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CSIRO'S SCIENCE-AND-THE-ENVIRONMENT MAGAZINE
No. 68 WINTER 1991
1
^^^^t
Registered by Australia Post Publication No. VBP 90 9878
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CONTENTS
COS
o. 68 WINTER 1991
3 Upfront
Tasmania's ear on the sky
Foxes attacked
Pulp mill research
CSIRO goes to Hollywood
Message received
Letters
The goal: sustainable
development
6 How high could the sea
rise?
The sea will rise if the world keeps
warming the big question is:
by how much?
10 Quick, complete waste
destruction
'Plasma arcs', hotter than the
surface of the Sun, can be
harnessed to destroy hazardous
wastes as they are produced.
13 Methuselah of the deep
Orange roughy, a delicacy of the
deep with a remarkably long life
span, is under threat from
over-fishing.
18 Tracking climate
change air under the
microscope
Precise measurements of the
composition of the atmosphere,
and of ancient tree rings, are
assisting climate-change
prediction.
Subscriptions
A subscription to Ecos costs only $18 for
one year or $34 for two years. Please send
your order and payment (made out to
Ecos) to: Ecos subscriptions, P.O. Box 225,
Dickson, A.C.T., 2602. Or you can phone us
with your subscription order, quoting your
Bankcard or Mastercard number; phone
(06) 276 6313.
25 Fungi to control pests
in the soil
Biological control of soil-dwelling
insect pests by specially selected
fungi is looking promising.
28 Plants in the sun
Scientists are examining how an
increase in harmful ultraviolet
radiation due to ozone depletion
may affect plant life.
31 Spectrum
Planning for future needs
An elusive vitamin under the
spotlight
Unwanted nitrates the
termite connection
36 No more 'bonsai'
banana trees?
A 2-mm-long wasp tackles the
banana aphid.
Ecos, CSIRO's science-and-the-environment
magazine, is published four times a year (in
February, May, August and November).
Editor: Robert Lehane
Staff Writers: Roger Beckmann and
Carson Creagh
Design:
Brian Gosnell
Typesetting: Francois Bertrand
Editorial
assistance: Yvonne Roberts
Correspondence should be addressed to:
The Editor, Ecos, P.O. Box 225, Dickson, A.C.T.
2602, Australia. Phone: (06) 276 6584. Telex:
62003. Fax: (06) 276 6641.
Material in Ecos may be reproduced;
acknowledgement of both CSIRO and Ecos
is requested.
Cover photo: Graeme Johnson
Printed for CSIRO, Limestone Avenue, Camp
bell, A.C.T., 2601, by A.E. Keating (Printing)
Pty Ltd, 299 Williamstown Road, Port
Melbourne, Vic. 3207.
ISSN 0311-4546
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UPFRONT
Tasmania's ear on the sky
A glance at the weather map reveals
how important Antarctica and the
Southern Ocean are to Australia's
climate. Yet little is known about just
how they exert so much influence on
our weather: hardly surprising, given
the storms and glacial cold that make
up so much of these regions' own
weather
A new generation of
environment-monitoring Earth
resources satellites will be launched
this decade as the world urgently
seeks to add to its knowledge of
global environmental processes
and it just happens that Tasmania is
ideally situated to take advantage of
the stream of information they will
beam down to us.
Scheduled to be in operation by the
end of this year, the $2-3 million
Tasmanian Earth Resources Satellite
Station (TERSS) is a joint venture
between the CSIRO Division of
Oceanography and the University of
Tasmania.
Historically, satellites have
transmitted information at low
frequencies on the S-band, between
2-2 and 2-3 gigahertz (GHz). This has
Foxes attacked
The fearsome fox, an introduced pest,
has been and continues to be a
disaster for our small native
mammals, as well as a nuisance for
farmers.
Accordingly, the CSIRO Division of
Wildlife and Ecology has set up a
program to devise an efficient
method of control. With a grant of
$250 000 from the Commonwealth
government in 1990, and further
funding from the Australian National
Parks and Wildlife Service's
endangered species program, the
Division has brought together a team
of eight to target the fox.
The biologists' strategy centres on
rendering the pests sterile by using
their own immune systems to attack
their gametes (eggs and sperm). In
effect, the animals will be inoculated
against themselves. But rather than
injecting the animals, the researchers
hope to use a virus, to which genes
for proteins found on fox egg and
sperm will be added, to perform the
inoculation.
The plan calls for the release of the
modified virus specific to foxes
into the wild population. As it
spreads, causing disease but probably
made signal tracking relatively easy,
but it limited the amount of
information that could be transmitted.
The new Earth resources satellites will
transmit data at much higher rates on
the X-band, between 8 and 84 GHz,
and nations wishing to benefit will
need ground stations capable of fine
tracking.
Australia already has one such
station, at Alice Springs (this station
receives information covering the
northern part of the continent, as well
as parts of the Indonesian archipelago
and the island of New Guinea), and
TERSS will permit coverage of
southern Australia, New Zealand and
Antarctica providing invaluable
insights into the forces that shape our
climate.
Building on satellite data-capture
technology developed at the CSIRO
Marine Laboratories in Hobart and at
the Division of Radiophysics in
Sydney, TERSS incorporates a high
degree of Australian technology. The
first satellite to come 'on line' will be
the European Space Agency's ERS-1,
launched in April, and TERSS is
designed to receive data from planned
Japanese, Soviet and United States
satellites.
little mortality, it will also be quietly
inoculating the animals against their
own germ cells. The normal
immunological response against the
invading virus will also include the
production of antibiotics that attack
the fox-gamete proteins that it carries.
Thus the female foxes' antibodies
will attack their own ova, and males'
their own sperm. Another feature is
that the females' antibodies could also
attack the males' sperm. The results
should be painless sterility and
eventually a decline in the numbers
of this pest. We'll let you know the
results as the research unfolds.
Pulp mill research
The CSIRO is managing a $15-million
pulp mill environmental research
program on behalf of the federal
government. The program, funded
by the Commonwealth, States and
industry, will play a key role in
enhancing the existing standards and
assessment procedures for the
approval and operation of any new
bleached eucalypt kraft pulp mills in
Australia.
The 5-year National Pulp Mills
Research Program started in 1990
will investigate the technologies
used in the kraft chemical pulping
process, and evaluate the
environmental impact of bleached
eucalypt kraft mills. To keep
everyone up to date, an important
function will be communication with
the industry and public.
A variety of CSIRO Divisions will be
involved in the research, along with a
range of universities and other
research institutions. The Division of
Forest Products will examine the
composition of effluents, as well as
the pulping and bleaching technology
used in mills. The Division of
Chemicals and Polymers will assess
alternative means of making effluents
environmentally benign by adapting
some existing treatment strategies.
The Division of Oceanography,
using knowledge of currents and
water movements, will provide
advanced models to simulate the
dispersal of effluent, while the Centre
for Advanced Analytical Chemistry
in the Division of Fuel Technology
will research a bioassay system able
to detect contaminants in the
environment. And finally, CSIRO's
Biometrics Unit in Adelaide will work
on applying the mathematical
techniques of risk-assessment
developed originally for economic
and human health problems to the
environmental issues involved.
Ecos 68, Winter 1991 3
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UPFRONT
Message received
The ingenious experiment that uses
sound to monitor the oceans'
temperature (see Ecos 66) has
reported its first successful
transmissions.
An underwater transmitter near
Heard Island in the southern Indian
Ocean sends sound waves around the
globe, which are picked up at various
recording stations. Sound travels
faster in warmer water, and precise
measurements of the travel times
over several years will reveal whether
average ocean temperatures are rising.
Scientists stationed aboard two
research vessels made experimental
transmissions from the sea off Heard
Island this summer. These were
successfully received by a range of
listening stations in Bermuda, South
Africa, Canada, India, Oregon,
California, Christmas Island and
elsewhere. Noise travels faster in the
sea than in the air it took just
3 hours for the signal to reach
Bermuda.
The scientists carried out extensive
biological surveys before, during and
after the transmissions to see whether
these had any effect on nearby
whales, dolphins and seals. Happily,
the animals appeared to behave
normally during the transmissions
and the researchers observed no
adverse reactions.
The experiment, and the
trans-Pacific collaboration it
represents, looks set to continue.
Watch this space.
As we head into winter, Ecos
introduces its new look for the
nineties. Hope you like it.
