Isotopic data obtained from the dinosaur eggshells and pedogenic nodules(pedonodules)are interpreted in terms of palaeoclimatology.The material studied originated from the Bayn Dzak locality,Southern Gobi Aimak,Mongol...Isotopic data obtained from the dinosaur eggshells and pedogenic nodules(pedonodules)are interpreted in terms of palaeoclimatology.The material studied originated from the Bayn Dzak locality,Southern Gobi Aimak,Mongolia,having Late Cretaceous(Campanian)age.Stratigraphically the Bayn Dzak locality belongs to the Djadokhta Formation.All the present data(lithology,type of paleosols,FPS-profiles,geochemistry),and the isotopic characteristics of the selected samples show unequivocally that the environments of the Bayn Dzak area in Late Cretaceous(Campanian)time were warm to summer-hot,seasonally dry.Wet seasons(most probably,which took place in the winter time)were not longer than two months with not more than 400 mm precipitation per year.The distribution of isotope data in the dinosaur eggshells show the main relation,which is the dependence ofδ^13C andδ^18O values,i.e.specimens with heavy carbon isotope ratios are characterized by lighter oxygen isotope composition and conversely.Thus,theδ^13C andδ^18O values of the dinosaur eggshells display a clear positive correlation.It may be consequent both with the difference of the isotope composition of diet of the egg-lying animals modified by physicochemical isotope fractionation due to metabolism and changes in the isotope environment,and/or diagenetic alteration of the eggshell carbonate.Obtained isotopic data on the studied dinosaur eggshell fragments and the soil carbonates lend support to our assumption that diagenesis did not play significant role in changing the isotopic values.The distribution ofδ^13C andδ^18O values in eggshells and in pedogenic carbonates shows the visible opposite dependencies.展开更多
In this work,an isotopic analysis of δ^(18)O,δ^(13)C,and NO_(3)^(-) concentrations was carried out to identify the origin and the processes related to the contamination of an aquifer located in the state of Guanajua...In this work,an isotopic analysis of δ^(18)O,δ^(13)C,and NO_(3)^(-) concentrations was carried out to identify the origin and the processes related to the contamination of an aquifer located in the state of Guanajuato,Mexico.The research identified the possible sources of δ^(13)C in groundwater.During groundwater flow,CO_(2) participates in different hydrogeochemical reactions in which the dissolution of carbonates or biochemical processes related to biodegradation stand out.Isotopic data of δ^(13)C,δ^(18)O,and the hydrogeochemical behavior of NO_(3)^(-) and HCO_(3)^(-) in water,in addition to isotopic data and the chemical composition of limestones in the study area,were determined to establish the isotopic signature and the processes undergone by the rocks.The isotopic signature of rock and water samples indicated that metamorphic limestones contributed with carbon dioxide to deep groundwater,while in the upper aquifer,bacterial metabolic reactions during nitrification–denitrification could modify the isotopic signature of δ^(13)C in some wells,although atmospheric contribution also plays a role.The modification of the carbon isotopic component is related to the precipitation of calcite in specific regions of the study area,input of atmospheric CO_(2),and soil(e.g.the possible participation of C4-type plants in the assimilation-release of carbon).This process is not confirmed or completely ruled out in this study since agriculture is excessively developed throughout the region.The joint interpretation of isotopic values and the hydrogeochemical behavior of major and conservative elements help in identifying possible pollution processes in which different carbon sources are related.展开更多
The correlation between the δ^13C and δ^13C-δ^18O in primary carbonates is affected by several factors such as hydrological balance, total CO2 concentrations, climatic condition and lake productivity. The influence...The correlation between the δ^13C and δ^13C-δ^18O in primary carbonates is affected by several factors such as hydrological balance, total CO2 concentrations, climatic condition and lake productivity. The influence of these factors on the δ^13C-δ^18O correlation may be different on different time scales. In this paper, two different-type lakes in southwestern China, Lake Erhai and Lake Chenghai, are selected to investigate the influence of climatic pattern on the δ^13C-δ^18O correlation and to evaluate the reliability of the δ^13C-δ^18O covariance as an indicator of hydrological closure. The results show that there exists good correlation between the δ^13C and δ^18O in Lake Erhai （overflowing open lake） and in Lake Chenghai （closed lake）. This suggests that the δ^13C-δ^18O covariance may be not an effective indicator of hydrological closure for lakes, especially on short time scales. On the one hand, a hydrologically open lake may display covariant δ^13C and δ^18O as a result of climatic influence. The particular alternate warm-dry and cold-wet climatic pattern in southwestern China may be the principal cause of the δ^13C-δ^18O covariance in Lake Erhai and Lake Chenghai. On the other hand, a hydrologically closed lake unnecessarily displays covariant trends between δ^13C and δ^18O because of the buffering effect of high CO2 concentration on the δ^13C shift in hyper-alkaline lakes. We should be prudent when we use the covariance between δ^13C and δ^18O to judge the hydrological closure of lake.展开更多
