Delingha is located in the northeast margin of Qaidam Basin.Bayin River alluvial proluvial fan is the main aquifer of Delingha,in which groundwater generally flows from north to south.The hydrochemistry results showed...Delingha is located in the northeast margin of Qaidam Basin.Bayin River alluvial proluvial fan is the main aquifer of Delingha,in which groundwater generally flows from north to south.The hydrochemistry results showed that two different hydrochemical evolution paths formed along southeast and southwest directions,respectively.Cl-Na type groundwater was formed in front of Gahai Lake,and SO_(4)·HCO_(3)-Na·Ca type groundwater was formed in front of Keluke Lake.The results of deuterium(D)and 18O revealed that the groundwater mainly originated from the continuous accumulation of precipitation during geological history under cold and humid climate conditions.In addition,results of ^(14)C indicated that the groundwater age was more than 1140 years,implying relatively poor renewal capability of regional groundwater.Moreover,our numerical modeling results showed that the regional groundwater level will continue to rise under the warm and humid climate conditions.展开更多
The north-eastern Arabian Sea(NE-AS)comes under a strong influence of land–ocean–climate interactions and regulates biogeochemical processes through the supply of huge amounts of dissolved and particulate materials ...The north-eastern Arabian Sea(NE-AS)comes under a strong influence of land–ocean–climate interactions and regulates biogeochemical processes through the supply of huge amounts of dissolved and particulate materials and nutrients via eolian and fluvial supply.These processes underwent dramatic changes in the coastal regions due to sea-level rise and climate change during the Holocene;however,their relative roles remain elusive.The NE-AS receives large amounts of dissolved and particulate fluxes,and therefore,reconstruction of the past surface water Nd isotope composition(eNd)and tracing the provenance of sediment using detrital eNd and geochemical records would enable us to assess the role of various processes controlling these fluxes to the northern Arabian Sea.In this study,we have generated authigenic and detrital eNd records and geochemical records in a sediment core from the coastal region of the NE-AS,offshore Saurashtra.We found that the authigenic eNd profile closely followed the Holocene sea-level records;early Holocene less radiogenic values(-8)were sharply shifted to more radiogenic values(-5.5)during the mid-Holocene(6–7 ka)and thereafter remained stable,close to the modern surface water eNd value.The detrital eNd record broadly followed the authigenic eNd record,however,they differ in magnitude.The geochemical records based on major and trace elemental abundances show a similar trend to the authigenic eNd record and concomitant changes with the Holocene sea-level.Our investigation reveals that lower sea-level stand combined with a stronger monsoon during the early Holocene resulted in enhanced fluvial weathering fluxes from the west-flowing rivers and contributed to less radiogenic Nd.This situation changed dramatically during the mid-Holocene due to the weakening of the south-west monsoon and rapid sea level rise,which caused enhanced influence of open ocean water characterised by more radiogenic eNd(-6)derived from the dissolution of dust from Arabia and African desserts.This dramatic shift in展开更多
This study is focused on climate-induced variation of sea level in Stockholm during 1873-1995. After the effect of the land uplift, is removed, the residual is characterized and related to large-scale temperature and ...This study is focused on climate-induced variation of sea level in Stockholm during 1873-1995. After the effect of the land uplift, is removed, the residual is characterized and related to large-scale temperature and atmospheric circulation. The residual shows an overall upward trend, although this result depends on the uplift rate used. However, the seasonal distribution of the trend is uneven. There are even two months （June and August） that show a negative trend. The significant trend in August may be linked to fresh water input that is controlled by precipitation. The influence of the atmospheric conditions on the sea level is mainly manifested through zonal winds, vorticity and temperature. While the wind is important in the period January-May, the vorticity plays a main role during June and December. A successful linear multiple-regression model linking the climatic variables （zonal winds, vorticity and mean air temperature during the previous two months） and the sea level is established for each month. An independent verification of the model shows that it has considerable skill in simulating the variability.展开更多
基金This work was supported by the National Natural Science Foundation of China(41672243)the China Geological Survey Program(DD20160291,DD20189270).
文摘Delingha is located in the northeast margin of Qaidam Basin.Bayin River alluvial proluvial fan is the main aquifer of Delingha,in which groundwater generally flows from north to south.The hydrochemistry results showed that two different hydrochemical evolution paths formed along southeast and southwest directions,respectively.Cl-Na type groundwater was formed in front of Gahai Lake,and SO_(4)·HCO_(3)-Na·Ca type groundwater was formed in front of Keluke Lake.The results of deuterium(D)and 18O revealed that the groundwater mainly originated from the continuous accumulation of precipitation during geological history under cold and humid climate conditions.In addition,results of ^(14)C indicated that the groundwater age was more than 1140 years,implying relatively poor renewal capability of regional groundwater.Moreover,our numerical modeling results showed that the regional groundwater level will continue to rise under the warm and humid climate conditions.
文摘The north-eastern Arabian Sea(NE-AS)comes under a strong influence of land–ocean–climate interactions and regulates biogeochemical processes through the supply of huge amounts of dissolved and particulate materials and nutrients via eolian and fluvial supply.These processes underwent dramatic changes in the coastal regions due to sea-level rise and climate change during the Holocene;however,their relative roles remain elusive.The NE-AS receives large amounts of dissolved and particulate fluxes,and therefore,reconstruction of the past surface water Nd isotope composition(eNd)and tracing the provenance of sediment using detrital eNd and geochemical records would enable us to assess the role of various processes controlling these fluxes to the northern Arabian Sea.In this study,we have generated authigenic and detrital eNd records and geochemical records in a sediment core from the coastal region of the NE-AS,offshore Saurashtra.We found that the authigenic eNd profile closely followed the Holocene sea-level records;early Holocene less radiogenic values(-8)were sharply shifted to more radiogenic values(-5.5)during the mid-Holocene(6–7 ka)and thereafter remained stable,close to the modern surface water eNd value.The detrital eNd record broadly followed the authigenic eNd record,however,they differ in magnitude.The geochemical records based on major and trace elemental abundances show a similar trend to the authigenic eNd record and concomitant changes with the Holocene sea-level.Our investigation reveals that lower sea-level stand combined with a stronger monsoon during the early Holocene resulted in enhanced fluvial weathering fluxes from the west-flowing rivers and contributed to less radiogenic Nd.This situation changed dramatically during the mid-Holocene due to the weakening of the south-west monsoon and rapid sea level rise,which caused enhanced influence of open ocean water characterised by more radiogenic eNd(-6)derived from the dissolution of dust from Arabia and African desserts.This dramatic shift in
文摘This study is focused on climate-induced variation of sea level in Stockholm during 1873-1995. After the effect of the land uplift, is removed, the residual is characterized and related to large-scale temperature and atmospheric circulation. The residual shows an overall upward trend, although this result depends on the uplift rate used. However, the seasonal distribution of the trend is uneven. There are even two months （June and August） that show a negative trend. The significant trend in August may be linked to fresh water input that is controlled by precipitation. The influence of the atmospheric conditions on the sea level is mainly manifested through zonal winds, vorticity and temperature. While the wind is important in the period January-May, the vorticity plays a main role during June and December. A successful linear multiple-regression model linking the climatic variables （zonal winds, vorticity and mean air temperature during the previous two months） and the sea level is established for each month. An independent verification of the model shows that it has considerable skill in simulating the variability.