You might not notice indeed, if the producers are successful,
you'll be too scared but the movie Arachnophobia includes
some eight-legged stars as all-Australian as Crocodile Dundee.
Mr Russell Moran of the CSIRO Division of Entomology
provided expert advice when the producers were looking for
spiders large and menacing enough to scuttle, lurk and
generally provide inspiration for leading actor Jeff Daniels's
fear of spiders. Keeping company in the movie with South
American bird-eating spiders is Delena cancerides, a common
and quite harmless Australian huntsman... and a species
regarded with affection by many householders.
However, the specimens of Delena featured in the movie
didn't come direct from Australia, since our laws forbid the
export of most kinds of wildlife. In fact, the spiders were
collected in New Zealand, where they arrived by accident. And
there's even greater irony in the situation: Australian redback
spiders (Latrodectus hasseltii) that apparently came to Australia
again, by accident late last century have since been
accidentally introduced into New Zealand... where they are
competing with the katipo, that country's native species of
Latrodectus.
Dr Hugh Tyndale-Biscoe of the
CSIRO Division of Wildlife and
Ecology comments: The behaviour of
the crows that Mr Campbell describes
is interesting.
In South America several predators
have developed similar strategies for
attacking toads by avoiding the
poison glands on the shoulders and
there have been observations similar
to those of Mr Campbell for some
Australian birds and mammals. In the
case of mammal predators the toads
are thrown on their backs and
attacked from the belly.
However, as well as the shoulder
glands, which secrete a strong poison,
the eggs contained in the ovaries of
females are also highly toxic and
must be avoided by predators.
In the Northern Territory
crocodiles have been observed eating
cane toads without ill effect. They use
a different strategy; they grasp the
toads in their jaws and shake them
vigorously before swallowing. The
inference is that in the process of
being shaken the toads eject most of
the poison from their shoulder
glands.
Other species such as goannas that
live in areas where toads occur avoid
them.
Write to Letters, Ecos, PO Box 225,
Dickson, ACT 2602.
Toad-eaters
I read with interest your Up Front
article 'Targeting toads'.
I live on an acreage block on the
northern outskirts of Brisbane. We
have quite a number of crows in the
area in fact they nest here.
I have observed, on a number of
occasions, crows feeding on the inside
of toads. They wrap their claws
around the neck of the toad, forcing it
to open its mouth, and then start
feeding.
I had found from time to time dead
toads in and around the yard and was
curious as to what was killing them. I
realise there are far more toads than
crows in our area, but I was pleased
to find they had a natural predator.
J. Denis Campbell
Narangba, Qld
4 Ecos 68, Winter 1991
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UPFRONT
The goal: sustainable development
If Australia is to maintain high
iving standards and a growing
population without continuing
environmental damage, it needs ESD
ecologically sustainable
development. That's easily said, but
is ESD an achievable goal? A major
federal government project is
attempting to come to grips with the
complex issues involved, define the
main areas needing action and
determine what that action should be.
Dr Roy Green, Director of the
CSIRO Institute of Natural Resources
and Environment, is a key player in
the exercise. As chair of the ESD
working groups on agriculture,
fisheries and forestry, he takes
seriously the Prime Minister's
message that consensus among
working group members should not
be achieved at the cost of 'lowest
common denominator' conclusions
that would 'do little to progress a
move towards ecologically
sustainable development'.
Dr Green believes that the
recommendations from the nine ESD
working groups will play a big part
in shaping Australia's future. He
expects some will be fairly easy and
inexpensive to implement, but others
will involve major attitudinal change
and expense and require a possibly
unprecedented degree of local, State
and national co-operation.
Sustainable development has many
definitions. One of the most popular
comes from the World Commission
on Environment and Development's
report 'Our Common Future',
published in 1987, which defines it
simply as 'development that meets
the needs of the present without
compromising the ability of future
generations to meet their own needs'.
According to our government's
discussion paper on ESD, 'the task
confronting us is to take better care of
the environment while ensuring
economic growth, both now and in
the future'.
Last year the nine working groups
began the job of identifying the main
issues, policy options and costs. Each
group has members drawn from theCommonwealth and State
governments, industry, conservation
interests and unions, and focuses on
one of nine major industry sectors
agriculture, forestry, fisheries, energy
production, manufacturing, mining,
transport, energy use and tourism.
Issues that extend across sectors, such
as climate change, 'biodiversity' and
public health, will be the subject of
an additional report.
Working to tight deadlines, the
groups have until July to produce
draft reports for circulation and
comment and then until October to
finalise them. Recommendations are
due to be discussed at a Premiers'
Conference in November, with
decisions following soon after.
How is it going? Very well, says Dr
Green. His three groups meet
monthly, usually spending one day indiscussions with people from the
industries concerned and another
preparing their report. To encourage
involvement in the consultation
program, they are holding meetings
around the country.
The groups have commissioned a
range of papers on issues and
strategies many from CSIRO
support teams set up to provide
technical input to each group. Dr
Green is heartened by the
co-operative attitudes and
willingness of the groups to explore
different points of view displayed so
far. Nevertheless, he expects some
'frank exchanges' within the working
groups before their reports are
finalised and envisages that some
recommendations may not be
unanimous, which is hardly
surprising, given the importance and
nature of some of the issues they have
to confront.
For example, the agriculture
working group, in coming to grips
with the massive problems of salinity,
erosion and acid soils, will have to
consider whether ecological
sustainability requires an end to
cropping in some areas and
reductions in stock numbers
possibly even complete destocking
in others.
Any such recommendation would
have major ramifications involving
the livelihoods of the farmers
involved and of business people who
provide services to them, with
changes in rural life-style, not to
mention demands on government for
compensation.
Dr Green sees 'economic
instruments' (preferably incentives
rather than penalties) as an important
means of bringing about necessary
changes in agricultural land use. He
suggests that we need a tax regime
that rewards management strategies
that preserve the land: again, easily
said but hard to come to grips with in
practice.
For agriculture, at least the facts
about the state of the land and the
way it is used, which the working
group needs as a starting point, are
generally available. But for fisheries
the information needed to set
sustainable catch limits on the size
of fish stocks, 'recruitment' rates and
so on is severely lacking. In
coming up with recommendations
aimed at ending Australia's sorry
sequence of collapses of over-exploited
fisheries, the working group will be
looking for efficient ways to improve
the data-base and to implement
conservatively set catch quotas.
Despite the prominence of forests
in environmental controversy, Dr
Green suspects the forestry working
group will have less difficulty than
the other two he chairs in setting a
course towards ecological
sustainability. He foresees short-term
problems in maintaining the forest
industries without adversely affecting
the native forests. In 20 or 30 years,
however, he expects plantations and
restricted areas of intensively
managed forest will provide most of
Australia's timber needs, dramatically
reducing the demand for logging in
other areas.
As a sign of the high priority it has
given the sustainable development
exercise, the government has
arranged monthly meetings between
the three group chairs and the
Ministers mainly concerned with the
issues under examination. (Professor
Stuart Harris of the Australian
National University heads the groups
on energy production, manufacturing
and mining and Professor David
Throsby of Macquarie University
those on transport, energy and
tourism.)
The reports of the nine working
groups will take a common approach
setting out 'where we are now' and
'where we need to be' to achieve
sustainability, comparing the two and
then providing conclusions and
recommendations. The tenth report
will deal with issues that span the
industry sectors. In its 80-100 pages,
each report will set out the key issues,
offer practical policy approaches and
identify as accurately as possible
what costs will have to be faced.
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Predictions of sea-level rise
due to global warming range
from minor to catastrophic.
Oceanographers have now
delved into the complexities
of the problem and produced
some firmly based answers.
he average air tempera
ture at the surface of Earth
has risen this century, as
has the temperature of
ocean surface waters. Be
cause water expands as it
heats, a warmer ocean means higher
sea levels.
We cannot yet say definitely that
the temperature rises are due to the
greenhouse effect; the heating may be
part of a 'natural' variability over a
long time-scale that we have not yet
recognised in our short 100 years of
recording. However, assuming the
build-up of greenhouse gases is res
ponsible, and that the warming will
continue, as seems likely, scientists
and inhabitants of low-lying coast
al areas would like to know the
probable extent of future sea-level
rises.
But calculating that is no easy task.
Models used for the purpose have
tended to treat the ocean as passive,
stationary and one-dimensional. Scient
ists assumed that heat simply diffused
into the sea from the atmosphere.
