higher than what’s allowed.




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One important radioisotope not removed in this process is tritium — a radioactive form of hydrogen with a half-life of 12.3 years. This means it takes 12.3 years for half of the radioisotope to decay.

Tritium is a carcinogenic byproduct of nuclear reactors and reprocessing plants, and is routinely released both into the water and air.

The Japanese government and the reactor operator plan to meet regulatory limits for tritium by diluting contaminated water. But this does not reduce the overall amount of radioactivity released into the environment.

How should the water be stored?

The Japanese Citizens Commission for Nuclear Energy is an independent organisation of engineers and researchers. It says once water is treated to reduce all significant isotopes other than tritium, it should be stored in 10,000-tonne tanks on land.

If the water was stored for 120 years, tritium levels would decay to less than 1,000th of the starting amount, and levels of other radioisotopes would also reduce. This is a relatively short and manageable period of time, in terms of nuclear waste.

Then, the water could be safely released into the ocean.

Nuclear waste storage in Australia

Australians currently face our own nuclear waste problems, stemming from our nuclear reactors and rapidly expanding nuclear medicine export business, which produces radioisotopes for medical diagnosis, some treatments, scientific and industrial purposes.




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This is what happens at our national nuclear facility at Lucas Heights in Sydney. The vast majority of Australia’s nuclear waste is stored on-site in a dedicated facility, managed by those with the best expertise, and monitored 24/7 by the Australian Federal Police.

But the Australian government plans to change this. It wants to transport and temporarily store nuclear waste at a facility at Kimba, in regional South Australia, for an indeterminate period. We believe the Kimba plan involves unnecessary multiple handling, and shifts the nuclear waste problem onto future generations.

The proposed storage facilities in Kimba are less safe than disposal, and this plan is well below world’s best practice.

The infrastructure, staff and expertise to manage and monitor radioactive materials in Lucas Heights were developed over decades, with all the resources and emergency services of Australia’s largest city. These capacities cannot be quickly or easily replicated in the remote rural location of Kimba. What’s more, transporting the waste raises the risk of theft and accident.

And in recent months, the CEO of regulator ARPANSA told a senate inquiry there is capacity to store nuclear waste at Lucas Heights for several more decades. This means there’s ample time to properly plan final disposal of the waste.

The legislation before the Senate will deny interested parties the right to judicial review. The plan also disregards unanimous opposition by Barngarla Traditional Owners.




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The Conversation contacted Resources Minister Keith Pitt who insisted the Kimba site will consolidate waste from more than 100 places into a “safe, purpose-built, state-of-the-art facility”. He said a separate, permanent disposal facility will be established for intermediate level waste in a few decades’ time.

Pitt said the government continues to seek involvement of Traditional Owners. He also said the Kimba community voted in favour of the plan. However, the voting process was criticised on a number of grounds, including that it excluded landowners living relatively close to the site, and entirely excluded Barngarla people.

Kicking the can down the road

Both Australia and Japan should look to nations such as Finland, which deals with nuclear waste more responsibly and has studied potential sites for decades. It plans to spend 3.5 billion euros (A$5.8 billion) on a deep geological disposal site.




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Intermediate level nuclear waste like that planned to be moved to Kimba contains extremely hazardous materials that must be strictly isolated from people and the environment for at least 10,000 years.

We should take the time needed for an open, inclusive and evidence-based planning process, rather than a quick fix that avoidably contaminates our shared environment and creates more problems than it solves.

It only kicks the can down the road for future generations, and does not constitute responsible radioactive waste management.


The following are additional comments provided by Resources Minister Keith Pitt in response to issues raised in this article (comments added after publication):

(The Kimba plan) will consolidate waste into a single, safe, purpose-built, state-of-the-art facility. It is international best practice and good common sense to do this.

Key indicators which showed the broad community support in Kimba included 62 per cent support in the local community ballot, and 100 per cent support from direct neighbours to the proposed site.

In assessing community support, the government also considered submissions received from across the country and the results of Barngarla Determination Aboriginal Corporation’s own vote.

The vast majority of Australia’s radioactive waste stream is associated with nuclear medicine production that, on average, two in three Australians will benefit from during their lifetime.

