Beryllium-7 （^7Be） and lead-210 （^210pb） activities were measured from October 2002 to January 2004 at Waliguan Observatory （WO： 36.287°N, 100.898°E, 3816 m a.s.l （above sea level） in northwest China...Beryllium-7 （^7Be） and lead-210 （^210pb） activities were measured from October 2002 to January 2004 at Waliguan Observatory （WO： 36.287°N, 100.898°E, 3816 m a.s.l （above sea level） in northwest China. ^7Be and ^210pb activities are high with overall averages of 14.74-3.5 mBq m^-3 and 1.8±0.8 mBq m^-3 respectively. For both 7Be and ^210pb, there are significant short-term and seasonal variations with a commonly low value in summer （May-September） and a monthly maximum in April （for ^7Be） and in December （for ^210pb）. The ratio of ^7Be/^210pb showed a broad maximum extending from April to July, coinciding with a seasonal peak in surface ozone （O3）. The seasonal cycles of ^7Be and ^210pb activities were greatly influenced by precipitation and thermal dynamical conditions over the boundary layer, especially for ^210Pb. The vertical mixing process between the boundary layer and the aloft air modulates the variations of ^7Be and ^210pb at WO in summer. It is indicated that air mass had longer residence time and originated from higher altitudes at WO in the spring-summer time and the winter in 2003. During an event with extremely high weeklyaveraged ^7Be concentration （24.8 mBq m^-3） together with high O3 levels and low water mixing ratio, we found that air masses had been convectively transported a long distance to WO from high latitude source regions in central Asia, where significant subsiding motions were observed. In another case with the extreme ^210pb activity of 5.7 mBq m^-3 high CO2 level and specific humidity （in winter）, air masses had come from south China and north Indian regions where 222Rn activities were high. This study, using ^7Be and ^210pb as atmospheric tracers, has revealed that complex interactions of convective mixing from the upper troposphere and long-range transports exist at WO.展开更多
210Po and 210Pb are increasingly used to constrain particle dynamics in the open oceans,however they are less used in coastal waters.Here,distributions and partitions of 210Po and 210Pb were examined in the Taiwan Str...210Po and 210Pb are increasingly used to constrain particle dynamics in the open oceans,however they are less used in coastal waters.Here,distributions and partitions of 210Po and 210Pb were examined in the Taiwan Strait,as well as their application to quantify particle sinking.Activity concentrations of dissolved 210Po and 210Pb(<0.6μm)ranged from 1.21 to 7.63 dpm/(100 L)and from 1.07 to 6.33 dpm/(100 L),respectively.Activity concentrations of particulate 210Po and 210Pb varied from 1.96 to 36.74 dpm/(100 L)and from 3.11 to 38.06 dpm/(100 L).Overall,particulate 210Po and 210Pb accounted for the majority of the bulk 210Po and 210Pb.210Po either in dissolved or particulate phases showed similar spatial patterns to 210Pb,indicating similar mechanisms for controlling the distributions of 210Po and 210Pb in the Taiwan Strait.The different fractionation coefficients indicated that particles in the Zhemin Coastal Current(ZCC)inclined to absorb 210Po prior to 210Pb while they showed an opposite effect in the Taiwan Warm Current(TWC).Based on the disequilibria between 210Po and 210Pb,the sinking fluxes of total particulate matter(TPM)were estimated to range from–0.22 to 3.84 g/(m2·d),showing an overall comparable spatial distribution to previous reported sediment accumulation rates.However,our sinking fluxes were lower than the sedimentation rates,indicating a sediment resuspension in winter and horizontal transport of particulate matter from the Taiwan Strait to the East China Sea.展开更多
基金the National Science Foundation of China （Grant Nos. 40175032 , 40575013）.
