The vapor pressure deficit(VPD)is an important variable used to characterize atmospheric aridity.This paper analyses the spatial and temporal characteristics of the decadal abrupt change(DAC)in the global land VPD aft...The vapor pressure deficit(VPD)is an important variable used to characterize atmospheric aridity.This paper analyses the spatial and temporal characteristics of the decadal abrupt change(DAC)in the global land VPD after 1980 using monthly scale data from the Climatic Research Unit.The results show that 60.5%of the global land area underwent a significantly increased decadal abrupt change(IDAC)in the VPD,and the persistent IDAC of the VPD was obvious in the middle and low latitudes of Eurasia,Africa and parts of South America but not in central North America or Western Siberia.From 1980 to 2020,most regions experienced no more than two persistent IDACs,while more than two significant increases occurred mainly around the Mediterranean and in eastern South America.The persistent IDAC occurred relatively early in the middle and low latitudes of Eurasia,Africa,and eastern South America and after 2000 in the high latitude regions,Eastern Europe,and near the Qinghai-Tibet Plateau.The regions where the persistent IDAC lasted longer than 10 years mainly included North Africa,West Asia,eastern South America,and parts of East Asia,indicating that the persistent increases in atmospheric aridity in these regions were obvious.In general,the persistent IDAC that began in 1993–2000 was significantly more than that occurred in other periods and lasted longer than that before 1990,suggesting that the land area experiencing an abrupt increase has an expansion after the 1990s and that the role of water limitation in this persistent IDAC in Central Asia and most of China strengthened.In addition,the VPD showed another large-scale persistent IDAC over the global land region in 2009,indicating that global atmospheric aridity intensified over the last decade.At the same time,in a few global regions,the VPD has exhibited decreased decadal abrupt changes(DDACs)with durations shorter than 2 years.展开更多
A new chemiluminescence(CL)reagent named 4-amino-5-thiocyanato-phthalyl-hydrazine(iso-luminol-SCN)is synthesized by the bromide-mediated substitution reaction of iso-luminol with sodium thiocyanate in dimethyl formami...A new chemiluminescence(CL)reagent named 4-amino-5-thiocyanato-phthalyl-hydrazine(iso-luminol-SCN)is synthesized by the bromide-mediated substitution reaction of iso-luminol with sodium thiocyanate in dimethyl formamide(DMF)at room temperature.Strong CL is observed for iso-luminol-SCN oxidized by hydrogen peroxide(H2O2)in the presence of Fe^(2+),with the CL intensity strongly depending on the concentration of Fe^(2+)and being hardly interferred by other common metal ions.Based on this fact,a flow injection CL method is established for the high sensitive and selective determination of Fe^(2+).The CL intensity was linearly correlated with the concentration of Fe^(2+)in the range of 1.0×10^(–8) mol·L^(-1) to 1.0×10^(–5) mol·L^(-1) following the equation CLnet=166.3c+57.7(c,×10^(–6) mol·L^(-1);n=7;R2=0.9988).The detection limit is calculated to be 3.2×10–9 mol·L^(-1) Fe^(2+)based on the 3S0/K principle.The relative standard deviation(RSD)was 3.7%for 1.0×10^(–6) mol·L^(-1) Fe^(2+)(n=11),a support for the precision of Fe^(2+)measurement.The recoveries of Fe^(2+)were obtained in the range of 98.8%—101.6%in three real water samples,showing the applicability and reliability by the proposed method.The possible CL mechanism is proposed based on the kinetic characteristic of the CL reaction and the CL spectrum.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2022YFF0801703)the National Natural Science Foundation of China(Grant Nos.42175053&41822503)。
文摘The vapor pressure deficit(VPD)is an important variable used to characterize atmospheric aridity.This paper analyses the spatial and temporal characteristics of the decadal abrupt change(DAC)in the global land VPD after 1980 using monthly scale data from the Climatic Research Unit.The results show that 60.5%of the global land area underwent a significantly increased decadal abrupt change(IDAC)in the VPD,and the persistent IDAC of the VPD was obvious in the middle and low latitudes of Eurasia,Africa and parts of South America but not in central North America or Western Siberia.From 1980 to 2020,most regions experienced no more than two persistent IDACs,while more than two significant increases occurred mainly around the Mediterranean and in eastern South America.The persistent IDAC occurred relatively early in the middle and low latitudes of Eurasia,Africa,and eastern South America and after 2000 in the high latitude regions,Eastern Europe,and near the Qinghai-Tibet Plateau.The regions where the persistent IDAC lasted longer than 10 years mainly included North Africa,West Asia,eastern South America,and parts of East Asia,indicating that the persistent increases in atmospheric aridity in these regions were obvious.In general,the persistent IDAC that began in 1993–2000 was significantly more than that occurred in other periods and lasted longer than that before 1990,suggesting that the land area experiencing an abrupt increase has an expansion after the 1990s and that the role of water limitation in this persistent IDAC in Central Asia and most of China strengthened.In addition,the VPD showed another large-scale persistent IDAC over the global land region in 2009,indicating that global atmospheric aridity intensified over the last decade.At the same time,in a few global regions,the VPD has exhibited decreased decadal abrupt changes(DDACs)with durations shorter than 2 years.
基金the Special Funds for Scientific Research of High-level Talents of Ankang University(No.2020 AKQDZR04)the Open Foundation of the Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province(No.2017001)the Shaanxi Provincial Innovation Experiment Program for University Students(No.S202011397059)for financial support.
文摘A new chemiluminescence(CL)reagent named 4-amino-5-thiocyanato-phthalyl-hydrazine(iso-luminol-SCN)is synthesized by the bromide-mediated substitution reaction of iso-luminol with sodium thiocyanate in dimethyl formamide(DMF)at room temperature.Strong CL is observed for iso-luminol-SCN oxidized by hydrogen peroxide(H2O2)in the presence of Fe^(2+),with the CL intensity strongly depending on the concentration of Fe^(2+)and being hardly interferred by other common metal ions.Based on this fact,a flow injection CL method is established for the high sensitive and selective determination of Fe^(2+).The CL intensity was linearly correlated with the concentration of Fe^(2+)in the range of 1.0×10^(–8) mol·L^(-1) to 1.0×10^(–5) mol·L^(-1) following the equation CLnet=166.3c+57.7(c,×10^(–6) mol·L^(-1);n=7;R2=0.9988).The detection limit is calculated to be 3.2×10–9 mol·L^(-1) Fe^(2+)based on the 3S0/K principle.The relative standard deviation(RSD)was 3.7%for 1.0×10^(–6) mol·L^(-1) Fe^(2+)(n=11),a support for the precision of Fe^(2+)measurement.The recoveries of Fe^(2+)were obtained in the range of 98.8%—101.6%in three real water samples,showing the applicability and reliability by the proposed method.The possible CL mechanism is proposed based on the kinetic characteristic of the CL reaction and the CL spectrum.
