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1.
Abstract

Naturally produced methane shows different δ13C-values with respect to its origin, e.g., geological or biological. Methane-production of ruminants is considered to be the dominant source from the animal kingdom. Isotopic values of rumen methane—given in literature—range between ?80‰ and -50‰ and are related to feed composition and also sampling techniques. Keeping cows, camels and sheep under identical feed conditions and sampling rumen gases via implanted fistulae we compared δPDB 13C-values of methane and CO2 between the species. Referring to mean values obtained from 4 or 5 samples at different times of 11 animals (n = 47) we calculated δPDB 13C-medians resulting in small but not significant differences within and significant differences between the species for CO2 and methane. The δPDB 13C-differences between methane and CO2 were statistically equal within and also between the species. Therefore a linear regression of methane values on CO2 is appropriate and leads to: δPDB 13C(methane)‰ = 1,57 * δPDB 13C(CO2)‰-47‰ with a correlation coefficient of r = 0,87.  相似文献   

2.
Abstract

Lower plants (algae, lichens, mosses) from the Antarctic continent have been analysed for their stable carbon isotope composition. In contrast to lichens and mosses which exhibit quite normal δ13C-values the studied microbial benthos is characterized by an extremely low carbon isotope fractionation (δ13C-values up to ?1.4‰. vs. PDB). Limited CO2 availability and bicarbonate uptake are probably the main factors responsible for this phenomenon.  相似文献   

3.
Abstract Stable isotope ((13)C, (18)O, (34)S) and trace element (Sr(2+), Mg(2+), Mn(2+), Ba(2+), Na(+)) investigations of elemental sulfur, primary calcites and mixtures of aragonite with secondary, post-aragonitic calcite from sulfur-bearing limestones have provided new insights into the geochemistry of the mineral forming environment of the native sulfur deposit at Machów (SE-Poland). The carbon isotopic composition of carbonates (δ(13)C = -41 to -47‰ vs. PDB) associated with native sulfur (δ(34)S = + 10 to + 15‰ vs. V-CDT) relates their formation to the microbiological anaerobic oxidation of methane and the reduction of sulfate derived from Miocene gypsum. From a comparison with experimentally derived fractionation factors the element ratios of the aqueous fluids responsible for carbonate formation are estimated. In agreement with field and laboratory observations, ratios near seawater composition are obtained for primary aragonite, whereas the fluids were relatively enriched in dissolved calcium during the formation of primary and secondary calcites. Based on the oxygen isotope composition of the carbonates (δ(18)O = -3.9 to -5.9‰ vs. PDB) and a secondary SrSO(4) (δ(18)O = + 20‰ vs. SMOW; δ(34)S = + 59‰ vs. V-CDT), maximum formation temperatures of 35°C (carbonates) and 47°C (celestite) are obtained, in agreement with estimates for West Ukraine sulfur ores. The sulfur isotopic composition of elemental sulfur associated with carbonates points to intense microbial reduction of sulfate derived from Miocene gypsum (δ(34)S ≈ + 23‰) prior to the re-oxidation of dissolved reduced sulfur species.  相似文献   

4.
Plitvice Lakes waters were collected at 14 sampling points, including springs, tributaries and lakes, for the period 2002-2007. The results of the physical and chemical conditions of calcite precipitation as well as the δ(13)C values of dissolved inorganic carbon (DIC) were used to study the processes influencing calcite precipitation. Significant differences between spring, lake and stream waters as well as changes in the downstream direction were observed. The correlation between δ(13)C(DIC) values and physico-chemical conditions for calcite precipitation showed that calcite precipitates in lake waters which are oversaturated with respect to CaCO(3) (I (sat) values 4-10) and with δ(13)C(DIC) values between-11.5 and-8.5 ‰. In spring waters, the δ(13)C(DIC) values were more negative, from-14 to-12 ‰, and I (sat) values of 1-2 indicated that equilibrium conditions for calcite precipitation were not attained. The downstream increase in δ(13)C(DIC) correlated with the increase in the δ(13)C values of calcite in the lake sediments, suggesting that the freshwater calcite was mainly of autochthonous origin and precipitated within the water column in isotopic equilibrium with DIC.  相似文献   

