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1.
Giovanni Chiodini Stefano Caliro Alessandro Aiuppa Rosario Avino Domenico Granieri Roberto Moretti Francesco Parello 《Bulletin of Volcanology》2011,73(5):531-542
We describe analytical details and uncertainty evaluation of a simple technique for the measurement of the carbon isotopic
composition of CO2 in volcanic plumes. Data collected at Solfatara and Vulcano, where plumes are fed by fumaroles which are accessible for direct
sampling, were first used to validate the technique. For both volcanoes, the plume-derived carbon isotopic compositions are
in good agreement with the fumarolic compositions, thus providing confidence on the method, and allowing its application at
volcanoes where the volcanic component is inaccessible to direct sampling. As a notable example, we applied the same method
to Mount Etna where we derived a δ13C of volcanic CO2 between −0.9 ± 0.27‰ and −1.41 ± 0.27‰ (Bocca Nuova and Voragine craters). The comparison of our measurements to data reported
in previous work highlights a temporal trend of systematic increase of δ13C values of Etna CO2 from ~ −4‰, in the 1970’s and the 1980’s, to ~ −1‰ at the present time (2009). This shift toward more positive δ13C values matches a concurrent change in magma composition and an increase in the eruption frequency and energy. We discuss
such variations in terms of two possible processes: magma carbonate assimilation and carbon isotopic fractionation due to
magma degassing along the Etna plumbing system. Finally, our results highlight potential of systematic measurements of the
carbon isotopic composition of the CO2 emitted by volcanic plumes for a better understanding of volcanic processes and for improved surveillance of volcanic activity. 相似文献
2.
13C of 367 C3 herbaceous plants was measured in loess area in northern China. Their δ13C values vary between −21.7%. and −30.0%., with a mean of −26.7%.. In the center of Loess Plateau (semimoist area) with annual
precipitation of 400–600 mm, the δ13
C values of C3 herbaceous plants range from −24.4%. to −28.5%., with a mean of −27.5%.. In the west of Loess Plateau (semiarid and arid
area) with annual precipitation less than 400 mm, they range between −21.7%. and −30.0%., with a mean of −26.2%.. Annual precipitation
is the main factor that makes δ13C values of C3 herbaceous plants in the west greater than those in the central Loess Plateau. The composition of δ13C in C3 plants increases with deceasing annual precipitation, and the mean change is −49%./100 mm. 相似文献
3.
Different types of sedimentary rocks and magmatic rocks show significant variations in their boron isotopic composition, with d 11B values usually within the range of -40? 30塠1]. The boron content of the continental crust is approximately 10?0-6, with … 相似文献
4.
We present an uncertainty analysis of ecological process parameters and CO2 flux components (R
eco, NEE and gross ecosystem exchange (GEE)) derived from 3 years’ continuous eddy covariance measurements of CO2 fluxes at subtropical evergreen coniferous plantation, Qianyanzhou of ChinaFlux. Daily-differencing approach was used to
analyze the random error of CO2 fluxes measurements and bootstrapping method was used to quantify the uncertainties of three CO2 flux components. In addition, we evaluated different models and optimization methods in influencing estimation of key parameters
and CO2 flux components. The results show that: (1) Random flux error more closely follows a double-exponential (Laplace), rather
than a normal (Gaussian) distribution. (2) Different optimization methods result in different estimates of model parameters.
Uncertainties of parameters estimated by the maximum likelihood estimation (MLE) are lower than those derived from ordinary
least square method (OLS). (3) The differences between simulated Reco, NEE and GEE derived from MLE and those derived from OLS are 12.18% (176 g C·m−2·a−1), 34.33% (79 g C·m−2·a−1) and 5.4% (92 g C·m−2·a−1). However, for a given parameter optimization method, a temperature-dependent model (T_model) and the models derived from
a temperature and water-dependent model (TW_model) are 1.31% (17.8 g C·m−2·a−1), 2.1% (5.7 g C·m−2·a−1), and 0.26% (4.3 g C·m−2·a−1), respectively, which suggested that the optimization methods are more important than the ecological models in influencing
uncertainty in estimated carbon fluxes. (4) The relative uncertainty of CO2 flux derived from OLS is higher than that from MLE, and the uncertainty is related to timescale, that is, the larger the
timescale, the smaller the uncertainty. The relative uncertainties of Reco, NEE and GEE are 4%−8%, 7%−22% and 2%−4% respectively at annual timescale.