Using basic physical laws, they would
then predict how much a known vol
ume of water would expand for a
given increase in temperature. But the
oceans are not one-dimensional, and
recent work by CSIRO oceano
graphers, taking into account a num
ber of subtle facets of the sea
including vast and complex ocean
currents suggests that the rise in
sea level may be less than some ear
lier estimates had predicted, although
still of concern.
The 'Villach Conference' on climate
change, held in 1986, produced widely
publicised figures for likely sea-level
rises of 20 cm and 1-4 m, corres
ponding to atmospheric temperature
increases of 1-5 and 4-5C respectively.
But Dr John Church, Dr Stuart God
frey, Dr David Jackett and Dr Trevor
McDougall, of the CSIRO Division of
Oceanography in Hobart, estimate
that the ocean warming resulting
from those temperature increases by
the year 2050 would raise the sea level
by between 10 cm and 40 cm.
That comparison does not tell the
complete story, as the CSIRO model
only takes into account the tem
perature effect on the oceans and their
consequent thermal expansion; it does
not consider changes in sea level
brought about by melting of ice
sheets and glaciers, and changes in
groundwater storage. When we
add on estimates of these from the
work of others, we arrive at figures
for total sea-level rises of 15 cm and 70
cm respectively.
HOW HIGH COULD
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ut first, how did the CSIRO
scientists arrive at their conclu
sions? It's certainly not easy try
ing to model accurately the enormous
complexities of the ever-changing
oceans, with their great volume,
massive currents and sensitivity to
the influence of land masses and the
atmosphere. Indeed, nailing jelly to
the wall could be easier.
For example, consider how heat en
ters the ocean. Does it just 'diffuse'
from the warmer air vertically into the
water, and heat only the surface layer
of the sea? (Warm water is less dense
than cold, so it would not spread
downwards.) Conventional models of
sea-level rise have considered that
this is the only method, but measure
ments have shown that the rate of
heat transfer into the ocean by vertical
diffusion is far lower in practice than
the figures many modellers have
adopted.
To help visualise this diffusion of
heat, imagine placing one end of a
metal bar near a fire. Eventually, the
other end will warm up. A similar
limited vertical diffusion of heat from
atmosphere to ocean was used in pre
vious models.
Much of the early work, for reasons
of simplicity, had to ignore the fact
that water in the oceans moves in
three dimensions. By movement, of
course, scientists don't mean waves,
which are too small individually to
consider, but rather movement of vast
volumes of water in huge currents. To
understand the importance of this, we
now need to consider another process
advection.
Imagine smoke rising from a chim
ney. On a still day it will slowly
spread out in all directions by means
of diffusion. With a strong directional
wind, however, it will all shift down
wind. This process is advection the
transport of prop
erties (notably heat
and salinity in the
ocean) by the move
ment of bodies of
air or water, rather
than by conduction
or diffusion.
Massive ocean
currents called gyres
do the moving. These
currents have far
more capacity to
store heat than does
the atmosphere. In
deed, just the top 3
m of the ocean con
tains more heat than
the whole of the at
mosphere.
he origin of gyres lies in the fact
that more heat from the Sun
reaches the Equator than the
Poles, and naturally heat tends to
move from the former to the latter.
Warm air rises at the Equator, and
draws in more air beneath it in the
form of winds (the 'Trade Winds')
that, together with other air move
ments, provide the main force driving
the ocean currents.
Water itself is heated at the Equator
and moves poleward, twisted by the
Earth's rotation and affected by the
The 3-D sea
Circumpolar
Currei
ntarctic
Convergence
THE SEA RISE?
How water masses
move and temperature
varies in the Southern
Ocean.
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Oceanographer lowering a probe that
measures electrical conductivity,
temperature and pressure as it falls. Each
provides an ocean profile of salinity and
temperature; many such measurements are
needed to work out the complex pattern of
water movement in the ocean.
positions of the continents. The re
sultant broadly circular movements be
tween about 10 and 40 N and S are
clockwise in the Northern Hemisphere
and anticlockwise in the Southern.
They flow towards the east at mid lat
itudes, and back to the west in the
equatorial region. They then flow to
wards the Poles, along the eastern
sides of continents, as the well-known
warm currents the Gulf Stream, the
East Australia Current or the Kuroshio.
When two different masses of water
meet, one will move beneath the other,
depending on their relative densities,
in a process termed subduction. The
densities are determined by tem
perature and salinity.
The convergence of water of differ
ent densities from the Equator and the
Poles in the interior of the oceans caus
es continuous subduction. This means
that water moves vertically as well as
horizontally. Cold water from the Poles
travels at depth it is denser than
warm water until it emerges at the
surface in another part of the world in
the form of a cold current.
For example, in our own hemi
sphere, water from the Southern Ocean
sinks at the Antarctic convergence, at
about 60 S, when confronted with
warmer water from more northerly lat
itudes. It then flows northwards at a
depth of about 1000 m. It will still be
about 600 m deep just south of the
Equator and will then flow westwards
at this depth, rising slowly back to the
surface in the Southern Ocean.
Thus, ocean currents, in three di
mensions, form a giant 'conveyor belt',
distributing heat from the thin surface
layer into the interior of the oceans and
around the globe. (Don't be confused
by the idea of a 'cold' current distrib
uting heat; if the surface water at 60 S
were heated just a degree or two more
than usual, because of a warmer at
mosphere, then it would carry a large
quantity of extra heat into the ocean in
terior.)
Water may take decades to circulate
in these 3-D gyres in the top kilometre
of the ocean, and centuries in the deep
er water.
With the increased atmospheric
temperatures due to the greenhouse
effect, the oceans' conveyor belt will
carry more heat into the interior. This
subduction moves heat around far
more effectively than simple diffu
sion.
Because warm water expands more
than cold when it is heated, earlier
workers had presumed that the sea
level would rise unevenly around the
globe. However, Dr Church and his
team point out that the inequalities
cannot persist; winds will act to con
tinuously spread out the expansion,
and their model is the first to consider
this. Of course, if global warming
changes the strength and distribution
of the winds as it may do then
this 'evening-out' process may not oc
cur, and the sea level could rise more
in some areas than others.
The ultimate test of any model
is how it fits reality. The CSIRO
scientists can't test their pre
dictions until the global temperature
has risen substantially, but they can
look at what has been happening in the
past and see how it squares with what
their model says should have hap
pened.
Measurements from around the
world during the last hundred years or
so have shown that the sea level has in
deed risen, probably by 10-20 cm.
Most estimates fall in the lower half of
this range. (The difference in estimates
depends partly on whether scientists
take into account the upward move
ment of the Earth's crust, which is 're
bounding' in slow motion after being
pressed down by the weight of glaciers
during the last Ice Age. The uneven
distribution of sea-level gauges around
the globe and inconsistent monitoring
further confuse the picture.)
Recent work has shown that the con
tribution to sea-level rise made by
melting around the edges of the ice
sheets in Antarctica and Greenland is
probably very small. Indeed, although
in some areas the ice is decreasing, in
other places ice sheets are actually
growing because of increased snowfall
brought about by greater evaporation
from the warmed oceans.
Using estimates of 0'4-0-6C for the
increase in average global temperature
from 1880 to 1980, the model put for
ward by Dr Church and his colleagues
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Possible sea rise by 2050
extent of sea rise (cm)
70
60
I- 50
produces a figure for sea-level rise dur
ing the past century of about 7 cm. The
contribution from the melting of tem
perate glaciers is estimated to be 4-6
cm; added to Dr Church's value, this
gives a total of 11-6 cm in the range
of the measured reality. The fact that
these figures alone seem able to ac
count for a good proportion of the rise
lends support to the idea that the con
tribution of ice-melt in Greenland and
Antarctica has so far been small.
The CSIRO scientists have concentra
ted on thermal expansion in their work
on sea-level rise because they believe it
will be the biggest component at
least for the near future. To arrive at es
timates of total rises, they have used
figures from others' work for ice-
melting.
The chart shows two sets of figures
for three different temperature rises
that may occur between now and 2050.
One set of values represents the rise
brought about by thermal expansion
only; the other shows possible total fig
ures, which include values for ice-melt.
Even the worst case where a 4-5 C
average global temperature increase
produces a total rise of 70 cm falls
short of most previous estimates. How
ever, as the scientists point out, the
upper extreme of their estimate is still
large enough to cause considerable
concern for many nations.
