Chemical events in the atmosphere

Chemical events in the atmosphere

CHEMICAL EVENTS I N THE ATMOSPHERE

AND THEIR IMPACT ON THE ENVIRONMENT

PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA

STUDIES IN ENVIRONMENTAL SCIENCE 26

ATMOSPHERE AND THEIR

0 COPYRIGHT 1986 PONTIFICIA ACADEMIA SCIENTIARUM - CITTA DEL VATICANO

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Library of Congress Cataloging in Publication Data

Study Week on: Chemical Events in the Atmosphere and Their Impact on the Environment (1983: Pontifical Academy of Sciences)

Chemical events in the atmosphere ant their impact on the environment (Studies in environmental science; 26) (Pontificiae Academiae Scientiamm Bibliography : p

Includes index

1 Atmospheric chemistry - Environmental aspects - Congresses 2 Environ-

mental chemistry - Congresses I Marini-Bettblo, G B (Giovanni Battista) 11 Pon- tificia Accademia delle scienze 111 Title IV Series V Series: Pontificiae Academia- Scientiarum scripta varia; 56

Other uolumes in this series

Atmospheric Pollution 1978 edited by M.M Benarie

Air Pollution Reference Measurement Methods and Systems edited by

T Schneider, H.W de Koning and L.J Brasser

Biogeochemical Cycling of Mineral-Forming Elements edited by P A

Truciinger and D.J Swaine

Potential Industrial Carcinogens and Mutagens by L Fishbein

Industrial Waste Managements by S.E Jergensen

Trade and Environment: A Theoretical Enquiry by H Siebert, J Eichber- ger, R Gronych and R Pethig

Field Worker Exposure during Pesticide Application edited by W.F Tordoir and E.A.H van Heemstra-Lequin

Atmospheric Pollution 1980 edited by M.M Benarie

Energetics and Technology of Biological Elimination of Wastes edited by

G Milazzo

Bioengineering, Thermal Physiology and Comfort edited by K Cena and J.A Clark

Atmospheric Chemistry Fundamental Aspects by E Mkszaros

Water Supply and Health edited by H van Lelyveld and B.C.J Zoeteman Man under Vibration Suffering and Protection edited by G Bianchi, K.V Frolov and A Oledzki

Principles of Environmental Science and Technology by S.E Jergensen and I Johnsen

Disposal of Radioactive Wastes by Z Dlouhf

Mankind and Energy edited by A Blanchpierre

Quality of Groundwater edited by W van Duijvenbooden, P Glasbergen and H van Lelyveld

Education and Safe Handling in Pesticide Appkation edited by E.A.H van Heemstra-Lequin and W.F Tordoir

Physicochemical Methods for Water and Wastewater Treatment edited by

L Pawlowski

Atmospheric Pollution 1982 edited by M.M Benarie

Air Pollution by Nitrogen Oxides edited by T Schneider and L Grant Environmental Radioanalysis by H.A Das, A Faanhof and H.A van der Sloot

Chemistry for Protection of the Environment edited by L Pawlowski, A.J Verdier and W.J Lacy

Determination and Assessment of Pesticide Exposure edited by M Sie- wierski

The Biosnhere: Problems and Solutions edited bv T.N VeziroGh

Address :

" P 0 N T I F I C I A A c A D E M I A s C I E N T I A R V M "

CASINA Pi0 IV CITTA DEL VATICAN0

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G.B MARINI-BETT~LO: Chemical Events in the Atmosphere and

Their Impact on the Environment (Introductory Remarks)

perties of Small Atmosphere Molecules

V.M CANUTO, J.S LEVINE, C.L IMHOFF, I GOLDMAN, T.R

AUGUSTSSON and 0 HUBICKYJ: The Young Sun, the Early

Earth and the Photochemistry of Oxygen, Ozone and For-

maldehyde in the Early Atmosphere

X PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 56

ATMOSPHERE AND THE SECONDARY PROCESSES:

