The future of plastics: reusing the bad and encouraging the good


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Plastic pollution: discarded plastic bags are a hazard to marine life.
Richard Whitcombe/Shutterstock, CC BY-ND

Kim Pickering, University of Waikato

Plastics have got themselves a bad name, mainly for two reasons: most are made from petroleum and they end up as litter in the environment.

However, both of these are quite avoidable. An increased focus on bio-derived and degradable composites as well as recycling could lessen pollution and, in fact, plastics could make a positive contribution to the environment.

Plastics for bad

The durability of plastics makes them so useful, but at the same time, it turns them into a persistent (and increasingly big) blot on the landscape, or more importantly the seascape, once discarded.


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


We’ve known for a while that bulk plastics are polluting the oceans. Converging sea currents are accumulating plastic waste in a floating island known as the Great Pacific Garbage Patch, which now covers an area larger than Greenland. The bigger bits of plastic are life-threatening to marine life and sea birds. They can strangle marine mammals or birds and build up in their stomachs and guts.

A dolphin entangled in fishing line and plastic bags (Indian Ocean).
from Shutterstock, CC BY-ND

More recently, awareness of microplastics has raised concern about their ubiquitous presence in the food chain. Commentators suggest that by 2050 there will be as much plastic in the sea as there is fish. Who wants to go catch some plastic then?


Read more: How microplastics make their way up the ocean food chain into fish


Beyond that, plastic production currently relies on petroleum and that has raised issues about health hazards, generally associated with petroleum-based products during production, use and disposal.

Plastics for good

Plastics can contribute positively to the environment in the following ways:

  • Reduced food wastage

Between one-quarter and one-third of all food produced is wasted through spoilage. But without plastic packaging, it would be considerably worse and have a larger carbon footprint.

Many of the recycling enthusiasts I know do not think about throwing out spoiled food that required energy in terms of planting, cultivating, harvesting and transporting and therefore will have added to greenhouse gas emissions.

  • Lightweight transport

The use of plastics in transportation (cars, trains and planes) will reduce fuel consumption. Their application (along with reinforcing fibres) in aerospace as alternatives to traditional metallic alloys has brought huge gains of fuel efficiency over the last few decades.

Incorporation of fibre-reinforced plastics in the Boeing 787 Dreamliner, for example, has resulted in fuel efficiencies that are similar to a family car (when measured by kilometres travelled per person). By the way, carbon fibre, the aerospace fibre of choice, is produced from plastic.

There are good things about plastics including benefits for the environment, but is it possible to make use of the good aspects and avoid the bad?

Future proofing plastics

Plastics are, chemically speaking, long chains or large cross-linked structures most commonly made up of a framework of carbon atoms.

For a long time, we have been using bio-derived plastics – naturally occurring materials such as animal skins including leather, gut and wood. These forms of plastic are complicated chemical structures that can only be made in nature at this stage.

Some of the early synthesised plastics were made from naturally occurring materials such as casein (from dairy) that was used for simple items such as buttons. The development of petroleum-based plastics has been a major distraction from such materials.

However, in the last couple of decades, bio-derived plastics have become available that provide good replacements. These include starch-based plastics such as polylactide (PLA), which is produced from corn starch, cassava roots or sugarcane and processed in the same way as petroleum-based plastics. Such plastics can be foamed or used to make drink bottles.

Plastic bottles ready to be recycled.
From Shutterstock, CC BY-ND

Recycling plastics is another essential step towards reducing the environmental load. Let’s face it: it is people who are doing the littering, not the plastics themselves. More effort could go into waste collection and a carrot/stick approach should include disincentives for littering and a plastic tax which would exclude recycled plastics.

Incentives are also needed to encourage product development that takes account of the full life cycle. In Europe, for instance, legislation has made it compulsory in the automotive industry for at least 85% of a car to be recycled. This has had a dramatic influence on the materials and design used in the industry.

Even with best efforts, it is unrealistic that we would capture all plastics for recycling. Biodegradable plastics could be a useful tool for preventing environmental damage. PLA (polylactide) is biodegradable, though slow to break down, and there are other forms available.

