The Hengduan Mountains is in the transitional zone between the Qinghai-Tibet Plateau(QTP)and the YunnanGuizhou Plateau in China,and a key area for elucidating the Quaternary environmental changes in Asia.The paleo-Dao...The Hengduan Mountains is in the transitional zone between the Qinghai-Tibet Plateau(QTP)and the YunnanGuizhou Plateau in China,and a key area for elucidating the Quaternary environmental changes in Asia.The paleo-Daocheng ice cap was located on the Shaluli Hilly Plateau in the northeastern Hengduan Mountains,the oldest moraines in the Hengduan Mountains region were found in the ice cap area.Such glacial landforms provide key evidence to study the timing when this area entered the cryosphere with the uplift of the QTP.However,it is difficult to collect suitable glacial boulders from these moraines for traditional terrestrial in-situ cosmogenic nuclide(TCN)exposure dating because of long-term severe moraine degradation.Here,we collected clast samples from the moraine surface and depth profile to constrain the age of the oldest moraine in Kuzhaori(moraine E)using TCN^(10)Be dating technique.The minimum^(10)Be ages of five clast samples from the moraine surface range from 187.4±1.5 to 576.8±4.3 ka,implying that the moraine has been seriously degraded since deposition.Based on the TCN^(10)Be concentrations of the samples from a depth profile and simulations,the exposure-erosion-inheritance history of the profile was obtained.By fitting to the profile^(10)Be concentrations using the chi-square test,the simulations yielded a reliable age of 626.0±52.5 ka for the moraine.Therefore,the oldest moraine(moraine E)in Kuzhaori was most likely formed at about 0.63Ma ago,corresponding to the marine isotope stage(MIS)16.This glaciation represents the maximum Quaternary glaciation after the QTP was elevated into the cryosphere by the Kunlun-Yellow River Tectonic Movement.展开更多
The rainfall changes in East Asian summer monsoon(EASM)regions on the orbital timescale remain controversial due to the lack of reliable rainfall records.Here,we present new multiproxy records(δ^(18)O,δ^(13)C,Sr/Ca ...The rainfall changes in East Asian summer monsoon(EASM)regions on the orbital timescale remain controversial due to the lack of reliable rainfall records.Here,we present new multiproxy records(δ^(18)O,δ^(13)C,Sr/Ca and Mg/Ca)of a230Thdated stalagmite from Hulu Cave in central eastern China.Multiproxy records reconstruct a regional hydroclimate history from 340 to 261 kyr BP(thousand years before present),approximately covering the antepenultimate glacial period.Theδ^(18)O record is dominated by the precessional cycles,suggesting that EASM responds to changes in Northern Hemisphere summer insolation(NHSI)on the orbital timescale.Significant correlations amongst theδ^(13)C,Sr/Ca and Mg/Ca suggest that a common factor,i.e.,the local hydrological cycle,controlled their variability,and their leading principal component can be used as a proxy linked to regional rainfall.This composite record bears a good similarity to those from the Chinese Loess Plateau,showing a gradually decreasing rainfall during the antepenultimate glacial period,consistent with changes in global ice volume.Superimposed on the long-term trend,three relative wetter intervals were responding to the higher NHSI periods,suggesting that EASM rainfall variability was induced by integrated effects of global ice volume and NHSI.The increased ice sheets and lower NHSI resulted in an increased meridional temperature gradient and southward shift of the westerlies,which shortened the duration of Meiyu and midsummer rainfall.The differences between the rainfall record and the stalagmiteδ^(18)O record indicate that the latter represents the overall EASM intensity linked to monsoon circulation,but does not directly reflect the rainfall changes at the cave sites.展开更多
We present a230Th-dated stalagmite oxygen isotope(δ^18O)record from Loushanguan Cave in the Yangtze River valley,China.The^δ18O record,if viewed as a proxy of the Asian summer monsoon(ASM)intensity,provides an ASM h...We present a230Th-dated stalagmite oxygen isotope(δ^18O)record from Loushanguan Cave in the Yangtze River valley,China.The^δ18O record,if viewed as a proxy of the Asian summer monsoon(ASM)intensity,provides an ASM history for the early Holocene with clear centennial-scale variability.A significant approximately 200-yr cycle between 10.2 and 9.1 ka BP(before present,where"present"is defined as the year AD 1950),as revealed by spectral power analyses,is of global significance and is probably forced by the Suess or de Vries cycle of solar activity.Here,we explore a physical mechanism to explain the relationship between the solar activity and the ASM.A strong coherence between the ASM and El Ni?o–Southern Oscillation(ENSO)has been observed by performing crosswavelet analyses on this cycle.Our study suggests that a strong(weak)ASM state corresponds to a warm(cold)ENSO,which is consistent with modern meteorological observations but contrasts with previous studies on regions far from the Meiyu rainbelt.We argue that the centennial fluctuations of the ASM are a fundamental characteristic forced by the solar activity,with the ENSO variability as a mediator.The relationship between ENSO and the ASM displayed spatial heterogeneity on the centennial scale during the early Holocene,which is a more direct analogue to the observed modern interannual variability of the ASM.展开更多
