【目的】全球变暖背景下,喀斯特地貌广布的西南地区可能面临石漠化加剧的风险,对该区域石漠化演变历史的重建具有重要意义。【方法】通过采自贵州省黔西县黑洞一支石笋(HD12)的29个230Th年龄和954个δ^(13)C数据,重建了该地区过去4 750...【目的】全球变暖背景下,喀斯特地貌广布的西南地区可能面临石漠化加剧的风险,对该区域石漠化演变历史的重建具有重要意义。【方法】通过采自贵州省黔西县黑洞一支石笋(HD12)的29个230Th年龄和954个δ^(13)C数据,重建了该地区过去4 750年的生态环境演变历史。【结果与结论】发现在4 322~3 526 a B.P.以及803~82 a B.P.时段存在两个显著的δ^(13)C正偏移,说明这两个时段洞穴上方的生态环境出现了恶化。HD12石笋δ^(13)C记录在约803 a B.P.的显著偏正持续了约290 a,其振幅达4.2‰,指示了该区域石漠化的扩张过程。这一时期西南地区多个洞穴石笋δ^(13)C值的一致偏正特征,可能指示了宋末靖康事件(823 a B.P.)后,人口的大量迁入和气候的干旱化导致了该区域石漠化的扩张。HD12石笋δ^(13)C值在4 322~3 526 a B.P.时期的偏正,振幅达4.9‰,其中4 322~3 977 a B.P.偏正过程对应于北半球4.2 ka事件,而3 777~3 526 a B.P.的偏正对应3.7 ka事件,两个时期的干旱事件在西南地区的多个石笋与湖泊记录中均有体现,说明在此期间,亚洲夏季风减弱,降水减少可能引起了该区域植被覆盖度大幅降低和土壤严重退化。展开更多
Tree radial growth can have significantly differ-ent responses to climate change depending on the environ-ment.To elucidate the effects of climate on radial growth and stable carbon isotope(δ^(13)C)fractionation of Q...Tree radial growth can have significantly differ-ent responses to climate change depending on the environ-ment.To elucidate the effects of climate on radial growth and stable carbon isotope(δ^(13)C)fractionation of Qing-hai spruce(Picea crassifolia),a widely distributed native conifer in northwestern China in different environments,we developed chronologies for tree-ring widths and δ^(13)C in trees on the southern and northern slopes of the Qilian Mountains,and analysed the relationship between these tree-ring variables and major climatic factors.Tree-ring widths were strongly influenced by climatic factors early in the growing season,and the radial growth in trees on the northern slopes was more sensitive to climate than in trees on the southern.Tree-ring δ^(13)C was more sensitive to climate than radial growth.δ^(13)C fractionation was mainly influenced by summer temperature and precipitation early in the growing season.Stomatal conductance more strongly limited stable carbon isotope fractionation in tree rings than photosynthetic rate did.The response between tree rings and climate in mountains gradually weakened as climate warmed.Changes in radial growth and stable carbon isotope fractionation of P.crassifolia in response to climate in the Qilian Mountains may be further complicated by continued climate change.展开更多
The Paleocene coals of the Salt Range in the Punjab Province of Pakistan have great economic potential;however,their trace element and stable isotopic characteristics have not been studied in detail except for a few s...The Paleocene coals of the Salt Range in the Punjab Province of Pakistan have great economic potential;however,their trace element and stable isotopic characteristics have not been studied in detail except for a few sporadic samples.In this study,a total of 59 coal samples of which 14 are obtained from open cast mines have been investigated for elemental composition andδ^(13)C-δ^(15)N isotopic signatures.Average contents of trace elements such as Co,Cr,Cu,Pb,Sr,Th,U,V,and Zn are 7.4,41.7,11.2,12.5,90.2,4.0,1.9,128,and 31.1 mg/kg,respectively.These values,when compared with the World Coal Clarke values,were relatively higher in low-rank coals in comparison with Clarke values for brown coals.Likewise,As(20.4 mg/kg),Co(6.6 mg/kg),Cr(22.4 mg/kg),Cu(^(13).3 mg/kg),Pb(19.2 mg/kg),Sr(^(15)4.7 mg/kg),Th(2.5 mg/kg),V(47.8 mg/kg),and Zn(75.1 mg/kg)were significantly higher in the sub-bituminous to bituminous coals of the Salt Range.Mineralogical analysis,based on X-ray diffraction and energy dispersive X-ray spectroscopy,revealed that the studied samples contain illite,kaolinite calcite,gypsum,pyrite,and quartz.Elemental affinity with organic and inorganic phases of coals calculated by an indirect statistical approach indicated a positive association of ash content with Ag,Al,Co,Cr,Cs,Cu,Mn,P,Rb,Pb,Th,U,and V,suggesting the presence of inorganic components in studied coals.However,As,Fe,Sr,and Zn exhibit negative correlations that imply their association with the organic fraction.Theδ^(13)C andδ^(15)N isotopic range and average−24.94‰to−25.86‰(−25.41‰)and−2.77‰to 3.22‰(0.96‰),respectively,reflecting 3C type modern terrestrial vegetation were common in the palaeomires of studied coal seams.In addition,the trivial variations of 0.92‰and 0.45‰among^(13)C and^(15)N values can be attributed to water level fluctuations and plant assemblies.展开更多