The variability in the figures now lies
less in our knowledge of the oceans'
thermal expansion than in the pre
dictions for global temperature rise,
and the extent of ice-melting. Of
course, estimating local changes in sea
Gary Critchley
level is a different matter; they also de
pend on local winds and geography,
and on changes in atmospheric pres
sure.
Whatever future awaits us, now that
the CSIRO oceanographers have in
troduced the complexities of ocean
behaviour into the debate, the
greenhouse-model-builders will be
incorporating the findings to give
increasingly refined predictions, to en
able society to make more informed
decisions.
Roger Beckmann
Currents near Australia
1 - 5 3 4 - 5
atmospheric temperature increase (C)
rises brought about by thermal expansion
total rises (including ice-melt)
More about the topic
A model of sea level rise caused by
ocean thermal expansion. J.A.
Church, J.S. Godfrey, D.R. Jackett
and T.J. McDougall. Journal of Cli
mate, 1991,4, (in press).
A ^
South Equatorial Current
Current
South Equatorial
Current
^ Leeuw in Cur ren t
West Australian ^Jk
nt
eddies
This view of the situation around Australia indicates the complexity of surface currents.
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Hotter than the surface of the Sun, 'plasma arcs' work like lightning to
destroy hazardous wastes safely
;':*=
Ralph Judd
complete waste
destruction
H l f - ^ l d
f t
If
jpj
CSIRO laboratory technician Mr Alan
Mundy prepares material for
pyrolysis by Plascon.
lchemists once sought
the secrets of the uni
verse through the trans
formation of the im
pure into the heavenly.
They looked on the
transmutation of base metal into gold
as a symbol of that transformation
and, incidentally, as a convenient way
of rewarding their patrons.
Since science has revealed the struc
ture of the universe (and the re
grettable impossibility of the trans
mutation of elements), alchemy has
become a symbol of magic rather than
reason.
Yet science can itself verge on the
magical. Imagine the satisfaction an al
chemist would feel if he were to be told
of an arc of pure energy, hotter than
the surface of the Sun, safely contained
and available at the flick of a switch to
blast the most horrific poisons ever de
vised into benign atoms.
Plascon, the plasma converter (also
known as a plasma arc furnace) de
veloped by a research group led by Dr
Subramania Ramakrishnan, of the
CSIRO Division of Manufacturing Tech
nology, may be based on the same
principles as lightning or the arc weld
er, but it has a magical potential to de
stroy hazardous toxic wastes by break
ing them down into their constituent
elements and, because its high tem
perature prevents the formation of
large molecules characteristic of haz
ardous chemicals, virtually eliminating
the risk of 'leakage' of hazardous sub
stances.
Best of all, it is so efficient in design
that the whole apparatus, including
scrubbers and cooling systems, takes
up less space than a shipping container
and can be built into production lines.
It could become an integral part of
industries that need to dispose of dan
gerous wastes and, at a unit cost of less
than $2 million, represents an econom
ical solution to a problem of increasing
environmental, social and political con-
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Plascon's 'heart' is surprisingly compact,
and its protective sheathing means little can
be seen of the arc itself, although it is hotter
than the surface of the Sun.
waste material
gas supply
An electric arc consists of plasma,
the 'fourth state' of matter an
ionised gas made up of mole
cules, atoms, ions and electrons that is
electrically neutral. If plasma is not to
discharge itself quickly (as plasma in
the form of lightning does), the supply
of free electrons must be maintained by
adding energy at a temperature of at
least 5000C.
This is best achieved by adding an
electric current, which means the plas
ma need not depend on oxygen; in
principle, any gas can be used, so that
plasma for waste destruction works by
pyrolysis (degradation by heat) rather
than incineration (degradation by ox
idation).
Toxic waste, in the form of gases,
liquids or even finely ground solids
mixed into a liquid, is fed under pres
sure into the core of an incandescent
arc between two copper electrodes,
using the same principle as the arc
welder but working at stupendous
temperatures 10 000 to 15 000, con
siderably hotter than the surface of the
Sun.
So much heat causes the molecules
of the material for disposal to dis
sociate into atoms that recombine as
safe, non-toxic compounds. In the case
of polychlorinated biphenyls (PCBs),
the hydrogen and chlorine recombine
to form hydrochloric acid that can be
used in industrial applications, while
99-9999999% of the toxic chemical is de
stroyed. Further, when combustion
takes place without oxygen, the con
stituents of the PCBs cannot recombine
to form dioxins.
Plascon had its beginnings in a collaborative research venture, be
tween the Division and Siddons
Ramset Ltd, to investigate industrial
applications for electric arcs. That ven
ture has already resulted in the com
mercial release of the Synchropulse
CDT pulsed-arc welding machine (an
international success that has led to
other commercially significant de-
Waste is fed under pressure into the core of
the incandescent arc, and converted into
simple, harmless molecules.
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velopments), a number of innovative
flux cored welding wires, new arc
welding processes and the plasma
torch for bonding metallic and ceramic
coatings.
Plasma arc furnaces for disposal of
hazardous wastes have been mooted
for more than a decade, but attempts to
design commercial-scale apparatus
have in the past been frustrated by the
fact that the waste stream must be
directed accurately at the core of the
arc if complex toxic molecules are to be
destroyed completely. The stream of
cold waste also tends to cool the arc,
displacing the zone of maximum
temperature away from the core and
resulting in incomplete pyrolysis.
Dr Ramakrishnan's group has over
come those problems with a patented
electricity and for the gas used to carry
the waste into the arc.
Although the commercial-scale Plas
con unit uses 200 kW of power, smaller
units using as little as 20 kW
could be constructed for industries that
produce less waste. The maximum
practicable limit is unknown, but ac
cording to Dr Ramakrishnan it would
be more efficient and economical to
link a number of 200-kW furnaces in
parallel rather than construct a single,
much larger, unit.
He also stresses that Plascon is not
intended as an alternative to conven
tional high-temperature incinerators
(which operate at a fraction of plasma's
temperature). Instead, it represents an
invaluable addition to them.
Conventional high-temperature in-
system that feeds waste directly into
the arc and sets up a thermal process in
which heat is generated within the
waste much like a domestic micro
wave oven.
The swirling gas flow stabilises the
arc column to ensure even heat dis
tribution, and an external magnetic
field interacts with the ionised gases to
maintain the arc in the correct shape,
maximising its effectiveness.
Dr Ramakrishnan and his research
group initially developed a 150-kW ex
perimental laboratory plasma torch,
testing it with safe chemicals such as al
cohol and isopropynol. They then built
a 50-kW protoype converter to dispose
of chlorophenols to simulate industrial
applications.
Plans are well advanced for a 200-
kW unit that will be able to dispose of
50 litres of waste per hour. They es
timate that, running 24 hours a day
(with a shutdown every 100 hours to
replace the electrodes), the 200-kW unit
will be able to dispose of a dozen 100-
litre drums of toxic waste every 24
hours for no more than a dollar a litre
and that most of that cost will be for
cinerators can dispose of large volumes
of waste, including contaminated soils,
organic compounds, pesticides, solids,
sludges even the containers used to
store toxic wastes but the fact that
their operating temperatures are too
low to prevent the recombination of
large molecules limits their use for dis
posing of toxic or hazardous wastes
(most of which are gases, liquids or sol
ids that can be ground and mixed with
liquids for treatment by Plascon).
Rotary-kiln incinerators, for ex
ample, operate at temperatures of 650
to 1200C, with a 'residence time' the
time taken to destroy waste within the
incinerator up to several hours.
Fluidised-bed incinerators work more
quickly, but at similar temperatures
(750-1000); two-stage infrared in
cinerators, designed primarily for
PCBs, dioxins and contaminated soils,
have a total residence time of 10 to 180
minutes and operate at 1250C.
The major disadvantages of all con
ventional incinerators are the relatively
low temperatures at which they work,
allowing the possibility of producing
dioxins or other toxic chemicals even
after incineration, and long residence
times. The 'high-temperature' incinera
tor under investigation for Australia,
for example, operates at 1200C and
needs about 20 minutes' residence
which also means the incinerator takes
20 minutes to come to a complete stop
after it has been shut down.
In contrast, Plascon has a residence
time measured in milliseconds... and if
it has to be shut down, it will take only
milliseconds more to destroy the ma
terial (less than 1 cubic centimetre) al
ready in the system.