This highlights the need for more research into controlling biodegradability, taking into account different applications and the need for infrastructure to deal with biodegradable plastics at the end of their life. Obviously, we don’t want our planes biodegrading during their 20 years of service, but one-use water bottles should break down within a short time after use.

The planet doesn’t have to become a toxic rubbish dump. In the short term, this will need some government action to encourage bio-derived, recyclable and biodegradable plastics to allow them to compete with petroleum-based products.

The ConversationThere are signs of improvement: increasing awareness of the harm plastics cause and a willingness of consumers to pay for plastic bags or to ban them. We need to stop dumping in our own backyard and remember that the environment is where we live. We ignore it at our peril.

Kim Pickering, Professor of materials science and engineering, University of Waikato

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

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Delhi suffers second smog crisis in 12 months, as wake-up calls go unheeded


Vijay Koul, CSIRO

A year ago Delhi was choking, as smog in the Indian capital soared to 16 times the government’s safe limit for particulate pollution. Now the same thing has happened again.

Levels of the most dangerous particles, called PM2.5, have once again reached last November’s levels: more than 700 micrograms per cubic metre in some parts of the city. Experts say that prolonged exposure to this level of pollution is equivalent to smoking more than two packs of cigarettes a day.

Just 12 months after the record-breaking pollution that should have been a major wake-up call, Delhi is again plunged into darkness. It is a big embarrassment that authorities were not better prepared for this year’s smog season.


Read more: As another smog season looms, India must act soon to keep Delhi from gasping


In July, I released a detailed analysis of the factors that cause Delhi’s November smog.

Based on data from India’s Central Pollution Control Board and from NASA, I concluded that Delhi’s record-breaking pollution in November 2016 was largely due to slow wind speeds and prevailing northerly winds, as well as Diwali fireworks, and the widespread practice of burning crop residues. Others, including the Delhi government, reported similar findings.

But this knowledge has not stopped it happening again, much to the frustration of Delhi residents who now face a second consecutive pollution-plagued winter.

Of course, the authorities do not control the wind speed or direction. But they can and should take steps to curb the other crucial factors.

Burning issue

In Haryana and Punjab states to the north of Delhi, farmers routinely burn their croplands after the summer harvest, ridding their fields of stubble, weed and pests and readying them for winter planting.

This agricultural event coincides with Diwali, India’s festival of lights, which features three or four nights of fireworks before and after the festival, in October or early November.

This series of NASA satellite images clearly shows the pollution plume moving across the landscape during the first two weeks of November. Red dots indicate live fires.

November 1.
NASA
November 8.
NASA
November 14.
NASA

These images show that crop burning is still continuing, especially in parts of Punjab. As the graph below shows, crop burning produced significant amounts of pollution from November 2, 2017, after an earlier pollution spike around October 20 due to Diwali.

https://datawrapper.dwcdn.net/ZHncI/1/

Other countries have taken measures to limit crop burning. In Australia, the Victorian state government strongly encourages farmers to retain crop stubble residues, although it allows sporadic burning. In some Canadian provinces, stubble burning is allowed by permit only.

There is no such legislation under consideration in India. But without a ban on crop burning, Delhi’s pollution woes are likely to continue.

It is high time that the government responded, before Delhi’s pollution gets even more out of hand. Particles in the PM2.5 size range can travel deep into the respiratory tract, reaching the lungs. Exposure to fine particles can cause short-term health effects such as eye, nose, throat and lung irritation, coughing, sneezing, runny nose and shortness of breath.

Exposure to fine particles can also affect lung function and worsen medical conditions such as asthma and heart disease. Studies have linked increases in daily PM2.5 exposure with increased respiratory and cardiovascular hospital admissions, emergency department visits and deaths. More than a million deaths in 2015 were attributed to India’s air pollution.

What governments and residents can do

There is a range of short- and long-term options to combat the problem.

