In the late 1980s the introduction of a new isotopic analytical technique of GC-C-MS that can determine the carbon isotopic composition at the molecular level has led to the appearence of the stable carbon isotopic ge...In the late 1980s the introduction of a new isotopic analytical technique of GC-C-MS that can determine the carbon isotopic composition at the molecular level has led to the appearence of the stable carbon isotopic geochemistry of biomarker compounds as a new field of scientific research. The relationship between the carbon isotopic compositions of biomarker compounds and biological precursors and diagenetic evolution is one of the key problems in this research field. Some studies on this problem have been carried out abroad in terms of organisms and modern sediments as well as the experiments of thermal simulation. Studied results show that the carbon isotopic compositions of biomarker compounds in the sediments are closely related to those in biological precursors and diagenetic evolution. For example, Reiley et al. have examined the carbon展开更多
The molecular compositions and com- pound-specific carbon isotope compositions of indi- vidual long-chain n-alkanes of atmospheric aerosols collected during two severe Asian dust episodes in Qingdao in spring of 2002 ...The molecular compositions and com- pound-specific carbon isotope compositions of indi- vidual long-chain n-alkanes of atmospheric aerosols collected during two severe Asian dust episodes in Qingdao in spring of 2002 were analyzed using gas chromatography/mass spectrometry (GC/MS) and gas chromatography/isotope ratio mass spectrometry (GC/IRMS). Typical plant wax n-alkanes (C29 and C31) had lower δ 13C values than those from anthropo- genic (engine exhaust) sources (C21―C23). The av- erage δ 13C value of plant wax n-alkane C29 in non-dust episode periods was -30.5‰ (?30.3‰― ?31.9‰), while -31.3‰ (?31.1‰―?31.5‰) in dust episode periods; for C31, it was ?31.4‰ (?31.1‰― ?33.0‰) in non-dust episode periods, and ?31.7‰ (?31.3‰―?32.6‰) in dust episode periods. Plant wax in the dust episode samples was mainly from herbaceous plants via long-range transport, while local plant wax was mainly from deciduous plants and woody plants. In North China coast, 83.3% of the plant wax in the severe dust episode samples was from C3 plants while 80.0% for the non-dust samples, indicating that plant wax transported to the north- western Pacific Ocean by airborne dust from East Asia was mainly from C3 plants. The results suggestthat the molecular and molecular-isotopic composi- tions of individual long-chain n-alkanes can, as an effective indicator, identify the terrestrial organic components in the dust from East Asia and sedi- ments in the northwest Pacific Ocean.展开更多
Carbon isotopes are measured for individual long-chain n-alkanes in sediments from the Nansha Sea. The features of carbon isotopic compositions of individual n-alkanes and their origins are studied. The results show t...Carbon isotopes are measured for individual long-chain n-alkanes in sediments from the Nansha Sea. The features of carbon isotopic compositions of individual n-alkanes and their origins are studied. The results show that the long-chain n-alkanes have a light carbon isotopic composition and a genetic feature of mixing sources, and low-latitude higher plants and microbes are considered to be their main end member sources. Based on the abundances and carbon isotopic compositions of individual n-alkanes, the fractional contributions of the two end member sources to individual n-alkanes are quantitatively calculated by using a mixing model. The obtained data indicate that the fractional contributions of the two biological sources are different in the three samples. A trend is that the contribution of microbes increases with the depth. These results provide the theory basis and quantitatively studied method for carbon isotopic applied research of individual n-alkanes.展开更多
The carbon isotopes of individual lipids in herbaceous plants and tree leaves in Ruoergai marsh were measured by the GC-IRMS analytical technique in order to understand the inherent relationships of carbon isotopes be...The carbon isotopes of individual lipids in herbaceous plants and tree leaves in Ruoergai marsh were measured by the GC-IRMS analytical technique in order to understand the inherent relationships of carbon isotopes between sedimentary and plant lipids from typical marsh environment. The analytical results show that the carbon isotopic compositions of n-alkanes in different kinds of plants differ significantly. Mean δ 13C values of n-alkanes in her-baceous plants (?32.2‰―?36.9‰) are 3.3‰ lower than those in woody plant (?27.2‰― ?35.0‰). The carbon isotopic compositions of fatty acids in organisms (?30.3‰― ?36.2‰) are very similar to those of n-alkanes and the δ 13C values for unsaturated fatty acids are within the range of those for saturated fatty acids. The differences in δ 13C values between plant lipids are obvious and range from 2.4‰ to 7.8‰. It is observed that the carbon isotopic compositions of sedimentary lipids are closely related to those of plant lipids. The carbon isotopic compositions (?27.0‰―?36.9‰) of n-alkanes, ≥C16 fatty acids, n-alkanols, sterols and n-alkanones in the sediments are similar to those of plant lipids and the carbon isotopic compositions of short-chain sedimentary lipids are similar to those of long-chain sedimentary homologues. These indicate that the sedimentary lipids are derived from high plants. However, the δ 13C values of C14:0 and C15:0 fatty acids in the sediments are lighter than those of the same carbon number saturated homologues in plants, reflecting the genetic features partially derived from bacteria. These data provide scientific evidence for carbon isotope-applied research of individual lipids.展开更多
