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| 1 | Relative humidity reconstruction for northwestern China's Altay Mountains using tree-ring δ^(18)O显示文摘Relative humidity is an important factor in water and water vapor feedback cycles.In this study,we established a 222-year annual tree-ring δ^(18)O chronology for Siberian larch(Larix sibirica Ldb.)from the Altay Mountains in northwestern China.Climate response analyses revealed that the relative humidity was the primary factor limiting tree-ring δ^(18)O fractionation.Based on our analysis,tree-ring δ^(18)O can be used to reconstruct the July–August relative humidity based on both a reasonable mechanism of tree-ring δ^(18)O fractionation and a statistically significant regression model.We used this model to reconstruct variations in the July–August relative humidity,and the model explained 47.4% of the total variation in the measured relative humidity data from 1961 to 2011.The relative humidity in the study area increased from 1900 to the 1990s and decreased thereafter.Two regime-shift dry periods were detected during the study period(one from 1817 to 1830 and the other from 2004 to 2011). | Guobao Xu Xiaohong Liu Dahe Qin Tuo Chen Wenzhi Wang Guoju Wu Weizhen Sun Wenling An Xiaomin Zeng | 2014 | Chinese Science Bulletin2014，59，2： | 14 |
| 2 | Increased mercury pollution revealed by tree rings from the China's Tianshan Mountains显示文摘Mercury (Hg)can be transported globally by the atmospheric circulation and it accumulates and biomagnifies along food chains [1,2].Due to its threats to human health and wildlife when converted to the neurotoxin methyl mercury,variations in Hg concentration in various ecosystems were paid more attention by scientists recently.Natural processes such as geothermal activities, volcanic activities,and weathering of Hg-containing rocks,can release a mass of Hg to the environment.Anthropogenic emissions had become the main atmospheric pollution source since the Industrial Revolution.A recent study indicated that half of the Hg presented in atmosphere was sourced from human activities and about 73%total mercury was released after 1850[3].Aiming to reduce the impact of Hg to environmental and human health,UNEP (United Nations Environment Programme)passed the Minamata Convention in 2013to limit Hg emission through contro|ling technologies on air pollution. | Huhu Kang Xiaohong Liu Junming Guo Guobao Xu Guoju Wu Xiaomin Zeng Bo Wang Shichang Kang | 2018 | Science Bulletin2018，63，20： | 4 |
| 3 | A novel mitochondrial tRNA gene mutation in a chinese family with dilated cardiomyopathy and sensorineural deafness显示文摘Objective: To determine whether a mutation of mitochondrial DNA induces familial dilated cardiomyopathy in Chinese families with cardiomyopathy,and analyzed the correlation between the genotype and phenotype. Methods: Affected members in three Chinese families of the familial dilated cardiomyopathy underwent clinical evaluation and DNA analysis. Polymerase chain reaction and direct DNA sequencing were used to screen for mitochondrial DNA mutation. The type of mtDNA variations and clinical situation were analysed on the patients with mitochondrial DNA mutation. Results: The mitochondrial A3434G mutation was identified in one of the three families,the 3434 th nucleotide A was replaced by G, which led to change of amino acid. No mutations were identified in the clinically unaffected members of the family and all members of the other two families. Conclusion: This study indicates that the mitochondrial A3434G mutation maybe related with familial dilated cardiomyopathy and deafness. | Xianghong Wu Xiumei Xie Guotian Ma Guoju Sun Xiaobin Chen | 2006 | Journal of Nanjing Medical University2006，20，5： | 3 |