Farmers in Haryana and Punjab should be banned from residue crop burning during October and November, and should be given financial compensation for the inconvenience.

Meanwhile, Delhi’s residents should consider driving less, either by carpooling or using public transport. The city’s authorities, meanwhile, could restrict the entry of polluting trucks and heavy-duty goods vehicles, gradually phase out and ultimately ban older vehicles, and increase parking charges or restrict families to a single car.

A reliable 24-hour power supply would help to reduce the reliance on heavily polluting diesel generators in offices and factories. Subsidies for cleaner fuels or electric or hybrid cars would also help.


Read more: Air pollution causes more than 3 million premature deaths a year worldwide


Authorities also have a duty to keep the public informed of pollution levels, through daily television, radio and social media updates, as well as pamphlets warning of the effects of air quality on health. On the worst days, schools should be closed and children and older people urged to stay indoors.

In the longer terms, a “green belt” could be planted around the city, to help soak up traffic-induced air and noise pollution.

The ConversationMany of these policies would involve significant upheaval. But Delhi needs action before it is too late. The alternative is to be plunged ever deeper into the murk.

Vijay Koul, Honorary fellow, CSIRO

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

Australia still lags behind in vehicle emissions testing



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Emissions from real-life urban driving can be much higher than advertised.
AMPG/Shutterstock.com

Zoran Ristovski, Queensland University of Technology and Nic Surawski, University of Technology Sydney

Australian cars are using 23% more fuel than advertised, according to a report from the Australian Automobile Association, which also claims that eco-friendly hybrid electric cars emit four times more greenhouse gas than the manufacturers advertise.

The report on real-world (that is, on-road) emission testing was commissioned by consultancy firm ABMARC to test 30 cars twice on Melbourne roads. The method used to measure both the emissions and the fuel consumption was a so-called Portable Emissions Measurement System (PEMS).


Read more: The VW scandal exposes the high tech control of engine emissions


They found that when compared to the laboratory limits, on-road vehicle NOx (a toxic gas pollutant) emissions were exceeded for 11 out of 12 diesel vehicles, and carbon monoxide (also a toxic gas) emissions were exceeded by 27% of tested petrol vehicles.

However, the key consideration here is the phrase “comparison to the laboratory limits” because on-road tests can’t directly be compared to the laboratory test limits, for several key reasons.

How are emissions from vehicles measured?

Australian Design Rules (ADR) stipulate that before introducing a new vehicle model on the market, every car or truck manufacturer in Australia has to test one new car in the laboratory.

This is done by placing the vehicle on a chassis dynamometer, connecting the exhaust to highly accurate emissions-measurement equipment, and driving the vehicle according to a strictly defined routine.

The chassis dynamometer simulates the load conditions that the vehicle would experience if it were driven on a road. In current practice, the New European Driving Cycle (NEDC) is used. This defines the speed of the vehicle and rate of acceleration for every second of the 20-minute test.

There is strict control of the testing protocol, with stipulations on how and when the gears should be changed, right down to minute details such as turning off the radio while the headlights are on. This strict control enables testers to compare the performance of different vehicles measured in different laboratories around the world.

However, these highly defined conditions have led to certain manufacturers enabling the car’s engine management system to recognise when it is being tested and to adopt and produce cleaner exhaust emissions. The most famous example of this is the recent VW scandal that affected millions of vehicles worldwide.

Even though the driving cycle has “new” in its name, NEDC was designed in the 1980s and today can be considered outdated.

Real Driving Emissions

To address these challenges, Real Driving Emissions (RDE) tests were developed. RDE tests measure the pollutants emitted by cars while driven on the road. To run a RDE test, cars are fitted with a Portable Emissions Measurement System (PEMS).

A PEMS is a complex piece of equipment that sits in the back of the car and monitors key pollutants emitted by the vehicle in real time as it is driven on the road.

These tests have proved extremely useful in highlighting some of the shortfalls of the laboratory tests. They can be run for much longer periods (several hours as compared with 15-30 minutes in the laboratory) and can give us information on long-term emission performance of the vehicles. They will not replace laboratory tests, but can provide additional information.