One of the most compelling ad
antages of Plascon, for in
dustry and the environment
alike, is its small size; a 200-kW unit,
including power supply, scrubber and
gas supply, is no larger than the aver
age office. It can be installed in-line and
on-site, as part of a factory's pro
duction line, and waste can be de
stroyed as it is produced.
Some conventional incinerators can
be constructed at a transportable size,
but they have such low capacity and
such high energy requirements that
mobile systems are only marginally
economic. It is easier to transport waste
to a central incinerator and store it be
fore disposal, but this involves high
costs and hazards during both trans
port and storage. Full-sized Plascon
units, on the other hand, could easily
be moved by rail, truck, ship or air to
hazardous-waste storage sites.
The commercial-scale unit under
development at the Div is ion of
Manufacturing Technology's Preston,
Melbourne, laboratories will be under
going on-line trials with a leading Aus
tralian chemical manufacturer within
12 months and will serve as a demons
tration model for the European, Scan
dinavian and United States firms that
have already approached Dr Rama
krishnan.
One company has expressed interest
in using Plascon to dispose of Ameri
can chemical weapons on Johnston
Atoll a task for which it is well suit
ed, not only because of its efficiency in
destroying hazardous substances but
also because of its ease of trans
portation. Dr Ramakrishnan, however,
says he would prefer 'to demonstrate
the technology working in Australian
industry and use that as a launching
pad for exports.
'It is an excellent opportunity for us
to prove to the world that we can win
the race to instal on-site waste-
elimination systems in our factories.'
Carson Creagh
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Photo: Thor Carter
You wouldn't normally expect a piece of fish that you are eating to be older
than your most aged acquaintance, but, if the fish is orange roughy, it could
well be. Most of the fish we eat, like the other animals we use for food, have
life spans considerably less than ours. Orange roughy, the quaintly named
fish that has only recently arrived in our shops and restaurants where it
is often called deep-sea perch is a striking exception.
Although the fish as a species had been known for some time from its occurrence in
small numbers in the Northern Hemisphere (with the scientific name Hoplostethus
atlanticus), sufficient quantities to make it a commercial proposition were discovered only
about 10 years ago by New Zealanders, and shortly thereafter near Tasmania.
Australia's fishing fleet started taking the new fish in 1985, with a catch of 400 tonnes.
But then fishermen found dense aggregations of roughy off Tasmania's north-western
coast, and elsewhere shortly afterwards, and catches rose to 4600 tonnes a year later.
They have been increasing ever since.
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Orange roughy eggs.
carried out a survey of the fish off St
Helens in July 1990 during an annual
spawning aggregation. The fishing
ground, centred around an underwater
'hill', had by this time been closed to
commercial fishing.
Fisheries biologists have developed
various techniques to estimate the bio
mass of fish stocks, and as nobody
knew which would be most suitable
for assessing orange roughy spawning
aggregations because nobody had ever
tried to estimate this species' stocks, the
CSIRO team adopted several different
approaches.
One involved counting the eggs
released. Using a plankton net
more than a metre in diameter,
lowered to a measured depth and then
hauled up vertically, the scientists were
able to measure the number of eggs in
a known volume of water. This was
also useful because for the first time it
allowed larvae to be caught, and en
abled researchers to record stages in
the development of the egg. Of course,
relating this to fish numbers relies on
knowledge of the average egg pro
duction per fish, and of whether a sig
nificant proportion of eggs sink to the
bottom and escape measurement
factors that are not yet fully es
tablished.
The most effective tool was an acous
tic sounder, which sends out a sound
and detects anything that reflects it.
Obviously the sea-bed does, but so too
do schools of fish and, with luck and
skill, scientists can distinguish their dif
ferent echoes from the bottom signal.
(The particular device used sent out a
split beam, producing a stereo effect to
improve detection.)
The problem lies in knowing wheth
er the 'marks' that register on the echo-
sounder's screen are orange roughy or
other species. (Fish do have various
'reflectivities' but the differences are
rarely great enough to permit un
ambiguous identification of a species.)
To help solve this, the scientists low
ered a camera down through the acous
tic marks, taking photographs at
known depths. They saw most orange
roughy at the bottom, whereas many
echoes had been above it. They then
put down trawling nets to depths close
to the sea-bed where marks had re
gistered. But the nets caught relatively
few orange roughy.
Were all the marks other species
then? Some were, as the roughy are
hunters and feed off smaller fish. But
soon it became clear that, as the camera
on its mounting came within about 100
metres of a 'mark', whatever comprised
the mark started to disperse. To help
reveal the nature of the schooled fish,
the scientists placed the transducing
part of the echo-sounder near a mark
but at least 100 m away to avoid scat
tering the shy fish, and such closeness
enabled the acoustic system to resolve
individual fish as marks. Many of the
fish detected in this way were indeed
of orange roughy size, suggesting that
they did comprise many of the 'dis
appearing' marks.
Despite the 15 000 tonnes taken fromSt Helens Hill by commercial boats be
fore that fishery was closed, it's clear
that not everything around the area is
orange roughy. Hence, estimating the
biomass of the spawning aggregation
by echo-sounding is no easy task, and
the scientists are still analysing their
data, and preparing for further field
work this year using the new CSIRO re
search vessel 'Southern Surveyor'. So
far, the best estimate of the biomass in
that area is 57 000 tonnes although
the egg-sampling technique suggested
The fish fetch high prices.
a greater abundance but Dr Koslow
stresses that the true figure could lie
between half and double this weight.
Orange roughy is now our largest
'fish crop', in terms of both
monetary value ($50 million in
1989) and tonnes netted. But for such
an important fishery it has a woefully
small biological data-base. Dr Koslow,
in collaboration with Divisional col
league Dr Cathy Bulman, has recently
completed research on the diet of
roughy in south-eastern Australian wa
ters, in an attempt to make good some
of our ignorance of the basic biology of
this denizen of the deep.
Tasmanian Department of Sea Fisheries
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What's where in the deep blue sea
top few tens of metres
flathead
40-100 m
deep sea trevalla
100-600 m
500-700 m
500-800 m (occasionally near surface)
orange roughy 1000-1200 m
The ocean depths 1 km or more down are home to orange roughy.
stocks of roughy can only occur where
prey is not limited. It also explains
their slow growth rate. If they live in a
zone that is relatively poor in food
compared with the top 200 m, yet are
also active, then they have little energy
left over for rapid growth. That is why
it takes them 20 years to reach a length
of just 30 cm.
Clear ly , such s low-growing fish
differ greatly from other species
caught for human food con
sumption. Knowledge of other fish
eries is inadequate when applied to
roughy. It's clear that the fish cannot
regenerate their stock as fast as other
commercially exploited species. Can
the roughy boom continue?
The opinion of the CSIRO scientists is
that it cannot. If we wish to have this
exceptionally valuable fish available to
earn export dollars years from now,
then we must reduce the quantity that
we are currently netting. Dr Smith be
lieves that, for the east coast Tasmanian
stock, the 'total allowable catch' must
be reduced from its current 12 000
tonnes (at which it was set without ac
curate knowledge of stock sizes) to no
more than 2700 tonnes. Even if this fig
ure is wrong by a factor of two (which
it could be in either direction), clearly
we can't continue taking the fish at the
level that we have for the last few
years, which is bad news for the 54
roughy-fishing boats operating in the
area.
Of course, orange roughy exists else
where in our territorial waters, in
cluding southern Tasmanian waters
and the Great Australian Bight. Suffice
it to say that only further research and
its careful application will enable us to
know how much roughy from other
sites constitutes a sustainable catch. We
should then be able to exploit this new
high-quality resource for a long time to
come.
Roger Beckmann
More about the topic
Age determination of orange roughy,
Hoplostethus atlanticus (Pisces, Tra-
chichthyidae) using 210Pb/226Ra dis-
equilibria. G.E. Fenton, S.A. Short
and D.A. Ritz. Marine Biology, 1991,
108 (in press).
St Helens roughy site 1990 season. J.
Lyle. Australian Fisheries, 1990, 49
(10), 27-8.
Biomass survey of orange roughy at St
Helens. A. Smith and A. Koslow.
Australian Fisheries, 1990, 49 (10), 29-
31.