Carbon isotopes of individual lipids in typical organisms from the Nansha sea area were measured by the GC-IRMS analytical technique. δ13C values of saturated fatty acids in different organisms examined are from 25.6...Carbon isotopes of individual lipids in typical organisms from the Nansha sea area were measured by the GC-IRMS analytical technique. δ13C values of saturated fatty acids in different organisms examined are from 25.6‰ to 29.7‰ with the average values ranging from 26.4‰ to 28.2‰ and the variance range of 1.8‰ between different organisms is also observed. Unsaturated fatty acids have heavy carbon isotopic compositions and the mean differences of 2.9‰–6.8‰ compared to the same carbon number saturated fatty acids. δ13C values of n-alkanes range from 27.5‰ to 29.7‰ and their mean values, ranging from 28.6‰ to 28.9‰, are very close in different organisms. The mean difference in δ13C between the saturated fatty acids and n-alkanes is only 1.5‰, indicating that they have similar biosynthetic pathways. The carbon isotopic variations between the different carbon-number lipids are mostly within ±2.0‰, reflecting that they experienced a biosynthetic process of the carbon chain elongation. At the same time, the carbon isotopic genetic relationships between the biological and sedimentary lipids are established by comparative studies of carbon isotopic compositions of individual lipids in organisms and sediments from the Nansha sea area, which provides scientific basis for carbon isotopic applied research of individual lipids.展开更多
Carbon isotopic compositions of individual n-alkanols and sterols in modern sediments from the Nan-sha Islands sea area are measured after derivatization to trimethylsilyl ethers by the new isotopic analytical techniq...Carbon isotopic compositions of individual n-alkanols and sterols in modern sediments from the Nan-sha Islands sea area are measured after derivatization to trimethylsilyl ethers by the new isotopic analytical technique of GC/C/IRMS. The effects of the three added silyl carbon atoms in every alcohol molecule on these compound isotopic compositions and the characteristics of their carbon isotopic compositions are studied. Then their biological sources are discussed using their carbon isotopic compositions.展开更多
基金Project supported by the National Natural Science Foundation of China.
文摘In the late 1980s the introduction of a new isotopic analytical technique of GC-C-MS that can determine the carbon isotopic composition at the molecular level has led to the appearence of the stable carbon isotopic geochemistry of biomarker compounds as a new field of scientific research. The relationship between the carbon isotopic compositions of biomarker compounds and biological precursors and diagenetic evolution is one of the key problems in this research field. Some studies on this problem have been carried out abroad in terms of organisms and modern sediments as well as the experiments of thermal simulation. Studied results show that the carbon isotopic compositions of biomarker compounds in the sediments are closely related to those in biological precursors and diagenetic evolution. For example, Reiley et al. have examined the carbon
基金This work was supported by the National Natural Science Foundation of China （Grant Nos： 40276016, 90211022）.
文摘The molecular compositions and com- pound-specific carbon isotope compositions of indi- vidual long-chain n-alkanes of atmospheric aerosols collected during two severe Asian dust episodes in Qingdao in spring of 2002 were analyzed using gas chromatography/mass spectrometry (GC/MS) and gas chromatography/isotope ratio mass spectrometry (GC/IRMS). Typical plant wax n-alkanes (C29 and C31) had lower δ 13C values than those from anthropo- genic (engine exhaust) sources (C21―C23). The av- erage δ 13C value of plant wax n-alkane C29 in non-dust episode periods was -30.5‰ (?30.3‰― ?31.9‰), while -31.3‰ (?31.1‰―?31.5‰) in dust episode periods; for C31, it was ?31.4‰ (?31.1‰― ?33.0‰) in non-dust episode periods, and ?31.7‰ (?31.3‰―?32.6‰) in dust episode periods. Plant wax in the dust episode samples was mainly from herbaceous plants via long-range transport, while local plant wax was mainly from deciduous plants and woody plants. In North China coast, 83.3% of the plant wax in the severe dust episode samples was from C3 plants while 80.0% for the non-dust samples, indicating that plant wax transported to the north- western Pacific Ocean by airborne dust from East Asia was mainly from C3 plants. The results suggestthat the molecular and molecular-isotopic composi- tions of individual long-chain n-alkanes can, as an effective indicator, identify the terrestrial organic components in the dust from East Asia and sedi- ments in the northwest Pacific Ocean.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 40072040)the Important Direction Project of Knowledge Innovation in Resource and Environment Field, the Chinese Academy of Sciences (Grant No. KZCX2-111) the Found
文摘Carbon isotopes are measured for individual long-chain n-alkanes in sediments from the Nansha Sea. The features of carbon isotopic compositions of individual n-alkanes and their origins are studied. The results show that the long-chain n-alkanes have a light carbon isotopic composition and a genetic feature of mixing sources, and low-latitude higher plants and microbes are considered to be their main end member sources. Based on the abundances and carbon isotopic compositions of individual n-alkanes, the fractional contributions of the two end member sources to individual n-alkanes are quantitatively calculated by using a mixing model. The obtained data indicate that the fractional contributions of the two biological sources are different in the three samples. A trend is that the contribution of microbes increases with the depth. These results provide the theory basis and quantitatively studied method for carbon isotopic applied research of individual n-alkanes.