RDE requirements will ensure that cars deliver low emissions during on-road conditions. In 2021, Europe will become the first region in the world to introduce such complementary on-road testing for new vehicles.

RDE tests still face several unresolved challenges. The first is that the PEMS are still being developed and are not as accurate as the lab measurement equipment. The second, and more important, is the variability that one encounters while driving in real-world road conditions.

In order to compare the RDE test results with the laboratory-based standards a “conformity factor” is defined as a “not to exceed limit” that takes into account the error of measurements. This error is due to the PEMS equipment being less accurate, the variability in road conditions and driving behaviour, and thus the fact that the RDE tests will not deliver exactly the same results for each run.

A conformity factor of 1.5 would mean that the emissions measured by the PEMS in an RDE test should not exceed the standard NEDC test by more than a factor of 1.5. This is exactly the value that European Union legislators want to introduce – but not before 2021.

Australia is years behind

Australia remains years behind the European Union when it comes to vehicle emission standards.

The Euro emissions standards define the acceptable limits for exhaust emissions of new vehicles sold in the EU. Australia introduced the Euro 5 emission standards in 2016 as compared to Europe, which introduced these in 2009. At that time EU abolished the Euro 5 standard for already new ones in 2015.


Read more: Australia’s weaker emissions standards allow car makers to ‘dump’ polluting cars


Australia needs to upgrade to meet Euro 6 standards in order to provide effective detection of new vehicles. These include measures such as remote sensing as part of a vehicles road-worthiness assessment. This would help to ensure the maintenance status of vehicles and deliver compliance with Euro 6 RDE legislation.

What the Australian Automobile Association report highlights most of all is that the in-use vehicles (whether or not they are hybrid vehicles), many of which fall under the Euro 5 standard (or older), have almost all failed emission tests.

The ConversationUntil Australia updates our vehicle testing regimes to meet international standards, it will remain extremely difficult for Australians who want to buy an energy-efficient vehicle to make an informed purchasing decision.

Zoran Ristovski, Professor, Queensland University of Technology and Nic Surawski, Lecturer – Air Quality/Vehicle Emissions, University of Technology Sydney

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

Mercury from the northern hemisphere is ending up in Australia



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Mercury pollution, often released from gold mining and coal power stations, is a global problem.
Shutterstock

Jenny Fisher, University of Wollongong; Dean Howard, Macquarie University; Grant C Edwards, Macquarie University, and Peter Nelson, Macquarie University

Mercury pollution has a long legacy in the environment. Once released into the air, it can cycle between the atmosphere and ecosystems for years or even decades before ending up deep in the oceans or land.

The amount of mercury in the ocean today is about six times higher than it was before humans began to release it by mining. Even if we stopped all human mercury emissions now, ocean mercury would only decline by about half by 2100.

To address the global and long-lasting mercury problem, a new United Nations treaty called the Minamata Convention on Mercury came into effect last month. The treaty commits participating countries to limit the release of mercury and monitor the impacts on the environment. Australia signed the Convention in 2013 and is now considering ratification.


Read more: Why won’t Australia ratify an international deal to cut mercury pollution?


Until now, we have only been able to guess how much mercury might be in the air over tropical Australia. Our new research, published in the journal Atmospheric Chemistry and Physics, shows that there is less mercury in the Australian tropics than in the northern hemisphere – but that polluted northern hemisphere air occasionally comes to us.

A global problem

While most of mercury’s health risks come from its accumulation in ocean food webs, its main entry point into the environment is through the atmosphere. Mercury in air comes from both natural sources and human activities, including mining and burning coal. One of the biggest mercury sources is small-scale gold mining – a trade that employs millions of people in developing countries but poses serious risks to human health and the environment.

Small-scale gold mining is an economic mainstay for millions of people, but it releases mercury directly into the air and water sources.

Once released to the air, mercury can travel thousands of kilometres to end up in ecosystems far away from the original source.

