Archaeological Chemistry IV - ACS Publications - American Chemical

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Isotope Measurements and Provenance Studies of the Shroud of Turin Robert H. Dinegar

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and Larry A. Schwalbe

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University of New Mexico—Los Alamos, Los Alamos, NM 87544 Los Alamos National Laboratory, Los Alamos, NM 87545

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The findings and conclusions of the 1978 investigation of the Shroud of Turin are reviewed, and a proposal for additional research that was submitted in 1984 is described. The research proposal centers primarily on two experiments: radiocarbon dating and the proposed measurements of the stable hydrogen and oxygen isotopic concentrations in the textile cellulose. The discussion of the dating experiment focuses on the history of attempts to perform the test during the past decade. That of stable isotope measurements treats the technical aspects of the method and their implications for locating the geographical origin of the Shroud.

THE

S H R O U D O F T U R I N R E S E A R C H P R O J E C T ( S T U R P ) , an A m e r i c a n team of scientists a n d technicians, c o n d u c t e d an extensive series of n o n d e s t r u c t i v e examinations of the S h r o u d i n O c t o b e r 1978. A b o u t 4 years later, the data r e d u c t i o n a n d analyses w e r e c o m p l e t e d . P u b l i c l y released a n d discussed i n several forms ( I , 2), the measurements a n d observations support the followi n g conclusions:

1. T h e b o d y image o n the c l o t h is the result of an o x i d a t i o n - d e h y d r a t i o n reaction of the cellulose material of the c l o t h itself rather than the result of an a p p l i e d p i g m e n t , stain, or dye. 2. T h e process for the formation of the b o d y image remains u n known. 0065-2393/89/0220-0409$06.00/0 © 1989 A m e r i c a n C h e m i c a l S o c i e t y

Allen; Archaeological Chemistry IV Advances in Chemistry; American Chemical Society: Washington, DC, 1989.

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3. T h e areas t r a d i t i o n a l l y i d e n t i f i e d as " b l o o d s t a i n s " contain blood-derived material. I n A u g u s t 1984, S T U R P s u b m i t t e d a proposal to p e r f o r m a d d i t i o n a l tests. T h e f o r m a l proposal, w h i c h consisted of 26 i n d i v i d u a l projects, a d dressed three b r o a d categories of c u r r e n t issues: questions about h o w the image was f o r m e d , conservation, a n d provenance. O f these issues, the most c o m p l e x a n d p e r p l e x i n g is h o w the image was p r o d u c e d o n the surface of the c l o t h . R o u g h l y h a l f the experiments i n the 1984 proposal w e r e a i m e d t o w a r d s o l v i n g this p r o b l e m . O f the r e m a i n i n g e x p e r i m e n t s , nearly a l l are r e l a t e d to conservation. S T U R P , along w i t h the authorities i n T u r i n w h o are e n t r u s t e d w i t h the care a n d p r e s e r v a t i o n of the r e l i c , recognize that a c o m p r e h e n s i v e characterization of the p h y s i c a l a n d c h e m i c a l state of the fabric (and its associated materials) is necessary to support v a l i d r e c o m m e n d a t i o n s for the safe h a n d l i n g a n d storage of the S h r o u d . T h e final two of the 26 projects p e r t a i n e d d i r e c t l y to questions of p r o v e nance. It is perhaps i r o n i c that so little apparent effort was g i v e n to this p r o b l e m . A f t e r a l l , k n o w i n g the t i m e a n d place of the S h r o u d s o r i g i n is c e n t r a l to w h a t m a n y w o u l d consider the paramount question: Was the S h r o u d of T u r i n , as pious t r a d i t i o n holds, the b u r i a l c l o t h of Jesus, or is it m e r e l y a c l e v e r l y hoaxed m e d i e v a l relic? T h e two experiments that w i l l p r o v i d e some insight to these questions are the focus of this chapter. B o t h i n v o l v e measurements of the isotopic c o m p o s i t i o n of the fabric. T h e first is the f a m i l i a r a n d w i d e l y p u b l i c i z e d radiocarbon p r o c e d u r e that s h o u l d give an accurate date of o r i g i n . T h e second is a study of the stable isotope ratios of h y d r o g e n a n d oxygen that c o u l d locate the Shroud's place of o r i g i n . A s w e i n t e n d to show, the attention a n d effort g i v e n to this research has been considerable.