文摘Beryllium-7 （^7Be） and lead-210 （^210pb） activities were measured from October 2002 to January 2004 at Waliguan Observatory （WO： 36.287°N, 100.898°E, 3816 m a.s.l （above sea level） in northwest China. ^7Be and ^210pb activities are high with overall averages of 14.74-3.5 mBq m^-3 and 1.8±0.8 mBq m^-3 respectively. For both 7Be and ^210pb, there are significant short-term and seasonal variations with a commonly low value in summer （May-September） and a monthly maximum in April （for ^7Be） and in December （for ^210pb）. The ratio of ^7Be/^210pb showed a broad maximum extending from April to July, coinciding with a seasonal peak in surface ozone （O3）. The seasonal cycles of ^7Be and ^210pb activities were greatly influenced by precipitation and thermal dynamical conditions over the boundary layer, especially for ^210Pb. The vertical mixing process between the boundary layer and the aloft air modulates the variations of ^7Be and ^210pb at WO in summer. It is indicated that air mass had longer residence time and originated from higher altitudes at WO in the spring-summer time and the winter in 2003. During an event with extremely high weeklyaveraged ^7Be concentration （24.8 mBq m^-3） together with high O3 levels and low water mixing ratio, we found that air masses had been convectively transported a long distance to WO from high latitude source regions in central Asia, where significant subsiding motions were observed. In another case with the extreme ^210pb activity of 5.7 mBq m^-3 high CO2 level and specific humidity （in winter）, air masses had come from south China and north Indian regions where 222Rn activities were high. This study, using ^7Be and ^210pb as atmospheric tracers, has revealed that complex interactions of convective mixing from the upper troposphere and long-range transports exist at WO.
基金The National Natural Science Foundation of China under contract Nos 41076043 and 51608142the Guangxi Young and Middle-aged Teachers’ Basic Ability Upgrading Project under contract No.2019KY0298the Guangxi Science and Technology Planning Project under contract No.Gui Ke-AD18126018
文摘210Po and 210Pb are increasingly used to constrain particle dynamics in the open oceans,however they are less used in coastal waters.Here,distributions and partitions of 210Po and 210Pb were examined in the Taiwan Strait,as well as their application to quantify particle sinking.Activity concentrations of dissolved 210Po and 210Pb(<0.6μm)ranged from 1.21 to 7.63 dpm/(100 L)and from 1.07 to 6.33 dpm/(100 L),respectively.Activity concentrations of particulate 210Po and 210Pb varied from 1.96 to 36.74 dpm/(100 L)and from 3.11 to 38.06 dpm/(100 L).Overall,particulate 210Po and 210Pb accounted for the majority of the bulk 210Po and 210Pb.210Po either in dissolved or particulate phases showed similar spatial patterns to 210Pb,indicating similar mechanisms for controlling the distributions of 210Po and 210Pb in the Taiwan Strait.The different fractionation coefficients indicated that particles in the Zhemin Coastal Current(ZCC)inclined to absorb 210Po prior to 210Pb while they showed an opposite effect in the Taiwan Warm Current(TWC).Based on the disequilibria between 210Po and 210Pb,the sinking fluxes of total particulate matter(TPM)were estimated to range from–0.22 to 3.84 g/(m2·d),showing an overall comparable spatial distribution to previous reported sediment accumulation rates.However,our sinking fluxes were lower than the sedimentation rates,indicating a sediment resuspension in winter and horizontal transport of particulate matter from the Taiwan Strait to the East China Sea.
基金国家自然科学基金面上项目“环境中Pu的地球化学运移”(编号:40873086),“黔中大气核素(Pb-210,Be-7)与气溶胶关系”(编号:40773071),“Pb-210和Be-7大气沉降通量研究”(编号:40373038),“利用7Be和210Pb示踪研究高原大气微量气体成分的输送特征”(编号:40175032)中美国际合作项目“Tracing recent climate and environmental changes by measuring lowlevel radionuclides in the Yunnan-Guizhou plateau,China(2001-2005)”资助