Horizontal and vertical distributions of δ^18 and δ^13 were investigated in shells of four planktonic foraminiferal species, Globigerinoides ruber, Globigerinoides sacculifer, Pulleniatina obliquiloculata and Neoglo...Horizontal and vertical distributions of δ^18 and δ^13 were investigated in shells of four planktonic foraminiferal species, Globigerinoides ruber, Globigerinoides sacculifer, Pulleniatina obliquiloculata and Neogloboquedrina dutertrei, from a total of 62 core-top sediment samples from the Indonesian throughflow region. Results were compared to modern hydrologic conditions in order to explore potential of proxies in reconstructing fluvial discharge and upper ocean water column characteristics in this region. Our results show that, in the Makassar Strait, both of depleted δ^18 and δ^13 of these four species were linked to freshwater input. In the Bali Sea,however, depleted δ^18 and δ^13 for these species may be due to different reasons. Depleted δ^18 was a result of freshwater input and as well influenced by along-shore currents while depleted δ^13 was more likely due to the Java-Sumatra upwelling. Comparison of shell δ^18 records and hydrographic data of World Ocean Atlas 2005 suggests that G. ruber and G. sacculifer calcify within the mixed-layer, respectively at 0–50 m and 20–75 m water depth, and P. obliquiloculata and N. dutertrei within the upper thermocline, both at 75–125 m water depth. N.dutertrei calcifies at slightly deeper water depth than P. obliquiloculata does. In general, δ^13 values of both G.ruber and G. sacculifer are larger than those of P. obliquiloculata and N. dutertrei at all sites, possibly related to depth habitats of these species and vertical distribution of nutrients in the Indonesian throughflow region.展开更多
Neogloboquadrina pachyderma is the most abundant planktonic foraminifera species found in the modern polar oceans. The δ^18O and δ^13C of N. pachyderma from the Western Arctic Ocean sediments were analyzed to reveal...Neogloboquadrina pachyderma is the most abundant planktonic foraminifera species found in the modern polar oceans. The δ^18O and δ^13C of N. pachyderma from the Western Arctic Ocean sediments were analyzed to reveal the implications of the proxies to environmental changes. The δ^18O from N. pachyderma in the Chukchi Sea reflect the water mass distribution in this area. Heavier δ^18O values were found along the Anadyr Current （AC） and lighter values in the central and eastern Chukchi Sea..These may reflect the freshwater signal from the Alaska Coastal Current （ACC） and Bering Sea Shelf Water （BSSW）. The light δ^18O signature in the high Arctic basin comes from the freshwater stored in the Arctic surface layer. The δ^18O distribution pattern in the Chukchi Sea is also influenced by the current system. High primary productivity along the AC results in heavy δ^18O. The relatively low primary productivity and the freshwater component from the BSSW and ACC may be the reason for this light δ^13C signal in the central and eastern Chukchi Sea. Our data reveal the importance of well ventilated Pacific Water through the Chukchi Sea into the Arctic Ocean.展开更多
Proton nuclear(^(1)H)is the observed nucleus on which most magnetic resonance imaging(MRI)applications depend.Most traditional^(1)H MRI can provide structural and functional information about organisms,while various n...Proton nuclear(^(1)H)is the observed nucleus on which most magnetic resonance imaging(MRI)applications depend.Most traditional^(1)H MRI can provide structural and functional information about organisms,while various non-proton nuclei(X-nuclei)MRI can provide more metabolic information.However,due to the relatively poor signal-to-noise ratio(SNR)of X-nuclei MRI,their applications are quite rare compared to^(1)H.Benefit from the rapid developments of MRI hardware and software technologies,X-nuclei MRI has recently attracted increasing interests in biomedical research.This review firstly introduces some current methods to improve the SNR of X-nuclei MRI.Secondly,this review describes biomedical applications of X-nuclei MRI,especially focusing on the current use of X-nuclei(^(13)C,^(17)O,^(19)F,^(23)Na and^(31)P)MRI to study related diseases in different organs,including the brain,liver,kidney,heart and bone.Finally,perspectives studies on X-nuclei imaging and its potential applications are described in biomedical research.展开更多
基金Supported by the State Program of the Geological Institute of Russian Academy of Sciences(No.0135-2019-0044)RFBR Project(No.18-04-00322)。