Determining the Age M a n y accept the S h r o u d as the authentic b u r i a l c l o t h of Jesus, b u t those w h o d e f e n d this b e l i e f must e x p l a i n the c o m p l e t e lack of records d o c u m e n t i n g the Shroud's existence throughout most of its supposed 2000-year history. F o r a l l w e k n o w today, the S h r o u d c o u l d have b e e n m a n u f a c t u r e d a short t i m e before its r e c o r d e d appearance i n the early 1350s. T h e issue of authenticity has therefore generated a n d sustained great interest i n the radiocarbon d a t i n g t e c h n i q u e . A n objective date is possible; i n fact, an att e m p t to date the S h r o u d has b e e n c o m p l e t e d .

Previous Proposals. M a n y investigators have h a d the i d e a of d a t i n g the c l o t h b y C - 1 4 d e t e r m i n a t i o n ever since 1955 w h e n W i l l a r d F. L i b b y s h o w e d that such analysis is b o t h possible a n d m e a n i n g f u l . E v i d e n t l y , these thoughts w e r e not f o l l o w e d u p , or the failure of attempts was k e p t secret,


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for there is l i t t l e , i f any, literature p u b l i s h e d d u r i n g the 1950s-1970s o n this subject. O n e d o c u m e n t e d attempt does exist (3), h o w e v e r , a n d that i n v o l v e d the g r o u p of investigators that later b e c a m e S T U R P . L i t t l e came of this organization's attempt i n the late 1970s. A t the t i m e , the position of the R o m a n C a t h o l i c C h u r c h , i n w h o s e care the c l o t h is e n t r u s t e d , was that any type of testing s h o u l d be nondestructive. I n a d d i t i o n , the established t e c h nology (the L i b b y c o u n t i n g method) r e q u i r e d an unacceptably large sample of c l o t h to be destroyed for a reliable answer. T h u s , w h e n S T U R P m a d e its formal request to the A r c h b i s h o p of T u r i n , M i c h e l l e P e l l e g r i n o , i n 1977 to r u n tests o n the S h r o u d , radiocarbon analysis was not m e n t i o n e d . T h e test p r o g r a m of S T U R P , w h i c h i n v o l v e d a c o m p r e h e n s i v e i n v e s t i gation of the c l o t h u s i n g m a n y wavelengths of the electromagnetic s p e c t r u m , photography, a n d the r e m o v a l of surface m a t e r i a l for c h e m i c a l analysis, was a p p r o v e d i n A p r i l 1978. A s S T U R P p r e p a r e d to go to T u r i n i n the fall, a w e l l - k n o w n A m e r i c a n scientist (4) m a d e an unsuccessful attempt to obtain threads a n d swatches of c l o t h that h a d b e e n r e m o v e d i n 1973 for a " q u i c k a n d d i r t y " age d e t e r m i n a t i o n . I n a d d i t i o n , two other A m e r i c a n scientists wrote a formal proposal for radiocarbon analysis of the c l o t h u s i n g n e w l y d e v e l o p e d m e t h o d s i n v o l v i n g t a n d e m accelerators a n d precise m i n i a t u r e p r o p o r t i o n a l counters. T h e latter request was s o m e h o w " l o s t " a n d C h u r c h authorities appeared u n w i l l i n g to have the S h r o u d carbon dated. T h o s e i n t e r e s t e d i n the c l o t h t h e n split into three camps. O n e g r o u p p u s h e d h a r d e r for i m m e d i a t e C - 1 4 testing. A second said the o r i g i n of the c l o t h was so w e l l - k n o w n that no part of i t s h o u l d be destroyed i n v e r i f y i n g its a n t i q u i t y . A t h i r d counseled m a k i n g plans for an age d e t e r m i n a t i o n i n several years. S T U R P was the vocal exponent of the last position. A t the b e g i n n i n g of the last w e e k of A u g u s t 1978, the H o l y S h r o u d of T u r i n was p u t o n p u b l i c display over the h i g h altar of the C a t h e d r a l of Saint J o h n the Baptist. T h e exposition m a r k e d the 400th anniversary of the Shroud's a r r i v a l i n T u r i n from Chambéry, F r a n c e . T h e p u b l i c exposition e n d e d the w e e k e n d of O c t o b e r 7 - 8 , 1978, d u r i n g w h i c h t i m e the Second International Sindonological C o n f e r e n c e was h e l d . T h o s e interested i n the S h r o u d came from a l l o v e r the w o r l d to participate. D u r i n g the m e e t i n g , the n e w l y n a m e d A r c h b i s h o p of T u r i n , Anastasio B a l l e s t r e r o , a n n o u n c e d that w h e n the scientific c o m m u n i t y c o u l d settle on the best way to d e t e r m i n e the age of the c l o t h , he w o u l d consider asking the o w n e r of the S h r o u d , the e x i l e d K i n g of Italy, U m b e r t o I I , to allow samples to be taken for analysis. H i s w o r d s w e r e g r e e t e d w i t h enthusiasm b y those h o l d i n g the t h i r d position m e n t i o n e d ; the other two camps r e d o u b l e d t h e i r efforts to have this decision changed to t h e i r positions. A state of tension a n d p o l i t i c a l i n t r i g u e d e v e l o p e d that is still v e r y m u c h evident. S T U R P Proposal. O n O c t o b e r 9, 1978, the S h r o u d was p l a c e d i n the V i s i t i n g P r i n c e ' s rooms of the R o y a l Palace of the H o u s e of Savoy, a n d the testing p r o c e e d e d continuously for 5 days. T h e data a n d analyses of m o r e