| 4 | Application and verification of simultaneous determination of cellulose δ^(13)C and δ^(18)O in Picea shrenkiana tree rings from northwestern China using the high-temperature pyrolysis method显示文摘Stable isotopes in tree-ring cellulose provide important data in ecological,archaeological,and paleoenvironmental researches,thereby,the demand for stable isotope analyses is increasing rapidly.Simultaneous measurement of cellulose δ^(13)C and δ^(18)O values from tree rings would reduce the cost of isotopic commodities and improve the analytical efficiency compared with conventional separate measurement.In this study,we compared the δ^(13)C and δ^(18)O values of tree-ringα-cellulose from Tianshan spruce(Picea schrenkiana)in an arid site in the drainage basin of the Urumqi River in Xinjiang of northwestern China based on separate and simultaneous measurements,using the combustion method(at1050°C)and the high-temperature pyrolysis method(at 1350°C and 1400°C).We verified the results of simultaneous measurement using the outputs from separate measurement and found that both methods(separate and simultaneous)produced similar δ^(13)C values.The two-point calibrated method improved the results(range and variation)of δ^(13)C and δ^(18)O values.The mean values,standard deviations,and trends of the tree-ring δ^(13)C obtained by the combustion method were similar to those by the pyrolysis method followed by two-point calibration.The simultaneously measured δ^(18)O from the pyrolysis method at 1400°C had a nearly constant offset with that the pyrolysis method at 1350°C due to isotopic-dependence on the reaction temperature.However,they showed similar variations in the time series.The climate responses inferred from simultaneously and separately measured δ^(13)C and δ^(18)O did not differ between the two methods.The tree-ring δ^(13)C and δ^(18)O values were negatively correlated with standardized precipitation evapotranspiration index from May to August.In addition,the δ^(18)O was significantly correlated with temperature(positive),precipitation(negative),and relative humidity(negative)from May to August.The tree-ring δ^(13)C and δ^(18)O values determined simultaneously through the high-temperature pyrolysis method could produce acceptable and reliable stable isotope series.The simultaneous isotopic measurement can greatly reduce the cost and time requirement compared with the separate isotopic measurement.These results are consistent with the previous studies at humid sites,suggesting that the simultaneous determination of δ^(13)C and δ^(18)O in tree-ringα-cellulose can be used in wide regions. | XU Guobao LIU Xiaohong SUN Weizhen CHEN Tuo ZHANG Xuanwen ZENG Xiaomin WU Guoju WANG Wenzhi QIN Dahe | 2018 | Journal of Arid Land2018，10，6： | 1 |
| 5 | Long-term mercury variations in tree rings of the permafrost forest,northeastern China显示文摘Permafrost is a potential mercury(Hg)pool released by thawing,which can raise the risk of Hg pollution under global warming.Tree rings are useful archives of environment-specific Hg exposure over long periods.We determined Hg concentrations in tree rings of two dominant tree species(Larix gmelinii Rupr.and Pinus sylvestris var.mongolica)at permafrost sites in northeastern China.The biweighted mean Hg concentrations ranged from 0.36 to 3.96 ng g^(-1) from 1840 to 2014.The tree-ring width had no significant influence on the Hg concentration.Larch Hg increased slightly before the 1970 s and peaked in the 1990 s.However,the pine Hg concentration increased continuously until the 1930 s,decreased rapidly until the 1970 s,then rose to a peak in the late 1980 s.The change of Hg concentrations in larch and pine revealed a time offset of 4 to 5 years,which implied possibly high mobility of Hg in pine tree rings.Higher Hg concentrations from 1920 to 1960 and subsequent decreases in isolated permafrost forests revealed the local geographical Hg cycling history.Lower Hg concentrations and faster increases in larch suggest the role of additional winter Hg loading for the evergreen pine and species-specific differences in root absorption in response to melting permafrost.Our results highlight possible geographical impacts on tree-ring Hg records,improve understanding of Hg cycles in permafrost forest,and suggest a need to sample additional species in a range of permafrost environments. | Huhu KANG Xiaohong LIU Junming GUO Qiuliang ZHANG Yabo WANG Jie HUANG Guobao XU Guoju WU Wensen GE Shichang KANG | 2022 | Science China Earth Sciences2022，65，7： | 0 |
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