210Pb dating method is an isotopic chronological method used for determining geological age of the past hundred years. Recently it has played a more and more active role in measuring sedimentation rates of lake facies...210Pb dating method is an isotopic chronological method used for determining geological age of the past hundred years. Recently it has played a more and more active role in measuring sedimentation rates of lake facies, continental slope and shelf, estuary and debouch, as well as the age of snow and ice, in studying recent sedimentation and enrichment of 210Pb in sea-surface micro-layers and in discussing pollution history in the past hundred years. As a result of research, many valuable achievements have been obtained.展开更多
Recently, there have been many reports on experiments of laser isotopic enrichment of SF6 with infrared multiphoton dissociation. The aim of all these experiments is the determination of the relative contents of 34SF6...Recently, there have been many reports on experiments of laser isotopic enrichment of SF6 with infrared multiphoton dissociation. The aim of all these experiments is the determination of the relative contents of 34SF6/32SF6 in the residual gases by IR or mass spectra. The present paper is a report on what we have achieved along this line and our success in extracting S from enriched SF6 through hydrolysis, separation, sodium reduction and iodine oxidation.展开更多
Stable isotopic compositions （δ18O and 6D） have been utilized as a useful indicator for evaluating the current and historical climatic and environmental changes. Therefore, it is vital to understand the relationshi...Stable isotopic compositions （δ18O and 6D） have been utilized as a useful indicator for evaluating the current and historical climatic and environmental changes. Therefore, it is vital to understand the relationship be- tween the stable isotopic contents in lake water and the variations of lake level, particularly in Lake Qinghai, China. In this study, we analyzed the variations of isotope compositions （δ18O, 6D and d-excess） in lake water and pre- cipitation by using the samples that were collected from Lake Qinghai region during the period from 2009 to 2012. The results showed that the average isotopic contents of δ18O and 6D in lake water were higher than those in pre- cipitation, which were contrary to the variations of d-excess. The linear regression correlations between δ18O and 6D in lake water and precipitation showed that the local evaporative line （LEL） in lake water （δD=5.88δ18O-2.41） deviated significantly from the local meteoric water line （LMWL）in precipitation （δD=8.26δ18O＋16.91）, indicating that evaporative enrichment had a significant impact on isotopic contents in lake water. Moreover, we also quanti- fied the Eli ratio （evaporation-to-input ratio） in Lake Qinghai based on the lake water isotopic enrichment model derived from the Rayleigh equation. The changes of E/I ratios （ranging from 0.29 to 0.36 between 2009 and 2012） clearly revealed the shifts of lake levels in Lake Qinghai in recent years. The average E/I ratio of 0.40 reflected that water budget in Lake Qinghai was positive, and consistent with the rising lake levels and the increasing lake areas in many lakes of the Tibetan Plateau. These findings provide some evidences for studying the hydrological balance or water budget by using δ18O values of lake sedimentary materials and contribute to the reconstruction of paleo- lake water level and paleoclimate from an isotopic enrichment model in Lake Qinghai.展开更多
文摘210Pb dating method is an isotopic chronological method used for determining geological age of the past hundred years. Recently it has played a more and more active role in measuring sedimentation rates of lake facies, continental slope and shelf, estuary and debouch, as well as the age of snow and ice, in studying recent sedimentation and enrichment of 210Pb in sea-surface micro-layers and in discussing pollution history in the past hundred years. As a result of research, many valuable achievements have been obtained.
文摘Recently, there have been many reports on experiments of laser isotopic enrichment of SF6 with infrared multiphoton dissociation. The aim of all these experiments is the determination of the relative contents of 34SF6/32SF6 in the residual gases by IR or mass spectra. The present paper is a report on what we have achieved along this line and our success in extracting S from enriched SF6 through hydrolysis, separation, sodium reduction and iodine oxidation.
基金financially supported by the National Natural Science Foundation of China (41130640, 91425301, 41321001, 41401057)the projects from the State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University
文摘Stable isotopic compositions （δ18O and 6D） have been utilized as a useful indicator for evaluating the current and historical climatic and environmental changes. Therefore, it is vital to understand the relationship be- tween the stable isotopic contents in lake water and the variations of lake level, particularly in Lake Qinghai, China. In this study, we analyzed the variations of isotope compositions （δ18O, 6D and d-excess） in lake water and pre- cipitation by using the samples that were collected from Lake Qinghai region during the period from 2009 to 2012. The results showed that the average isotopic contents of δ18O and 6D in lake water were higher than those in pre- cipitation, which were contrary to the variations of d-excess. The linear regression correlations between δ18O and 6D in lake water and precipitation showed that the local evaporative line （LEL） in lake water （δD=5.88δ18O-2.41） deviated significantly from the local meteoric water line （LMWL）in precipitation （δD=8.26δ18O＋16.91）, indicating that evaporative enrichment had a significant impact on isotopic contents in lake water. Moreover, we also quanti- fied the Eli ratio （evaporation-to-input ratio） in Lake Qinghai based on the lake water isotopic enrichment model derived from the Rayleigh equation. The changes of E/I ratios （ranging from 0.29 to 0.36 between 2009 and 2012） clearly revealed the shifts of lake levels in Lake Qinghai in recent years. The average E/I ratio of 0.40 reflected that water budget in Lake Qinghai was positive, and consistent with the rising lake levels and the increasing lake areas in many lakes of the Tibetan Plateau. These findings provide some evidences for studying the hydrological balance or water budget by using δ18O values of lake sedimentary materials and contribute to the reconstruction of paleo- lake water level and paleoclimate from an isotopic enrichment model in Lake Qinghai.