Supported by the National Natural Science Foundation of China (Grant No. 30570347), Innovative Research International Partnership
Project of the Chinese Academy of Sciences (Grant No. CXTD-Z2005-1) and National Basic Research Program of China (Grant No.
2002CB412502) 相似文献
5.
JiaZhu Li GuoAn Wang XianZhao Liu JiaMao Han Min Liu XiaoJuan Liu 《中国科学D辑(英文版)》2009,52(11):1714-1723
Variations in carbon isotopic ratios (δ
13C) of C3 plants and distribution of C4 plants were investigated along an altitudinal transect on the eastern slope of Mount Gongga, and the environmental effects
on them were discussed. It is shown that plants with C4 photosynthetic pathway mainly occur at altitudes below 2100 m a.s.l., suggesting that the low summer temperature is responsible
for the distributional pattern. In addition, δ
13C of C3 plants increases with elevation at the region above 2000 m a.s.l. with the characteristics of humid climate, and the increase
rate in δ
13C for C3 plants is about 1.3% per kilometer. Temperature determines the altitudinal trend of δ
13C. 相似文献
6.
Expeditions to Muztagata (in the eastern Pamirs) during the summer seasons of 2002 and 2003 collected precipitation samples
and measured their oxygen isotopes. The δ
18O in precipitation displays a wide range, varying from −17.40‰ to +1.33‰ in June-September 2002 and from −22.31‰ to +4.59‰
in May-August 2003. The δ
18O in precipitation correlates with the initial temperature of precipitation during the observing periods. The positive correlation
between δ
18O and temperature suggests that δ
18O can be used as an indicator of temperature in this region. The δ
18O values in fresh-snow samples collected from two snow events at different elevations on the Muztagata Glacier show a strong
“altitude effect”, with a ratio of nearly −0.40% per 100 m from 5500 m to 7450 m. 相似文献
7.
Wang Guoan Han Jiamao Zhou Liping Xiong Xiaogang Tan Ming Wu Zhenhai Peng Jun 《中国科学D辑(英文版)》2006,49(1):97-102
Carbon isotope ratios (δ
13C) of 89 C4 plant samples were determined from the loess area in North China. δ
13C values vary between −10.5‰ and −14.6‰ with a mean of −12.6‰. Along a precipitation gradient from the semi-moist area to
the semiarid area, then to the arid area, the δ
13C values of C4 plants show a slight decreasing trend. The δ
13C values of C4 plants in the dry season are found lower than those in the wet season. These trends are opposite to those observed for C3 species. 相似文献
8.
WeiHua Wu JieDong Yang ShiJin Xu GaoJun Li HongWei Yin XianCong Tao 《中国科学D辑(英文版)》2009,52(8):1059-1067
To evaluate influence of chemical weathering of the Qinghai-Tibet Plateau (QTP) on seawater 87Sr/86Sr variation, river water and sediment samples were collected, and their Sr concentrations and isotopic compositions analyzed,
from the seven large rivers that originated from the QTP. By combining these with the data of the Ganges, Brahmaputra, Indus
and Irrawaddy originated in the southern QTP, the total Sr flux of the eleven rivers reaches 3.47×109 mol·a−1, which accounts for 10.2% of the total Sr flux transported by the global rivers. The weighted mean 87Sr/86Sr is 0.71694, higher than the average value of the global rivers. The 87Srex (87Sr flux in excess of the seawater 87Sr/86Sr ratio) of the Chinese seven rivers is 1.55×106 mol·a−1, only accounting for about 6% of the value of the eleven rivers originated from QTP, and the Ganges-Brahmaputra system accounts
for 86%. We assume that the QTP rivers have no strontium contributions to the oceans before ∼40 Ma and the Sr fluxes of the
global rivers, except the QTP eleven rivers, are constant, then a maximum linear increase in Sr fluxes of the QTP rivers from
zero to the modern value in response to tectonic uplift can explain ∼69% increase of seawater 87Sr/86Sr over the past ∼40 Ma and the remainder of 31% is perhaps provided from other factors.