5.
Abstract

The isotopic compositions of biogenic carbon dioxide and methane from different sites were investigated. The δ13C values of methane vary mainly between ?55‰ and ?75‰ whereas δ13C values of carbon dioxide were found from about + 11‰ to ?23‰. Especially the latter ones are not so typical for microbial gases. The different sites don't vary over the whole scales but form certain groups. Secondary effects like diffusion change the δ values of both components in an even more negative direction, while oxidation processes near the surface result in more positive δ13C values for methane and very negative δ13C values for carbon dioxide.  相似文献   

6.
Abstract

Stable isotope (13C, 18O, 34S) and trace element (Sr2+, Mg2+, Mn2+, Ba2+, Na+) investigations of elemental sulfur, primary calcites and mixtures of aragonite with secondary, post-aragonitic calcite from sulfur-bearing limestones have provided new insights into the geochemistry of the mineral forming environment of the native sulfur deposit at Machów (SE-Poland). The carbon isotopic composition of carbonates (δ13C = ?41 to ?47‰ vs. PDB) associated with native sulfur (δ34S = + 10 to + 15‰ vs. V-CDT) relates their formation to the microbiological anaerobic oxidation of methane and the reduction of sulfate derived from Miocene gypsum. From a comparison with experimentally derived fractionation factors the element ratios of the aqueous fluids responsible for carbonate formation are estimated. In agreement with field and laboratory observations, ratios near seawater composition are obtained for primary aragonite, whereas the fluids were relatively enriched in dissolved calcium during the formation of primary and secondary calcites. Based on the oxygen isotope composition of the carbonates (δ18O = ?3.9 to ?5.9‰ vs. PDB) and a secondary SrSO418O = + 20‰ vs. SMOW; δ34S = + 59‰ vs. V-CDT), maximum formation temperatures of 35°C (carbonates) and 47°C (celestite) are obtained, in agreement with estimates for West Ukraine sulfur ores. The sulfur isotopic composition of elemental sulfur associated with carbonates points to intense microbial reduction of sulfate derived from Miocene gypsum (δ34S ≈ + 23‰) prior to the re-oxidation of dissolved reduced sulfur species.  相似文献   

7.
δ(13)C values of gaseous acetaldehyde were measured by gas chromatograph-combustion-isotope ratio mass spectrometer (GC-C-IRMS) via sodium bisulfite (NaHSO(3)) adsorption and cysteamine derivatisation. Gaseous acetaldehyde was collected via NaHSO(3)-coated Sep-Pak(?) silica gel cartridge, then derivatised with cysteamine, and then the δ(13)C value of the acetaldehyde-cysteamine derivative was measured by GC-C-IRMS. Using two acetaldehydes with different δ(13)C values, derivatisation experiments were carried out to cover concentrations between 0.009×10(-3) and 1.96×10(-3)?mg·l(-1)) of atmospheric acetaldehyde, and then δ(13)C fractionation was evaluated in the derivatisation of acetaldehyde based on stoichiometric mass balance after measuring the δ(13)C values of acetaldehyde, cysteamine and the acetaldehyde-cysteamine derivative. δ(13)C measurements in the derivertisation process showed good reproducibility (<0.5?‰) for gaseous acetaldehyde. The differences between predicted and measured δ(13)C values were 0.04-0.31?‰ for acetaldehyde-cysteamine derivative, indicating that the derivatisation introduces no isotope fractionation for gaseous acetaldehyde, and obtained δ(13)C values of acetaldehyde in ambient air at the two sites were distinct (-34.00?‰ at an urban site versus-31.00?‰ at a forest site), implying potential application of the method to study atmospheric acetaldehyde.  相似文献   