Polycyclic aromatic hydrocarbons(PAHs)are ubiquitous toxic organic pollutants in the natural environment that are strongly associated with socioeconomic activities.Exploring the distribution,sources,and ecological tox...Polycyclic aromatic hydrocarbons(PAHs)are ubiquitous toxic organic pollutants in the natural environment that are strongly associated with socioeconomic activities.Exploring the distribution,sources,and ecological toxicity of PAHs is essential to abate their pollution and biological risks.The 16 priority PAHs in different lakeside city estuarine sediments in the northern Taihu Lake in China were determined using gas chromatography-mass spectrometry.Results showed that total concentrations of PAHs(ΣPAHs)ranged from 672.07 to 5858.34 ng g^(^(-1)),with a mean value of 2121.37 ng g^(^(-1)).High-molecular-weight PAHs(4-6 rings)were dominant,accounting for 85%of theΣPAHs detected.Due to the barrier of gate/dam in the estuarine area,the concentrations of PAHs in the sediments were significantly different between the river mouth and lake side.Changes in total organic carbon(TOC)content and the spatial distribution of PAHs in the sediments were consistent.Sediment pollution assessment explored using the fuzzy evaluation model indicated 75%of slight PAH pollution.Some estuarine sediments(22%)concentrated in the east of the Wuli Lake in the Meiliang bay of the Taihu Lake were moderately or heavily polluted.The PAHs may lead to occasional detrimental biological consequences in the area.Diagnostic ratios and principal component analysis-multiple linear regression suggested vehicle emission and natural gas combustion as the primary PAH contributors(81%).展开更多
Based on 467 pairs ofδ^(18)O andδ^(13)C records and 8230 Th dates from a stalagmite(BF4)from Xiniu Cave,central China,we present a reconstruction of 9-yr resolution monsoon rainfall record for the past 4700 years.Ou...Based on 467 pairs ofδ^(18)O andδ^(13)C records and 8230 Th dates from a stalagmite(BF4)from Xiniu Cave,central China,we present a reconstruction of 9-yr resolution monsoon rainfall record for the past 4700 years.Ourδ^(18)O record shows good coherence with East Asian summer monsoon(EASM)rainfall proxies from adjacent regions during the overlapping intervals,suggesting thatδ^(18)O signal in BF4 can be interpreted as a monsoon rainfall proxy.Theδ^(13) C variations are related to changes in local processes at the cave site,and regional rainfall and temperature changes.Based on theδ18 O record,a series of dry periods can be identified at 4500-4200,3500-3200,2800-2500,1900-1600,1400-1200,700-500,and 400-200 yr BP,while a series of wet periods can be identified at 4200-3600,2400-2200,3200-2800,1100-900,600-400,and 200-100 yr BP.Power spectrum analysis on ourδ^(18) O record reveals significant cycles at 470 and 80 yr,coinciding with the typical solar periodic variations.This result suggests that changes in solar activity play a dominant role in driving centennial-decadal monsoon rainfall variation in central China.Due to minor changes in solar irradiance(less than 1.5 W m^(-2))over the past 4700 years,our record was further compared to the El Nino-Southern Oscillation(ENSO)and Pacific Decadal Oscillation(PDO)proxies,confirming that solar forcing on monsoon rainfall changes might be amplified by the ENSO and PDO variations.From 600 to 150 yr BP(the Little Ice Age,LIA),a positive shift of 2‰can be revealed in both theδ^(18)O andδ^(13)C records,indicating a cold/dry climatic pattern.By comparing ourδ^(18)O andδ^(13)C records with historical documents,we suggest that the climatic deteriorations between 450 and 250 yr BP may have caused serious social unrest at the end of the Ming Dynasty.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.41971009&41503054)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDA2000300)。
