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1.
Fine-grained diamonds, the most abundant form of circumstellar dust isolated from primitive meteorites, have elemental and isotopic characteristics that are dependent on the host meteorite type. Carbon isotopic compositions vary from -32 to -38 per mil, and nitrogen associated with the diamond changes in overall abundance by over a factor of four from 0.2 to 0.9 weight percent, between ordinary and CM2-type chondrites. Although the ratio of carbon to nitrogen evolves in a distinctive way during combustion of diamond separates, metamorphic degassing of nitrogen is not the main cause of the differences in nitrogen content. The data suggest that intrinsic differences must have been inherited by the diamonds at the time of their formation and that the diamonds were distributed heterogeneously in the solar nebula during condensation. However, the hypothesis that a distinct nitrogen carrier remains hidden within the diamond cannot be ruled out. 相似文献
2.
Lunar rock 66095 contains a hydrated iron oxide and has an unusual amount of water for a lunar rock (140 to 750 parts per million), 90 percent of which is released below 690 degrees C. The deltaof water released at these low temperatures varies from -75 to -140 per mil relative to standard mean ocean water (SMOW). The small amount of water released between 690 degrees and 1300 degrees C has a delta of about -175 +/-25 per mil SMOW. These delta values are not unusual for terrestrial water. The delta(18)O of water extracted from 110 degrees to 400 degrees C has a value of +5+/- I per mil SMOW, similar to the value for lunar silicates from rock 66095 and different from the value of -4 to -22 per mil found for samples of terrestrial rust including samples of rusted meteoritic iron. The amount of carbon varies from 11 to 59 parts per million with a delta(13)C from -20 to -30 per mil relative to Pee Dee belemnite. Only very small amounts of reduced species (such as hydrogen, carbon monoxide, and methane) were found, in contrast to the analyses of other lunar rocks. Although it is possible that most of the water in the iron oxide (goethite) may be terrestrial in origin or may have exchanged with terrestrial water during sample return and handling, evidence presented herein suggests that this did not happen and that some lunar water may have a deltaD that is indistinguishable from that of terrestrial water. 相似文献
3.
Oró J Updegrove WS Gibert J McReynolds J Gil-Av E Ibanez J Zlatkis A Flory DA Levy RL Wolf C 《Science (New York, N.Y.)》1970,167(3918):765-767
Organogenic elements, mainly carbon, nitrogen, phosphorus, and sulfur are present in the particulate material and in a breccia rock from Tranquillity Base in amounts ranging from 5 to 4200 parts per million. The major compounds of carbon released by heating are carbon monoxide and carbon dioxide; the former predominates. Small amounts of other compounds of carbon have also been observed. Sulfur can be released as hydrogen sulfide by treatment with acid. The carbon isotopic delta(13L)C values are definitely nonterrestrial (+ 13 to + 18.5 per mil). 相似文献
4.
Friedman I O'neil JR Adami LH Gleason JD Hardcastle K 《Science (New York, N.Y.)》1970,167(3918):538-540
The water content of the breccia is 150 to 455 ppm, with a deltaD from-580 to -870 per mil. Hydrogen gas content is 40 to 53 ppm with a deltaD of -830 to -970 per mil. The CO(2) is 290 to 418 ppm with delta (13)C = + 2.3 to + 5.1 per mil and delta(18)O = 14.2 to 19.1 per mil. Non-CO(2) carbon is 22 to 100 ppm, delta(13)C = -6.4 to -23.2 per mil. Lunar dust is 810 ppm H(2)O (D = 80 ppm) and 188 ppm total carbon(delta(13)C = -17.6 per mil). The (18)O analyses of whole rocks range from 5.8 to 6.2 per mil. The temperature of crystallization of type B rocks is 1100 degrees to 1300 degrees C, based on the oxygen isotope fractionation between coexisting plagioclase and ilmenite. 相似文献
5.
