Nuclear and Chemical Dating Techniques - ACS Publications

14

Downloaded by UNIV OF MASSACHUSETTS AMHERST on May 31, 2018 | https://pubs.acs.org Publication Date: January 29, 1982 | doi: 10.1021/bk-1982-0176.ch014

Tree Thermometers and Commodities: Historic Climate Indicators L. M. LIBBY University of California—Los Angeles, Environmental Science and Engineering, Los Angeles, CA 90024 L. J. PANDOLFI Global Geochemistry Corporation, Canoga Park, CA 91303 In four modern trees, we find that the carbon, hydrogen, and oxygen isotope ratios track the modern temperature records; namely we find that trees are recording thermometers. In a 200 year sequence of a Japanese cedar, we find that there are the same periodicities of variation of D/H and O/ O as have been found in O/ O in a Greenland ice well. We find the same periodicities in uranium and organic carbon concentrations versus depth in a sea core from the Santa Barbara Channel, and in carbon-14 variations in a sequence of Bristlecone pine from southern California. We find in a 2000 year sequence of Japanese cedar and in a 1000 year sequence of European oak that D/H and O/ O are related to each other by a slope of 8, just as they are in world-wide precipitation. In a 72 year sequence of Sequoia gigantea, measured year by year for its oxygen isotope ratios, we find the 10.5 year cycle of sunspot numbers, but we do not find the 21 year cycle of sunspot magnetism. This we believe indicates that the sun is affecting the earth's climate with non-magnetic particles, probably photons. All these phenomena, we believe, are related to periodic changes in sea surface temperature caused by periodic changes in the sun, as are the variations in commercial commodities, and consequent variations in prices and wages. 18

18

16

18

16

16

Furthermore we f i n d t h a t t h e catch o f blue crab i n t h e Chesapeake Bay shows a p e r i o d i c v a r i a t i o n o f 10.7 years i n agreement w i t h t h e s o l a r photocycle o f 10.5 y e a r s , but does not show a v a r i a t i o n p e r i o d i c w i t h the 21 year s o l a r magnetic c y c l e .

0097-6156/82/0176-0245$13.55/0 © 1982 American Chemical Society Currie; Nuclear and Chemical Dating Techniques ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

246

N U C L E A R AND

C H E M I C A L DATING T E C H N I Q U E S

We f u r t h e r f i n d t h a t the p r i c e of wheat and the l a b o r e r ' s wage vary i n agreement w i t h the temperature record i n Europe s i n c e 1250 A.D.


Principles The onset o f t e s t i n g o f hydrogen bombs i n the atmosphere l e d t o an understanding of isotope f r a c t i o n a t i o n i n the water vapor t h a t d i s t i l l s from the ocean surfaces throughout the world. This i n f o r m a t i o n d e r i v e d from the establishment of a g l o b a l network of 155 c o l l e c t i n g s t a t i o n s i n 65 c o u n t r i e s i n the p e r i o d beginning i n 1953 and c o n t i n u i n g t o the present by the Interna tional Atomic Energy Agency and the World Meteorological O r g a n i z a t i o n . Monthly meteorological data (amount of p r e c i p i t a t i o n and temperature) were r e p o r t e d , and monthly samples of p r e c i p i t a t i o n were measured f o r t r i t i u m , deuterium t o hydrogen r a t i o , and oxygen-18 t o oxygen-16 r a t i o [ l ] . The measured r a t i o s are expressed as: 1

delta D = (((D/H) - (D/H) s

delta

1 8

0 = (((

1 8

0/

1 6

0)

s

s t d

- (

)/(D/H)

1 8

0/

1 6

0)

s t d

s t d

) ) χ 10

))/(

1 8

3

0/

ppt 1 6

0)

s t d

) χ 10

3

ppt

where s u b s c r i p t s r e f e r s t o the sample, s u b s c r i p t s t d r e f e r s t o standard mean ocean water (SMOW), and ppt means p a r t s per thousand. The e r r o r of measurement of d e l t a D i s about ±2 ppt and of d e l t a 0 i s about 0.2 ppt. The p l o t of world d a t a , o f d e l t a D versus d e l t a 0 ( f i g u r e 1 ) , shows t h a t a l l the measurements f o r t e r r e s t r i a l surface waters l i e on a l i n e w i t h a slope of e i g h t c h a r a c t e r i z i n g Rayleigh d i s t i l l a t i o n of water vapor from the sea surface t o form atmospheric precipitation. T h i s p l o t w i t h i t s slope of e i g h t was o r i g i n a l l y demonstrated by Harmon C r a i g [2,3] and by W. Dansgaard [ 4 ] . The l i n e i s expressed by the r e l a t i o n 1 8