文摘Isotopic data obtained from the dinosaur eggshells and pedogenic nodules(pedonodules)are interpreted in terms of palaeoclimatology.The material studied originated from the Bayn Dzak locality,Southern Gobi Aimak,Mongolia,having Late Cretaceous(Campanian)age.Stratigraphically the Bayn Dzak locality belongs to the Djadokhta Formation.All the present data(lithology,type of paleosols,FPS-profiles,geochemistry),and the isotopic characteristics of the selected samples show unequivocally that the environments of the Bayn Dzak area in Late Cretaceous(Campanian)time were warm to summer-hot,seasonally dry.Wet seasons(most probably,which took place in the winter time)were not longer than two months with not more than 400 mm precipitation per year.The distribution of isotope data in the dinosaur eggshells show the main relation,which is the dependence ofδ^13C andδ^18O values,i.e.specimens with heavy carbon isotope ratios are characterized by lighter oxygen isotope composition and conversely.Thus,theδ^13C andδ^18O values of the dinosaur eggshells display a clear positive correlation.It may be consequent both with the difference of the isotope composition of diet of the egg-lying animals modified by physicochemical isotope fractionation due to metabolism and changes in the isotope environment,and/or diagenetic alteration of the eggshell carbonate.Obtained isotopic data on the studied dinosaur eggshell fragments and the soil carbonates lend support to our assumption that diagenesis did not play significant role in changing the isotopic values.The distribution ofδ^13C andδ^18O values in eggshells and in pedogenic carbonates shows the visible opposite dependencies.
基金financed by PAPIIT,and the grant number is IA101019PAPIIT for its support and the scholarships provided to students Cuellar Ramírez E。
文摘In this work,an isotopic analysis of δ^(18)O,δ^(13)C,and NO_(3)^(-) concentrations was carried out to identify the origin and the processes related to the contamination of an aquifer located in the state of Guanajuato,Mexico.The research identified the possible sources of δ^(13)C in groundwater.During groundwater flow,CO_(2) participates in different hydrogeochemical reactions in which the dissolution of carbonates or biochemical processes related to biodegradation stand out.Isotopic data of δ^(13)C,δ^(18)O,and the hydrogeochemical behavior of NO_(3)^(-) and HCO_(3)^(-) in water,in addition to isotopic data and the chemical composition of limestones in the study area,were determined to establish the isotopic signature and the processes undergone by the rocks.The isotopic signature of rock and water samples indicated that metamorphic limestones contributed with carbon dioxide to deep groundwater,while in the upper aquifer,bacterial metabolic reactions during nitrification–denitrification could modify the isotopic signature of δ^(13)C in some wells,although atmospheric contribution also plays a role.The modification of the carbon isotopic component is related to the precipitation of calcite in specific regions of the study area,input of atmospheric CO_(2),and soil(e.g.the possible participation of C4-type plants in the assimilation-release of carbon).This process is not confirmed or completely ruled out in this study since agriculture is excessively developed throughout the region.The joint interpretation of isotopic values and the hydrogeochemical behavior of major and conservative elements help in identifying possible pollution processes in which different carbon sources are related.
基金the National Natural Science Foundation of China（Grant No.40673068）the National Basic Research Program of China（Grant No.2006CB403201）。
文摘The correlation between the δ^13C and δ^13C-δ^18O in primary carbonates is affected by several factors such as hydrological balance, total CO2 concentrations, climatic condition and lake productivity. The influence of these factors on the δ^13C-δ^18O correlation may be different on different time scales. In this paper, two different-type lakes in southwestern China, Lake Erhai and Lake Chenghai, are selected to investigate the influence of climatic pattern on the δ^13C-δ^18O correlation and to evaluate the reliability of the δ^13C-δ^18O covariance as an indicator of hydrological closure. The results show that there exists good correlation between the δ^13C and δ^18O in Lake Erhai （overflowing open lake） and in Lake Chenghai （closed lake）. This suggests that the δ^13C-δ^18O covariance may be not an effective indicator of hydrological closure for lakes, especially on short time scales. On the one hand, a hydrologically open lake may display covariant δ^13C and δ^18O as a result of climatic influence. The particular alternate warm-dry and cold-wet climatic pattern in southwestern China may be the principal cause of the δ^13C-δ^18O covariance in Lake Erhai and Lake Chenghai. On the other hand, a hydrologically closed lake unnecessarily displays covariant trends between δ^13C and δ^18O because of the buffering effect of high CO2 concentration on the δ^13C shift in hyper-alkaline lakes. We should be prudent when we use the covariance between δ^13C and δ^18O to judge the hydrological closure of lake.