Chang S Kvenvolden K Lawless J Ponnamperuma C Kaplan IR 《Science (New York, N.Y.)》1971,171(3970):474-477
Total carbon in the Apollo 12 sample 12023 fines was 110 micrograms per gram of sample with a carbon isotopic abundance delta(13)C (relative to the Pee Dee belemnite standard) of +12 per mil. Hydrolysis of the fines with deuterium chloride yielded undeuterated methane along with deuterated hydrocarbons, thus confirming the presence of 7 to 21 micrograms of carbon per gram of sample as carbide and about 2 micrograms of carbon per gram of sample as indigenous methane. After vacuum pyrolysis of the fines to 1100 degrees C the following gases were detected in the relative abundance: carbon monoxide carbon dioxide methane. Variations of the delta(13)C value with the pyrolysis temperature indicated the presence of carbon with more than one range of isotopic values. The observed delta(13)C value of +14 per mil for lunar carbide is much higher than that of carbide in meteorites. These results suggest that lunar carbide is either indigenous to the moon or a meteoritic contribution that has been highly fractionated isotopically. 相似文献
6.
The stable-carbon isotope ratios for the flesh of marine and terrestrial animals from Canada's Pacific coast differ by 7.9 +/- 0.4 per mil, reflecting the approximately 7 per mil difference between oceanic and atmospheric carbon. This difference is passed on to human consumers. The carbon isotopic values (delta(13)C) for human collagen thus yield direct information on the relative amounts of marine and terrestrial foods in prehistoric diets. 相似文献
7.
Schoell M Schouten S Damsté JS de Leeuw JW Summons RE 《Science (New York, N.Y.)》1994,263(5150):1122-1125
The difference in carbon-13 ((13)C) contents of hopane and sterane biomarkers in the Monterey formation (Naples Beach, California) parallels the Miocene inorganic record of the change in (18)O (delta(18)O), reflecting the Miocene evolution from a well-mixed to a highly stratified photic zone (upper 100 meters) in the Pacific. Steranes (delta(13)C = 25.4 +/- 0.7 per mil versus the Pee Dee belemnite standard) from shallow photic-zone organisms do not change isotopically throughout the Miocene. In contrast, sulfur-bound C(35) hopanes (likely derived from bacterial plankton living at the base of the photic zone) have systematically decreasing (13)C concentrations in Middle and Late Miocene samples (delta(13)C = -29.5 to -31.5 per mil), consistent with the Middle Miocene formation of a carbon dioxide-rich cold water mass at the base of the photic zone. 相似文献
8.
Eclogitic diamonds have a large range of delta13C values, whereas peridotitic diamonds do not. Paired delta15N-delta13C-N variations in 40 eclogitic diamonds from the Jwaneng kimberlite in Botswana show that neither the influence of recycled biogenic carbon nor the global and primordial heterogeneity of mantle carbon are likely for the origin of the large delta13C range; the data instead support a fractionation process. It is proposed that carbonatitic mantle melts from which diamonds crystallize undergo different evolutions before diamond precipitation, when percolating through either a peridotite or an eclogite. These different evolutions, reflecting the presence or absence of olivine, can account for their respective delta13C distributions. 相似文献
9.
Analyses of stable carbon isotopes from two sample suites from sandstone uranium (tabular) ores show interesting variations. Organic carbon associated with high-grade uranium ore is heavy (delta(13)C = -16.9 to -19.6 per mil, where delta(13)C = (13)C/(12)C relative to the Pee Dee belemnite standard) relative to the adjacent lower-grade samples (-22.7 to -26.4 per mil). It is suggested that the heavy isotopic values for the are samples are related to a radiation and chemical isotope effect that has occurred mainly because of an alpha-radiation dose of 10(11) rads. 相似文献
10.
