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University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln

USGS Staff -- Published Research US Geological Survey

1967

Elephant Teeth from the Atlantic Continental Shelf

Frank C. Whitmore Jr. U.S. Geological Survey

K. O. Emery Woods Hole Oceanographic Institution

H. B. S. Cooke Dalhousie University

Donald J. P. Swift Puerto Rico Nuclear Center

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Whitmore, Frank C. Jr.; Emery, K. O.; Cooke, H. B. S.; and Swift, Donald J. P., " Teeth from the Atlantic Continental Shelf" (1967). USGS Staff -- Published Research. 236. https://digitalcommons.unl.edu/usgsstaffpub/236

This Article is brought to you for free and open access by the US Geological Survey at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in USGS Staff -- Published Research by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Science, New Series, Vol. 156, No. 3781 (Jun. 16, 1967), pp. 1477-1481

mergence ended probably about 25,000 ago. Accordingly, the outer part of the shelf must have been exposed for about 10,000 years; the inner part, about 20,000 years. Reports The presence of the teeth of masto- dons and atop the relict sand indicates that these lived there during the last exposure. Evidence of the reasonableness of their presence on the shelf is the discovery of many Elephant Teeth from the Atlantic Continental Shelf hundreds or perhaps thousands of and through- Abstract. Teeth of and mammoths have been recovered by fisher- out the entire eastern United States men from at least 40 sites on the continental shelf as deep as 120 meters. Also and Canada (8). Moreover, students of present are submerged shorelines, peat deposits, lagoonal shells, and relict sands. large have long Evidently and other large mammals ranged this region during the known that these animals must have glacial stage of low sea level of the last 25,000 years. traveled across exposed continental shelves in order to reach islands where Occasionally newspapers report the (Fig. 2) range back to 11,000 years their remains occur: notable examples dredging by fishermen of elephant teeth ago (3, 4). are Japan, England, Mediterranean from the continental shelf. Some speci- The fact that throughout most of the islands, Java, Sumatra, and other mens have reached museums, while shelf the sands have remained relatively islands of the East Indies, and small others have been lost; probably many undisturbed is indicated by terraces islands off southern California. In all more were thrown back into the ocean marking former stillstands of sea level examples known to us the maximum or remain unreported. This compilation during the period when the shoreline present depth of the intervening strait of known finds is intended to spur the crossed the shelf. Sands atop the north- or shelf is less than 120 m. This depth reporting of other discoveries both past central part of Georges Bank and sands is significant in view of a calculation, and future. southeast of Cape Cod (southeast of based upon estimated volume of ice, The teeth are molars and Boston, Fig. 2), however, have been that during the glaciation the from both mastodons and mammoths shaped into actively moving waves of sea level was about 123 m below the (Fig. 1). All offshore discoveries known sand. Foundation borings for radar present level (9). In each of the cited to us were on the continental shelf off towers in both areas revealed silts be- areas, molars or bones of elephants the northeastern United States and on neath the sands at 40 to 60 m below have been found on the sea floor. Off its northeastward extension as Georges sea level; a shell in one of the silts had Japan, molars of mastodon and Bank (Fig. 2) (Table 1). The average a radiocarbon age of 11,465 years (5). naumanni (Makiyama) have been depth of recovery is 36 m; the maxi- Other evidence of widespread stratifica- dredged from a depth of 80 m in the mum may be 120 m. Some uncertainty tion in the top 80 m beneath the con- strait west of Kyushu