8.
Secondary carbonate precipitates (dripstones) formed on concrete surfaces in four different environments--Mediterranean and continental open-space and indoor environments (inside a building and in a karstic cave)--were studied. The fabric of dripstones depends upon water supply, pH of mother solution and carbonate-resulting precipitation rate. Very low δ(13)C (average-28.2‰) and δ(18)O (average-18.4‰) values showed a strong positive correlation, typical for carbonate precipitated by rapid dissolution of CO(2) in a highly alkaline solution and consequent disequilibrium precipitation of CaCO(3). The main source of carbon is atmospheric or biogenic CO(2) in the poorly ventilated karstic cave, which is reflected in even lower δ(13)C values. Statistical analysis of δ(13)C and δ(18)O values of the four groups of samples showed that the governing factor of isotope fractionation is not the temperature, but rather the precipitation rate.  相似文献   

9.
Abstract

Carbon and nitrogen stable isotope compositions of organic matter, TOC/TN ratio, and manganese concentration in a sediment core that was collected in northern part of Lake Baikal (VER92ST10-GC2, water depth at 922 m, about 3 m long) were investigated to elucidate the origin of the sedimentary organic matter and its associated environmental factors.

The sediment core was composed of mainly two parts: turbidite sections and other sections. Constant δ13C and δ15N values of the turbidite sections were observed (- 26.8 ±0.2 ‰ for δ13C and 3.2 ± 0.1 ‰ for δ15N) throughout the core. The higher δ13C in turbidite sections (about - 27 ‰) than that of the other sections (- 31 to - 29 ‰) was clearly observed, and δ15N was different between turbidite sections (about 3‰) and other sections (3 to 5 ‰). δ13C of other sections was close to that of pelagic phytoplankton, indicating that sediment other than turbidite sections is composed of autochthonous components. The variation of stable isotopes in other sections may be possibly caused by the changes in either phytoplankton growth rate or contribution ratios of terrestrial to aquatic plants for δ13C. Either denitrification or fluctuation of δ15N in pelagic phytoplankton can be the cause of variable δ15N in other sections.  相似文献   

10.
Abstract A Liquid Chromatography-Combustion (LC-C) Interface, based on a moving wire technique, has been built and tested. The LC effluent is deposited onto a transport wire, which carries the sample through solvent evaporation and combustion ovens. CO(2) from the combustion step is analysed in an isotope ratio mass spectrometer. Performance of the interface was tested by loop injections of sucrose and glucose into a liquid flow of methanol/water (80/20). Accuracy and precision of δ(13)C(PDB) < 1‰ was achieved for sample concentrations > 500 ng/ul (5μl loop), sufficient for studies at natural isotope ratios. In case of (13)C tracer applications the detection limit was determined to be about 20 pg carbon tracer (on wire).  相似文献   

11.
Abstract

We evaluated the use of δ15N- and δ13C-values to monitor the development of food web complexity and biodiversity in a regenerating ecosystem. Therefore a model food chain was established feeding cultivated woodlice (Porcellio dilatatus) on a cellulolytic fungus (Chaetomium globosum) grown on cellulose paper. Two diets of different quality (C:N ratios of 54 vs. 200) with different δ15N- (1.3‰ vs. 3.1‰) but identical δ13C-values caused low and high dietary stress in animals of treatment A and B, respectively. After an incubation time of 7 weeks amount, elemental and isotopic composition of collected faeces and exuviae as well as woodlice and remaining food were determined.