Seven carbonaceous chondrites have been analyzed for soluble organic compounds, carbonate, and residual carbon. Carbon-13/carbon-12 isotopic mneasurements on these fractions gave the following values relative to a marine carbonate standard: carbonate, +40 to +70 per mil; residual carbon, -15 to -17 per mil; soluble organic material, -17 to -27 per mil, with one value of -5.5 per mil. These values are interpreted to indicate that carbonate, residual carbon, and part of the extractable organic material are endogenous to these meteorites. 相似文献
11.
The Murchison and Allende chondrites contain up to 5 parts per million carbon that is enriched in carbon-13 by up to + 1100 per mil (the ratio of carbon-12 to carbon-13 is approximately 42, compared to 88 to 93 for terrestrial carbon). This "heavy" carbon is associated with neon-22 and with anomalous krypton and xenon showing the signature of the s-process (neutron capture on a slow time scale). It apparently represents interstellar grains ejected from late-type stars. A second anomalous xenon component ("CCFXe") is associated with a distinctive, light carbon (depleted in carbon-13 by 38 per mil), which, however, falls within the terrestrial range and hence may be of either local or exotic origin. 相似文献
12.
Measurements of stomatal density and delta(13)C of limber pine (Pinus flexilis) needles (leaves) preserved in pack rat middens from the Great Basin reveal shifts in plant physiology and leaf morphology during the last 30,000 years. Sites were selected so as to offset glacial to Holocene climatic differences and thus to isolate the effects of changing atmospheric CO(2) levels. Stomatal density decreased approximately 17 percent and delta(13)C decreased approximately 1.5 per mil during deglaciation from 15,000 to 12,000 years ago, concomitant with a 30 percent increase in atmospheric CO(2). Water-use efficiency increased approximately 15 percent during deglaciation, if temperature and humidity were held constant and the proxy values for CO(2) and delta(13)C of past atmospheres are accurate. The delta(13)C variations may help constrain hypotheses about the redistribution of carbon between the atmosphere and biosphere during the last glacial-interglacial cycle. 相似文献
13.
Values of the oxygen isotope ratios (delta(18)O) in tree-ring cellulose closely reflect the delta(18)O values in atmospheric precipitation and hence mean annual temperature. The change in delta(18)O in cellulose is 0.41 per mil per degree Celsius for selected near-coastal stations. The values of delta(18)O in precipitation and cellulose also change with altitude, as demonstrated for Mount Rainier, Washington. A temperature lapse rate of 5.2 degrees +/- 0.5 degrees C per 1000 meters calculated from cellulose delta(18)O values agrees with the accepted mean annual lapse rate of 5 degrees C per 1000 meters for this region. Cellulose delta(18)O values and delta(18)O values of carbon dioxide equilibrated with leaf water differ by a fixed 16 per mil. 相似文献
14.
Reduced carbon in early Precambrian cherts of the Fig Tree and upper and middle Onverwacht groups of South Africa is isotopically similar (the average value of delta(13)C(PDB) is -28.7 per mil) to photosynthetically produced organic matter of younger geological age. Reduced carbon in lower Onverwacht cherts (Theespruit formation) is anomalously heavy (the average value of delta(13)C(PDB) is -16.5 per mil). This discontinuity may reflect a major event in biological evolution. 相似文献
15.
Earlier workers have described a submarine gas seep in Norton Sound having an unusual mixture of petroleum-like, low-molecular-weight hydrocarbons. Actually, only about 0.04 percent of the seeping gas is hydrocarbons and 98 percent is carbon dioxide. The isotopic compositions of carbon dioxide (delta(13)C(PDB) = -2.7 per mil) and methane (delta(13)C(PDB) = -36 per mil, where PDB is the Peedee belemnite standard) indicate that geothermal processes are active here. 相似文献
16.