Measuring mercury in the tropics

While the United Nations was gathering signatures for the Minamata Convention, we were busy measuring mercury at the Australian Tropical Atmospheric Research Station near Darwin. Our two years of measurements are the first in tropical Australia. They are also the only tropical mercury measurements anywhere in the Maritime Continent region covering southeast Asia, Indonesia, and northern Australia.

We found that mercury concentrations in the air above northern Australia are 30-40% lower than in the northern hemisphere. This makes sense; most of the world’s population lives north of the Equator, so most human-driven emissions are there too.

More surprising is the seasonal pattern in the data. There is more mercury in the air during the dry season than the wet season.

The Australian monsoon appears to be partly responsible for the seasonal change. The amount of mercury jumps up sharply at the start of the dry season when the winds shift from blowing over the ocean to blowing over the land.

In the dry season the air passes over the Australian continent before arriving at the site, while in the wet season the air usually comes from over the ocean to the west of Darwin.
Howard et al., 2017 (modified)

But wind direction can’t explain the whole story. Mercury is likely being removed from the air by the intense rains that characterise the wet season. In other words, the lower mercury in the air during the wet season may mean more mercury is being deposited to the ocean and the land at this time of year. Unfortunately, there simply isn’t enough information from Australian ecosystems to know how this impacts local plants and wildlife.

Fires also play a role. Mercury previously absorbed by grasses and trees can be released back to the atmosphere when the vegetation burns. In our data, we see occasional large mercury spikes associated with dry season fires. As we move into a bushfire season predicted to be unusually severe, we may see even more of these spikes.

Air from the north

Although mercury levels were usually low in the wet season, on a few days each year the mercury jumped up dramatically.

To figure out where these spikes were coming from, we used two different models. These models combine our understanding of atmospheric physics with real observations of wind and other meteorological parameters.

Both models point to the same source: air transported from the north.

Australia is usually shielded from northern hemispheric air by a “chemical equator” that stops air from mixing. This barrier isn’t static – it moves north and south throughout the year as the position of the sun changes.

A few times a year, the chemical equator moves so far south that the top end of Australia actually falls within the atmospheric northern hemisphere. When this happens, polluted northern hemisphere air can flow directly to tropical Australia.

We observed 13 days when our measurement site near Darwin sampled more northern hemisphere air than southern hemisphere air. On each of these days, the amount of mercury in the air was much higher than on the days before or after.

Tracing the air backwards in time showed that the high-mercury air travelled over the Indonesian archipelago before arriving in Australia. We don’t yet know whether that mercury came from pollution, fires, or a mix of the two.

The highest mercury is observed when the air comes from the northern hemisphere.
Howard et al., 2017 (modified)

A global solution

To effectively reduce mercury exposure in sensitive ecosystems and seafood-dependent populations around the world, aggressive global action is necessary.

The cross-boundary influences on mercury that we have observed in northern Australia highlight the need for the type of multinational collaboration that the Minamata Convention will foster.

The ConversationOur new data establish a baseline for monitoring the effectiveness of new actions taken under the Minamata Convention. With the first Conference of the Parties having taken place last week, hopefully it will only be a matter of time before we begin to see the benefit.

Jenny Fisher, Senior Lecturer in Atmospheric Chemistry, University of Wollongong; Dean Howard, , Macquarie University; Grant C Edwards, Senior lecturer, Macquarie University, and Peter Nelson, Pro Vice Chancellor (Research Performance and Innovation), Macquarie University

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

The new Great Barrier Reef pollution plan is better, but still not good enough


Jon Brodie, James Cook University; Alana Grech, James Cook University, and Laurence McCook, James Cook University

The draft water quality improvement plan, released by the federal and Queensland governments this week, aims to reduce the pollution flowing from water catchments to the Great Barrier Reef over the next five years.

It is part of the overarching Reef 2050 Long-Term Sustainability Plan to protect and manage the reef until mid-century.

Water quality is one of the biggest threats to the reef’s health, but the new guidelines still fall short of what’s required, given the available scientific evidence.