基金Important DirectionProject of Knowledge Innovation in Resource and Envionment Field,Chinese Academy of Sciences(Grant No.KZCX3-SW-128)the National Key Basic Research and Development Project(Grant No.2002CB211701) the Nationa1 Natual Science Foundat ion of China(Grant No.40072040).
文摘The carbon isotopes of individual lipids in herbaceous plants and tree leaves in Ruoergai marsh were measured by the GC-IRMS analytical technique in order to understand the inherent relationships of carbon isotopes between sedimentary and plant lipids from typical marsh environment. The analytical results show that the carbon isotopic compositions of n-alkanes in different kinds of plants differ significantly. Mean δ 13C values of n-alkanes in her-baceous plants (?32.2‰―?36.9‰) are 3.3‰ lower than those in woody plant (?27.2‰― ?35.0‰). The carbon isotopic compositions of fatty acids in organisms (?30.3‰― ?36.2‰) are very similar to those of n-alkanes and the δ 13C values for unsaturated fatty acids are within the range of those for saturated fatty acids. The differences in δ 13C values between plant lipids are obvious and range from 2.4‰ to 7.8‰. It is observed that the carbon isotopic compositions of sedimentary lipids are closely related to those of plant lipids. The carbon isotopic compositions (?27.0‰―?36.9‰) of n-alkanes, ≥C16 fatty acids, n-alkanols, sterols and n-alkanones in the sediments are similar to those of plant lipids and the carbon isotopic compositions of short-chain sedimentary lipids are similar to those of long-chain sedimentary homologues. These indicate that the sedimentary lipids are derived from high plants. However, the δ 13C values of C14:0 and C15:0 fatty acids in the sediments are lighter than those of the same carbon number saturated homologues in plants, reflecting the genetic features partially derived from bacteria. These data provide scientific evidence for carbon isotope-applied research of individual lipids.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 40072040) the Important Direction Project of Knowledge Innovation in Resource and Environment Field, Chinese Academy of Sciences (Grant No. KZCX3-SW-128) the National Outstanding Youth Science Foundation of China(Grant No. 40072040).
文摘Carbon isotopes of individual lipids in typical organisms from the Nansha sea area were measured by the GC-IRMS analytical technique. δ13C values of saturated fatty acids in different organisms examined are from 25.6‰ to 29.7‰ with the average values ranging from 26.4‰ to 28.2‰ and the variance range of 1.8‰ between different organisms is also observed. Unsaturated fatty acids have heavy carbon isotopic compositions and the mean differences of 2.9‰–6.8‰ compared to the same carbon number saturated fatty acids. δ13C values of n-alkanes range from 27.5‰ to 29.7‰ and their mean values, ranging from 28.6‰ to 28.9‰, are very close in different organisms. The mean difference in δ13C between the saturated fatty acids and n-alkanes is only 1.5‰, indicating that they have similar biosynthetic pathways. The carbon isotopic variations between the different carbon-number lipids are mostly within ±2.0‰, reflecting that they experienced a biosynthetic process of the carbon chain elongation. At the same time, the carbon isotopic genetic relationships between the biological and sedimentary lipids are established by comparative studies of carbon isotopic compositions of individual lipids in organisms and sediments from the Nansha sea area, which provides scientific basis for carbon isotopic applied research of individual lipids.
基金Project supported by the National Natural Science Foundation of China and Project of the Multidisciplinary Oceanographic Expedition of Chinese Academy of Sciences to Nansha Islands
文摘Carbon isotopic compositions of individual n-alkanols and sterols in modern sediments from the Nan-sha Islands sea area are measured after derivatization to trimethylsilyl ethers by the new isotopic analytical technique of GC/C/IRMS. The effects of the three added silyl carbon atoms in every alcohol molecule on these compound isotopic compositions and the characteristics of their carbon isotopic compositions are studied. Then their biological sources are discussed using their carbon isotopic compositions.