and from 90 m about position and depth of the finds tinental shelf is provided by many in the Inland Sea (10). In the English results from the fact that the scallop continuous seismic profiles (6) showing Channel, especially from Dogger Bank or clam trawls may be dragged several the common presence of four or five at 30 to 40 m, bones of many Pleisto- kilometers along the bottom before reflecting horizons, each of which is cene mammals, including mammoths, being hauled. probably a sediment surface produced have long been reported by fishermen Most of the continental shelf is during a low sea level associated with (11). Off southern California about floored by detrital sand that is iron a glacial stage of the Pleistocene epoch. 1950, R. S. Dietz recovered an upper stained and generally coarser grained Thus the present surface of the con- second and an upper third of than sediments closer to the present tinental shelf is not older than the Archidiskodon imperator Leidy at a shore (1). For these reasons the sand is Wisconsin glaciation, and much of it depth of 5 m near Huntington Beach, considered relict from times of glacially has received little subsequent sedi- and other finds of bones and molars lowered sea level. Present on or just ment. from near Santa Barbara have been below the surface of the sand at water The evidence indicates that the pres- reported since 1960 by oil company depths as great as 90 m are shells of ent continental shelf was a broad divers. oysters, Crassostrea virginica (Gmelin), coastal plain about 15,000 years ago, The distribution pattern of elephant that lived in depths shallower than and that it gradually submerged as teeth on the sea floor off the Atlantic about 6 m. Supporting evidence of water from glacial ice returned to the coast (Fig. 2) shows three concentra- former shallow water is provided by ocean. The sea-level rise curve derived tions: Georges Bank, off New York exposures of intertidal salt-marsh peat from the present water depths of the City, and off the mouth of Chesapeake that is now as deep as 59 m. Fresh- dated shells and peat differs only Bay. These parts of the continental shelf water peats also are present. Compari- slightly from that of Shepard (7), which are the most intensively exploited for son of samples of peat taken from the is based upon data from many places scallops, clams, and bottom fishes, all sea floor (eight) and from ponds ashore in the world. The region had been sub- of which require the dragging of heavy shows that the pollen assemblages are merged during several earlier inter- trawls along the bottom. Thus the dis- the same throughout (2). Radiocarbon glaciations; although the dates are tribution pattern merely reflects the dates for these oyster shells and peats poorly known, the next previous sub- intensity of effort or the degree of op- 16 JUNE 1967 1477 are portunity for finds, as well as the extent that apparently preferred by Mammu- Most elephant specimens to which specimens are rescued and thus primigenius (Blumenbach) in isolated teeth. patterns are gen- passed to scientific institutions. It is Siberia and Alaska (12). erically and, to some extent, specifically notable that specimens at our disposal Occurrence of a suitable diet does characteristic, and certain features of came from relatively few ships' cap- not, however, prove that the mammoth mammoth molars may have ecologic sig- tains. teeth found on the continental shelf nificance. Very generally, the distribu- Occurrence of the teeth as far as represent the . The 11 tion of types of mammoth teeth in the 300 km from the present shore and mammoth teeth available from the area periglacial land areas of the late- their wide distribution show that the between 42?08' and 36?46'N (Fig. 2) Pleistocene epoch of proboscideans lived on the shelf. One (Table 1) are somewhat different from indicates the presence of animals hav- may assume, therefore, that this region isolated molars of several of ing fairly hypsodont teeth with many was well covered with land vegetation. Mammuthus