Read more: Cloudy issue: we need to fix the Barrier Reef’s murky waters.


The draft plan, which is open for comment until October, presents several important and commendable advances in the management of water quality on the Great Barrier Reef. It addresses all land-based sources of water pollution (agricultural, urban, public lands and industrial) and includes social, cultural and economic values for the first time.

The principal sources of pollution are nitrogen loss from fertiliser use on sugar cane lands, fine sediment loss from erosion on grazing lands, and pesticide losses from cropping lands. These are all major risk factors for the Great Barrier Reef.

The draft plan also presents updated water quality targets that call for reductions in run-off nutrients and fine sediments by 2025. Each of the 35 catchments that feeds onto the reef has its own individual set of targets, thus helping to prioritise pollution-reduction measures across a region almost as large as Sweden.

The reef’s still suffering

The Great Barrier Reef suffered coral bleaching and death over vast areas in 2016, and again this year. The 2017 Scientific Consensus Statement, released with the draft water quality plan (and on which one of us, Jon Brodie, was an author), reports:

Key Great Barrier Reef ecosystems continue to be in poor condition. This is largely due to the collective impact of land run-off associated with past and ongoing catchment development, coastal development activities, extreme weather events and climate change impacts such as the 2016 and 2017 coral bleaching events.

Stronger action on the local and regional causes of coral death are seen to be essential for recovery at locations where poor water quality is a major cause of reef decline. These areas include mid-shelf reefs in the Wet Tropics region damaged by crown of thorns starfish, and inner-shelf reefs where turbid waters stop light reaching coral and seagrass. Human-driven threats, especially land-based pollution, must be effectively managed to reduce the impacts on the Great Barrier Reef.

But although the draft plan provides improved targets and a framework for reducing land-based pollution, it still doesn’t reflect the severity of the situation. The 2017 Scientific Consensus Statement reports that “current initiatives will not meet the water quality targets” by 2025.

This is because the draft plan does not provide any major new funding, legislation or other initiatives to drive down land-based pollution any further. As the statement explains:

To accelerate the change in on-ground management, improvements to governance, program design, delivery and evaluation systems are urgently needed. This will require greater incorporation of social and economic factors, better targeting and prioritisation, exploration of alternative management options and increased support and resources.


Read more: The Great Barrier Reef’s safety net is becoming more complex but less effective


The draft plan calls on farmers to go “beyond minimum standards” for practices such as fertiliser use in sugar cane, and minimum pasture cover in cattle grazing lands. But even the minimum standards are unlikely to be widely adopted unless governments implement existing legislation to enforce the current standards.

The draft plan is also silent on the impact of land clearing on water quality, and the conversion of grazing land to intensively farmed crops such as sugar cane, as proposed in the White Paper on Developing Northern Australia.

The federal and Queensland governments have committed A$2 billion over ten years to protect the Great Barrier Reef. Under the draft plan, about half of this (A$100 million a year) will be spent on water quality management. This is not an increase in resourcing, but rather the same level of funding that has been provided for the past seven years.

More than loose change

There is a very strong business case for major increases in funding to protect the Great Barrier Reef. Even with conservative assumptions, the economics firm Jacobs has estimated that protecting the industries that depend on the reef will require A$830 million in annual funding – more than four times the current level.


Read more: What’s the economic value of the Great Barrier Reef? It’s priceless.


The draft water quality plan acknowledges the need for a “step change” in reef management, and to “accelerate our collective efforts to improve the land use practices of everyone living and working in the catchments adjacent to the Reef”.

This need is echoed in many other reports, both government and scientific. For example, the 2017 Scientific Consensus Statement makes several wide-ranging recommendations.

One of them is to make better use of existing legislation and policies, including both voluntary and regulatory approaches, to improve water quality standards.

This recommendation applies to both Commonwealth and Queensland laws. These include the federal Great Barrier Reef Marine Park Act 1975, which restricts or bans any activities that “may pollute water in a manner harmful to animals and plants in the Marine Park”, and the Environment Protection and Biodiversity Conservation Act 1999, which prohibits any action, inside or outside the marine park, that affects the Great Barrier Reef’s World Heritage values.