基金The National Natural Science Foundation of China under contract No.41176044Shaanxi Provincial Technology Foundation for Selected Overseas Chinese Scholar under contract Shaan Renshe[2015]No.1190
文摘Horizontal and vertical distributions of δ^18 and δ^13 were investigated in shells of four planktonic foraminiferal species, Globigerinoides ruber, Globigerinoides sacculifer, Pulleniatina obliquiloculata and Neogloboquedrina dutertrei, from a total of 62 core-top sediment samples from the Indonesian throughflow region. Results were compared to modern hydrologic conditions in order to explore potential of proxies in reconstructing fluvial discharge and upper ocean water column characteristics in this region. Our results show that, in the Makassar Strait, both of depleted δ^18 and δ^13 of these four species were linked to freshwater input. In the Bali Sea,however, depleted δ^18 and δ^13 for these species may be due to different reasons. Depleted δ^18 was a result of freshwater input and as well influenced by along-shore currents while depleted δ^13 was more likely due to the Java-Sumatra upwelling. Comparison of shell δ^18 records and hydrographic data of World Ocean Atlas 2005 suggests that G. ruber and G. sacculifer calcify within the mixed-layer, respectively at 0–50 m and 20–75 m water depth, and P. obliquiloculata and N. dutertrei within the upper thermocline, both at 75–125 m water depth. N.dutertrei calcifies at slightly deeper water depth than P. obliquiloculata does. In general, δ^13 values of both G.ruber and G. sacculifer are larger than those of P. obliquiloculata and N. dutertrei at all sites, possibly related to depth habitats of these species and vertical distribution of nutrients in the Indonesian throughflow region.
基金funded by the National Basic Research Program of China (Grant no. G2007CB815903)the National Natural Science Foundation of China (Grant nos.41030859 and 40321603)+2 种基金the China Program for International Polar Year 2007-2008the China Geological Survey Project(Grant no. H[2011]01-14-04)part of the project"First Chinese National Arctic Research Expedition" and "Second Chinese National Arctic Research Expedition" supported by the Ministry of Finance of China and organized by the Chinese Arctic and Antarctic Administration (CAA),SOA
文摘Neogloboquadrina pachyderma is the most abundant planktonic foraminifera species found in the modern polar oceans. The δ^18O and δ^13C of N. pachyderma from the Western Arctic Ocean sediments were analyzed to reveal the implications of the proxies to environmental changes. The δ^18O from N. pachyderma in the Chukchi Sea reflect the water mass distribution in this area. Heavier δ^18O values were found along the Anadyr Current （AC） and lighter values in the central and eastern Chukchi Sea..These may reflect the freshwater signal from the Alaska Coastal Current （ACC） and Bering Sea Shelf Water （BSSW）. The light δ^18O signature in the high Arctic basin comes from the freshwater stored in the Arctic surface layer. The δ^18O distribution pattern in the Chukchi Sea is also influenced by the current system. High primary productivity along the AC results in heavy δ^18O. The relatively low primary productivity and the freshwater component from the BSSW and ACC may be the reason for this light δ^13C signal in the central and eastern Chukchi Sea. Our data reveal the importance of well ventilated Pacific Water through the Chukchi Sea into the Arctic Ocean.
基金supported by Chinese Academy of Sciences MRI Technology Alliance under Grant 2020GZ1003.
文摘Proton nuclear(^(1)H)is the observed nucleus on which most magnetic resonance imaging(MRI)applications depend.Most traditional^(1)H MRI can provide structural and functional information about organisms,while various non-proton nuclei(X-nuclei)MRI can provide more metabolic information.However,due to the relatively poor signal-to-noise ratio(SNR)of X-nuclei MRI,their applications are quite rare compared to^(1)H.Benefit from the rapid developments of MRI hardware and software technologies,X-nuclei MRI has recently attracted increasing interests in biomedical research.This review firstly introduces some current methods to improve the SNR of X-nuclei MRI.Secondly,this review describes biomedical applications of X-nuclei MRI,especially focusing on the current use of X-nuclei(^(13)C,^(17)O,^(19)F,^(23)Na and^(31)P)MRI to study related diseases in different organs,including the brain,liver,kidney,heart and bone.Finally,perspectives studies on X-nuclei imaging and its potential applications are described in biomedical research.