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High-tech measurements and ancient
tree rings and ice cores are
helping clarify climate-change
predictions
TRACKING CLIMATE
CHANGE AIR UNDER
THE MICROSCOPE
P o l i t i c i a n s a n d t r e a s u r e r s
aren't the only people wor
ried about balancing bud
gets: scientists studying the
greenhouse effect are put
ting increasing effort into
investigating the pattern of with
drawals from and deposits to the
global atmosphere trace-gas budget.
Without a better understanding of the
cycles involved, predicting future cli
mate change will remain an uncertain
exercise.
Researchers are striving to learn
more about how our atmosphere is
changing by upgrading conventional
approaches as in GASLAB, described
below and are also looking at less
conventional avenues such as tree
rings studies, which not only have
much to tell us about the past but also
provide hints of how the past affects
the present and the future.
Most trees lay down annual growth
rings, and for some species and in
some regions there's a clear relation
ship between climate and the width of
rings. Interest in tree-ring studies, as an
indicator of climate change, focuses on
trees whose rings are reliable indi
cators of annual growth: eucalypts in
arid Australia, for example, aren't suit
able because they produce growth
rings in response to rainfall more thanto seasonal changes in temperature.
The most suitable species for tree-
ring dating (dendrochronological)
studies are forest trees from temperate
and boreal (cold) regions, where low
winter temperatures ensure minimum
growth followed by strong summer
growth... and thus well-defined growth
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A remote mountain lake in western Tasmania, site of recent tree-ring climate studies
on sub-alpine Huon pine.
rings. Temperate and boreal trees also
exhibit marked variation, or 'sensiti
vity', in ring widths from year to year,
so it is easier to recognise distinctive
ring width patterns and common
'signatures' that, presumably, represent
a common response to climate change
(or dendroclimatology).
Measurement of ring widths among
a large number of trees in one area pro
vides a 'site chronology', a record of
ring behaviour that smooths out the
skewing effect of shading, nutrient
depletion or insect attack on individual
trees. However, the regional effects of
large-scale insect infestation, pollution,
changes in land-use or even variations
in flowering and fruiting cycles are
harder to eliminate from calculations,
so researchers look for the right kinds
of trees (long-lived species with well-
defined annual-growth ring patterns)
in the right kinds of areas (where trees
experience some environmental stress)
to measure the impact of climate on
tree growth.
The trees of Tasmania's cool rain
forests may provide the best
opportunity yet to study past
climate change, since several species
suitable for ring-width dating grow
side by side there; Huon pine
(Lagarostrobus franklinii), King Billy
pine (Athrotaxis selaginoides), celery-top
pine (Phyllocladus aspleniifolius), pencil
pine (Athrotaxis cupressoides), a hybrid
King Billy-pencil pine (Athrotaxis laxi-
folia) and Dyselma archeri.
Not only do these species show dif
ferences in their responses to climate
change, allowing scientists to separate
physiological effects from climatic
ones, but they are also found in a
variety of environments, from low-
altitude high-rainfall river flats to
exposed sub-alpine plateaux. And, even
better, at least four of them live for
1000 years or more. Such long chrono
logies are very important: researchers
can trace the effects of age more easily
in long-lived species, follow slow
changes in the environment and assess
the impact of human influence during
the past 100-200 years against a much
longer period of equilibrium.
Ice cores also provide records of past
climate change, but tree rings have the
advantage of being easier to collect and
can provide more accurately dated
information. Snow may take decades to
compress into ice, so the air (which sci
entists use to study changes in isotopes
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over long periods) that is trapped by
this process may be many years
younger than the ice surrounding it,
while the cellulose in each tree ring
reflects the composition of the atmo
sphere during the year in which it was
laid down.
And, because tree-ring material can
be dated to a particular year, clim-
atologists can study precisely periodic
phenomena such as the El Nino effect
over thousand-year time scales and
can compare tree-ring evidence for
even longer-period changes, such as
changes associated with ocean circula
tions, with data from other sources.
The study of Tasmanian tree rings,
as well as satisfying scientific interest
in ancient climates, also has much to
tell us about more immediate concerns,
such as the greenhouse effect.
Curiously, one of the most important
tools for examining recent changes in
the atmosphere is also used to look at
the distant past radiocarbon dating,
which measures the gradual decay of
the carbon-14 (14C) isotope.
An 8000-year-long continuous se
quence of tree rings and partially fossil
ised ('sub-fossil') logs in the Northern
Hemisphere has been used to calibrate
the radiocarbon 'calendar' that is
extrapolated to date organic material
formed over the past 40 000 years or so.
But the Southern Hemisphere has a
quite different history of climate and
carbon exchange between organic
material and the atmosphere, so the
discovery of 1000-year-old living
Tasmanian pines and of sub-fossil logs
up to 13 000 years old
offers an exciting
opportunity to verify
t h e N o r t h e r n
Hemisphere calendarand to extend it
beyond 8000 years to
the most recent ice
age, some 12 000
years ago a period
during which the
planet underwent rapid changes on a
scale similar to those threatening us
today.
T
asmanian tree-ring research has
involved CSIRO scientists on sev
eral occasions during the past
decade. Early Tasmanian exploratory
work was carried out by Dr John
Ogden of the Australian National
University and by Dr Don Adamson of
Macquarie University, with extensive
Southern Hemisphere tree-ring sam
pling by the late Dr Val LaMarche of
the University of Arizona Tree Ring
Research Laboratory in the 1970s.
Climatologist Dr Barrie Pittock of the
Division of Atmospheric Research
worked with Dr LaMarche in Tucson,
Arizona, to construct a chronology of
summer temperatures in Tasmania
since 1780, having discovered that
growth rings in several Tasmanian spe
cies of pine show a response to changes
in summer temperatures.
In 1979, Division of Atmospheric
Research scientist Dr Roger Francey
obtained a grant from the National
Energy Research Development and
Demonstration Council (NERDDC) to
investigate whether the isotopic com
position of cellulose in Tasmanian tree
rings could be used to chart changes in
atmospheric carbon dioxide (CO2)
levels as a result of fossil fuel combus
tion. Since CO2 from the burning of
fossil fuels is depleted in 13C, and since
trees obtain all their CO2 from the
atmosphere, the tree rings should show
this change.
Dr Francey and his colleagues (in
cluding Mr Trevor Bird of the CSIRO
Division of Forestry, Dr Mike Barbetti
of the University of Sydney, Dr Gerald
Nanson of the Univers i ty of
Wollongong, Dr Roger Gifford of the
CSIRO Division of Plant Industry and
Dr Graham Farquhar from the
Australian National University) con
ducted field work at Stanley River in
north-western Tasmania each summer
from 1979 to 1982.
Dr Francey found that the stable iso
topes trapped in tree rings did not just
record the composition of atmospheric
C02, they also indicated that trees had
adjusted to increased levels of this gas
in the atmosphere. In fact, his results
suggested that trees increased their
assimilation of C02 by 10% between
1870 and 1970. At the same time, Dr
Barbetti began the huge task of con
structing a fossil tree-ring chronology
back to the most recent ice age.
In 1989 Mr Mike Peterson of the
Tasmanian Forestry Commission dis
covered stands of sub-alpine Huon
pine (this species was previously
thought to be restricted to river plains
and margins). These high-altitude trees
demonstrated a much more marked
sensitivity to temperature pre
sumably due to the harshness of their
mountain-top environment than the
Stanley River material.
Prompted by Trevor Bird, Dr Ed
Cook of the Lamont-Doherty Labora
tory for Climatic Research, New York,
spent 2 weeks in 1990 conducting den-
droclimatological studies of Tasmanian
Air sample n
Monthly samples of air
collected around the
world come to GASLAB
for analysis.
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In 10 years
concentration (parts per trillion)
400-j
_
, . - "
-
,--'*'CFC-12
300-
200-
^ ^ - ^ ^ - ^ C F C - 1 1
100-
year
"
9 7 8 8 0 8 2 8 4 8 6 8 8
Concititrations of the chlorofluorocarbons
CFC-11 and CFC-12 rose by about 5% per
year in the 1980s. Measurements are from
Tasmania's Cape Grim 'baseline'
monitoring station.
tree-ring samples: Dr Cook returned to
Tasmania last summer and, assisted by
Mr Bird, Mike Peterson, Mike Barbetti
and Roger Francey (with logistical sup
port from the Tasmanian Forestry
Commission, CSIRO, the Hydro-Electric
Commission and Tasminco), collected
living tree cores and sub-fossil wood.
