The Qinghai-Tibet Plateau(QTP)possesses the largest areas of permafrost in the midand low latitude regions on the earth and many large lakes in the permafrost area.Based on a comprehensive investigation around certain...The Qinghai-Tibet Plateau(QTP)possesses the largest areas of permafrost in the midand low latitude regions on the earth and many large lakes in the permafrost area.Based on a comprehensive investigation around certain typical lakes,this study found that although the presence of lakes formed different ranges of unfrozen zones in permafrost,the heating effect of lake water on surrounding permafrost is limited to a small extent.The temperature of permafrost around the lake is closely related to the distance to the lake and the ice content of the permafrost.Around lakes are ice-rich permafrost zones and permafrost temperature in this area is significantly lower than that far away from the lake,which indicates that the existence of lakes in the QTP has special effect on the permafrost distribution.Based on the monitoring results,this study presents the typical distribution pattern of the permafrost around large lakes and discusses the reasons for the distribution pattern.Due to the huge area of lakes and the significant impact of lakes on permafrost distribution,it is suggested to re-estimate the total permafrost area and underground ice storage in the QTP.展开更多
Objective:To establish HPLC fingerprint of Nauclea officinalis stems in different harvesting periods,and analyze the effect of harvest time on the quality of the medicinal materials by combining with chemical pattern ...Objective:To establish HPLC fingerprint of Nauclea officinalis stems in different harvesting periods,and analyze the effect of harvest time on the quality of the medicinal materials by combining with chemical pattern recognition.Methods:The analysis was performed on Sun Fire-C18(150 mm×4.6 mm,5μm)column.The mobile phase consisted of acetonitrile-0.1%phosphoric acid solution(gradient elution)at a flow rate of 1.0 mL/min.Results:The HPLC fingerprint of Nauclea officinalis stems was established and 12 common peaks were determined,and 3 chromatographic peaks were identified by comparison with the mixed references.There were some differences in the quality of Nauclea officinalis in different harvesting periods.The OPLS-DA analysis successfully predicted four main markers of quality difference.Conclusion:The established HPLC fingerprint could reflect the composition characteristics of Nauclea officinalis stems in different harvesting period,and the main markers that influence the composition difference of the stems could be used as key indicators for the quality control.展开更多
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(XDA23060703)the National Natural Science Foundation of China(41671068)the State Key Laboratory of Cryospheric Science(SKLCS-ZZ-2023)。
文摘The Qinghai-Tibet Plateau(QTP)possesses the largest areas of permafrost in the midand low latitude regions on the earth and many large lakes in the permafrost area.Based on a comprehensive investigation around certain typical lakes,this study found that although the presence of lakes formed different ranges of unfrozen zones in permafrost,the heating effect of lake water on surrounding permafrost is limited to a small extent.The temperature of permafrost around the lake is closely related to the distance to the lake and the ice content of the permafrost.Around lakes are ice-rich permafrost zones and permafrost temperature in this area is significantly lower than that far away from the lake,which indicates that the existence of lakes in the QTP has special effect on the permafrost distribution.Based on the monitoring results,this study presents the typical distribution pattern of the permafrost around large lakes and discusses the reasons for the distribution pattern.Due to the huge area of lakes and the significant impact of lakes on permafrost distribution,it is suggested to re-estimate the total permafrost area and underground ice storage in the QTP.
基金supported by Major Science and Technology Project of Hainan Province(ZDKJ201805)。
文摘Objective:To establish HPLC fingerprint of Nauclea officinalis stems in different harvesting periods,and analyze the effect of harvest time on the quality of the medicinal materials by combining with chemical pattern recognition.Methods:The analysis was performed on Sun Fire-C18(150 mm×4.6 mm,5μm)column.The mobile phase consisted of acetonitrile-0.1%phosphoric acid solution(gradient elution)at a flow rate of 1.0 mL/min.Results:The HPLC fingerprint of Nauclea officinalis stems was established and 12 common peaks were determined,and 3 chromatographic peaks were identified by comparison with the mixed references.There were some differences in the quality of Nauclea officinalis in different harvesting periods.The OPLS-DA analysis successfully predicted four main markers of quality difference.Conclusion:The established HPLC fingerprint could reflect the composition characteristics of Nauclea officinalis stems in different harvesting period,and the main markers that influence the composition difference of the stems could be used as key indicators for the quality control.