obtained on land. We tooth plates. Such teeth typify Mam- Evidence of such vegetation is pro- should also point out that most of the muthus primigenius (Blumenbach), the vided by the finding of twigs, seeds, specimens recovered come from the woolly mammoth, that probably ate and pollens of , pine, and fir wide-ranging mastodon Mammut ameri- tundra grasses and the foliage of within peat deposits that are now deeply canum (Kerr), although this domi- conifers. submerged; freshwater diatoms also are nance in the collections may well reflect Generally south of the range of found (4). The age of this material is the greater inherent strength of masto- M. primigenius on land was M. columbi 11,000 years (4), and the assemblage don molars than of the fissile plated (Falconer), the . indicates a boreal climate similar to molars of the mammoth. The ranges of the two species, and of

Table 1. Proboscidean teeth dredged from the sea floor off the Atlantic coast of North America. Depths in parentheses are taken from charts. Abbreviations: R, right; L, left; M2 second upper molar; M, third lower molar; AMNH, American Museum of ; ANSP, Acad- emy of Natural Sciences, Philadelphia, Pa.; CB, collection of C. Berringer, Brielle, N.J.; HLM, collection of H. L. Milholen, 51 Linden Avenue, Hampton, Va.; LAH, collection of L. A. Huber, Div. of Shell Fisheries, State of , Bivalve, N.J.; LGO, Lamont Geological Observatory, Columbia University; LS, collection of L. Samborski, 103 Coffin Avenue, New Bedford, Mass.; MCZ, Museum of Comparative Zoology, Har- vard University; NL, collection of Captain N. Lepire (casts in U.S. National Museum); PU, Princeton University; USNM, U.S. National Museum; WCC, collection of W. C. Childs, Box 301, Linwood, N.J.; WJD, collection of Mrs. W. J. Davis, Box 96, White Marsh, Va. * Source Water Col- Speci- Location, Speci Locatio, Species, description coordinates depth lected Ship, finder .me~~nNo.(N,W) (m) (yr) 1 MCZ 7757 Mammuthus sp., LM, 42?08', 67016' 90 1961 2 LGO Mammuthus sp., LM, 41055/, 67030' 80 1963 Acadian Pal, E. D'Entremont 3 MCZ 7756 Mammuthus sp., LM, 41015', 67030' (40) 4 USNM 23785 Mammuthus sp., RM, 39?52', 73058' 20 1962 Arlihe Snow, H. W. Taylor 5 AMNH 39538 Mammuthus sp., molar 39035', 72040' (75) 6 USNM 22791 Mammuthus sp., LM3 37030', 75045' Tidal flat 1961 7 HLM Mammuthus sp., M3 -37?, 75? 40 H. L. Milholen 8 AMNH 22566 Mamanmuthussp., RM3" 37?00', 75043' (20) 9 USNM 23569 Mammuthus sp., LM, 36?51', 75002' 35 1965 Aloha, M. Isaksen 10 ANSP Mammuthus sp., LM2 ,336?46', 74045' (80) 1931? 11 ANSP Mammuthus sp., LM3 -336?46', 74045' (80) 1931? 12 LGO Maemmutamericanunm (Kerr), 41041', 66003' 76 1964 Karen Sweeny, V. F. D'Eau part of RM3 13 Unknown M. americanlun (Georges Bank) 1949 New Bedford scalloper 14 MCZ M. americanurn, molar (Georges Bank) 1949 15 MCZ M. americanurn, molar (Georges Bank) 1955 16 CB M. americanum, three molars 40016', 73054' 20 1966 Kingfisher, J. Benninger 17 AMNH 45897, M. americanum, two molars -40?10', 73020' (40) 45899 18 AMNH 26967 M. americanum, LM -40, 73? (30) 19 PU 18001 M. americanum, molar ,40, 74? (20) 1962* Osmundsen 20 AMNH 39580 M. americanunm,molar 39?50', 73005' (60) 1948? 21 AMNH 45951 M. americanum, two molars .39?50', 73015' (50) 22 USNM 23786 M. americanum, LM, 39?46', 73056' 20 1965 23 PU 14725 M. arnericanurn,RM2 ,-3945', 73030' (40) 1948* M. Gabrysez 24 PU 16307 M. americanurn, LMS ,39?45', 73030' (40) 1954* North Star, R. Goodman 25 PU 16308 M. americanum, LM2' 39045', 73030' (40) 1954* T. Philip 26 PU 16345 M. americanum, M3 -39o45', 73030/ (40) 1950* E. Dempsey, F. Colona 27 AMNH 22633 M. americanum, M3 39043', 73012/ 46 Scalloper 28 AMNH 1919 M. anmericanum,molar 39042', 72047'/60 29 LAH M. americanum, molar 39040', 73050' -20 Clam dredger 30 AMNH 32651 M. americanum, molar -39?35', 74W00' (20) 31 PU 16343 M. americanum?, section of ,39?30', 72030' 40 1950* 32 WCC M. americanum, molar -39?00', 74015' (30) 1955 33 PU 18002 M. americanum, LM2 -39?00', 74030' (20) 1962* Waicus 34 AMNH 22569 M. americanum, RM2 38?35', 73020' 90-120 35 LS M. americanumn,molar -.3730', 7500' 55 1965 Laura A., L. R. Samborski 36 MCZ M. americanum, molar 36?56', 74053' 55 1959 37 ANSP 15231 M. americanum, LM2 -36?46', 74045' (80) 1931? 