Among the striking results of his pre
liminary study of sub-alpine material is
that ring widths are larger today than
at any time in the past 1000 years, most
likely as a result of the greenhouse
effect. This finding is consistent with
Dr Francey's earlier observations.
Tasmania's pines are providing an
opportunity to tackle two of the most
vexing questions in the whole mystery
of the global carbon balance the
response of vegetation to changing
atmospheric composition over long
periods and the stability of ocean air-
sea exchange over centuries.
Despite its association with such
volatile phenomena as fire and
rust, oxygen is a remarkably
stable element so stable, in fact, that
the oxygen isotopes trapped by grow
ing Tasmanian pines 1000 years ago
represent a 'time capsule' replete with
information about the climate of that
era. Scientists studying global climate
change can compare this information
with similar time capsules of oxygen
from the ice of Greenland, Scandinavia,
North America and Antarctica, and
with samples of air from these and
other locations. They need such a
broad range of collection sites because
land masses and oceans and hence
biomass are so unevenly distributed.
The bulk of humanity lives in the
Northern Hemisphere, which is where
most greenhouse gases are emitted; but
the great oceans of the Southern
Hemisphere also drive climate change.
Researchers have therefore set up a
world-wide sampling network to trace
the paths of atmospheric gases through
time and space, in an effort to learn
more about the forces that shape the
world's climate.
For measuring greenhouse and
ozone-depleting gases, GASLAB (Global
Atmospheric Sampling LABoratory) is
the newest 'star' on the world stage. It
was officially opened by CSIRO Chief
Executive Dr John Stocker late last year
at the Div is ion of Atmospher ic
Research's Aspendale headquarters,
Melbourne. This major laboratory facil
ity is devoted to the most precise and
efficient measurement of atmospheric
gases whose names have become
household terms as concern for the
health of Earth and its atmosphere has
grown.
Its leadership in the measurement of
greenhouse-effect and stratospheric
ozone-depleting gases stems from the
combination of the state-of-the-art spe
cially modified instruments for all of
the major gas 'species' involved that
have been installed.
The Finnigan-MAT252 stable iso
tope ratio mass spectrometer was
released in Germany last year, and
GASLAB houses only the second such
instrument manufactured. Its specifica
tions exceed those of any previous,
similar instrument: GASLAB's MAT252
has an attachment especially modified
by Dr Francey that enables the auto
matic extraction and analysis of CO2 in
air, making it the most powerful faci
lity for atmospheric CO2 isotope stud
ies in the world. It will be further
enhanced this year, in association with
scientists in New Zealand, to permit
precise measurement of the stable iso
topes of methane (CH4) and carbon
monoxide (CO) in air.
A Carle S-Series gas chroma-
tograph (GC) is optimised for the high-
precision determination of atmospheric
methane concentrations; a second
(borrowed) Carle GC is currently
optimised for the analysis of CO2 in
very small samples, such as those
obtained from ice cores.
A trace-analytical GC analyses
carbon monoxide and hydrogen (H2)
concentrations in air. While neither
species plays a direct role in the green
house effect or in stratospheric ozone
depletion, CO is an important pre
cursor for CO2 in tropical regions; and
both CO and H2 are intimately
involved in the chemistry of the atmo
sphere and help determine the destruc
tion rates of other, important gases
such as CH4.
A Shimadzu GC measures nitrous
oxide (N2O), which is responsible for
about 3% of greenhouse warming; this
instrument was specially modified by
an American colleague, Dr Jim Elkins,
to optimise its efficiency and precision
for c lean air measurements. A
Shimadzu dual-column GC (also mod
ified by Dr Elkins) measures the
chlorofluorocarbons CFC-11, CFC-12,
CFC-113 and other halocarbons, chlo
roform, methyl chloroform and carbon
tetrachloride. These are greenhouse
gases, but they also include the main
culprits in the destruction of strato
spheric ozone.
A further GASLAB feature involves
the development of automated, multi-
sample carousels. Data from all
Antarctic ice-core measurements show how concentrations of the two
main contributors to greenhouse warming have shot up this century.
Methane levels have risen by more than 100% since the increase
began, and carbon dioxide levels by about 25%.
From the ice record
carbon dioxide
(parts per million by volume)
340
320-
300-
280
260
methane
(parts per billion by volume)
'1600
1600 1700 1800
1900 year
600
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instruments are stored in a centralised
computer, which also controls mea
surement sequences, makes decisions
on data quality and assists with pro
cessing and analysis.
The Div is ion has appointed Dr
aul Steele to play a central role
in the upgrading of GASLAB's
instruments and the use of its facilities
to unravel many of the trace-gas uncer
tainties that hamper accurate forecasts
of future atmospheric conditions.
Following groundwork by Dr Paul
Fraser of the Division of Atmospheric
Research, Australian-born Dr Steele
established, developed and operated
the United States National Oceanic
and Atmospheric Administration CH4-
monitoring network.
How does GASLAB use this formid
able array of instruments? Division of
Dr Colin Allison with GASLAB's new
high-precision mass spectrometer, used to
study isotopes of greenhouse gases.
Atmospheric Research scientists have
two basic strategies to put the labor
atory's facilities to the best possible
use.
The first involves collecting a series
of precise and comprehensive 'snap
shots' of the world's atmosphere, with
the aim of understanding in detail the
sources, sinks and exchange mechan-
g isms of its principal gases. In particu-
s lar, the accurate definition of regular
I daily, seasonal and 4- to 5-year (El
Nino) variations will help determine
net exchanges of gases forced, for
example, by temperature and/or
biology, or by ocean mixing. In the
future they will extend this sort of
'biogeochemical' modelling approach
to decades as records accumulate.
The second measurement strategy
involves (usually less-precise) infor
mation that spans much longer periods
from decades to millennia by
examination of 'archived' air or clues in
preserved material such as ice cores,
tree rings and so on. Identifying the
impact of human activity and pre
dicting future levels of key gases are
easier if measurements cover hundreds
of years or more, making the enhanced
sensitivity of GASLAB's instruments
'Defrosting' the climate of the past from Antarctic ice
Polar ice sheets provide a natural archive of past atmospheric
records; they sample the global 'background' atmosphere
unperturbed by cities or forests. A range of information is
recorded together in the same medium ancient air in the bub
bles, temperature-related isotopes in the ice and trace
substances that relate to atmospheric circulation, volcanic erup
tions, nuclear weapons 'events' and solar activity and, of
course, ice cores can be dated from such information. Natural
ice is generally a good storage material for gas species, in
some cases even better than man-made containers.
Law Dome, 100 km from Australia's Casey Station, is an
ideal site for collecting ice cores. Its simple flow pattern and
relatively high annual snowfall allow ice layers to build up undis
turbed and unmelted for most of its 1200-m thickness. Ice cores
with excellent age resolution can be drilled, from recent times
(containing air from the 1970s, which can be compared with
measurements from baseline stations in other locations) back to
pre-industrial times and even to the last ice age, about 12 000
years ago.
To obtain core samples from depths of less than 500 metres,
AAD glaciologists use thermal drills. An electrically heated metal
head melts its way through the ice at about 2 m per hour, taking
cores 100-200 mm in diameter in sections about 2 m long.
Below 500 m the borehole closes during drilling if not filled
with a fluid, because of the overburden pressure of the ice.
Glaciologists use mechanical drills consisting of a motor-driven
rotary cutting head at the end of the drill, itself suspended on a
cable some kilometres long (monitoring the borehole's distortion
itself provides information on the flow dynamics of the Antarctic
ice sheet, which in some locations is more than 4 km thick). The
glaciologists conduct initial core analysis and sampling at the
drill site, then package and ship the remainder of the cores to
Australia in refrigerated containers.
Back in Melbourne, aad glaciologists determine the ice chro
nology by counting annual layers: these are seldom visible, but
are revealed by analysis of species that vary seasonally, such
as the isotopic concentration of 180 (which is temperature-
dependent) or hydrogen peroxide (produced in the atmosphere
by sunlight). They then check this kind of dating by identifying
signals in trace substances that are attributed to specific events
for example, the sulfuric acid peak from the eruption of
Tambora, Indonesia, in 1815 A.D.
The air enclosed in bubbles, however, is younger than the
surrounding ice. Snow only becomes dense enough to seal air
into bubbles at depths of 70 m or so: but Law Dome accu
mulates snow quickly enough in some places, the equivalent
of 1 -2 m of water each year to enclose air that can be dated
to within several years, an obvious advantage for studies of the
atmosphere over the past century or two.