The increase of δ15N-values of woodlice relative to the diet was 5.7‰ and 2.5‰ in treatments A and B, respectively, whereas δ13C-shifts were 1.0‰ and 1.6‰, showing a reverse relationship. Modelling of elemental and isotopic mass balances indicated that faeces recycling explains the unexpected high 15N-enrichments. Moreover, 13C-enrichments were positively correlated to the degree of starvation. Considering the effects of starvation and recycling of faeces, stable isotopes represent a useful tool to elucidate trophic interactions in regenerating food webs.  相似文献   

12.
Plitvice Lakes waters were collected at 14 sampling points, including springs, tributaries and lakes, for the period 2002–2007. The results of the physical and chemical conditions of calcite precipitation as well as the δ13C values of dissolved inorganic carbon (DIC) were used to study the processes influencing calcite precipitation. Significant differences between spring, lake and stream waters as well as changes in the downstream direction were observed. The correlation between δ13CDIC values and physico-chemical conditions for calcite precipitation showed that calcite precipitates in lake waters which are oversaturated with respect to CaCO3 (I sat values 4–10) and with δ13CDIC values between?11.5 and?8.5 ‰. In spring waters, the δ13CDIC values were more negative, from?14 to?12 ‰, and I sat values of 1–2 indicated that equilibrium conditions for calcite precipitation were not attained. The downstream increase in δ13CDIC correlated with the increase in the δ13C values of calcite in the lake sediments, suggesting that the freshwater calcite was mainly of autochthonous origin and precipitated within the water column in isotopic equilibrium with DIC.  相似文献   

13.
Abstract The groundwaters studied and labelled as mineral water were "natural mineral waters" for bottled waters and "natural curative waters" for heal therapeutical applications. They were characterized either by a specific mineralization or their suitability for balneology. To reveal the actual hydrological situation isotope investigations using (2)H, (18)O, (3)H, (12)C and (14)C (DIC) and (34)S (sulphate) were included in a study describing samples of 24 mineral water deposits in Saxonia. The water was classified into 4 hydrochemical types of genesis. Due to different hydrogeological and hydrochemical situations widely scattered isotope ratios were measured. Most of the investigated mineral waters are containing at least parts of younger waters (with residence times less than about 40 years). Correlations between chemical composition and the tritium content could be observed within different springs from the areas Bad Brambach, Bad Elster and Burkhardswalde. Strong variations in δ(34)S were found in samples with low sulphate content, showing different sulphur sources, as well as microbiological reactions. On the other hand mineral waters from Bad Brambach and Bad Elster show nearly the same δ(34)S value of about 6‰ CDT despite beeing of a different chemical type. The δ(13)C values between -22 and -2.2y PDB are related to different sources of CO(2).  相似文献   

14.
单个流体包裹体同位素在研究岩矿古流体成因、矿床、油气和大地构造演化动力学等多个领域具有十分重要的意义,激光拉曼光谱是一项可以分析单个流体包裹体同位素的有效方法。本文提出应用显微激光拉曼光谱法来计算CO_2气体碳同位素值δ~(13)C。利用自行设计的装置将~(12)CO_2和~(13)CO_2按比例分别与N2混合,对混合气体样品进行显微激光拉曼测试分析后确定~(12)CO_2和~(13)CO_2的拉曼参数,这为用激光拉曼分析碳同位素值δ~(13)C奠定了理论基础。通过对不同比例的~(12)CO_2/~(13)CO_2人工合成CO_2包裹体样品和胜利油田CO_2天然气藏样品进行激光拉曼光谱分析,发现CO_2气体碳同位素摩尔分数比N_(13)/N_(12)与拉曼参数之间存在数学关系式,由此建立了根据碳同位素计算公式δ~(13)C=[(C_(13)/C_(12))_(样品)/(C_(13)/C_(12))_(标准)-1]×1 000‰,用激光拉曼分析获得的CO_2气体有关激光拉曼参数来计算δ~(13)C值的方法。按照该方法,应用显微激光拉曼光谱对胜利油田CO_2天然气藏样品分析计算其δ~(13)C值为-5.318‰,与用质谱仪分析测出的δ~(13)C值(-5.6‰)比较,其相对误差较小(≈5%),可以初步建立起应用显微激光拉曼光谱测定CO_2气体碳同位素值δ~(13)C的定量方法。  相似文献   