THE EFFECT OF GEOLOGICAL AND ANTHROPIC COMPONENTS W.L CHAMEIDES and D.D DAVIS: The Photochemistry of Tro-

pospheric Trace Species: the Central Role of Radicals and

G FIOCCO: Perturbations of the Atmosphere and of the Climate

System Induced by Volcanic Eruptions: Relevance of Some

K.Ya KONDRATYEV, V.A IVANOV, D.V POZDNYAKOV and M.A

PROKOFYEV: Natural and Anthropogenic Aerosols: a Com-

F.S ROWLAND, D.R BLAKE, S.C TYLER and Y MAKIDE: In-

creasing Concentrations of Perhalocarbons, Methylchloro-

form and Methane in the Atmosphere 305

J.G ANDERSON: Role and Fate of Ozone in the Atmosphere 341

111

THE EFFECTS ON THE ENVIRONMENT

OF CHEMICAL REACTIONS IN THE ATMOSPHERE

T.F MALONE: Toward a Better Understanding of Atmospheric

R REVELLE: Carbon Dioxide and Other Greenhouse Gases in

Ocean, Atmosphere, and Biosphere, and Future Climatic

X I PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 56

G.B MARINI-BETT~LO: Chemical Reactions in the Atmosphere

and Their Impact on Human Health and Animal Life 607

E SALATI and P.B VOSE: The Water Cycle in Tropical Forests,

With Special Reference to the Amazon 623 S.O WANDIGA: Effects of Chemical Events on Environment in

FINAL CONSIDERATIONS AND CONCLUSIONS

SUBJECT INDEX

AUTHOR INDEX

FOREWORD

Scripta Varia which contains the papers presented during the Study Week

are included in the volume These proceedings are of great interest;

person, or insignificant to those who flee the reality of our present world

general public, either because they are hidden by concealed interests or because they have such slow effects that even their additive results are difficult to perceive

occurring in the atmosphere, because they are not instantaneous, cannot easily be perceived; unless an event of great proportions occupies the

distant future destroy the quality of life, or life itself Should we be pessimistic? Yes, certainly, unless we can change the mentality of many

of the developmental processes of our society This can be done only

if scientists, technologists, sociologists and economists working together can change many of the priorities of our present times and, by recognition

of the facts, convince policy makers and the industrialists of the urgency

to take measures to prevent the every-day increasing menace of slow destruction of the wonders of our world, which if protected will conserve

XIV PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 56

the joy everyone experiences when admiring the blue sky, the smoke-free air, the clear water of a waterfall, the greenness of our mountains, prairies and forests

all participants, and which he has applied in editing this volume As always, Professor Marini-Betthlo brought perfection to his actiuity I t is my

CARLOS CHAGAS

President of the Pontifical Academy of Sciences

LIST OF PARTICIPANTS

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JAMES G ANDERSON, Harvard University, Center of Earth and Planetary Physics, Cambridge, USA

FRANK ARNOLD, Max-Planck-Institut fiir Physik, Heidelberg, Federal Republic of Germany

CYRILL BROSSET, Swedish Water and Air Pollution Research Institute, Goteborg, Sweden

VITTORIO CANUTO, NASA Institute for Space Studies, New York, USA

WILLIAM L CHAMEIDES , School of Geophysical Sciences, Georgia Institute of Technology, Atlanta, USA

PAUL CRUTZEN, Max-Planck-Institut f i r Chemie, Maim, Federal Republic of Germany

GIORGIO FIOCCO, Dipartimento di Fisica, Universith Roma, La Sa- pienza - Rome, Italy

F KENNETH HARE, Trinity College, Toronto, Canada

CARLETON J HOWARD, Environmental Research Laboratories, NOOA, Boulder, Colorado, USA

WILHELM KNABE, Landesanstalt fiir Okologie, Recklinghausen, Federal Republic of Germany

J LAG, Institutt for Jordbunnslaere med Statens Jordundersskelse,

AS- NLH, Norway

XVIII PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 56

ARNALDO LIBERTI, Dipartimento di Chimica, Universiti Roma La Sapienza - Rome, Italy