1 8

18 delta D = 8 delta

0 + c o n s t a n t ; constant - 0

where the slope of e i g h t can r e a d i l y be computed from the measured temperature c o e f f i c i e n t s f o r ((D/H).,. . V(D/H) ) and f o r ifti£ I Q I C 11qui α vapor Rayleigh d i s t i l l a t i o n i s a process i n which the condensate i s immediately removed from the vapor a f t e r formation (by f a l l o u t of r a i n and snow i n the meteorological case) and leads t o a higher 1

F i g u r e s i n b r a c k e t s i n d i c a t e the l i t e r a t u r e r e f e r e n c e s a t the end of t h i s paper.

Currie; Nuclear and Chemical Dating Techniques ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

14.

LIBBY

AND PANDOLFI

Historic Climate Indicators

247

f r a c t i o n a t i o n than processes which occur a t e q u i l i b r i u m , due t o k i n e t i c e f f e c t s which are not t h e o r e t i c a l l y understood. To each p o i n t on t h e l i n e o f f i g u r e 1 t h e r e corresponds a temperature of d i s t i l l a t i o n (see f i g u r e 2 ) . In f i g u r e 1, t h e p o i n t s a t very l a r g e i s o t o p e d e p l e t i o n s ( d e l t a D * -300 p p t and d e l t a 0 * -40 ppt) have been measured i n very c o l d i c e from t h e bottom o f t h e A n t a r c t i c i c e cap, l a i d down i n i c e ages. P o i n t s a t small d e p l e t i o n s ( d e l t a D * 0 ppt and d e l t a 0 ~ 0 ppt) have been measured i n t r o p i c a l p r e c i p i t a t i o n d i s t i l l e d from warm oceans. P o i n t s between have been measured i n middle l a t i t u d e s . The IAEA monthly measurements show seasonal v a r i a t i o n s i n t h a t t h e heavy isotopes a r e depleted i n p r e c i p i t a t i o n when water vapor d i s t i l l s o f f c o l d oceans i n t h e w i n t e r s and enriched i n p r e c i p i t a t i o n when water vapor d i s t i l l s o f f warm oceans i n t h e summers. See f i g u r e 3 f o r monthly isotope v a r i a t i o n s i n p r e c i p i t a t i o n , f o r example i n S t u t t g a r t . This e f f e c t was found i n the successive seasonal l a y e r s o f i c e o f both the Greenland i c e cap and the A n t a r c t i c i c e cap, show ing v a r i a t i o n s l i k e those i n p r e c i p i t a t i o n i n temperate r e g i o n s , but on the average more depleted i n the h e a v i e r i s o t o p e s . Moreover, i n t h e l a r g e s c a l e , i n the g r e a t depths o f the i c e cap c o n t a i n i n g i c e l a i d down 10,000 years ago and more i n the l a s t i c e age, the' i c e i s more depleted i n t h e heavy isotopes than can be found i n any modern day p r e c i p i t a t i o n . Thus i t becomes e v i d e n t t h a t i n t h e p o l a r i c e caps there i s s t o r e d the h i s t o r y o f the surface temperatures o f the f a r northern and f a r southern oceans, from which d i s t i l l e d , f o r the most p a r t , the h i s t o r i c p r e c i p i t a t i o n l a i d down i n the i c e caps. For temperate r e g i o n s , t h e h i s t o r y o f t h e surface tempera t u r e o f the oceans i s s t o r e d i n the g l a c i e r s o f those r e g i o n s , but g l a c i e r s have random advances and r e t r e a t s which s p o i l the o r d e r l y sequence o f the h i s t o r i c y e a r l y i c e l a y e r s . However, t h e h i s t o r y o f t h e surface temperatures o f the tem perate oceans should be s t o r e d i n t h e r i n g s o f t r e e s which grew i n t h e temperate regions o f t h e world and which s u b s i s t e d on p r e c i p i t a t i o n which d i s t i l l e d from those oceans. Each t r e e r i n g should c o n t a i n some kind o f average annual value o f the i s o t o p e r a t i o s i n t h e p r e c i p i t a t i o n o f t h e year corresponding t o t h e ring. 1 8


1 8

The wood i n each r i n g i s formed a c c o r d i n g t o the r e a c t i o n , + H2O -» wood + oxygen gas As f o r t h e carbon isotope r a t i o s i n t r e e r i n g s , these d e r i v e from and r e f l e c t carbon isotope r a t i o s i n atmospheric carbon d i o x i d e . There i s some evidence suggesting t h a t t h e r a t i o C / C i n atmospheric carbon d i o x i d e v a r i e s s e a s o n a l l y i n such a way t h a t t h e isotope r a t i o i s l a r g e i n t h e summer. For example, f i g u r e 4 shows monthly v a r i a t i o n s i n t h e s t a b l e carbon isotope r a t i o i n atmospheric carbon d i o x i d e a t Spitsbergen, on the P a c i f i c 1 3

12

American Chemical Society Library 1155 16th St. N. w.