15.
We first measured the δ(13)C and δ(15)N values of root holoparasite Cynomorium songaricum and its hosts from 19 sites across four provinces in northwest China, in an attempt to investigate their nutritional relationship at the Tibetan plateau and the surrounding Gobi desert. Our study showed that the δ(13)C of C. songaricum closely mirrored the values of its hosts, Nitraria tangutorum and N. sibirica across all sampling sites. C. songaricum was significantly depleted in (13)C compared to host plants at the Tibetan plateau, showing an average parasite/host δ(13)C difference of-0.6?‰. In contrast, (15)N of C. songaricum was significantly enriched by+1.3?‰ compared to the hosts, implying that these holoparasites had other nitrogen resources. Although no difference in the δ(13)C and δ(15)N values between holoparasites and hosts was detected, the δ(13)C and δ(15)N values of holoparasites were significantly correlated with those of their hosts at the Gobi desert. The δ(13)C versus δ(15)N values were significantly but negatively correlated for the hosts; however, holoparasite/host variation in δ(13)C was not correlated with the variation in δ(15)N. The δ(13)C versus δ(15)N values were negatively correlated in C. songaricum, and this relationship tended to be magnified along the increasing elevations independent of the host plants. C. songaricum at the Tibetan plateau exhibited different δ(13)C and δ(15)N signatures compared with those at the Gobi desert. Furthermore, both δ(13)C and δ(15)N values of C. songaricum and its host plants in salt marshes at the Tibetan plateau were different from those in sand sites at the Tibetan plateau and the Gobi desert. Our results indicate that the isotopic difference depends on the different altitudes and habitats and is host-specific.  相似文献   

16.
δ13C and δ18O values from sapwood of a single Pinus uncinata tree, from a high elevation site in the Spanish Pyrenees, were determined to evaluate the differences between whole wood and resin-free whole wood. This issue is addressed for the first time with P. uncinata over a 38-year long period. Results are also compared with published isotope values of α-cellulose samples from the same tree. The differences in δ13C and δ18O between whole wood and resin-free whole wood vary within the analytical uncertainty of 0.3 and 0.5?‰, respectively, indicating that resin extraction is not necessary for sapwood of P. uncinata. Mean differences between cellulose and whole wood are 0.9?‰ (δ13C) and 5.0?‰ (δ18O), respectively. However, further analyses of different species and other sites are needed to evaluate whether the findings reported here are coherent more generally.  相似文献   

17.
Abstract We report preliminary results of our provenance study of marble from the Telephos Frieze of the Pergamon altar. The emphasis here is on the stable isotope geochemistry of marble. The obtained δ(13)C values (2.4 to 3.5‰) vary insignificantly. However, the δ(18)O values give two clusters. The isotopically light marbles (close to -9.5‰) derive from panels 1-8 and the heavy marbles (-3.5 to -1.0‰) derive from panels 11-50. Mineralogical, petrographic and geochemical investigations (accessory minerals, grain size distribution, rare earth elements) further refined the marble characteristics. In spite of certain differences observed (grain size distributions, isotopy and contents of certain elements) for the two marble groups, the present data support a common provenance. So far, east Aegean islands and the Marmara region are favored.  相似文献   

18.
Tracers can be used to monitor emissions of leachate from landfills in order to detect hydrological pathways and to evaluate environmental pollution. We investigated the stable carbon isotope ratio (δ13C–Σ CO 2) in dissolved inorganic carbon and tritium (3H) in water, in addition to the tracers of pollution commonly found in relatively high concentrations in leachate, such as chloride (Cl), organic matter (COD), nitrogen (total and NH4–N), iron (Fe), electrical conductivity (EC) and pH. The sampling was performed at seven landfills in the south-eastern part of Norway during a period of 5 years. The objective was to evaluate the potential for tracing leachate in the environment with emphasis on groundwater pollution. By measuring the δ13C–Σ CO 2 in leachates, groundwaters and surface waters, the influence of leachate can be identified. The value of δ13C–Σ CO 2 varied from?5.5 to 25.9 ‰ in leachate, from?25.4 to 14.7 ‰ in groundwater and from?19.7 to?13.1 ‰ in creeks. A comparison of the carbon isotope ratio with COD, EC and the concentrations of total and NH 4–N, Cl and Fe showed that δ13C–Σ CO 2 is a good tracer for leachate due to higher sensitivity compared to other parameters. The mean concentrations of all the studied parameters were higher in the leachate samples; however, only the carbon isotope ratio showed significant differences between all the groups with strong and middle pollution and samples with low pollution, showing that it can be used as a convenient tracer for leachate in groundwater and surface water. The carbon isotope ratio showed strong correlation between nitrogen, EC and bicarbonate, but not with pH. Tritium was only sporadically found in measureable concentrations and is not considered as a suitable tracer at the sampled locations.  相似文献   