38 WJD M. americanum, LM, 36027', 74049' 60 1965 Dragger, W. Mansfield 39 NL M. americanum, LM2, and LM3 36?22', 75003' 50 1965 Ruth Lea, N. Lepire 40 USNM 20562 M. ainericanum, molar fragment -35?, 76? (20) 1952 41 G. Stires M. americanum, LM 40 03', 73?50' (26) 1967 Trinity, G. Stires Acquisition by Princeton University. 1478 SCIENCE, VOL. 156 other species that we shall discuss, ap- pear to have overlapped considerably if our criteria for isolated Icm identifying I cm teeth are sound. Mammuthus columbi had coarser teeth, with fewer plates, that can be taken to indicate on softer vegetation, in accordance with distribution in a warmer climate. A species morphologically and perhaps geographically intermediate between these two was M. jeffersonii (Osborn). Farther south and southwest are found still coarser teeth, with fewer plates and thicker enamel; they characterize Archidiskodon imperator Leidy, the imperial mammoth. A number of specimens of each of the four species of mammoth men- tioned have been measured; the respec- tive ranges of variation are compared graphically (Fig. 3) with the variation found in our collection from the con- tinental shelf. Proceeding from generalized con- sideration to examination of individual teeth, one finds appreciable overlap between species, one reason being in- dividual variation, especially in thick- ness of dental plates. Possibly more important, although not quantitatively 4 _ proved, may be the existence of races, 1. teeth from the continental shelf. (1) Mammuthus sp., upper third molar of the that we have dis- Fig. Elephant species just (Table 1, No. 2);(2) Manmmutamericanuin (Kerr), lower third molar (Table 1, cussed, fostered by geographic or eco- No. 12); (3 and 4) Mammuthus sp., lower third molar (Table 1, No. 9), medial and logic isolating factors. Some races may crown views, respectively. display characteristics of which the sum or average places them intermediate be- tween two species. Existence of such races is reasonable in terms of our knowledge of evolutionary mechanisms, and it seems to be indicated by the geographic variation observable in North American mammoths. Observ- able chronologic change also was tak- ing place in mammoth lines; it probably proceeded at a fairly rapid rate in late- Pleistocene time. Thus, in the study of isolated ele- phant teeth when the age of the speci- mens is in doubt, it is difficult to dis- tinguish between morphologic change in time and morphologic variation in space. By contrast the mastodon Mammut americanum (Kerr) is mor- phologically homogeneous in both time and space over a large area of north- eastern North America; its remains are common in mountainous areas as well as in lowlands. Mastodons were cer- tainly not evolving with the rapidity that characterized the mammoths. Another obstacle to accurate classi- fication of mammoth molars results from the mode of replacement of ele- Fig. 2. Offshore sources of mastodon or mammoth teeth. Note that all sites are within phant teeth. An elephant uses essen- the area of relict sand that also contains shallow-water oysters and intertidal peat for tially only four molars at a time-one which radiocarbon dates are indicated. 16 JUNE 1967 1479 stature, perhaps a dwarf variety of A. S. Romer has informed us of a Mammuthus primigenius or of M. report by T. Barbour (15) that some- jeffersonii. However, the metric differ- where off Fire Island, New York, a ences (Fig. 3) prevent definite assign- collection of remains of extinct Patago- ment of the continental-shelf specimens nian mammals also lies on the bottom: to any of the recognized species of it was destined for the Museum of Mammuthus. We assign no specific Comparative Zoology at Harvard, but name to the mammoth teeth from the was lost when a sailing ship bound for continental shelf, believing that as a New York was wrecked. The wreck oc- group they have unifying characteristics curred between 1874 and 1910, the pe- in which they differ from other popula- riod of Alexander Agassiz's activity as tions, but we do not know enough to director and patron of the museum. assign them to an existing or a new When the vessel's hull disintegrates, species. these will be scattered on the sea Withdrawal of the water from the floor to confound future marine geol- continental shelf, followed 10,000 to ogists. 