Currie; Nuclear and Chemical Dating Techniques ACS Symposium Series; Washington, American Chemical Washington, DC, 1982. D. Society: C. 20030


248

N U C L E A R A N D C H E M I C A L DATING T E C H N I Q U E S

(1953- 1963) INTERNATIONAL ATOMIC ENERGY AGENCY, VIENNA, 1969 - ENVIRONMENTAL ISOTOPE DATA NO 1. WORLD SURVEY OF ISOTOPE CONCENTRATION IN PRECIPITATION. 1953 - 1963 TECHNICAL REPORT SERIES NO. 96

4*^

C. TAYLOR -10° C ^ .

-iso| (D/H - ( • 3 ° C . C . TAYLOR)

- -100I 18

D = 7.7950 + 4.14Î | 0.99132 CORRELATION COEFFICIENT 1.084 ERROR ON INTERCEPT I Ν = 110

'» t, Γ

-10

-15 18

-20

-25

-30

16

M 0 / 0 > IN PARTS PER THOUSAND

* NORD. GREENLAND 81.6° Ν LAT

* BETHEL, ALASKA 61° Ν LAT TEHERAN. IRAN 36° Ν LAT GENOA. ITALY 4 4 ° Ν LAT » NEW DELHI, INDIA 28.6° Ν LAT • KHARTOUM, SUDAN 15.6° Ν LAT SEYCHELLES 4.6° Ν LAT

GOOSE BAY. NEWFUNDLAND 5 3 ° Ν LAT GREENEDAL, GREENLAND 61° Ν LAT AZORES. PORTUGAL 37.8° Ν LAT VIENNA, AUSTRIA 4 8 ° Ν LAT » KARACHI. PAKISTAN 25° Ν LAT WIND HOEK. S. AFRICA 22.6° S LAT •ASCENSION. ISLAND 8 ° Ν LAT DAR ES SALAAM. TANZANIA 7° S LAT

• • •

ISFJORD. NORWAY 78° Ν LAT LIST A, NORWAY 58 Ν LAT VALENTIA. IRELAND 52° Ν LAT REKJAVIK . ICELAND 6 4 ° Ν LAT GIBRALTAR, UK 36° Ν LAT STUTTGART. W. GERMANY 4 9 ° Ν LAT • BAHRAIN. PERSIAN GULF 2 6 ° Ν LAT

• BOMBAY. INDIA 19° Ν LAT SALISBURY. RHODESIA 18° S LAT

• DEEP ICE WELL. BYRD STATION. ANTARCTICA. S. EPSTEIN. R.P. SHARP. A.S. GOW 1000 B.P. TO 75.000 B.P. (ESTIMATED) SCIENCE. 168. 1570-1572 (1970) TROPOSPHERIC VAPOR. 5 KM ALTITUDE. C.B. TAYLOR. INS-R-107 FEB 1972. INST NUCLEAR SCI. LOWER HUTT. NEW ZEALAND (PREPRINT) β

Proceedings of the National Academy of Sciences

Figure 1. Deuterium isotope ratio vs. oxygen isotope ratio for world-wide precipi tation (IAEA data), showing the slope of eight (31).


L I B B Y AND P A N D O L F I


249


14.

Figure 2. Deuterium isotope ratios in world-wide precipitation vs. monthly average air temperatures showing that for every point on the line in Figure 1, there is a corresponding average air temperature.


250

TECHNIQUES


N U C L E A R A N D C H E M I C A L DATING

Figure 3.

Monthly oxygen and deuterium isotope ratios plotted vs. temperature in Stuttgart precipitation.