THOMAS F MALONE, Holcomb Research Institute, Indianapolis, USA G.B MARINI-BETTOLO, Pontifical Academician, Universiti di Roma

La Sapienza and Istituto di Chimica Universiti Cattolica del S Cuore, Rome, Italy

DAVID PHILLIPS, The Royal Institution, London, England

ALBERTE PULLMAN, Institut de Biologie Physico-Chimique, Paris, France

SILVIO RANZI, Honorary Pontifical Academician, Department of Biology, University of Milan, Italy

ROGER REVELLE, University of California, San Diego, La Jolla, USA F.S ROWLAND, University of California, Department of Chemistry, Irvine, USA

ENEAS SALATI, Centro de Energia Nuclear na Agricultura, Siio Paulo,

Patidpants in the Study Week

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PONTIFICAL AUbIENCE

On November 12, 1983, His Holiness John Paul I1 granted an

Audience in the “Sala Regia” of the Apostolic Palace in the Vatican to

45 Members of the Pontifical Academy of Sciences gathered in Plenary Session to discuss the subject “Science in the Service of Peace”, to 20 scientists participating in the Study Week organized by the Academy on

“Chemical Events in the Atmosphere and their Impact on the Environ- ment”, and to 15 scientists of a Working Group convened by the Academy

to discuss “ Specificity in Biological Interactions ”

His Holiness John Paul I1 addressed to the participants an important speech on the role of Science for Peace and in particular the role of scientific community extended to all nations, concluding:

Gentlemen, as men of thought and sciknce, as pilgrims of the truth,

as explorers in the different branches of science and knowledge, about man and the universe, who submit yourselves to the labour of observing, thinking, searching, so that man may be ever more man and may find

in nature the proper environment for his development: I ask you to work for justice, love and peace, and to believe that today more than ever the Catholic Church is your ally, this Church which loves true science and right thinking, this Church which prays for you and which

in my person, respecting your beliefs, invokes upon each one of you the blessing of God

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SCIENTIFIC PAPERS

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INTRODUCTION

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CHEMICAL EVENTS I N THE ATMOSPHERE

AND THEIR IMPACT ON THE ENVIRONMENT

INTRODUCTORY REMARKS

G B MARINI-BETTOLO

I am glad to greet here today all you distinguished scientists from all over the world who have accepted the invitation of the Pontifical Academy of Sciences for the Study Week on "Chemical Events in the Atmosphere and Their Impact on the Environment "

As the scientist responsible for the organization of the Study Week,

I should like to present some information about the philosophy, the methodology and the scope of the present meeting, that is, the guidelines followed by $all the previous Study Weeks

The main object of the Pontifical Academy of Sciences is to invite

to the Vatican distinguished scientists of different disciplines from all over the world to discuss problems which are of importance both for their scientific aspect and for their impact on society

The subjects that will be discussed this week have been in recent years nhe object of several conferences, round tables, and seminars at

various levels all over the world Many of you know each other well, having participated in specific and specialized discussions which have taken place even in the last months on some of the topics we will discuss here

I think that a particular aspect of our Study Week is the multidisci- plinary approach to the problem, in the presence of scholars of different disciplines : physicists, geologists, chemists, meteorologists, biologists, bo- tanis t s , emlogis ts

"he problem of the impact on the environment, or better, on the biosphere, of ohemical events occurring in the atmosphere is at present

4 PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 56

of considerable importance I hope that the discussions which will follow the presentations can develop new ideas and even indicate new Pnes of action

I n the last decade many experiments have been made in stratosphere

and (troposphere chemistry, as well as in the laboratory on models, on the

causes of acid depositions and on the role of fluorocarbons on the ozone layer and the impact of the COz increase in the atmosphere on the cli-

mate and on oceans The studies have given (important results tor our

knowledge and tor the advancement of science

Nevertheless, not all scientists fully agree on the interpretations of the above data since the phenomena are numerous and complex This

appears very clearly if one goes through the literature of the last years, and even of the last weeks, where many discrepant interpretations are found of the chemical events which occur in the atmosphere I believe that a discussion which could help to clear some of the controversial interpretations could be of interest