20,000 years later by resubmergence, Molars of mastodons and mammoths limits the time span of the elephant and bones of other land mammals have population of the shelf. The time span been recovered by fishermen from at may have been even more limited if least 40 sites on the Atlantic continental 0 15 2u shelf. LENGTH/ LAMELLAERATIO early man (Clovis or a related culture) Each site is within a broad area caused the disappearance of elephants of sand that is relict from a time of Fig. 3. of mammoth-tooth dimen- Graph from the land between 11,000 glacially lowered sea level. Also in this sions, based on measurements adjacent published intertidal salt-marsh has (.16) and on measurements by two of us and 6000 years ago (13). The mam- area, peat been (F.C.W. and H.B.S.C.) of specimens in moth population of the continental recovered from depths as great as 59 Table 1. Lamellar frequency, number of shelf is as unified in its dental charac- m. Radiocarbon dates for these ma- tooth 100 mm; index of plates per hypso- teristics as are most species of Mam- terials range back to 11,000 years ago. donty, (height x 100)/width. muthus. The unity of the sample rein- The number and distribution of the forces our conclusion, based upon study teeth, some of which have been found of their tooth , that the near the seaward edge of the relict- sand indicate in each half of each jaw. As it erupts specimens of continental-shelf mam- area, that mammoths and mastodons the shelf and is worn by use, each cheek tooth moth represent a single species. ranged in large numbers the moves forward along the jaw. The front The 33 molars and one fragment of during last 25,000 years. Various other of the tooth wears away, and as it does tusk from mastodons are assigned to subarctic mammals, such as musk also so the anterior enamel plates drop out Mammut americanum (Kerr). The dis- oxen, undoubtedly abound- ed. Few remains of one by one. At the same time, the tribution of the mastodon remains is other mammals have been tooth rotates in a plane parallel to the not materially different from that of recovered, probably because are less identified in trawler anterior-posterior orientation of the jaw, the mammoth (Fig. 2), but new finds they easily hauls than are the and with resultant constant change in the from farther south may exhibit a large conspicu- ous teeth. angle between the wear surface of the difference in range. proboscidean tooth and the enamel plates. Thus a Besides elephant teeth, remains of FRANK C. WHITMORE, JR. U.S. comparison of teeth at different stages other Pleistocene land mammals have Geological Survey, of wear is difficult. The measurement been dredged from the continental shelf Washington, D.C. K. 0. EMERY system used in the construction of Fig. off the Atlantic coast of the United Woods Hole 3 represents an effort by Cooke to can- States. Richards (14) listed horse, , Oceanographic Institution, cel out some of these variables. musk ox, and giant ; we have Woods Hole, Massachusetts Mammoth teeth from the Atlantic seen or received reports of the H. B. S. COOKE continental shelf have many plates com- following: Department of Geology, Dalhousie Nova Scotia posed of enamel that, in most speci- University, Halifax, DONALD J. P. SWIFT mens, is as thin as in teeth of the woolly Ovibovine?, Symbos sp., USNM 23787 mammoth. The ratio of number of Left of a musk ox, probably Puerto Rico Nuclear Center, Mayaguez tooth to tooth is the same of an extinct ; dredged by fishing plates length vessel Aloha 64 km northeast of References and Notes as in coarser-toothed of Cape specimens Charles, Virginia (37?30'N, 74?44'W), in 1. K. O. Emery, in Colson Symp. Bristol En- mammoth and in finer-toothed gland April 1965 (Butterworths, London, woolly 46 m of water during May 1966. 