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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


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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.


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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


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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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