Supported by National Natural Science Foundation of China (Grant Nos. 40473009, 40331001, 40873001) 相似文献
9.
The sorption of Eu species onto nano-size silica-water interfaces is investigated at pH range of 1―8.5 and the initial Eu
concentrations (CEu) of 2×10−5, 2×10−4 and 2×10−3 M using fluorescence spectroscopy. The sorption rate of Eu is initially low, but significantly increases at pH > 4. For the
initial CEu of 2×10−5, 2×10−4 and 2×10−3 M, the dissolved Eu species are completely sorbed onto silica-water interfaces at pH = 4.75, −5.8 and 6.6, respectively,
with the respective sorption densities of −1.58×10−8, 1.58×10−7 and 1.58×10−6 mol/m2. The sorbed Eu species at pH < 6 is aquo Eu3+, which is sorbed onto silica-water interfaces as an outer-sphere complex at pH < 5, but may be sorbed as an inner-sphere
bidentate complex at 5 < pH < 6, due to the decrease of the NH2O to −6 at pH = 6. At pH = 6 – 8, Eu(OH)2+, Eu(CO3)+and Eu(CO3)2
− form in the solutions, and Eu(CO3)+is dominant at pH = −7.5. These ions may be sorbed onto silica-water interfaces as inner-sphere bidentate complexes or multi-nuclear
pre-cipitates. 相似文献
10.
The northeastern area of Sichuan Basin, southwestern China, is the area with the maximal reserve of natural gas containing
higher hydrogen sulphide (H2S) that has been found among the petroliferous basins of China, with the proven and controlled gas reserve of more than 200
billion cubic meters. These gas pools, with higher H2S contents averaging 9%, some 17%, are mainly distributed on structural belts of Dukouhe, Tieshanpo, Luojiazhai, Puguang,
etc., while the oolitic-shoal dolomite of the Triassic Feixianguan Fm. (T1f) is the reservoir. Although many scholars regard the plentiful accumulation of H2S within the deep carbonate reservoir as the result of Thermochemical Sulfate Reduction (TSR), however, the process of TSR
as well as its residual geological and geochemical evidence is still not quite clear. Based on the carbon isotopic analysis
of carbonate strata and secondary calcite, etc., together with the analysis of sulfur isotopes within H2S, sulphur, gypsum, iron pyrites, etc., as well as other aspects including the natural gas composition, carbon isotopes of
hydrocarbons reservoir petrology, etc., it has been proved that the above natural gas is a product of TSR. The H2S, sulphur and calcite result from the participation of TSR reactions by hydrocarbon gas. During the process for hydrocarbons
being consumed due to TSR, the carbons within the hydrocarbon gas participate in the reactions and finally are transferred
into the secondary calcite, and become the carbon source of secondary calcite, consequently causing the carbon isotopes of
the secondary calcite to be lower (−18.2‰). As for both the intermediate product of TSR, i.e. sulfur, and its final products,
i.e. H2S and iron pyrites, their sulfur elements are all sourced from the sulfate within the Feixianguan Fm. During the fractional
processes of sulfur isotopes, the bond energy leads to the 32S being released firstly, and the earlier it is released, the lower δ 34S values for the generated sulphide (H2S) or sulfur will be. However, for the anhydrite that participates in reactions, the higher the reaction degree, the more
32S is released, while the less 32S remains and the more δ 34S is increased. The testing results have proved the process of the dynamic fractionation of sulfur isotopes. 相似文献
11.