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than 100 h of c l o t h observation have b e e n discussed for almost a decade. T h e results have b e e n p u b l i s h e d i n m a n y journals. M o s t , i f not a l l , of the articles w e r e refereed, a n d , to o u r k n o w l e d g e , not one was rejected. T h e general conclusions r e a c h e d b y S T U R P scientists w e r e those o u t l i n e d at the b e g i n n i n g of this chapter. N e i t h e r the data nor the conclusions themselves have b e e n c h a l l e n g e d . W h a t has b e e n a r g u e d , almost ad nauseam, is w h e t h e r the w o r k can b e i n t e r p r e t e d for o r against a v e r y early chronological date. N o p u b l i s h e d article b y any S T U R P scientist takes e i t h e r p o s i t i o n . I n 1979, S T U R P began decisive action to obtain p e r m i s s i o n to carbon date the S h r o u d . A C - 1 4 c o m m i t t e e was f o r m e d . Scientists from a l l over the w o r l d w e r e contacted a n d asked i f they w e r e i n t e r e s t e d i n j o i n i n g the the effort. S o m e r e s p o n d e d negatively, c i t i n g the religious nature of the project. O t h e r s f a i l e d to answer. W i t h various levels of enthusiasm, several agreed to b e c o m e i n v o l v e d . T h e A r i z o n a , B r o o k h a v e n , a n d Rochester laboratories from the U n i t e d States, as w e l l as O x f o r d a n d H a r w e l l of the U n i t e d K i n g d o m answered affirmatively. L a t e r , the B r i t i s h M u s e u m a n d the F e d e r a l Institute of Technology i n Z u r i c h j o i n e d the effort. T h i s array of scientists was d e e m e d q u i t e sufficient to carry out the age d e t e r m i n a t i o n i n the most objective m a n n e r . T h e i n c l u s i o n of b o t h methods of C - 1 4 d e t e r m i n a t i o n , accelerator a n d counter, was thought to ensure the most accurate a n d precise dating. T h e c h a i r m a n of the S T U R P C - 1 4 c o m m i t t e e kept the group i n f o r m e d a n d coordinated b y letter, t e l e p h o n e , a n d personal visits over the e n s u i n g years. I n 1983, at the radiocarbon conference i n B r a d f o r d , E n g l a n d , i t was suggested that a laboratory i n t e r c o m p a r i s o n e x p e r i m e n t b e u n d e r t a k e n . T h e B r i t i s h M u s e u m agreed to s u p p l y three samples of c l o t h of k n o w n dates to each laboratory. T h e i n t e r c o m p a r i s o n tests w e r e c a r r i e d out a n d the results r e p o r t e d at the radiocarbon conference h e l d i n T r o n d h e i m , N o r w a y i n J u n e 1985. T h e proceedings of that m e e t i n g contain the data a n d the r e p o r t p r e s e n t e d b y the B r i t i s h M u s e u m (5). A n interlaboratory agreement o n the dates was clearly established. Interestingly, a serendipitous result of this test was to b r i n g to l i g h t that the actual date of one of the samples f u r n i s h e d b y the B r i t i s h M u s e u m was not correctly k n o w n at a l l ! W h i l e the i n t e r c o m p a r i s o n e x p e r i m e n t was b e i n g p e r f o r m e d , a proposal for n e w tests o n the S h r o u d , of w h i c h radiocarbon d a t i n g was p r e e m i n e n t , was d r a w n u p b y S T U R P . T h e proposal d a t i n g project was a p p r o v e d b y the o r i g i n a l five laboratories, a n d the composite proposal was sent to the C a r d i n a l A r c h b i s h o p of T u r i n i n the fall of 1984 for e n d o r s e m e n t a n d f o r w a r d i n g to the See of R o m e , w h i c h u p o n the death of U m b e r t o I I h a d b e c o m e the o w n e r of the c l o t h . T h e P o n t i f i c a l A c a d e m y of Sciences thus r e c e i v e d the report for c o m m e n t . W i t h i n this atmosphere, S T U R P a n d the radiocarbon laboratories i n v o l v e d h e l d a special m e e t i n g on the S h r o u d dating d u r i n g the radiocarbon conference i n T r o n d h e i m . It was q u i c k l y seen a n d made absolutely clear that one laboratory was d e d i c a t e d to h a v i n g the e x p e r i m e n t c o m e u n d e r the