251


L i B B Y AND PANDOLFI

Figure 4. Monthly variations in the stable carbon isotope ratio in atmospheric C0 at Spitsbergen, on the Pacific Coast of the United States, in Sweden, and at Bariloche, Argentina. 2


252

NUCLEAR AND

C H E M I C A L DATING T E C H N I Q U E S

Coast of the United S t a t e s , i n Sweden, and a t B a r i l o c h e , Argentina [6-10], but such v a r i a t i o n s are not p r i m a r i l y r e l a t e d t o ocean s u r f a c e temperatures. K e e l i n g i n t e r p r e t s these seasonal i s o t o p i c v a r i a t i o n s as caused by t r e e s p r e f e r e n t i a l l y removing C 0 from the atmosphere i n summer when they are growing but not i n w i n t e r when they are dormant. Wood i s composed approximately of c e l l u l o s e and l i g n i n . C e l l u l o s e i s a m u l t i p l e a l c o h o l of schematic formula (H-C-0-H) so 1 2

2


n

t h a t the r e a c t i o n f o r formation of c e l l u l o s e may be w r i t t e n , C0

2

+ H0 2

(H-C-0-H) + 0 n

2

L i g n i n c o n t a i n s interconnected aromatic and a l i p h a t i c r i n g s [11] (see f i g u r e 5) and a l i p h a t i c chains c o n t a i n i n g about 30 percent oxygen by weight i n the form of e t h e r , c a r b o n y l , and hydroxy! bonds. Wood i s approximately 25 percent l i g n i n [ 1 1 ] , i t s percentage v a r y i n g somewhat from s p r i n g wood t o summer wood, and i t i s p o s s i b l e t h a t i t s percentage may vary somewhat from r i n g t o r i n g , so t h a t i n p r i n c i p l e , i t s v a r i a t i o n might a f f e c t the temperature c o e f f i c i e n t of wood formation. Assuming the p r i n c i p l e o f thermodynamic e q u i l i b r i u m t o hold i n the formation of wood, a very slow process, we have estimated what e f f e c t as much as 10 percent v a r i a t i o n i n the percentage of l i g n i n may have on the temperature c o e f f i c i e n t f o r the formation of wood. We f i n d i t t o be about 1.5 percent. We, Libby and P a n d o l f i , have f e l t t h a t a 1.5 percent uncer t a i n t y i s t o l e r a b l e w i t h i n the l i m i t s of other e r r o r s i n h e r e n t i n the method, and t h e r e f o r e we have always analyzed whole wood i n our study of isotope v a r i a t i o n s i n t r e e - r i n g sequences. In a n a l y z i n g whole wood, one i s confronted by the q u e s t i o n of whether t o use wet or dry c h e m i s t r i e s . Of course i f one decides t o separate c e l l u l o s e from l i g n i n , then one i s f o r c e d t o use wet c h e m i s t r i e s . I t i s only i n whole wood a n a l y s i s t h a t dry chemistry becomes p o s s i b l e . With wet c h e m i s t r i e s , performed n e c e s s a r i l y w i t h hydrogen- and oxygen-containing s o l v e n t s , there i s always the r i s k of i s o t o p e exchange w i t h the s o l v e n t . See f o r example the review a r t i c l e of H. Taube [12]. He shows t h a t there e x i s t s i n t i m a t e exchange o f hydroxyl oxygen (-0-H) w i t h carbonyl oxygen (-C0-0H) under a l l c o n d i t i o n s of a c i d i t y and a l k a l i n i t y i n l i q u i d s such as water, ketones, aldehydes, and a l c o h o l s . Sepal1 and Mason [13] d e s c r i b e exchange o f c e l l u l o s e and whole wood hydrogens w i t h hydrogen i n water as being r a p i d and e f f e c t i v e , l e a d i n g one t o expect s i m i l a r exchanges w i t h other s o l v e n t s con t a i n i n g OH groups. The exchange o f hydrogen i n c e l l u l o s e w i t h water was found t o be 50 percent i n one hour a t 25 °C. With dry chemistry t h e r e i s no p o s s i b i l i t y f o r i s o t o p e exchange w i t h the reagents, and f o r t h i s reason we have always used dry chemistry.



14.

253


LIBBY AND PANDOLFI

H2ÇOH HC CO

H2ÇOH HC HC

M e o k ^ O M e H COH H Ç - \ ^ O M e 0 CH HC Ο 2

H C0H 2

H2COH Γ —CH

HgCOH HCOH |-0

HC

-CH

£

£

ι HÇ-AyJoMeHC OMe HoCOH OH HC

X

"H?

Y°*

HÇ CO

HCORVWUH

0

0

V

C

ÇH HH2gÇC0OHH S ^^ HCOH H Ç —

C

^° >Me OH

2

Ο OÇ

ÇH*

3.

HCOH

H

Hg-—0

OH

0

f| Μ

ll

2Ç0H

Nuclear and Chemical Dating Techniques - ACS Publications

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