Discrimination of abiogenic and biogenic alkane gases 总被引:5,自引:0,他引:5
JinXing Dai CaiNeng Zou ShuiChang Zhang Jian Li YunYan Ni GuoYi Hu Xia Luo ShiZhen Tao GuangYou Zhu JingKui Mi ZhiSheng Li AnPing Hu Chun Yang QingHua Zhou YanHua Shuai Ying Zhang ChengHua Ma 《中国科学D辑(英文版)》2008,51(12):1737-1749
We have combined the analytical data of the carbon isotope distribution pattern, R/Ra and CH4/3He values of abiogenic and biogenic (referring to the thermogenic and bacterial or microbial) alkane gases in China with those of alkane gases from USA, Russia, Germany, Australia and other countries. Four discrimination criteria are derived from this comparative study: 1) Carbon isotopic composition is generally greater than -30‰ for abiogenic methane and less than -30‰ for biogenic methane; 2) Abiogenic alkane gases have a carbon isotopic reversal trend (δ 13C1> δ 13C2> δ 13C3> δ 13C4) with δ 13C1>-30‰ in general; 3) Gases with R/Ra >0.5 and δ 13C11 δ 13C2>0 are of abiogenic origin; 4) Gases (meth- ane) with CH4/3He≤106 are of abiogenic origin, whereas gases with CH4/3He≥1011 are of biogenic origin. 相似文献
12.
The sorption of AuCl4
−,AuCl2
− and Au(S2O3)3- on δ-MnO2 was investigated at pH2–11.6, 0.01 mol/L and 0.1 mol/L NaNO3 solutions. At pH 4 in two electrolyte strength solutions, Au sorption densities on δ-MnO2 are 0.18–0.21 and 0.28μmoL/m2 for AuCl4
− and Au(S2O3)2
3-, respectively, and the Au surface coverage is approximate to or lower than 1%. This adsorption of the two Au complexes decreases
as the solution pH increases, which conforms to the sorption regularity of the anion on δ-MnO2. The Au sorption decreases in the sequence of Au(S2O3)2
3- >AuCl4
− >AuC12
−. The intrinsic equilibrium constants (logK
int) of the three Au complexes are 1.17–2.7, much higher than those of Cu and Cd. The hydrolysis products of AuCl4
- are preferentially adsorbed by δ-MnO2 and the inner-sphere Au-surface complexes are formed on the surface.
Project supported by the National Studying-abroad Foundation, the National Natural Science Foundation of China (Grant No.
49573200) and the Australian Mining Industry. 相似文献
13.
Distribution and significance of C~_(40) alkanes in the extracts of Cretaceous source rocks from the Songliao Basin 总被引:2,自引:0,他引:2
Feng ZiHui Fang Wei Zhang JuHe Li ZhenGuang Huang ChunYan Wang Xue Zhao QinLing Huo QiuLi 《中国科学D辑(英文版)》2007,50(10):1510-1520
Source rock extracts and crude oils from the Songliao Basin were analyzed by high-temperature gas chromatography (HTGC), gas chromatography-mass spectrometry (HTGC-MS) and gas chromatography-isotope ratio-mass spectrometry (GC-IRMS), for high molecular-weight alkanes. The distributions of n-alkanes in the Nenjiang Formation extracts are in the C14―C63 range; a bimodal distribution occurs in the C-21 and C21―40 regions. The C30―C37 n-alkanes are accompanied by C29―C35 hopanes, whereas the high molecular-weight C45―C47 n-alkanes co-occur with abundant isoalkanes, alkylcyclohexanes and alkylcyclopentanes. The high δ 13C values of the n-alkanes and the microscopic maceral compositions indicate a highly diversified organic source input for the Nenjiang Formation source rocks, ranging from aquatic plants, blue alge-bacteria, to land plant material. In contrast, n-alkanes in the rock extracts of the Qingshankou Formation are characterized by a single modal distribution, with relatively low abundances of C29―C35 hopanes, but high molecular-weight isoalkanes, alkylcyclohexanes and alkylcyclopentanes. The relatively low δ 13C values of C22―C44 n-alkanes and organic material compositions indicate that the source rocks in the Qingshankou Formation contain dominantly type I algal organic matter. The relative abundance of C 40 compounds in source rocks changes little at low maturity stage, but decreases drastically at higher maturity levels, with a concurrent reduction in the odd/even carbon predominance. In crude oils, in contrast, the relative abundance of C 40 compounds appears to relate closely with the oil source and oil viscosity. 相似文献
14.