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single a n d d i r e c t oversight o f the P o n t i f i c a l A c a d e m y o f Sciences. T h e a d amant stance a n d c o n t i n u a l l o b b y i n g o f this o n e laboratory caused a severe tension i n t h e project that exists to this day. Pontifical Academy of Sciences Criteria. I n the last w e e k i n S e p t e m b e r 1986, at t h e i n v i t a t i o n of the C a r d i n a l A r c h b i s h o p of T u r i n a n d t h e Pontifical A c a d e m y o f Sciences, scientists f r o m S T U R P , the a n a l y z i n g r a diocarbon laboratories (now i n c l u d i n g a Swiss team), a textile expert f r o m H o l l a n d , a n d a n archaeologist from H o n g K o n g m e t i n T u r i n to discuss d a t i n g the S h r o u d . A l s o present as observers w e r e F r e n c h radiocarbon experts. T h e m e e t i n g was c h a i r e d b y the p r e s i d e n t o f t h e Pontifical A c a d e m y o f Sciences, b u t u n d e r t h e oversight o f the A r c h b i s h o p o f T u r i n a n d his s c i e n tific advisors. A f t e r 3 days o f meetings i t was d e c i d e d that 1. T h e samples for radiocarbon d a t i n g w o u l d b e taken from t h e r e l i c b y t h e D u t c h c l o t h expert, u n d e r t h e d i r e c t i o n of t h e scientific advisors to t h e C a r d i n a l A r c h b i s h o p . 2. T h e samples a n d " b l i n d s " w o u l d first b e u n w o v e n b y t h e B r i t i s h M u s e u m a n d t h e n d i s t r i b u t e d to t h e laboratories i n volved. 3. T h e a d d i t i o n a l tests o n t h e c l o t h as o u t l i n e d i n the S T U R P proposal w o u l d t h e n b e c a r r i e d out. 4. T h e radiocarbon data w o u l d b e collated b y t h e B r i t i s h M u s e u m , t h e statistical d e p a r t m e n t o f the P o l y t e c h n i c Institute i n T u r i n , a n d a t h i r d group designated b y t h e Pontifical A c a d emy. 5. T h e date of the S h r o u d of T u r i n w o u l d b e a n n o u n c e d to the w o r l d b y E a s t e r 1988. In A p r i l 1987, T u r i n r e c e i v e d positive instructions from R o m e o n h o w to p r o c e e d . T h e s e d i r e c t e d that n o m o r e t h a n three samples w e r e to b e taken, w h i c h r e q u i r e d that three laboratories b e chosen from t h e six that had offered t h e i r services. T h e choices w e r e made after l o n g d e l i b e r a t i o n and careful consultations. T h e c r i t e r i a u s e d for t h e selection w e r e • the specific experience i n the field of archaeological radiocarbon dating • t h e sample size r e q u i r e d b y t h e laboratory • t h e i n t e r n a t i o n a l m i x of the group T h e c r i t e r i o n o f sample size e l i m i n a t e d those laboratories that use t h e t r a d i t i o n a l L i b b y c o u n t i n g m e t h o d . T h i s situation was v e r y unfortunate because