I wish to call your attention to the fact ,that the discussions, which will be published in a rather extensive form, constitute one of the most interesting aspects of these Study Weeks

The assessment and interpretation of the impact on the biosphere of chemicals produced in the atmosphere under different conditions may lead

to a better diagnosis of the present state of degradation of some environ- ments and thus make it possible to establish new strategies

The various steps of the discussion could be:

1 the present knowledge regarding chemical events in the atmo- sphere, both of common components and man-made substances or natural emissions;

2 a critical review of the interpretation of the results so far obtained;

3 the identification of the gaps which make it impossible ,to

complete our diagnosis;

4 the discussion regarding future strategies in order to reduce noxious effects on biosphere of the chemical events in the atmosphere The conclusions reached should be condensed in a document, together with a critical examination of our present knowledge in this iield

It is our hope that the Study Week may suggest some new ap- proaches to solve the problems involved in our discussions and that in any case it may lead to a better understanding of the chemical events

in the atmosphere for the progress of science and the benefit of humankind

I

STRUCTURE, COMPONENTS AND PRIMARY PROCESSES

IN THE ATMOSPHERE

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PHOTOCHEMICAL REACTIONS

I N THE ATMOSPHERE

D PHILLIPS

Davy Faraday Research Laboratory, The Royal Institution

21 Albemarle Street, London WIX 4BS

This review presents both a view of unresolved problems relating

to the photochemistry of atmospheric constituents of global importance and some more parochial assessments of problems particular to the U.K

To begin with the latter, while it is right that there should be concern over the quality of air, and the subsequent effects of polluted air on the environment, it should be remembered that the air quality in cities in the U.K is probably better now than at any time in the previous several hundred years Thus John Evelyn, in 1611, said:

“It is this horrid smoake which obscures our churches, and makes our palaces look old, which fouls our clothes and corrupts the waters ”

Matters really did not improve much until after the disaster of December 5th, December 8th 1952, when the combined effects of a temperature inversion, particulate matter and sulphur dioxide emissions, largely from domestic coal fires, resulted in the premature deaths of some 4000 people, mainly elderly and those suffering from respiratory problems This led directly to the Clean Air Act of 1953, which on a fairly rapid timescale led to the control of particulate matter emissions, and is a good example

of the speed with which Governments can act if suitably motivated As

a child in u r h n Tyneside, it never occurred to me that the colour of build- ings was anything other than jet-black Indeed, if you visit many urban buildings nowadays which had been repaired prior ,to 1952 and have sub- sequently been cleaned you will find pieces of stone which do not match the originals There was no need, since within twelve months, the colour

8 PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 56

would in any case be black No one could argue that the environment has been significantly improved by the control of particulate matter, the days

of the London “pea-souper” are now long gone, but it could be said that the success of this legislation may have led to complacency with regard

to the other, invisible emissions, most notably that of SOL

Again, this is not a new phenomenon In 1846 Michael Faraday

was asked by his club, the Athenaeum, to explain why new leather arm- chairs were disintegrating rapidly, and it did not take him long to diagnose that the cause was atmospheric SO2 from domestic coal fires denaturing the leather

The emission of tropospheric sulphur oxide, and that of NO, emission,

is now of great concern, known colloquially, but inaccurately as “acid rain” Acid deposition would be a better description of the phenomenon

The immediate consequences of emission of SO2 and NO, are of course simply stated, the production downwind, either locally, or more often nowadays far away, of sulphuric acid and nitric acid, which may

be deposited dry or in precipitation on the ground

An attempt is made here to identify some of the remaining problems

in understanding the chemistry, particularly the photochemistry, of lthese processes

Photochemistry associated with acid rain

There is clear evidence that the photochemical conversion of sulphur dioxide to acid is a minor but significant process The possible mechanisms for the photochemical oxidation have been dealt with by many authors, but the review by Cox provides a basis for discussion [ 11

The possible mechanisms are:

(i) Homogeneous direct photolysis of sulphur dioxide in the presence (ii) Homogeneous gas-phase oxidation by hydroxyl radicals, OH, (iii) Homogeneous gas-phase reactions involving ozone-olefin inter- (iv) Heterogeneous reactions on the surface of particulate matter (v) Homogeneous aqueous phase reactions in water droplets in the

of oxygen

HOz, and peroxy radicals, of photochemical origin

actions in urban atmospheres

atmosphere

CHEMICAL EVENTS IN THE ATMOSPHERE AND THEIR IMPACT ON THE ENVIRONMENT 9

The mechanisms of direct photolysis, reaction (1) - (3, oxidation by

OH, H02, RO, and R02, reactions ( 6 ) - ( l l ) , and ozone-olefin reactions,

(12) lead to the estimated rates of SO2 conversion shown in Table 1

HOS020 + NO2 + HOSOZONOZ ,(nitryl sulphuric acid) (11)

10 PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 56

TAB 1 [ 11 - Rates of Homogeneous SO2 Oxidalion

cm3 molecule - 1 s - 1 molecules (1111-3 oxidn rate

02

0.6

(0.03)

1.7 (0.03) 0.07

It is clear from this work that the homogeneous free radical reactions are probably the most significant, but the role of aqueous phase oxidation

by H202 and of heterogeneous oxidation are still in doubt, and require further investigation The formation of aerosols is also of some importance

I t has been suggested that in clouds, the rate of droplet formation may be proportional to the light intensity, which clearly deserves further attention The formation of particles in the atmosphere is also very poorly under-

stood, and requires much further work The sole paper [ 2 ] dealing with

this phenomenon in any quantitative way investigates the processes occur- ring, summarized in Scheme 1, upon the direct excitation of SO2 into the second singlet state at wavelengths > 190 nm, a process clearly not of importance in the troposphere

Before passing on to other aspects of atmospheric photochemistry,

we might just anticipate later discussion of the effects of acid deposition, and indeed the location of this From the parochial UK viewpoint the region most affected is southern Scandinavia, Tables 2 and 3 giving the total contributions by country to deposition in this region [ 3 I

Other later papers in this volume will comment upon the effects on soil and water in lakes and rivers, of this acid deposition, but it may be noted in passing that the Royal Society of London, the Norwegian Academy

of Science and Letters, and the Royal Swedish Academy of Sciences have recently agreed to initiate a further long term collaborative programme

of research into the effects of acidification of surface waters in Norway

region distribution distribution distribution total deposition

of wet of dry of total mg SO, m-2 a-1

deposition deposition deposition annual average per 100 kt

22.2 32.2 9.9 7.2 6.9 2.9 3.9 3.7 1.9 2.3 2.7 2.4 0.5 0.5 0.8 100.0

30.7 17.4 10.7 10.1 5.2 3.9 3.5 3.4 3.4 3.4 3.2 2.4 0.9 0.5 1.3 100.0

3 .O

1 .o

323

Annual average wet deposition 2022 mg SO, m-, a-1

Annual average dry deposition 893 mg SO, m-2 a-1

12 PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 56

TAB 3 [ 3 ] - Deposition by Regions for Each Year 1972-1974 (percentages

of grand total for each year)

20.9 5.5 11.3 8.5 3.1 3.4 2.9 3.1 3.2 2.9 3.9

1 .o

1 .o

0.1 1.2 72.0

7.2 12.7 2.5 1.8 2.1

1 .o

0.8

1 .o

0.5 0.8 0.8 0.5 0.1 0.1 0.2 32.1

22.6 11.3

5.1

6.9 3.5 3.2 2.0 2.1 2.3 2.6 1.7 3.3 0.0

0.3

1 .o

67.9

8.5 10.3 2.3 2.5 2.4 0.9 1.6 0.9 0.5 0.6 0.5 1.2 0.1 0.3 0.3 32.9

28.7 7.5 4.9

7 ‘9 2.7 2.4 1.8 1.4 2.9 2.4 1.1 1.1

1 .o

0.6 0.7 67.1

Europe presently emits - 33 M Tonneslyr

and Sweden and the implication for fisheries Specifically excluded, how- ever, from this programme will be the questions of how industrial dis- charges create acid deposition, and to what degree reductions in UK sulphur dioxide emissions would change the acidity of rainfall over affected areas

of Scandinavia The questions to be addressed are:

1 In the affected areas of Norway and Sweden, what are the factors,

in addition to pH, that in practice determine the fishery status of lakes?