1965), vol. 1. Columbian mammoths. However, the Symbos cavifrons (Leidy), PU 16340 2. By K. O. Emery, R. Wigley, A. A. Bartlett, combination of more numerous dental Left frontal and core of an extinct M. Rubin, and E. S. Barghoorn. musk ox; dredged by D. Leeds 64 km 3. W. Harrison, R. J. Malloy, G. A. Rusnak, plates and relatively low crowns shows J. Terasmae, J. Geol. 73, 201 (1965); J. C. southeast of Atlantic City, New Jersey, in A. H. J. S. continental-shelf mam- Medcof, Clarke, Jr., Erskine, that the teeth of 60 m of water; given to Princeton Uni- J. Fisheries Res. Board Can. 22, 631 (1965); moths differ from those of the species versity in 1950. A. S. Merrill, K. O. Emery, M. Rubin, Science 147, 398 (1965). described. These features could reason- scotti Lydekker, PU 16342 4. K. O. Emery, R. L. Wigley, M. Rubin, of an extinct moose- Limnol. R 97 ably belong to a elephant or to Right metacarpal Oceanog. Spec. 10, (1965). like ; dredged from Hudson Can- 5. J. M. Zeigler, S. D. Tuttle, H. J. Tasha, one that ate the coarse offered G. S. . Geol. Soc. Amer. 705 forage yon, off New York, in 160 m of water by Giese, 75, conifers. The size of the teeth in- (1964). by T. Phillips, E. Dempsey, and F. Colona; 6. J. Ewing, X. Le Pichon, M. Ewing, J. dicates that the animals were small in given to Princeton University in 1950. Geophys. Res. 68, 6303 (1963); S. T. Knott, 1480 SCIENCE, VOL. 156 H. Hoskins, R. H. Weller, Trans. Amer. 15. T. Barbour, A Naturalist's Scrapbook (Har- concentration differences in bicarbonate Geophys. Union 44, 64 (1963). vard Univ. Press, Cambridge, Mass., 1946). 7. F. P. Shepard, Essays in Marine Geology 16. H. F. Osborn, (American and carbonate. The total flux of carbon (Univ. of Southern California Press, Los Museum Press, New York, 1942), vol. 2, Angeles, 1963), vol. 1. p. 935. dioxide across such a film, which is 8. J. L. Forsyth, Ohio Conservation Bull. 27(9), 17. We thank D. Baird (Princeton University), equal to the total flux of carbon at any 16 (1963); 0. P. Hay, Carnegie Inst. Publ. W. C. Childs (Linwood, N.J.), Mrs. W. J. 322, 1 (1923); G. L. Jepsen, New Jersey Davis (White Marsh, Va.), R. F. Flint point in the film, is State Museum Bull. 6, 10, 11 (1960). ( University), J. Hahn (Woods Hole 9. W. L. W. R. M. Donn, Farrand, Ewing, Oceanographic Inst.), M. C. McKenna N37= N1 + N2 + N J. Geol. 70(2), 206 (1962). (American Museum of Natural History), (2) 10. Nobuo Ikebe, Manzo Chiji, Shiro Ishida, M. L. Milholen (Hampton, Va.), H. G. where N is mass flux J. Geosci. Osaka City Univ. 9(3), 47 (1966); Richards ( of Natural Sciences of (/sec cm2). Hiroshi Niino, personal communication, Nov. Philadelphia), A. S. Romer (Harvard Univ.), Expressions for the flux of the species 1966; specimen in at Yashima National R. L. Wigley (Bureau of Commercial Park, Takamatsu, Shikoku. Fisheries Biological Laboratory, Woods Hole, present in the film are (6) 11. J. F. de Veen Visserij-Nieuws 18(6), 187 (1965). Mass.), and Dr. and Mrs. H. E. Wood II 12. W. R. Farrand, Science 133, 729 (1961). (Cape May Court House, N.J.) for speci- 13. C. V. Haynes, Jr., ibid. 145, 1408 (1964); mens and data; and C. E. Ray, U.S. National N2=-D3= \X) J. B. Griffin, The of the United Museum, for critically reading the manu- States (Princeton Univ. Press, Princeton, script and identifying the National Museum N.J., 1965), p. 655; P. S. Martin, Nature musk-ox specimen. Contribution No. 1885 of N2 ac_ CXF al9) 212, 339 (1966). the Woods Hole Oceanographic Institution. -Dxa RT ax 14. H. G. Richards, Bull. Geol. Soc. Amer. 70(12), 1769 (1959). 25 January 1967 E N2 =- D2 (C2 2C2F a (3) Dx - RT ax