Another recommendation is to rethink existing land-use plans. For instance, even the best practice in sugar cane farming is inconsistent with the nitrogen fertiliser run-off limits needed to meet water quality guidelines. One option is to shift to less intensive land uses such as grazing in the Wet Tropics region – a priority area for nitrate fertiliser management because of its link to crown of thorns starfish outbreaks. This option is being explored in a NESP project.

The ConversationThese changes would require significantly increased funding to support catchment and coastal management and to meet the draft plan’s targets. Government commitment to this level of management is essential to support the resilience of the Great Barrier Reef to climate change.

Jon Brodie, Professorial Fellow, ARC Centre of Excellence for Coral Reef Studies, James Cook University; Alana Grech, Assistant Director, ARC Centre of Excellence for Coral Reef Studies, James Cook University, and Laurence McCook, Adjunct Principal Research Fellow, Partner Investigator, ARC Centre of Excellence for Coral Reef Studies, James Cook University

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

Noise from offshore oil and gas surveys can affect whales up to 3km away



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Migrating humpback whales avoid loud, nearby sounds.
BRAHSS, Author provided

Rebecca Dunlop, The University of Queensland and Michael Noad, The University of Queensland

Air guns used for marine oil and gas exploration are loud enough to affect humpback whales up to 3km away, potentially affecting their migration patterns, according to our new research.

Whales’ communication depends on loud sounds, which can travel very efficiently over distances of tens of kilometres in the underwater environment. But our study, published today in the Journal of Experimental Biology, shows that they are affected by other loud ocean noises produced by humans.

As part of the BRAHSS (Behavioural Response of Humpback whales to Seismic Surveys) project, we and our colleagues measured humpback whales’ behavioural responses to air guns like those used in seismic surveys carried out by the offshore mining industry.


Read more: It’s time to speak up about noise pollution in the oceans


Air guns are devices towed behind seismic survey ships that rapidly release compressed air into the ocean, producing a loud bang. The sound travels through the water and into the sea bed, bouncing off various layers of rock, oil or gas. The faint echoes are picked up by sensors towed by the same vessel.

During surveys, the air guns are fired every 10-15 seconds to develop a detailed geological picture of the ocean floor in the area. Although they are not intended to harm whales, there has been concern for many years about the potential impacts of these loud, frequent sounds.

Sound research

Although it sounds like a simple experiment to expose whales to air guns and see what they do, it is logistically difficult. For one thing, the whales may respond to the presence of the ship towing the air guns, rather than the air guns themselves. Another problem is that humpback whales tend to show a lot of natural behavioural variability, making it difficult to tease out the effect of the air gun and ship.

There is also the question of whether any response by the whales is influenced more by the loudness of the air gun, or how close the air blast is to the whale (although obviously the two are linked). Previous studies have assumed that the response is driven primarily by loudness, but we also looked at the effect of proximity.

We used a small air gun and a cluster of guns, towed behind a vessel through the migratory path of more than 120 groups of humpback whales off Queensland’s sunshine coast. By having two different sources, one louder than the other, we were able to fire air blasts of different perceived loudness from the same distance.

We found that whales slowed their migratory speed and deviated around the vessel and the air guns. This response was influenced by a combination of received level and proximity; both were necessary. The whales were affected up to 3km away, at sound levels over 140 decibels, and deviated from their path by about 500 metres. Within this “zone”, whales were more likely to avoid the air guns.

Each tested group moved as one, but our analysis did not include the effects on different group types, such as a female with calf versus a group of adults, for instance.

The ConversationOur results suggest that when regulating to reduce the impact of loud noise on whale behaviour, we need to take into account not just how loud the noise is, but how far away it is. More research is needed to find out how drastically the whales’ migration routes change as a result of ocean mining noise.

Rebecca Dunlop, Senior Lecturer in Physiology, The University of Queensland and Michael Noad, Associate Professor, The University of Queensland

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