2 What are the biological, chemical and hydrogeological charac- teristics of catchments which determine whether the composition of sur- face waters falls within a range acceptable to fish?

3 In Norway and Sweden, to what extent are these characteristics being adversely affected by the acid deposition itself?

4 What changes would be brought about in water chemistry and fishery status in Norway and Sweden by given levels of reduction of man- made sulphur deposition?

CHEMICAL EVENTS IN THE ATMOSPHERE AND THEIR IMPACT ON THE ENVIRONMENT 13

Photochemistry of course plays a crucial role in the whole of tropos- pheric atmospheric chemistry, not just in locally confined events such as those involving acid deposition discussed above, and in the well-documented

“photochemical smog” of Californian cities, which is now a local problem

of very widespread incidence throughout the world

The key intermediate chemical species in the troposphere is undoubted-

ly the hydroxyl radical OH, the major source being the photolysis of tropospheric ozone, and subsequent reaction of the product 0 (ID) with water (13), (14), in competition with collisional quenching to give 0 (’P)

(13, which subsequently reforms ozone (16)

The hydroxyl radical so produced the major oxidising species in the troposphere, and a complete picture of its chemistry holds the key to furthering progress in understanding tropospheric chemistry, The chemistry discussed in detail elsewhere, is of course very complex To take, for ex- ample, the cycle of reactions with carbon monoxide, which may be net producers or destroyers of tropospheric ozone depending upon the con- centration of oxides of nitrogen present In the presence of NO, the cycle

(16)-(20) occurs, without loss of OH or NO, whereas at low NO concentra- tions, the cycle (17), (18) and (21), again without loss of OH

14 PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 56

Since methane reacts with hydroxyl, the level of methane in the troposphere is of great interest There are some indications that the methane level is increasing, which could be due to an increased methane release rate, or a decrease in hydroxyl concentration Clearly it will be of great importance to establish which of these possibilities is occurring Despite progress in understanding tropospheric chemistry, there is

still a pressing need for improvements, with the following problems requiring at tention

and negatively correlated (after Figure 3, ref 4)

CHEMICAL EVENTS IN THE ATMOSPHERE AND THEIR IMPACT ON THE ENVIRONMENT 15

(i) understanding the sources and sinks of minor constituents, such

as CH4, CO, 0 3 , NO, NOz, N&, N20, H2, OH; H02 etc., and their detailed geographical location and intensities on a global scale On a very parochial level this will improve understading of local conditions such as photo- chemical smog, which can be considered merely to be an exaggerated or perturbed normal troposphere

(ii) in situ measurements of radical intermediates, particularly OH

on a global scale, a problem which has to date been barely tackled (iii) laboratory measurements of rate-constants, particularly those of organic reactions involving peroxy and exy-radicals

(iv) modelling of the chemistry, transport, dynamics, radiative trans- fer, etc., of the troposphere Here 3D models are desirable, but as yet too expensive in computer time

On the whole it is probably true to say that tropospheric chemistry

is rather less well understood than that of the stratosphere, although of course, since the input of material from the troposphere to the stratosphere must affect the chemistry of the latter, the uncertainties in tropospheric chemistry are reflected in that of the stratosphere

STRATOSPHERIC CHEMISTRY

I n this introductory paper there is no attempt to preempt the dis- cussions by later authors concerning these problems However, an attempt

is made here to pin-point some remaining problems

On the simplest possible level, the ozone in the stratosphere is main- tained by the Chapman mechanism, ( I J ) , (16), (22-24) plus the catalytic

cycles which in cryptic form are shown as (25)-(30)