文摘The Hengduan Mountains is in the transitional zone between the Qinghai-Tibet Plateau(QTP)and the YunnanGuizhou Plateau in China,and a key area for elucidating the Quaternary environmental changes in Asia.The paleo-Daocheng ice cap was located on the Shaluli Hilly Plateau in the northeastern Hengduan Mountains,the oldest moraines in the Hengduan Mountains region were found in the ice cap area.Such glacial landforms provide key evidence to study the timing when this area entered the cryosphere with the uplift of the QTP.However,it is difficult to collect suitable glacial boulders from these moraines for traditional terrestrial in-situ cosmogenic nuclide(TCN)exposure dating because of long-term severe moraine degradation.Here,we collected clast samples from the moraine surface and depth profile to constrain the age of the oldest moraine in Kuzhaori(moraine E)using TCN^(10)Be dating technique.The minimum^(10)Be ages of five clast samples from the moraine surface range from 187.4±1.5 to 576.8±4.3 ka,implying that the moraine has been seriously degraded since deposition.Based on the TCN^(10)Be concentrations of the samples from a depth profile and simulations,the exposure-erosion-inheritance history of the profile was obtained.By fitting to the profile^(10)Be concentrations using the chi-square test,the simulations yielded a reliable age of 626.0±52.5 ka for the moraine.Therefore,the oldest moraine(moraine E)in Kuzhaori was most likely formed at about 0.63Ma ago,corresponding to the marine isotope stage(MIS)16.This glaciation represents the maximum Quaternary glaciation after the QTP was elevated into the cryosphere by the Kunlun-Yellow River Tectonic Movement.
基金supported by the National Nature Science Fundation of China(Grant Nos.42002200&42071105)the Open Fund for the State Key Laboratory of Loess and Quaternary Geology(Grant No.SKLLQG1922)+1 种基金the Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJQN201900536)the Chongqing Nature Science Fund(Grant No.cstc2020jcyj-msxm X0598)。
文摘The rainfall changes in East Asian summer monsoon(EASM)regions on the orbital timescale remain controversial due to the lack of reliable rainfall records.Here,we present new multiproxy records(δ^(18)O,δ^(13)C,Sr/Ca and Mg/Ca)of a230Thdated stalagmite from Hulu Cave in central eastern China.Multiproxy records reconstruct a regional hydroclimate history from 340 to 261 kyr BP(thousand years before present),approximately covering the antepenultimate glacial period.Theδ^(18)O record is dominated by the precessional cycles,suggesting that EASM responds to changes in Northern Hemisphere summer insolation(NHSI)on the orbital timescale.Significant correlations amongst theδ^(13)C,Sr/Ca and Mg/Ca suggest that a common factor,i.e.,the local hydrological cycle,controlled their variability,and their leading principal component can be used as a proxy linked to regional rainfall.This composite record bears a good similarity to those from the Chinese Loess Plateau,showing a gradually decreasing rainfall during the antepenultimate glacial period,consistent with changes in global ice volume.Superimposed on the long-term trend,three relative wetter intervals were responding to the higher NHSI periods,suggesting that EASM rainfall variability was induced by integrated effects of global ice volume and NHSI.The increased ice sheets and lower NHSI resulted in an increased meridional temperature gradient and southward shift of the westerlies,which shortened the duration of Meiyu and midsummer rainfall.The differences between the rainfall record and the stalagmiteδ^(18)O record indicate that the latter represents the overall EASM intensity linked to monsoon circulation,but does not directly reflect the rainfall changes at the cave sites.
基金Supported by the National Natural Science Foundation of China(40701013,41877453,and 41572151)National Key Research and Development Program of China(2018YFA0605603)。
文摘We present a230Th-dated stalagmite oxygen isotope(δ^18O)record from Loushanguan Cave in the Yangtze River valley,China.The^δ18O record,if viewed as a proxy of the Asian summer monsoon(ASM)intensity,provides an ASM history for the early Holocene with clear centennial-scale variability.A significant approximately 200-yr cycle between 10.2 and 9.1 ka BP(before present,where"present"is defined as the year AD 1950),as revealed by spectral power analyses,is of global significance and is probably forced by the Suess or de Vries cycle of solar activity.Here,we explore a physical mechanism to explain the relationship between the solar activity and the ASM.A strong coherence between the ASM and El Ni?o–Southern Oscillation(ENSO)has been observed by performing crosswavelet analyses on this cycle.Our study suggests that a strong(weak)ASM state corresponds to a warm(cold)ENSO,which is consistent with modern meteorological observations but contrasts with previous studies on regions far from the Meiyu rainbelt.We argue that the centennial fluctuations of the ASM are a fundamental characteristic forced by the solar activity,with the ENSO variability as a mediator.The relationship between ENSO and the ASM displayed spatial heterogeneity on the centennial scale during the early Holocene,which is a more direct analogue to the observed modern interannual variability of the ASM.