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one laboratory of the six best m e e t i n g the experience c r i t e r i o n was one of the two r e q u i r i n g the larger sample size. H a r w e l l was thus e l i m i n a t e d , e v e n t h o u g h i t h a d p e r f o r m e d m o r e radiocarbon experiments t h a n the other five laboratories c o m b i n e d . B r o o k h a v e n , the other counter laboratory, was e l i m i n a t e d because i t , too, r e q u i r e d a large sample a n d was r e l a t i v e l y i n e x p e r i e n c e d i n archaeological dating. T h i s e l i m i n a t i o n was also unfortunate, b u t from another standpoint: B r o o k h a v e n h a d d o n e the p i o n e e r d e v e l o p m e n t of the s m a l l p r o p o r t i o n a l counter t e c h n i q u e . T h e accelerator laboratory at R o c h ester r e q u i r e d a sufficiently s m a l l sample, b u t they w e r e passed over b y reason of little experience i n archaeological dating a n d t h e i r use of " n o n d e d i c a t e d " e q u i p m e n t . A r i z o n a , O x f o r d , a n d the F e d e r a l Institute of T e c h nology i n Z u r i c h w e r e left after the application of a l l t h r e e criteria. T h e other scientists t a k i n g part i n the o v e r a l l investigation of the c l o t h , the B r i t i s h M u s e u m for overseeing the date d e t e r m i n a t i o n , and S T U R P for other exp e r i m e n t s , r e m a i n e d unaffected. T h e reaction of the laboratories to the p r o p o s e d choices was p r e d i c t a b l e . B o t h Rochester a n d B r o o k h a v e n d e n o u n c e d the decision as scientifically flawed a n d q u e s t i o n e d the qualifications of those w h o h a d a d v i s e d the C h u r c h authorities. H a r w e l l expressed d i s a p p o i n t m e n t at not b e i n g chosen a n d l i k e wise disagreed w i t h the d e c i s i o n to cut the n u m b e r of laboratories f r o m six to three. A r i z o n a , O x f o r d , a n d Z u r i c h gave the o p i n i o n that any date o b t a i n e d w o u l d be m o r e w i d e l y accepted i f all the laboratories w e r e i n v o l v e d instead of just three. Current Protocol. T h e C - 1 4 testing protocol at this t i m e is essentially that s u b m i t t e d b y S T U R P i n 1984 w i t h the modifications that took place i n T u r i n i n 1986. T h e few major changes that w e r e made to c o n f o r m to the sample-size c r i t e r i o n caused the loss of use of the c o u n t e r m e t h o d a n d a n increase i n the e r r o r associated w i t h any date f r o m ± 1 0 0 years to about ± 2 5 0 years. A l t h o u g h the criticisms of the p l a n offered b y the C h u r c h authorities are v a l i d a n d t h o u g h t - p r o v o k i n g , the protocol c e r t a i n l y w i l l a l l o w a c o n c l u s i o n as to w h e t h e r the c l o t h is of m e d i e v a l o r i g i n o r i f it comes from a m u c h earlier time. O n the n i g h t of A p r i l 2 1 , 1988, C a r d i n a l B a l l e s t r e r o , L u i g i G o n e l l a , a n d G i o v a n n i R i g g i , (Vice P r e s i d e n t of S T U R P ) w i t h the advice of a c l o t h expert f r o m L y o n s , F r a n c e , r e m o v e d fabric samples from the S h r o u d a n d gave t h e m to M i c h a e l T i t e of the B r i t i s h M u s e u m for d i s t r i b u t i o n to the three laboratories. S l o w l y , the radiocarbon d a t i n g of the S h r o u d is b e i n g a c c o m p l i s h e d a n d the C h u r c h ' s decision to give free h a n d to the scientific c o m m u n i t y is e v i d e n t .