文摘【目的】全球变暖背景下,喀斯特地貌广布的西南地区可能面临石漠化加剧的风险,对该区域石漠化演变历史的重建具有重要意义。【方法】通过采自贵州省黔西县黑洞一支石笋(HD12)的29个230Th年龄和954个δ^(13)C数据,重建了该地区过去4 750年的生态环境演变历史。【结果与结论】发现在4 322~3 526 a B.P.以及803~82 a B.P.时段存在两个显著的δ^(13)C正偏移,说明这两个时段洞穴上方的生态环境出现了恶化。HD12石笋δ^(13)C记录在约803 a B.P.的显著偏正持续了约290 a,其振幅达4.2‰,指示了该区域石漠化的扩张过程。这一时期西南地区多个洞穴石笋δ^(13)C值的一致偏正特征,可能指示了宋末靖康事件(823 a B.P.)后,人口的大量迁入和气候的干旱化导致了该区域石漠化的扩张。HD12石笋δ^(13)C值在4 322~3 526 a B.P.时期的偏正,振幅达4.9‰,其中4 322~3 977 a B.P.偏正过程对应于北半球4.2 ka事件,而3 777~3 526 a B.P.的偏正对应3.7 ka事件,两个时期的干旱事件在西南地区的多个石笋与湖泊记录中均有体现,说明在此期间,亚洲夏季风减弱,降水减少可能引起了该区域植被覆盖度大幅降低和土壤严重退化。
基金supported by Basic Research Operating Expenses of the Central level Non-profit Research Institutes (IDM2022003)National Natural Science Foundation of China (42375054)+2 种基金Regional collaborative innovation project of Xinjiang (2021E01022,2022E01045)Young Meteorological Talent Program of China Meteorological Administration,Tianshan Talent Program of Xinjiang (2022TSYCCX0003)Youth Innovation Team of China Meteorological Administration (CMA2023QN08).
文摘Tree radial growth can have significantly differ-ent responses to climate change depending on the environ-ment.To elucidate the effects of climate on radial growth and stable carbon isotope(δ^(13)C)fractionation of Qing-hai spruce(Picea crassifolia),a widely distributed native conifer in northwestern China in different environments,we developed chronologies for tree-ring widths and δ^(13)C in trees on the southern and northern slopes of the Qilian Mountains,and analysed the relationship between these tree-ring variables and major climatic factors.Tree-ring widths were strongly influenced by climatic factors early in the growing season,and the radial growth in trees on the northern slopes was more sensitive to climate than in trees on the southern.Tree-ring δ^(13)C was more sensitive to climate than radial growth.δ^(13)C fractionation was mainly influenced by summer temperature and precipitation early in the growing season.Stomatal conductance more strongly limited stable carbon isotope fractionation in tree rings than photosynthetic rate did.The response between tree rings and climate in mountains gradually weakened as climate warmed.Changes in radial growth and stable carbon isotope fractionation of P.crassifolia in response to climate in the Qilian Mountains may be further complicated by continued climate change.
基金the Higher Education Commission Pakistan for funding the lab research under its International Research Support Initiative Program (IRSIP) programthe Department of Environmental Science, Quaid-i-Azam University, Islamabad (especially Environmental Hydro geochemistry Lab)the Environment & Sustainability Institute and Camborne School of Mines, University of Exeter, for technical support in conducting lab analysis
文摘The Paleocene coals of the Salt Range in the Punjab Province of Pakistan have great economic potential;however,their trace element and stable isotopic characteristics have not been studied in detail except for a few sporadic samples.In this study,a total of 59 coal samples of which 14 are obtained from open cast mines have been investigated for elemental composition andδ^(13)C-δ^(15)N isotopic signatures.Average contents of trace elements such as Co,Cr,Cu,Pb,Sr,Th,U,V,and Zn are 7.4,41.7,11.2,12.5,90.2,4.0,1.9,128,and 31.1 mg/kg,respectively.These values,when compared with the World Coal Clarke values,were relatively higher in low-rank coals in comparison with Clarke values for brown coals.Likewise,As(20.4 mg/kg),Co(6.6 mg/kg),Cr(22.4 mg/kg),Cu(^(13).3 mg/kg),Pb(19.2 mg/kg),Sr(^(15)4.7 mg/kg),Th(2.5 mg/kg),V(47.8 mg/kg),and Zn(75.1 mg/kg)were significantly higher in the sub-bituminous to bituminous coals of the Salt Range.Mineralogical analysis,based on X-ray diffraction and energy dispersive X-ray spectroscopy,revealed that the studied samples contain illite,kaolinite calcite,gypsum,pyrite,and quartz.Elemental affinity with organic and inorganic phases of coals calculated by an indirect statistical approach indicated a positive association of ash content with Ag,Al,Co,Cr,Cs,Cu,Mn,P,Rb,Pb,Th,U,and V,suggesting the presence of inorganic components in studied coals.However,As,Fe,Sr,and Zn exhibit negative correlations that imply their association with the organic fraction.Theδ^(13)C andδ^(15)N isotopic range and average−24.94‰to−25.86‰(−25.41‰)and−2.77‰to 3.22‰(0.96‰),respectively,reflecting 3C type modern terrestrial vegetation were common in the palaeomires of studied coal seams.In addition,the trivial variations of 0.92‰and 0.45‰among^(13)C and^(15)N values can be attributed to water level fluctuations and plant assemblies.