基金supported by the National Natural Science Foundation of China (No. 41673107)the National Water Pollution Control and Treatment Science and Technology Major Project, China (No. 2017ZX07203-005)the Major Project of Jiangsu Provincial Department of Education, China (No. 20KJA170001)。
文摘Polycyclic aromatic hydrocarbons(PAHs)are ubiquitous toxic organic pollutants in the natural environment that are strongly associated with socioeconomic activities.Exploring the distribution,sources,and ecological toxicity of PAHs is essential to abate their pollution and biological risks.The 16 priority PAHs in different lakeside city estuarine sediments in the northern Taihu Lake in China were determined using gas chromatography-mass spectrometry.Results showed that total concentrations of PAHs(ΣPAHs)ranged from 672.07 to 5858.34 ng g^(^(-1)),with a mean value of 2121.37 ng g^(^(-1)).High-molecular-weight PAHs(4-6 rings)were dominant,accounting for 85%of theΣPAHs detected.Due to the barrier of gate/dam in the estuarine area,the concentrations of PAHs in the sediments were significantly different between the river mouth and lake side.Changes in total organic carbon(TOC)content and the spatial distribution of PAHs in the sediments were consistent.Sediment pollution assessment explored using the fuzzy evaluation model indicated 75%of slight PAH pollution.Some estuarine sediments(22%)concentrated in the east of the Wuli Lake in the Meiliang bay of the Taihu Lake were moderately or heavily polluted.The PAHs may lead to occasional detrimental biological consequences in the area.Diagnostic ratios and principal component analysis-multiple linear regression suggested vehicle emission and natural gas combustion as the primary PAH contributors(81%).
基金Supported by the National Natural Science Foundation of China(42071105,41571102,41931178,41672164,and 41172314)U.S.Nature Science Foundation(1702816)+1 种基金Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(164320H116)111 Program of China(D19002)。
文摘Based on 467 pairs ofδ^(18)O andδ^(13)C records and 8230 Th dates from a stalagmite(BF4)from Xiniu Cave,central China,we present a reconstruction of 9-yr resolution monsoon rainfall record for the past 4700 years.Ourδ^(18)O record shows good coherence with East Asian summer monsoon(EASM)rainfall proxies from adjacent regions during the overlapping intervals,suggesting thatδ^(18)O signal in BF4 can be interpreted as a monsoon rainfall proxy.Theδ^(13) C variations are related to changes in local processes at the cave site,and regional rainfall and temperature changes.Based on theδ18 O record,a series of dry periods can be identified at 4500-4200,3500-3200,2800-2500,1900-1600,1400-1200,700-500,and 400-200 yr BP,while a series of wet periods can be identified at 4200-3600,2400-2200,3200-2800,1100-900,600-400,and 200-100 yr BP.Power spectrum analysis on ourδ^(18) O record reveals significant cycles at 470 and 80 yr,coinciding with the typical solar periodic variations.This result suggests that changes in solar activity play a dominant role in driving centennial-decadal monsoon rainfall variation in central China.Due to minor changes in solar irradiance(less than 1.5 W m^(-2))over the past 4700 years,our record was further compared to the El Nino-Southern Oscillation(ENSO)and Pacific Decadal Oscillation(PDO)proxies,confirming that solar forcing on monsoon rainfall changes might be amplified by the ENSO and PDO variations.From 600 to 150 yr BP(the Little Ice Age,LIA),a positive shift of 2‰can be revealed in both theδ^(18)O andδ^(13)C records,indicating a cold/dry climatic pattern.By comparing ourδ^(18)O andδ^(13)C records with historical documents,we suggest that the climatic deteriorations between 450 and 250 yr BP may have caused serious social unrest at the end of the Ming Dynasty.