Locating the Geographic Origin O u r discussion of the d a t i n g proposal centers m o r e o n the h i s t o r i c a l r e c o r d of efforts to a c c o m p l i s h the w o r k t h a n i t does o n the m o r e f a m i l i a r t e c h n i c a l


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aspects of the p r o b l e m . I n our discussion of p l a c i n g , the situation is r e v e r s e d . U n l i k e radiocarbon d a t i n g , the i d e a of m e a s u r i n g the stable isotope ratios of h y d r o g e n a n d oxygen to locate the geographic o r i g i n of the S h r o u d is fairly recent. T h e m e t h o d is not w i d e l y k n o w n or appreciated, a n d a t e c h n i c a l discussion therefore is the most appropriate. Previous Physical Studies. T h u s far, the available p h y s i c a l e v i d e n c e c o n c e r n i n g the S h r o u d s o r i g i n is suggestive b u t scanty a n d largely i n c o n c l u s i v e . I n 1973, a fabric sample was r e m o v e d from the edge of the S h r o u d near one e n d a n d g i v e n to a B e l g i a n textile expert (Raes) for study. U n f o r t u n a t e l y , despite several provocative observations, i n c l u d i n g that of the Z - t w i s t , w h i c h is apparently u n u s u a l for l i n e n , Raes (6) was unable place the o r i g i n of the m a t e r i a l e i t h e r from the twist or from the 3:1 h e r r i n g b o n e weave type of the fabric. S t i l l , h e d i d report finding traces of cotton i n w i t h the flax fibers a n d suggested that the l i n e n m a y have b e e n s p u n w i t h the same e q u i p m e n t u s e d p r e v i o u s l y for cotton. T h e latter observation supports a M i d d l e E a s t e r n manufacture (because cotton was not g r o w n i n E u r o p e at the time), b u t i t does not p r o v e the conjecture. A second p i e c e of e v i d e n c e is offered b y F r e i (7-9) w h o s t u d i e d surface debris that was r e m o v e d f r o m the S h r o u d w i t h sticky tape. A m o n g the collected materials, he observed a n d i d e n t i f i e d p o l l e n from plants that are u n i q u e l y indigenous to Palestine a n d A n a t o l i a (JO). Some c o n c l u d e from these observations that the S h r o u d o r i g i n a t e d i n the M i d d l e E a s t a n d was subsequently b r o u g h t to E u r o p e v i a C o n s t a n t i n o p l e (4). B u t w e consider i t just as l i k e l y that the S h r o u d was p r o d u c e d i n E u r o p e a n d subsequently transported to P a l e s t i n e , perhaps o n one of the C r u s a d e s , w h e r e it was exposed to the local p o l l e n r a i n . Stable Isotope Method. A t this p o i n t , the evidence for p l a c i n g the Shroud's o r i g i n is suggestive, b u t m o r e w o r k is clearly necessary i f w e h o p e to reconstruct a c o n v i n c i n g h i s t o r i c a l scenario. So far, the evidence has b e e n somewhat i n d i r e c t ; that is, it involves i n c i d e n t a l materials associated w i t h the fabric. T h e stable isotope e x p e r i m e n t is qualitatively different f r o m the earlier ones because, l i k e radiocarbon, it involves d i r e c t measurements o n the fabric itself. T h e S h r o u d is a l i n e n textile that consists of cellulose d e r i v e d from flax. E a c h of the constituent elements of the cellulose (hydrogen, c a r b o n , a n d oxygen) exists i n several stable isotopic forms. T h e l i g h t e r isotopes * H , C , and 0 are generally m o r e abundant, b u t smaller concentrations of the heavier D ( H ) , C , a n d O are also present i n measurable amounts. I n any sample, the relative quantities D / H , C / C , a n d 0 / 0 d e p e n d o n the p h y s i c a l , c h e m i c a l , a n d biological history of the m a t e r i a l . 1 2