Di Chen JianPing Yuan ShiPing Xu XiaoGang Zhou Yan Zhang XiaoMing Xu ZhiWen Zou GuRen Zhang JiangHai Wang 《中国科学D辑(英文版)》2009,52(5):655-659
Two types of Hepialus larvae with different diets were distinguished in the Sejila Mountain, Tibetan Plateau based on the stable carbon isotope
data of the host Hepialus larva of Cordyceps sinensis and its closely adjacent tender plant roots and humus fractions. Type I is the larva chiefly fed by soil humus, and characterized
by the δ 13C values of −22.6‰ to −23.4‰, and more than −23.4‰ in its heads. Type II is the larva chiefly fed by tender plant roots, and
characterized by the δ 13C values of −24.6‰ to −27.6‰, and less than −24.6‰ in its heads. Our result has exceeded the traditional understanding that
their food sources only come from the tender plant roots, and may provide evidence for choosing cheap and high-quality foods
and further establishing artificial habitats in their large-scale reproduction.
Supported by the National Key Technology R & D Program (Grant No. 2007BAI32B05) 相似文献
15.
Tao Zhen Shen ChengDe Gao QuanZhou Sun YanMin Yi WeiXi Li YingNian 《中国科学D辑(英文版)》2007,50(7):1103-1114
High-resolution sampling, measurements of organic carbon contents and 14C signatures of selected four soil profiles in the Haibei Station situated on the northeast Tibetan Plateau, and application
of 14C tracing technology were conducted in an attempt to investigate the turnover times of soil organic carbon and the soil-CO2 flux in the alpine meadow ecosystem. The results show that the organic carbon stored in the soils varies from 22.12×104 kg C hm−2 to 30.75×104 kg C hm−2 in the alpine meadow ecosystems, with an average of 26.86×104 kg C hm−2. Turnover times of organic carbon pools increase with depth from 45 a to 73 a in the surface soil horizon to hundreds of
years or millennia or even longer at the deep soil horizons in the alpine meadow ecosystems. The soil-CO2 flux ranges from 103.24 g C m−2 a−1 to 254.93 gC m−2 a−1, with an average of 191.23 g C m−2 a−1. The CO2 efflux produced from microbial decomposition of organic matter varies from 73.3 g C m−2 a−1 to 181 g C m−2 a−1. More than 30% of total soil organic carbon resides in the active carbon pool and 72.8%281.23% of total CO2 emitted from organic matter decomposition results from the topsoil horizon (from 0 cm to 10 cm) for the Kobresia meadow. Responding to global warming, the storage, volume of flow and fate of the soil organic carbon in the alpine meadow
ecosystem of the Tibetan Plateau will be changed, which needs further research.
Supported by the National Natural Science Foundation of China (Grant Nos. 40231015, 40471120 and 40473002) and the Guangdong
Provincial Natural Science Foundation of China (Grant No. 06300102) 相似文献
16.
Comprehensive geochemical identification of highly evolved marine carbonate rocks as hydrocarbon-source rocks as exemplified by the Ordos Basin 总被引:2,自引:0,他引:2
Tenger 《中国科学D辑(英文版)》2006,49(4):384-396
China’s widespread marine carbonate rock series are mostly characterized by intensive thermal evolu- tion and low abundance of organic matter, especially the Lower Paleozoic carbonate rocks have experienced multi-episodes of tectonics and prolonged history of thermal evolution, thus making it more complicatedethe development and distribution of hydrocar- bon-source rocks reflected in the sedimentary, bio- logical and geochemical facies. Consequently, it seems much less powerful to assess the … 相似文献
17.
Dajing Cu-Sn-Ag-Pb-Zn ore deposit, in the Inner Mongolia Autonomous Region of China, is a fissure-filling hydrothermal ore
deposit. The δD values of quartz-hosted inclusion water are centered at −100%.– −130%.. The δ34S values of sulfide ore minerals and δ13
C values of carbonate gangue minerals vary from −0.3%. to 2.6%. and from −2.9%. to −7.0%., respectively. Integrated isotopic
data point to two major contributions to the mineralizing fluid that include a dominant meteoric-derived groundwater, and
sulfur and carbon species from hypogene magma. Linear trends are exhibited on the gaseous H2O versus CO2 plot, and plots of CO, N2, CH4, and C2H6. It is shown by quantitative simulation that magma degassing cannot explain the linear trends. Hence, these linear trends
are interpreted in terms of mixing of CO2-rich magmatic fluid with meteoric-derived groundwater. The groundwater circulated in Paleozoic sedimentary rocks and absorbed
CO, N2, CH4, C2H6 and radiogenic Ar from organic matter. Cooling effects resulting from mixing have caused the precipitation of ore minerals. 相似文献
18.