Gilmour I Russell SS Arden JW Lee MR Franchi IA Pillinger CT 《Science (New York, N.Y.)》1992,258(5088):1624-1626
One hypothesis for the origin of the nanometer-size diamonds found at the Cretaceous-Tertiary (K-T) boundary is that they are relict interstellar diamond grains carried by a postulated asteroid. The (13)C/(12)C and (15)N/(14)N ratios of the diamonds from two sites in North America, however, show that the diamonds are two component mixtures differing in carbon and nitrogen isotopic composition and nitrogen abundance. Samples from a site from Italy show no evidence for either diamond component. All the isotopic signatures obtained from the K-T boundary are material well distinguished from known meteoritic diamonds, particularly the fine-grain interstellar diamonds that are abundant in primitive chondrites. The K-T diamonds were most likely produced during the impact of the asteroid with Earth or in a plasma resulting from the associated fireball. 相似文献
17.
The variability of the carbon-13/carbon-12 ratio in honeys was evaluated preliminary to use of the ratio to detect the addition of high-fructose corn syrup to honey. Eighty-four honey samples representing 34 states and including 37 floral types from 17 plant families were analyzed. The mean value of the per mil increment in carbon-13 (delta13C) for all samples is -25.2 per mil, and the coefficient of variation is 3.7 percent. This is the smallest variation yet encountered for a honey constituent or physical property. The range and magnitude of the values suggest that the floral sources are C(3) plants. 相似文献
18.
Rau G 《Science (New York, N.Y.)》1978,201(4359):901-902
Plankton (larger than 76 micrometers) taken from an undisturbed oligotrophic was found to have delta(13)C values (=(13)/(12)C relative to the Pee Dee be- belemnite standard) rangingfrom -44 to -47 per mil. This extraordinary (13)C depletion, together with characteristics of the inorganic carbon pool, indicates that lake respiration as well as surrounding soil respiration provide important carbon sources for plankton production in this lake. 相似文献
19.
Brooks JM Kennicutt MC Fisher CR Macko SA Cole K Childress JJ Bidigare RR Vetter RD 《Science (New York, N.Y.)》1987,238(4830):1138-1142
Mussels, clams, and tube worms collected in the vicinity of hydrocarbon seeps on the Louisiana slope contain mostly "dead" carbon, indicating that dietary carbon is largely derived from seeping oil and gas. Enzyme assays, elemental sulfur analysis, and carbon dioxide fixation studies demonstrate that vestimentiferan tube worms and three clam species contain intracellular, autotrophic sulfur bacterial symbionts. Carbon isotopic ratios of 246 individual animal tissues were used to differentiate heterotrophic (8(13)C = -14 to -20 per mil), sulfur-based (8(13)C = -30 to -42 per mil), and methane-based (8(13)C = <-40 per mil) energy sources. Mussels with symbiotic methanotrophic bacteria reflect the carbon isotopic composition of the methane source. Isotopically light nitrogen and sulfur confirm the chemoautotrophic nature of the seep animals. Sulfur-based chemosynthetic animals contain isotopically light sulfur, whereas methane-based symbiotic mussels more closely reflect the heavier oceanic sulfate pool. The nitrogen requirement of some seep animals may be supported by nitrogen-fixing bacteria. Some grazing neogastropods have isotopic values characteristic of chemosynthetic animals, suggesting the transfer of carbon into the background deep-sea fauna. 相似文献
20.
Schaefer H Whiticar MJ Brook EJ Petrenko VV Ferretti DF Severinghaus JP 《Science (New York, N.Y.)》2006,313(5790):1109-1112
We report atmospheric methane carbon isotope ratios (delta13CH4) from the Western Greenland ice margin spanning the Younger Dryas-to-Preboreal (YD-PB) transition. Over the recorded approximately 800 years, delta13CH4 was around -46 per mil (per thousand); that is, approximately 1 per thousand higher than in the modern atmosphere and approximately 5.5 per thousand higher than would be expected from budgets without 13C-rich anthropogenic emissions. This requires higher natural 13C-rich emissions or stronger sink fractionation than conventionally assumed. Constant delta13CH4 during the rise in methane concentration at the YD-PB transition is consistent with additional emissions from tropical wetlands, or aerobic plant CH4 production, or with a multisource scenario. A marine clathrate source is unlikely. 相似文献