The facility will create a new, safe industry for the Kimba community, including 45 jobs in security, operations, administration and environmental monitoring.The Conversation

Tilman Ruff, Associate Professor, Education and Learning Unit, Nossal Institute for Global Health, School of Population and Global Health, University of Melbourne and Margaret Beavis, Tutor Principles of Clinical Practice Melbourne Medical School

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

We estimate there are up to 14 million tonnes of microplastics on the seafloor. It’s worse than we thought



Shutterstock

Britta Denise Hardesty, CSIRO; Chris Wilcox, CSIRO, and Justine Barrett, CSIRO

Nowhere, it seems, is immune from plastic pollution: plastic has been reported in the high Arctic oceans, in the sea ice around Antarctica and even in the world’s deepest waters of the Mariana Trench.

But just how bad is the problem? Our new research provides the first global estimate of microplastics on the seafloor — our research suggests there’s a staggering 8-14 million tonnes of it.

This is up to 35 times more than the estimated weight of plastic pollution on the ocean’s surface.

What’s more, plastic production and pollution is expected to increase in coming years, despite increased media, government and scientific attention on how plastic pollution can harm marine ecosystems, wildlife and human health.

These findings are yet another wake-up call. When the plastic we use in our daily lives reaches even the deepest oceans, it’s more urgent than ever to find ways to clean up our mess before it reaches the ocean, or to stop making so much of it in the first place.

Breaking down larger plastic

Our estimate of microplastics on the seafloor is huge, but it’s still a fraction of the amount of plastic dumped into the ocean. Between 4-8 million tonnes of plastic are thought to enter the sea each and every year.




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Most of the plastic dumped into the ocean likely ends up on the coasts, not floating around the ocean’s surface or on the seafloor. In fact, three-quarters of the rubbish found along Australia’s coastlines is plastics.

A dead albatross with plastic in its stomach from Midway Atoll
Plastic including toothbrushes, cigarette lighters, bottle caps and other hard plastic fragments are found in the stomachs of many marine species.
Britta Denise Hardesty

The larger pieces of plastic that stay in the ocean can deteriorate and break down from weathering and mechanical forces, such as ocean waves. Eventually, this material turns into microplastics, pieces smaller than 5 millimetres in diameter.

Their tiny size means they can be eaten by a variety of marine wildlife, from plankton to crustaceans and fish. And when microplastics enter the marine food web at low levels, it can move up the food chain as bigger species eat smaller ones.

But the problem isn’t as well documented for microplastics on the seafloor. While plastics, including microplastics, have been found in deep-sea sediments in all ocean basins across the world, samples have been small and scarce. This is where our research comes in.

Collecting samples in the Great Australian Bight

We collected samples using a robotic submarine in a range of sea depths, from 1,655 to 3,062 metres, in the Great Australian Bight, up to 380 kilometres offshore from South Australia. The submarine scooped up 51 samples of sand and sediment from the seafloor and we analysed them in a laboratory.

Sampling of deep sea sediments took place using an underwater robot.
CSIRO, Author provided

We dried the sediment samples, and found between zero and 13.6 plastic particles per gram. This is up to 25 times more microplastics than previous deep-sea studies. And it’s much higher than studies in other regions, including in the Arctic and Indian Oceans.

While our study looked at one general area, we can scale up to calculate a global estimate of microplastics on the seafloor.

Using the estimated size of the entire ocean — 361,132,000 square kilometres — and the average number and size of particles in our sediment samples, we determined the total, global weight as between 8.4 and 14.4 million tonnes. This range takes into account the possible weights of individual microplastics.

How did the plastic get there?

It’s important to note that since our location was remote, far from any urban population centre, this is a conservative estimate. Yet, we were surprised at just how high the microplastic loads were there.

Plastic waste floating in the ocean
Areas with floating rubbish on the ocean’s surface have plastic on the seafloor.
Shutterstock

Few studies have conclusively identified how microplastics travel to their ultimate fate.

Larger pieces of plastic that get broken down to smaller pieces can sink to the seafloor, and ocean currents and the natural movement of sediment along continental shelves can transport them widely.

But not all plastic sinks. A 2016 study suggests interaction with marine organisms is another possible transport method.

Scientists in the US have shown microbial communities, such as bacteria, can inhabit this marine “plastisphere” — a term for the ecosystems that live in plastic environments. The microbes weigh the plastic down so it no longer floats. We also know mussels and other invertebrates may colonise floating plastics, adding weight to make them sink.




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The type of rubbish will also determine whether it gets washed up on the beach or sinks to the seafloor.