D4 + N4=-z apRT(-x ax RTa'-x Carbon Dioxide-Oxygen Separation: Facilitated Transport of where subscript 4 refers to the cations, D is diffusivity (cm2/sec), F is Fara- Carbon Dioxide across a Liquid Film day's constant in cal/volt equivalents, R is the gas constant in cal/deg mole, sp is Abstract. An immobilized of an aqueous bicarbonate-carbonate solution film electrical potential in volts, and x is more was developed which was 4100 times permeable to carbon dioxide than to distance into the film in centimeters. If was reaction-rate and thus it could oxygen. The carbon dioxide transport limited, the effect of small concentrations of be increased by addition to the film of catalysts for the hydrolysis of carbon hydrogen and hydroxide ions is dioxide. neglected, at steady state the following relations obtain The steady-state transport of carbon a porous cellulose acetate film similar dioxide across an aqueous film is in- to that made for a reverse osmosis N, + 2 N2 = 0 (4) creased if there is a concentration process for desalination (4). The mem- N4 = 0 (5) difference in bicarbonate cross the film brane contained 60 percent water; it (1). Presumably a carrier transport was 0.007 cm thick, and it had carbon and at all points in the film mechanism is operative in this process dioxide and oxygen permeabilities of C4 = C1 2 C2 as it is in the transport of oxygen in 40 X 10-9 and 2 X 10-9, respectively. + (6) aqueous hemoglobin solutions (2). The Compared with a film of pure water, If the diffusivities of bicarbonate and mechanism of facilitated carbon dioxide the effective area for permeation in the carbonate are equal, which is a good transport in bicarbonate solutions has cellulose acetate film was decreased approximation, then by differentiating not been elucidated in detail. We very roughly by a factor of 1.7; thus Eq. 6 with respect to x and combining studied the transport of carbon dioxide the diffusion coefficients were lowered it with Eqs. 3 to 5, it can be shown that across thin films of concentrated aque- approximately by a factor of 3. the potential gradient ous carbonate-bicarbonate solutions. To increase the carbon dioxide per- The work led to a better of the immobilized understanding meability liquid (7) of carbon dioxide transport in this sys- film we considered methods of estab- __0ax tem, and to the of an a difference in concentration in development lishing Thus there is no difference "immobilized" membrane which bicarbonate across the film. The rela- potential liquid across the film if the diffusivities of is selective for carbon dioxide tion at carbon highly equilibrium among bicarbonate and carbonate are and is suitable for removal of carbon and carbonate is equal. dioxide, bicarbonate, that is zero and sub- dioxide in a closed Assuming 0p/O1x life-supporting 3 into the environment. C2 = K(C)2/C3 (1) stituting Eq. Eq. 2, expres- sion for the total flux of carbon dioxide Because of its carbon dioxide where C is concentration high Cmole/cm3) N3T is solubility water is an obvious choice as and subscripts 1, 2, and 3 refer here a membrane for separation of carbon and in subsequent equations to bicar- N- D3(C2O- C3) + D1 (C1?-- C1L) dioxide and oxygen, and it has better bonate, carbonate, and carbon dioxide, L 2 L permeation characteristics for this ap- respectively. At 25?C the value of K is (8) plication than any polymeric material. approximately 1.3 X 10-4 (5). In the where superscripts 0 and L refer to the The carbon dioxide permeability of proper range of carbon dioxide con- high-pressure and low-pressure sides of pure water is 210 X 10-9 cm (STP) cm/ centrations and for bicarbonate and the film, respectively. In the following sec cm2 cm-Hg (3), and the carbon carbonate concentrations of the order discussion we assume that the diffusivi- dioxide-oxygen separation factor (ratio of moles per liter, a bicarbonate-car- ties of carbonate and bicarbonate are of carbon dioxide permeability - to bonate film across which there is par- equal. If, in fact, they differed by as oxygen permeability) is 22. For an tial pressure difference in carbon much as 20 percent, the effect on the immobilized film of water we selected dioxide may have large and opposing total flux of CO2 would be negligible, 16 JUNE 1967 1481