At the Division of Atmospheric Research, researchers extract
air from the ice at icelab, where they place carefully prepared
samples (cooled to -80 to reduce the water vapour pressure
and to make the ice more brittle) in a crushing flask. They evac
uate the flask and crush the ice, which contains about 120 mL
of air per kilogram, then vacuum-dry the liberated air and con
dense it in traps at -269 before taking the traps to GASLAB and
measuring the gases mentioned above.
The results show that significant changes have occurred in
many trace gases. Prior to 1800 A.D., CO2 concentrations
appear to have fluctuated around an average of about 285
parts per million (p.p.m.), but have since increased to 345
p.p.m. a rise closely associated with the CO2 released from
fossil-fuel consumption. Methane concentrations began to rise
about 50 years earlier than CO2, possibly due to agriculture,
and have since doubled. Nitrous oxide has increased by about
8%, mostly during this century.
Australian Antarctic Division
A glaciologist retrieves an
ice core from a depth of
300 m in Law Dome,
Antarctica. Air extracted
from the ice at ICELAB is
measured in GASLAB to
study past changes in the
composition of the
atmosphere.
22 Ecos 68, Winter 1991
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even more relevant: the MAT252
system, for example, requires air sam
ples less than 1 /500th as large as used
by the Division's previous instruments.
E i the r way , GASLAB has pa r
icularly good access to samples
for both kinds of measurement. In
1984, with funding from NERDDC,
Division scientists Roger Francey, Paul
Fraser and Dr Graeme Pearman set up
a pilot global network of six stations
focusing primarily on the isotopes of
C02, but also providing GC analyses of
C02, CH4, CO and, on occasions, CFCs.
The program's results were so valuable
that it was continued and expanded to
the present world-wide network (see
the map on page 20).
Monthly samples of clean air in 5-L
glass flasks come to Aspendale from
the Arctic (Alert, Canada, and Point
Barrow on Alaska's northern coast),
North America (Fraserdale, Canada;
Cheeka Peak, Washington; and Niwot
Ridge, Colorado); Asia (the province of
Gujerat, in north-western India); the
Pacific (Mauna Loa, at 4169 m Hawaii's
second-highest peak; and Samoa);
Australia (Darwin-Jabiru; the Great
Barrier Reef; Cape Grim, Tas.; and
aircraft sample-collection over Bass
Strait and the Great Australian Bight
by commercial Australian Airlines
flights and by CSIRO aircraft); New
Zealand (aircraft sample-collection by
that country's Meteorological Service);
and Antarctica.
As well, the CSIRO research vessel
Franklin and Australian Antarctic
Division (AAD) re-supply ships collect
samples at sea; AAD also supports reg-
Dr Roger Francey with cylinders of air
collected at Cape Grim, Tasmania, since
1978, which have been 'archived' for future
analysis.
ular sampling at Macquarie Island and
at Mawson Station. Recently, German
scientists have provided Northern
Hemisphere stratospheric samples from
high-altitude balloon flights launched
from Sweden.
The 'anchor' of the sample network is
the Cape Grim Baseline Air Pollution
Station in north-western Tasmania.
Operated by the Bureau of Meteoro
logy in co-operation with the Division
of Atmospheric Research, Cape Grim is
closely integrated with GASLAB.
For examining change over longer
eriods, GASLAB is focusing on
archived samples held in stainless
steel cylinders and on Antarctic ice
cores with unparalleled time re
solution. With considerable foresight,
almost 20 years ago Paul Fraser ini
tiated a program to store Cape Grim air
'for a rainy day'. In anticipation of
changing atmospheric composition and
improved instrumentation (now pro
v ided by GASLAB) , sys temat ic
Trevor Bird (left) and Dr Ed Cook remove core samples from fire-killed Huon pines.
collections of air one to four times a
year began at Cape Grim in 1978,
under conditions of strong south
westerly Southern Ocean winds.
Air is collected in oxygen tanks
made of stainless steel (from World
War II aircraft) and in specially pre
pared aluminium gas cylinders. These
are all but submerged in a container of
liquid nitrogen, which lowers the inter
nal temperature of the flasks to about
-180 and creates a partial vacuum.
When the top of the flask is opened, air
rushes in (with the help of a small
pump) and liquefies. On thawing, the
cylinder pressure reaches a level of
about 30 atmospheres.
As well as collecting atmospheric gas
samples at Mawson and the South
Pole, AAD also provides Antarctic ice
cores for GASLAB analysis. Air is
removed from bubbles within the cores
by ICELAB (Ice Core Extraction
LABoratory), an annexe to GASLAB.
As part of the Division's ICELAB
initiative, Mr David Etheridge was
recruited from AAD to design and
implement improved methods for air
extraction from ice cores and to play a
central role in collaborative ice core
studies.
Ice cores from polar ice sheets and
glaciers provide layers of atmospheric
and climatic information up to thou
sands of years old... layers that in
many ways resemble the growth rings
of trees. Field teams from AAD collect
cores from Law Dome, Antarctica, and
transport them to cold storage in
Melbourne, where annual layers are
dated and past temperatures are cal
culated from the relative numbers of
lsO isotopes in each sample (see the
box on page 22).
For measurement of trace gases, ice
core samples are crushed under
vacuum and the air released from the
bubbles is collected in traps immersed
in liquid helium at -260. These traps
are transported to GASLAB, where ana
lysts check for a range of gas species, in
particular for C02, CH4, N20 and halo-
carbons by gas chromatography, and
for CO2 and CH4 carbon isotopes by
mass spectrometry. Graeme Pearman is
developing a new instrument to meas
ure the very small decrease in oxygen
expected to accompany fossil-fuel
combustion, while Mr Ian Galbally is
designing an O3 detector to look for
possible changes in tropospheric chem
istry over the industrial period.
The GASLAB-ICELAB complex, which
represents the integration and sub
stantial upgrading of several relatively
independent research efforts, was
Ecos 68, Winter 1991 23
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The gases gaslab measures
OXYGEN (02)
Photosynthesis and respiration, the key processes of life, keep oxygen the
second-most abundant gas in the atmosphere circulating. As human populations
have expanded, the combustion of fuels and the destruction of forests have not only
increased carbon dioxide levels, but may also have caused a very small but poten
tially measurable depletion of atmospheric oxygen.
Because 02 is essentially insoluble in the oceans (unlike C02), the effects of the
human impact on global 02 should be reflected directly in atmospheric measure
ments. A small-volume, high-precision oxygen analyser will measure historical
changes in atmospheric 02 using air trapped in Antarctic ice, while GASLAB's
MAT252 mass spectrometer traces changes in isotope ratios.
CARBON DIOXIDE (C02)
Levels of atmospheric C02 have risen by about 25% since 1800 due largely to the
burning of fossil fuels, deforestation, agriculture and cement production. C02 is the
main contributor to enhanced greenhouse warming. The GASLAB Carle gas chro-
matograph provides precise measurements of it from samples as small as 10 mL.
The scientists hope their research will add to our knowledge of the roles of oceans
and plants in absorbing excess C02.
NITROUS OXIDE (N20)
N20 contributes about 3% of the enhanced greenhouse warming and atmospheric
levels have risen since the industrial revolution by about 9%. Sources of atmo
spheric N20 include the oceans, soil disturbance, biomass burning, fertilisers and
fossil fuel combustion. Since N20 and C02 have the same molecular mass and are
not distinguished by the mass spectrometer, GASLAB uses N20 data to correct iso-
topic measurements of C02 in air samples. N20 levels are measured by the gas
chromatograph.
METHANE (CH4), CARBON MONOXIDE (CO) AND HYDROGEN (H2)
Levels of CH4, the second-largest contributor to the greenhouse effect, have risen
by some 125% since 1800, mainly as a result of fossil-fuel combustion, biomass
burning and emissions from livestock, rice fields and landfills. Changes jn CO and
H2 (as well as CH4) reflect atmospheric levels of hydroxyl radical (OH ), a major
'scavenger' of atmospheric pollutants. Motor vehicles are an important source of the
increase in CO levels, which, like CH4, are measured by gas chromatograph.
CHLOROFLUOROCARBONS
Chlorofluorocarbons (CFCs) have contributed an estimated 11% of the enhanced
greenhouse warming since their wide-scale use began in the 1950s, and are the
most
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