For example, in a previous study we found cigarette butts, plastic fragments, bottlecaps and food wrappers are common on land, though rare on the seabed. Meanwhile, we found entangling items such fishing line, ropes and plastic bags are common on the seafloor.

Microplastics at the water's edge
We were surprised at just how high the microplastic loads were in such a remote location.
CSIRO

Interestingly, in our new study we also found the number of plastic fragments on the seafloor was generally higher in areas where there was floating rubbish on the ocean’s surface. This suggests surface “hotspots” may be reflected below.

It’s not clear why just yet, but it could be because of the geology and physical features of the seabed, or because local currents, winds and waves result in accumulating zones on the ocean’s surface and the seabed nearby.

Stop using so much plastic

Knowing how much plastic sinks to the ocean floor is an important addition to our understanding of the plastic pollution crisis. But stemming the rising tide of plastic pollution starts with individuals, communities and governments – we all have a role to play.

Reusing, refusing and recycling are good places to start. Seek alternatives and support programs, such as Clean Up Australia Day, to stop plastic waste from entering our environment in the first place, ensuring it doesn’t then become embedded in our precious oceans.




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The Conversation


Britta Denise Hardesty, Principal Research Scientist, Oceans and Atmosphere Flagship, CSIRO; Chris Wilcox, Senior Principal Research Scientist, CSIRO, and Justine Barrett, Research assistant, CSIRO

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

A brutal war and rivers poisoned with every rainfall: how one mine destroyed an island



Locals living downstream of the abandoned mine pan for gold in mine waste.
Matthew Allen, Author provided

Matthew G. Allen, The University of the South Pacific

This week, 156 people from the Autonomous Region of Bougainville, in Papua New Guinea, petitioned the Australian government to investigate Rio Tinto over a copper mine that devastated their homeland.

In 1988, disputes around the notorious Panguna mine sparked a lengthy civil war in Bougainville, leading to the deaths of up to 20,000 people. The war is long over and the mine has been closed for 30 years, but its brutal legacy continues.




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When I conducted research in Bougainville in 2015, I estimated the deposit of the mine’s waste rock (tailings) downstream from the mine to be at least a kilometre wide at its greatest point. Local residents informed me it was tens of metres deep in places.

I spent several nights in a large two-story house built entirely from a single tree dragged out of the tailings — dragged upright, with a tractor. Every new rainfall brought more tailings downstream and changed the course of the waterways, making life especially challenging for the hundreds of people who eke out a precarious existence panning the tailings for remnants of gold.

The petition has brought the plight of these communities back into the media, but calls for Rio Tinto to clean up its mess have been made for decades. Let’s examine what led to the ongoing crisis.

Triggering a civil war

The Panguna mine was developed in the 1960s, when PNG was still an Australian colony, and operated between 1972 and 1989. It was, at the time, one of the world’s largest copper and gold mines.

It was operated by Bougainville Copper Limited, a subsidiary of what is now Rio Tinto, until 2016 when Rio handed its shares to the governments of Bougainville and PNG.

When a large-scale mining project reaches the end of its commercial life, a comprehensive mine closure and rehabilitation plan is usually put in place.




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But Bougainville Copper simply abandoned the site in the face of a landowner rebellion. This was largely triggered by the mine’s environmental and social impacts, including disputes over the sharing of its economic benefits and the impacts of those benefits on predominantly cashless societies.

Following PNG security forces’ heavy-handed intervention — allegedly under strong political pressure from Bougainville Copper — the rebellion quickly escalated into a full-blown separatist conflict that eventually engulfed all parts of the province.

By the time the hostilities ended in 1997, thousands of Bougainvilleans had lost their lives, including from an air and sea blockade the PNG military had imposed, which prevented essential medical supplies reaching the island.

The mine’s gigantic footprint

The Panguna mine’s footprint was gigantic, stretching across the full breadth of the central part of the island.

The disposal of hundreds of millions of tonnes of tailings into the Kawerong-Jaba river system created enormous problems.

Rivers and streams became filled with silt and significantly widened. Water flows were blocked in many places, creating large areas of swampland and disrupting the livelihoods of hundreds of people in communities downstream of the mine. These communities used the rivers for drinking water and the adjacent lands for subsistence food gardening.

Several villages had to be relocated to make way for the mining operations, with around 200 households resettled between 1969 and 1989.

In the absence of any sort of mine closure or “mothballing” arrangements, the environmental and socio-economic impacts of the Panguna mine have only been compounded.