I 6

2

1 3

l s

1 3

1 2

1 8

1 6

T h e isotopic compositions of oxygen a n d h y d r o g e n i n cellulose are p a r t i c u l a r l y i n f l u e n c e d b y the climate i n w h i c h the plant grew. C l i m a t e affects isotope ratios i n p r i m a r i l y two ways. F i r s t , t e m p e r a t u r e affects cellulose


416


c o m p o s i t i o n t h r o u g h its effects o n the isotopic concentrations of the local p r e c i p i t a t i o n . I n g e n e r a l , the magnitudes 0 / 0 and D / H in rainwater decrease w i t h cooler temperatures (J J), a n d c o r r e s p o n d i n g decreases i n b o t h c a r b o n - b o u n d D / H (12, 13) a n d 0 / 0 (14) ratios i n p l a n t cellulose have b e e n o b s e r v e d a n d m e a s u r e d . T h e second factor, the h u m i d i t y of the g r o w i n g e n v i r o n m e n t , affects the isotope ratios of terrestrial p l a n t cellulose t h r o u g h its influence o n the transpiration process. L o w h u m i d i t i e s p r o m o t e t r a n spiration a n d concentrate leaf w a t e r c o n t a i n i n g the h e a v i e r isotopes, because w a t e r molecules c o n t a i n i n g * H a n d 0 have h i g h e r vapor pressures a n d evaporate m o r e r e a d i l y . T h e effects of transpiration have also b e e n o b s e r v e d e x p e r i m e n t a l l y (15, 16). 1 8

1 8

1 6

1 6

1 6

H o t , a r i d climates therefore cause plant cellulose to have h i g h e r relative concentrations o f the h e a v i e r h y d r o g e n a n d oxygen isotopes than cellulose from plants g r o w n i n cool, moist e n v i r o n m e n t s . T h e isotope ratios of cellulose have b e e n u s e d as r e l i a b l e indicators of the c l i m a t e i n w h i c h the plants g r e w (17). R e c e n t l y , D e N i r o et al. (18) d e m o n s t r a t e d h o w D / H a n d O / 0 ratios of cellulose p r e p a r e d f r o m m o d e r n a n d h i s t o r i c linens of k n o w n p r o v e n a n c e from E u r o p e a n d the M i d d l e E a s t (Israel a n d E g y p t ) are r e l a t e d to the climates i n these regions. T h i s v e r y study was i n fact u n d e r t a k e n to s u p p l y a data base to w h i c h similar measurements o n the S h r o u d c o u l d be c o m p a r e d to establish its geographical o r i g i n . T h e work's c o n c l u s i o n is that such a d e t e r m i n a t i o n is i n d e e d possible, although over a l i m i t e d range, the data sets f r o m E u r o p e a n d Israel overlap slightly, thus i n t r o d u c i n g the chance o f an ambiguous result. l s

