A 109.91 m ice core was recovered from Dome A (or Dome Argus), the highest ice feature in Antarctica, during the 2004/05 austral summer by the 21st Chinese National Antarctic Research Expedition (CHINARE-21). Both met...A 109.91 m ice core was recovered from Dome A (or Dome Argus), the highest ice feature in Antarctica, during the 2004/05 austral summer by the 21st Chinese National Antarctic Research Expedition (CHINARE-21). Both methane profile along the core and firn densification model calculation suggest that the close-off depth is at about 102.0 m with an ice age about 4200 a. Stable isotopes (δ18O and δD) of the chips samples produced during each run of ice core drilling at Dome A, together with those of the other cores recovered from the eastern inland Antarctica, suggest a relative stable climate with a temperature fluctuation amplitude about ±0.6°C at the eastern inland Antarctica during the late Holocene. The average d-excess (or d =δ D-8δ 18O) of 17.1‰ along the Dome A core is probably the highest among the Antarctic inland ice cores, which may be resulted from the kinetic fractionation during the snow formation under an oversaturation condition. Moreover, the increasing trend of d-excess during the late Holocene reflects mainly the migration of the water source area for precipitation at Dome A towards low latitudes. This paper presents the first results of a shallow ice core recovered from the unexplored highest area of the Antarctic ice sheet, providing a background for the proposing deep ice core drilling at Dome A.展开更多
To contain the outbreak of COVID-19 in Wuhan,unprecedented interventions,including city lockdown and community closure,have been implemented.However,most of the current studies focused on evaluation of the city lockdo...To contain the outbreak of COVID-19 in Wuhan,unprecedented interventions,including city lockdown and community closure,have been implemented.However,most of the current studies focused on evaluation of the city lockdown,but paid limited attention to the impacts of the community containment measures within the city.This research addressed this important issue from the perspective of urban planning,based on the epidemic and remote sensing data of 194 communities of Wuhan.We found that the number of confirmed cases of communities is highly related to urban planning factors,e.g.area percentage of buildings and density of neighboring markets.These factors are relevant to the residents’activity patterns,which therefore impact the mode of virus transmission.Our research confirmed the effectiveness of the community-oriented control strategies,provided a valuable reference for other cities that are suffering from the epidemic,and exhibited new thoughts into future urban planning.展开更多
基金Supported by National Natural Science Foundation of China (Grant Nos. 40825017 and 40576001)One Hundred Talents Program of Chinese Academy of Sciences, Knowledge Innovation Project of the Chinese Academy of Sciences (Grant No. KZCX3-SW- 354)+1 种基金National Key Technology R & D Program (Grant No. 2006BAB18B01)and the Programme International de Cooperation Scientifique (PICS) Project "Climate and Environment in Antarctica and the Himalayas" (CLEAH, PICS no3499)
文摘A 109.91 m ice core was recovered from Dome A (or Dome Argus), the highest ice feature in Antarctica, during the 2004/05 austral summer by the 21st Chinese National Antarctic Research Expedition (CHINARE-21). Both methane profile along the core and firn densification model calculation suggest that the close-off depth is at about 102.0 m with an ice age about 4200 a. Stable isotopes (δ18O and δD) of the chips samples produced during each run of ice core drilling at Dome A, together with those of the other cores recovered from the eastern inland Antarctica, suggest a relative stable climate with a temperature fluctuation amplitude about ±0.6°C at the eastern inland Antarctica during the late Holocene. The average d-excess (or d =δ D-8δ 18O) of 17.1‰ along the Dome A core is probably the highest among the Antarctic inland ice cores, which may be resulted from the kinetic fractionation during the snow formation under an oversaturation condition. Moreover, the increasing trend of d-excess during the late Holocene reflects mainly the migration of the water source area for precipitation at Dome A towards low latitudes. This paper presents the first results of a shallow ice core recovered from the unexplored highest area of the Antarctic ice sheet, providing a background for the proposing deep ice core drilling at Dome A.
基金This work is supported by the National Natural Science Foundation of China[grant number 41771360]the National Natural Science Foundation of China[grant number 41971295]+3 种基金the National Program for Support of Top-notch Young Professionalsthe Hubei Provincial Natural Science Foundation of China[grant number 2017CFA029]the National Key R&D Program of China[grant number 2016YFB0501403]the Shenzhen Science and Technology Program[grant number JCYJ20180306170645080].
文摘To contain the outbreak of COVID-19 in Wuhan,unprecedented interventions,including city lockdown and community closure,have been implemented.However,most of the current studies focused on evaluation of the city lockdown,but paid limited attention to the impacts of the community containment measures within the city.This research addressed this important issue from the perspective of urban planning,based on the epidemic and remote sensing data of 194 communities of Wuhan.We found that the number of confirmed cases of communities is highly related to urban planning factors,e.g.area percentage of buildings and density of neighboring markets.These factors are relevant to the residents’activity patterns,which therefore impact the mode of virus transmission.Our research confirmed the effectiveness of the community-oriented control strategies,provided a valuable reference for other cities that are suffering from the epidemic,and exhibited new thoughts into future urban planning.
