THE QUESTION OF INCREASE O F ATMOSPHERIC COP Table 3. Amount of carbon, computed as CO,, in sedimentary rocks, hydrosphere, atmosphere and bioaphere from data given by RUBEY (1951). HUTCHINSON (1954), and SVERDRUP et al. (1942) system in equilibrium, the following relation holds by definition : t (sea) kl -=-=-. t Total on Earth: 1o18 gms 21 (atm) k, So A, In units t (sea), the average lifetime of a carbon atom as a member of the marine reservoir, is equal to the average apparent C14 age of marine Carbonate in sediments. .. 67,000 28,500 material. Organic carbon insediments ~5.000 I 0,600 I CO, in the atmosphere (A,) An apparent C14 age of marine material is 2.31 0.i Living matter on Iand'. ... 0.3 obtained by comparison of the CX4activity Dead organic matter on with that of a wood standard corrected for 1.1 2.6 land. ................. isotopic fractionation effects in nature or in the CO, +H&O. in oceana .... 0.8 0.3 CO, as HCO; in ocean* . . laboratory by mass spectrometric measurement 48.7 114.7 CO, as C q in ocean, .... 6.c 14.2 of the C13/C12 ratios. In marine carbonate the Total inorganic carbon in C13/C12 ratio is about 2.5 % higher than in ocean.. ............... 129.7 55.c land plants (NIERand GULBRANSEN, 1939 and Dead organic matter in ocean ................. I0 CRAIG 1953, 1954). Because of the double 4.4 Living organic matter in mass difference the effect for C14 should be 0.c 0.0 ocean ................. twice as large as that for C13, if the isotopic Total carbon in ocean (So) 59. 140 distribution is established sufficiently rapidly so 1 Living organic matter on land estimated that radioactive decay of C14 can be neglected. from assays of standing timber in the world': If, after normalizing to equal C13/C12ratios, forests. 30 yo of land surface is relatively thick a lower C14 concentration is found than that forest, averaging about 5,000 board feet/acre 0' of the wood standard, then t h i s difference is commercial size timber or 0.26 gm COl/cm! of forest. Assuming that total living matter ir attributed here to the effect of radioactivity, forests is twice the amount of timber, and thai and is ex ressed as apparent age. A detailed other components of the biosphere are l/a 0: study o f t e expected relationship between the total gives 0.34 x id8gm CO, in land biosphere isotopic fractionation factors for C'3 and C14 * Carbon dioxide components in sea water art assumed t o be in equilibrium with a CO, partia in the bio-geochemical cycle of carbon has pressure of 3 x 10-* atmospheres; chlorinity been made by CRAIG(1954). 20 X;temperature: 10' C: alkalinity: 2.46X 10-: Assuming from the then available C14 meq/L. Under these conditions p H = 8.18 measurements that shell and wood have the Volume of the Ocean = 1-37x 1oZ4cma. This i! probably an underestimate, because the watei same specific C14 activi? CRAIG (1954) below the thermocline contains CO, produced attributed this unexpecte result to slow by oxidation of organic matter, and the averagt transfer of CO, across the ocean-atmosphere temperature of the ocean is somewhat less thar interface resulting in a radiocarbon age of 400 10' c. years for surface ocean bicarbonate. Since then, more precise C14 measurements, supplemented irough the sea-air interface, if assumptions are by mass s ectroscopic C13 determinations, have made with respect to mixing rates of the water been pub 'shed by SUESS(1954,1955)and by (1955)(see also HAYESET AL., 1955). masses in the oceans: (a) the apparent C14 age RAFTER of marine materials and (b) the effects of The standard error of about 0.5 % corresponds industrial coal combustion on the C14 con- to an uncertainty in the age values of about centration in the atmosphere (SUBSS1953). 40 years. The apparent ages calculated from the Experimental data on these two subjects are published measurements are as follows: inadequate for rigorous quantitative interpretaAtlantic: (SUESS,1954). tion but are sufficiently accurate to allow Mercenaria mercenaria Shells 440 yrs. estimates of the order of magnitude of the rate Nantucket sound (from under constant for the exchange. 45 ft of water) Flesh 540 yrs. Considering the combined marine and Sargassum weed from sea suratmospheric carbon reservoir as a closed face, 36'24' N, 69'37' W 320 yrs. of A, K P, Telfus IX (1957). 1