Since the end of mining activities 30 years ago, tailings have continued to move down the rivers and the waterways have never been treated for suspected chemical contamination.




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Long-suffering communities

The 156 complainants live in communities around and downstream of the mine. Many are from the long-suffering village of Dapera.

In 1975, the people of Dapera were relocated to make way for mining activities. Today, it’s in the immediate vicinity of the abandoned mine pit. As one woman from Dapera told me in 2015:

I have travelled all over Bougainville, and I can say that they [in Dapera] are the poorest of the poor.

They, and others, sent the complaint to the Australian OECD National Contact Point after lodging it with Melbourne’s Human Rights Law Centre.

The complainants say by not ensuring its operations didn’t infringe on the local people’s human rights, Rio Tinto breached OECD guidelines for multinational enterprises.

The Conversation contacted Rio Tinto for comment. A spokesperson said:

We believe the 2016 arrangement provided a platform for the Autonomous Bougainville Government (ABG) and PNG to work together on future options for the resource with all stakeholders.

While it is our belief that from 1990 to 2016 no Rio Tinto personnel had access to the mine site due to on-going security concerns, we are aware of the deterioration of mining infrastructure at the site and surrounding areas, and claims of resulting adverse environmental and social, including human rights, impacts.

We are ready to enter into discussions with the communities that have filed the complaint, along with other relevant parties such as BCL and the governments of ABG and PNG.

A long time coming

This week’s petition comes after a long succession of calls for Rio Tinto to be held to account for the Panguna mine’s legacies and the resulting conflict.

A recent example is when, after Rio Tinto divested from Bougainville Copper in 2016, former Bougainville President John Momis said Rio must take full responsibility for an environmental clean-up.

And in an unsuccessful class action, launched by Bougainvilleans in the United States in 2000, Rio was accused of collaborating with the PNG state to commit human rights abuses during the conflict and was also sued for environmental damages. The case ultimately foundered on jurisdictional grounds.

Two people, one waist-deep in tailings.
Hundreds of millions of tonnes of tailings were deposited in the rivers.
Matthew Allen, Author provided

Taking social responsibility

This highlights the enormous challenges in seeking redress from mining companies for their operations in foreign jurisdictions, and, in this case, for “historical” impacts.

The colonial-era approach to mining when Panguna was developed in the 1960s stands in stark contrast to the corporate social responsibility paradigm supposedly governing the global mining industry today.




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Indeed, Panguna — along with the socially and environmentally disastrous Ok Tedi mine in the western highlands of PNG — are widely credited with forcing the industry to reassess its “social license to operate”.

It’s clear the time has come for Rio to finally take responsibility for cleaning up the mess on Bougainville.The Conversation

Matthew G. Allen, Professor of Development Studies, The University of the South Pacific

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

The ocean is swimming in plastic and it’s getting worse – we need connected global policies now



Fotos593 / shutterstock

Steve Fletcher, University of Portsmouth and Keiron Philip Roberts, University of Portsmouth

It seems you cannot go a day without reading about the impact of plastic in our oceans, and for good reason. The equivalent of a garbage truck of plastic waste enters the sea every minute, and this increases every day. If we do nothing, by 2040 the amount of plastic entering the ocean will triple from 13 million tonnes this year, to 29 million tonnes in 2040. That is 50kg of waste plastic entering the ocean for every metre of coastline.

Add to that almost all the plastic that has entered the ocean is still there since it takes centuries to break down. It is either buried or broken down into smaller pieces and potentially passes up the food chain creating further problems.

Despite this, plastic has also been a saviour. During the COVID-19 pandemic plastic used in face masks, testing kits, screens and to protecting food has enabled countries to come out of lockdown during and support social distancing. We still need to use these items until sustainable and “COVID safe” alternatives are available. But we also need to look to the future to reduce our dependence on plastic and its impact on the environment. With plastic in the ocean being a global problem, we need global agreements and policies to reverse the plastic tide.




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Ambitious policies are needed

Environment ministers of the G20 group of the world’s most economically powerful countries and regions met on September 16 to discuss their immediate challenges, with marine plastic pollution a top priority. A key item for discussion was “safeguarding the planet by fostering collective efforts to protect our global commons”. This means working out how we can continue to use the planet’s resources sustainably without harming the environment.

