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
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
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
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
CO2-rich cold springs occur near the active volcanoes at Wudalianchi （五大连池）, Northeast China. The springs are rich in CO2, with HCO3-as the predominant anion and have elevated contents of total dissolved solid ...CO2-rich cold springs occur near the active volcanoes at Wudalianchi （五大连池）, Northeast China. The springs are rich in CO2, with HCO3-as the predominant anion and have elevated contents of total dissolved solid （TDS） （〉1 000 mg/L）, Fe^2＋ （〉20 mg/L）, Sr （〉1 mg/L）, and dissolved Si （〉20 mg/L）. The compositions of escaped and dissolved gases of the springs are similar. The δ^13C values of escaped gases and dissolved gases in mineral springs at Wudalianchi vary from -8.77‰ to -4.53‰ and -8.24‰ to -5.26‰, while δ^18O values vary from -10.68‰ to -7.65‰ and -10.30‰ to -8.84‰, respectively, indicating the same upper mantle origin of CO2 of escaped gases and dissolved gases in the springs. Carbon and oxygen isotope fractionations and water-CO2 exchange were weak in the process of groundwater flow. The 4He content exceeds 5 000×10-6 cm^3·STP/mL in escaped gases of the mineral springs, and the 3He/4He ratios of the escaped and dissolved gases vary from 2.64Ra to 3.87Ra and 1.18Ra to 3.30Ra, respectively. It can be postulated that the CO2 of mineral springs deriving from the magma chamber of the upper mantle moves upward to the surface, to increase the content of 4He in the mineral springs and decrease the ratio of 3He/4He. The helium origin of escaped gases in springs can be calculated with the MORB-crust mixing model, but that in the north spring can be better explained with the MORB-crust-air mixing model due to the effect of mixing with surface water. However, dissolved helium in springs, except the north spring, is better explained with the MORB-crust-ASW mixing model.展开更多
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 the National Natural Science Foundation of China(Nos.40425001,40602031,40830748),and Russian Fund for Basic Research
文摘CO2-rich cold springs occur near the active volcanoes at Wudalianchi （五大连池）, Northeast China. The springs are rich in CO2, with HCO3-as the predominant anion and have elevated contents of total dissolved solid （TDS） （〉1 000 mg/L）, Fe^2＋ （〉20 mg/L）, Sr （〉1 mg/L）, and dissolved Si （〉20 mg/L）. The compositions of escaped and dissolved gases of the springs are similar. The δ^13C values of escaped gases and dissolved gases in mineral springs at Wudalianchi vary from -8.77‰ to -4.53‰ and -8.24‰ to -5.26‰, while δ^18O values vary from -10.68‰ to -7.65‰ and -10.30‰ to -8.84‰, respectively, indicating the same upper mantle origin of CO2 of escaped gases and dissolved gases in the springs. Carbon and oxygen isotope fractionations and water-CO2 exchange were weak in the process of groundwater flow. The 4He content exceeds 5 000×10-6 cm^3·STP/mL in escaped gases of the mineral springs, and the 3He/4He ratios of the escaped and dissolved gases vary from 2.64Ra to 3.87Ra and 1.18Ra to 3.30Ra, respectively. It can be postulated that the CO2 of mineral springs deriving from the magma chamber of the upper mantle moves upward to the surface, to increase the content of 4He in the mineral springs and decrease the ratio of 3He/4He. The helium origin of escaped gases in springs can be calculated with the MORB-crust mixing model, but that in the north spring can be better explained with the MORB-crust-air mixing model due to the effect of mixing with surface water. However, dissolved helium in springs, except the north spring, is better explained with the MORB-crust-ASW mixing model.