Carbon and hydrogen isotopic characteristics of natural gases from the Luliang and Baoshan basins in Yunnan Province, China 总被引:2,自引:1,他引:2
XU Yongchang LIU Wenhui SHEN Ping WANG Wanchun WANG Xiaofeng Tenger YAN Yaomin & LIU Ruobin . Lanzhou Center of Oil & Gas Resources Institute of Geology Geophsics Chinese Academy of Sciences Lanzhou China . Research Institute of Petroleum Exploration Production SINOPEC Beijing China . South Branch of Petroleum Exploration Production Company SINOPEC Kuming China 《中国科学D辑(英文版)》2006,49(9):938-946
The Luliang and Baoshan basins are two small ba- sins in Yunnan Province. In the recent ten years or so, there have been found a number of natural gas pools of commercial importance in the two basins. Although the gas pools are small in size, the natural … 相似文献
19.
The static closed chamber technique is used in the study on the CH4 and N2O fluxes from the soils of primeval Abies fabri forest, the succession Abies fabri forest and the clear-cut areas of mid-aged Abies fabri forest in the Gongga Mountain from May 1998 to September 1999. The results indicate the following: (i) The forest soil serves
as the source of atmospheric N2O at the three measurement sites, while the fluxes of CH4 are all negative, and soil is the sink of atmospheric CH4. The comparative relations of N2O emissions between the three sites are expressed as primeval Abies fabri forest < clear-cut areas < succession Abies fabri forest, and those of CH4 consumption fluxes are primeval Abies fabri forest < succession Abies fabri forest < clear-cut areas, (ii) Significant seasonal variations of N2O emission at various sites were observed, and two emission peaks of N2O occurr during summer (July—August) and spring (February—March), whereas N2O emission is relatively low in winter and spring (mid March—April). Seasonal variations of CH4 consumption at each measurement site fluctuate drastically with unclear regularities. Generally, CH4 consumption fluxes of succession Abies fabri forest and clear-cut areas are higher from mid May to late July but lower in the rest of sampling time, while the CH4 flux keeps a relatively high value even up to September in primeval Abies fabri forest. In contrast to primeval Abies fabri forest, the CH4 absorbabilities of succession Abies fabri forest and clear-cut areas of mid-aged Abies fabri forest are weaker. Particularly, the absorbability of the clear-cut areas is even weaker as compared with the other two sites,
for the deforestation reduces the soil absorbability of atmospheric CH4. (iii) Evident diurnal variation regularity exists in the N2O emissions of primeval Abies fabri forest, and there is a statistic positive correlation between the fluxes of N2O and air temperature (R=0.95, n=11, α· 0.01), and also the soil temperature of 5-cm layer (R=0.81, n=11, α> 0.01), whereas the CH4 diurnal variation regularities are unclear and have no significant correlation with the soil temperature of 5-cm layer and
air temperature. 相似文献
20.
Comparative study on CO2 sources in soil developed on carbonate rock and non-carbonate rock in Central Guizhou 总被引:1,自引:0,他引:1
In this paper, by using concentration and carbon stable isotope the CO2 sources of soil profiles developed on limestone, dolostone and claystone basements in Central Guizhou, China are comparatively
studied. The results show that CO2 concentration of soil profiles developed on different basements is different, having the following sequence: limestone ;
dolostone;claystone. Below the soil depth of 20 cm from the surface the δ13 value of CO2 in soil profile developed on limestone ranges from -12.811%. - -13.492%.(PDB), that in soil profile developed on dolostone
varys from -13.212%. - -14.271%.(PDB) and that in soil profile developed on claystone is about-20.234%. - -21.485%.(PDB).
Taking the carbon isotope of soil organic matter and carbonate rock as two isotopic endmembers, the proportion of soil CO2 generated by dissolution of carbonate rock is calculated, about 21%–25% for soil profile developed on limestone basement,
19%–21% for soil profile developed on dolostone basement. There is almost no influx of CO2 generated by the dissolution of carbonate rock in soil profile developed on claystone basement. 相似文献