A global analysis of plastics policies over the past two decades found that typical reactions to marine plastic litter were bans or taxes on individual or groups of plastic items within single countries. So far, 43 countries have introduced a ban, tax or levy on plastic bags. Other plastic packaging or single-use plastic products were banned in at least 25 countries, representing a population of almost 2 billion people in 2018.

But plastic waste doesn’t respect land or ocean borders, with mismanaged plastic waste easily migrating from country to country when leaked into the environment. Policies also need to consider the entire plastics life cycle to stand a chance of being effective. For example, the inclusion of easier to recycle plastics in consumer products sounds positive, but their actual recycling rate depends on effective sorting and collection of plastic waste, and appropriate infrastructure being in place.




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Ultimately, a joined up but adaptable set of rules and guidelines are needed so all plastic producers and users can prevent its leakage across all stages of the plastics life cycle.

The G20 has sought to lead action on marine plastic litter through a 2017 Action Plan on Marine Litter which set out areas of concern and possible policy interventions, and through connections to initiatives such as the UN Environment Programme’s Global Partnership on Marine Litter and most recently the Osaka Blue Ocean Vision. The Osaka vision was agreed under the Japanese G20 presidency in 2019 and commits countries to “reduce additional pollution by marine plastic litter to zero by 2050”. Although an agreement led by the G20, it now has the support of 86 countries.

But even with these agreements in place, plastic entering the ocean will still only reduce by 7% by 2040. We need ambitious new agreements as current and emerging policies do not meet the scale of the challenge.

A consensus is forming that the G20 and other global leaders must focus on a systemic change of the plastics economy. This includes focusing on “designing out” plastics, promoting technical and business innovation, immediately scaling up actions known to reduce marine plastic litter, and transitioning to a circular economy in which materials are fully recovered and reused. These actions have the potential to contribute to the G20’s vision of net-zero plastics entering the ocean by 2050, but only if ambitious actions are taken now.The Conversation

Steve Fletcher, Professor of Ocean Policy and Economy, University of Portsmouth and Keiron Philip Roberts, Research Fellow in Clean Carbon Technologies and Resource Management, University of Portsmouth

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

How bushfires and rain turned our waterways into ‘cake mix’, and what we can do about it



The Murray River at Gadds Reserve in north east Victoria after Black Summer bushfires.
Paul McInerney, Author provided

Paul McInerney, CSIRO; Anu Kumar, CSIRO; Gavin Rees, CSIRO; Klaus Joehnk, CSIRO, and Tapas Kumar Biswas, CSIRO

As the world watched the Black Summer bushfires in horror, we warned that when it did finally rain, our aquatic ecosystems would be devastated.

Following bushfires, rainfall can wash huge volumes of ash and debris from burnt vegetation and exposed soil into rivers. Fires can also lead to soil “hydrophobia”, where soil refuses to absorb water, which can generate more runoff at higher intensity. Ash and contaminants from the fire, including toxic metals, carbon and fire retardants, can also threaten biodiversity in streams.




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As expected, when heavy rains eventually extinguished many fires, it turned high quality water in our rivers to sludge with the consistency of cake mix.

In the weeks following the first rains, we sampled from these rivers. This is what we saw.

Sampling the upper Murray River

Of particular concern was the upper Murray River on the border between Victoria and NSW, which is critical for water supply. There, the bushfires were particularly intense.

Sludge in Horse Creek near Jingellic following storm activity after the fire.
Paul McInerney/Author Provided

When long-awaited rain eventually came to the upper Murray River catchment, it was in the form of large localised storms. Tonnes of ash, sediment and debris were washed into creeks and the Murray River. Steep terrain within burnt regions of the upper Murray catchment generated a large volume of fast flowing runoff that carried with it sediment and pollutants.

We collected water samples in the upper Murray River in January and February 2020 to assess impacts to riverine plants and animals.

Our water samples were up to 30 times more turbid (cloudy) than normal, with total suspended solids as high as 765 milligrams per litre. Heavy metals such as zinc, arsenic, chromium, nickel, copper and lead were recorded in concentrations well above guideline values for healthy waterways.

Ash and sediment blanketing cobbles in the Murray River.
Paul McInerney/Author Provided

We took the water collected from the Murray River to the laboratory, where we conducted a number of toxicological experiments on duckweed (a floating water plant), water fleas (small aquatic invertebrates) and juvenile freshwater snails.