1 6

W e support S T U R P ' s proposal to measure stable isotope ratios f r o m the S h r o u d fabric. T h e data c o u l d establish the geographical o r i g i n of the c l o t h i n a d i r e c t a n d u n a m b i g u o u s way. Isotope ratio information is i n t e r e s t i n g i n itself, b u t it c o u l d have an i m p a c t on other issues as w e l l . F o r example, to someone familiar w i t h the range of artistic techniques a n d traditions available at a specific t i m e a n d location, an accurate historical p l a c e m e n t of the S h r o u d c o u l d suggest h o w the image was f o r m e d . I n conservation, the i n f o r m a t i o n c o u l d prove useful i f the S h r o u d w e r e to be u n i q u e l y classified w i t h textiles of s i m i l a r o r i g i n . T h e data may e v e n be a critical s u p p l e m e n t to the r a d i ocarbon results if, as M e a c h a m (19) notes, the presence of volcanic activity i n the area w h e r e the S h r o u d l i n e n was p r o d u c e d c o u l d affect the o u t c o m e of the C testing. 1 4

Summary O u r u n d e r s t a n d i n g of the p h y s i c a l a n d c h e m i c a l characteristics of the S h r o u d of T u r i n has increased e n o r m o u s l y i n the past 10 years, b u t the w o r k d o n e thus far still leaves u n a n s w e r e d some of the most i n t r i g u i n g questions asked about this most r e m a r k a b l e object. F o r e m o s t a m o n g these are w h e n a n d w h e r e the S h r o u d came to be. W e b e l i e v e studies of the stable a n d unstable


23.

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isotopes of the fabric w i l l establish this information. O t h e r questions a n d p r o b l e m s r e m a i n . I n o u r v i e w , the t i m e is r i g h t to address these issues, a n d to see this d o n e , w e encourage the c o n t i n u e d cooperation that w e have seen b e t w e e n the C h u r c h a n d the scientific c o m m u n i t y .

References 1. Schwalbe, L. Α.; Rogers, R. N . Anal Chim. Acta 1982, 135, 3. 2. Jumper, E . J.; Adler, A . D.; Jackson, J . P.; Pellicori, S. F.; Heller, J . H.; Druzik, J. R. In Archaeological Chemistry—III; Lambert, J . B., E d . ; Advances in C h e m istry 205; American Chemical Society: Washington, DC, 1984; Chapter 22. 3. Private communication of John P. Jackson to Willard F. Libby, December 1976. 4. Wilson, I. The Shroud of Turin, revised ed.; Doubleday: Garden City, NY, 1979; p 242. 5. Burleigh, R.; Leese, M.; Tite, M. Radiocarbon 1986, 28(2A), 571. 6. Raes, G . Report of the Turin Commission on the Holy Shroud; translated from Italian by Screenpro Films, London, 1976. (Screepro Films, 5 Meard St., London W1V 3HQ, UK.) 7. F r e i , M. Naturwiss. Rundsch. 1979, 32, 133. 8. F r e i , M. Shroud Spectrum International 1982, (3), 3. (The Indiana Center for Shroud Studies, R. 3, Box 557, Nashville, I N 47448.) 9. Wilson, I. The Shroud of Turin, revised ed.; Doubleday: Garden City, NY, 1979; p 293. 10. Bulst, W. Shroud Spectrum International 1984, (10), 20. 11. Foerstel, H.; Huetzen, H. Nature (London) 1983, 304, 614. 12. Epstein, S.; Yapp, C. J . Earth Planet. Sci. Lett. 1976, 30, 252. 13. Yapp, C. J.; Epstein, S. Nature (London) 1982, 297, 636. 14. Burk, R. L.; Stuiver, M. Science 1981, 211, 1417. 15. Dongman, G.; Foerstel, H.; Wagener, K . Nature (London) New Biol. 1972, 240, 127. 16. Epstein, S.; Thompson, P.; Yapp, C. J . Science 1977, 198, 1209. 17. Brenninkmeijer, C. A . M.; van Geel, B.; Mook, W. G . Earth Planet. Sci. Lett. 1982, 61, 283. 18. D e N i r o , M. J.; Sternberg, L. D.; Marino, B. D.; Druzik, J . R. Geochim. Cosmochim. Acta, in press. 19. Meacham, W. Shroud Spectrum International 1986, (19), 15. RECEIVED for review June 11, 1987. ACCEPTED revised manuscript May 9, 1988.


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