19.
A survey study was conducted on man-made plantations located at two different areas in the arid region of Syria to determine the variations in natural abundances of the 15N and 13C isotopes in leaves of several woody legume and non-legume species, and to better understand the consequence of such variations on nitrogen fixation and carbon assimilation. In the first study area (non-saline soil), the δ15N values in four legume species (Acacia cyanophylla,?1.73 ‰ Acacia farnesiana,?0.55 ‰ Prosopis juliflora,?1.64 ‰; and Medicago arborea,+1.6 \textperthousand) and one actinorhizal plant (Elaeagnus angustifolia,?0.46 to?2.1 ‰) were found to be close to that of the atmospheric value pointing to a major contribution of N2 fixing in these species; whereas, δ15N values of the non-fixing plant species were highly positive. δ13C ‰; in leaves of the C3 plants were found to be affected by plant species, ranging from a minimum of?28.67 ‰; to a maximum of?23 ‰. However, they were relatively similar within each plant species although they were grown at different sites. In the second study area (salt affected soil), a higher carbon discrimination value (Δ13C ‰) was exhibited by P. juliflora, indicating that the latter is a salt tolerant species; however, its δ15N was highly positive (+7.03 ‰) suggesting a negligible contribution of the fixed N2. Hence, it was concluded that the enhancement of N2 fixation might be achieved by selection of salt-tolerant Rhizobium strains.  相似文献   

20.
Using a theoretical model and mass isotopic balance, biogas (methane and CO2) released from buried products at their microbial degradation was analysed in the landfill of municipal and non-toxic industrial solid organic waste near Kaluga city, Russia. The landfill contains about 1.34×106 tons of waste buried using a ‘sandwich technique’ (successive application of sand–clay and waste layers). The δ13C values of biogenic methane with respect to CO2 were?56.8 (±2.5) ‰, whereas the δ13C of CO2 peaked at+9.12‰ (+1.4±2.3‰ on average), reflecting a virtual fractionation of carbon isotopes in the course of bacterial CO2 reduction at the landfill body. After passing through the aerated soil layers, methane was partially oxidised and characterised by δ13C in the range of?50.6 to?38.2‰, evidencing enrichment in 13C, while the released carbon dioxide had δ13C of?23.3 to?4.04‰, respectively. On the mass isotopic balance for the δ13C values, the methane production in the landfill anaerobic zone and the methane emitted through the aerated landfill surface to the atmosphere, the portion of methane oxidised by methanotrophic bacteria was calculated to be from 10 to 40% (averaged about 25%). According to the theoretical estimation and field measurements, the annual rate of methane production in the landfill reached about 2.9(±1.4)×109 g C CH4 yr?1 or 5.3(±2.6)×106 m3 CH4 yr?1. The average rates of methane production in the landfill and methane emission from landfill to the atmosphere are estimated as about 53 (±26) g C CH4 m?2 d?1 (or 4 (±2) mol CH4 m?2 d?1) and 33 (±12) g C CH4 m?2 d?1 (or 2.7 (±1) mol CH4 m?2 d?1), respectively. The calculated part of methane consumed by methanotrophic bacteria in the aerated part of the landfill was 13(±7) g C CH4 m?2 d?1 (or 1.1(±0.6) mol CH4 m?2 d?1) on average.  相似文献   

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