What we found

During a seven-day exposure to the bushfire affected river water, the growth rate of duckweed was reduced by 30-60%.

The water fleas ingested large amounts of suspended sediments when they were exposed to the affected water for 48 hours. Following the exposure, water flea reproduction was significantly impaired.

And freshwater snail egg sacs were smothered. The ash resulted in complete deaths of snail larvae after 14 days.




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These sad impacts to growth, reproduction and death rates were primarily a result of the combined effects of the ash and contaminants, according to our preliminary investigations.

But they can have longer-term knock-on effects to larger animals like birds and fish that rely on biota like snail eggs, water fleas and duckweed for food.

What happened to the fish?

Immediately following the first pulse of sediment, dead fish (mostly introduced European carp and native Murray Cod) were observed on the bank of River Murray at Burrowye Reserve, Victoria. But what, exactly, was their cause of death?

A dead Murray Cod found on the banks of the Murray River following storms after the bushfires.
Paul McInerney/Author Provided

Our first assumption was that they died from a lack of oxygen in the water. This is because ash and nutrients combined with high summer water temperatures can trigger increased activity of microbes, such as bacteria.

This, in turn can deplete the dissolved oxygen concentration in the water (also known as hypoxia) as the microbes consume oxygen. And wide-spread hypoxia can lead to large scale fish kills.




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But to our surprise, although dissolved oxygen in the Murray River was lower than usual, we did not record it at levels low enough for hypoxia. Instead, we saw the dead fish had large quantities of sediment trapped in their gills. The fish deaths were also quite localised.

In this case, we think fish death was simply caused by the extremely high sediment and ash load in the river that physically clogged their gills, not a lack of dissolved oxygen in the water.

These findings are not unusual, and following the 2003 bushfires in Victoria fish kills were attributed to a combination of low dissolved oxygen and high turbidity.

So how can we prepare for future bushfires?

Preventing sediment being washed into rivers following fires is difficult. Installing sediment barriers and other erosion control measures can protect specific areas. However, at the catchment scale, a more holistic approach is required.




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One way is to increase efforts to re-vegetate stream banks (called riparian zones) to help buffer the runoff. A step further is to consider re-vegetating these zones with native plants that don’t burn easily, such as Blackwood (Acacia melanoxylin).

Streams known to host rare or endangered aquatic species should form the focus of any fire preparation activities. Some species exist only in highly localised areas, such as the endangered native barred galaxias (Galaxias fuscus) in central Victoria. This means an extreme fire event there can lead to the extinction of the whole species.

Ash and dead fish on the banks of the Murray River near Jingellic following Black Summer fires.
Paul McInerney/Author Provided

That’s why reintroducing endangered species to their former ranges in multiple catchments to broaden their distribution is important.

Increasing the connectivity within our streams would also allow animals like fish to evade poor water quality — dams and weirs can prevent this. The removal of such barriers, or installing “fish-ways” may be important to protecting fish populations from bushfire impacts.

However, dams can also be used to benefit animal and plant life (biota). When sediment is washed into large rivers, as we saw in the Murray River after the Black Summer fires, the release of good quality water from dams can be used to dilute poor quality water washed in from fire affected tributaries.




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Citizen scientists can help, too. It can be difficult for researchers to monitor aquatic ecosystems during and immediately following bushfires and unmanned monitoring stations are often damaged or destroyed.

CSIRO is working closely with state authorities and the public to improve citizen science apps such as EyeOnWater to collect water quality data. With more eyes in more areas, these data can improve our understanding of aquatic ecosystem responses to fire and to inform strategic planning for future fires.

These are some simple first steps that can be taken now.

Recent investment in bushfire research has largely centred on how the previous fires have influenced species’ distribution and health. But if we want to avoid wildlife catastrophes, we must also look forward to the mitigation of future bushfire impacts.The Conversation

Paul McInerney, Research scientist, CSIRO; Anu Kumar, Principal Research Scientist, CSIRO; Gavin Rees, Principal Research Scientist, CSIRO; Klaus Joehnk, Principal research scientist, CSIRO, and Tapas Kumar Biswas, Senior scientist, CSIRO

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

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.




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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.




Read more:
Sustainable shopping: how to stop your bathers flooding the oceans with plastic


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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Pristine Antarctic fjords contain similar levels of microplastics to open oceans near big civilisations


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.




Read more:
The government’s electricity shortlist rightly features pumped hydro (and wrongly includes coal)


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.