N^(6)-Methyladenosine(m^(6)A)is the most common modification in the transcriptome of biological RNA and plays roles that include maintaining the stability and transportation of mRNA,mRNA precursor shearing,polyadenyla...N^(6)-Methyladenosine(m^(6)A)is the most common modification in the transcriptome of biological RNA and plays roles that include maintaining the stability and transportation of mRNA,mRNA precursor shearing,polyadenylation,and the initiation of translation.With the improving understanding of RNA methylation,m^(6)A modification is known to play vital roles in plant development and growth.The multi-petalization of flowering plants has high ornamental and research value in horticultural landscapes.However,the mechanism of RNA methylation in flower formation in Magnolia wufengensis,a classical multi-petalizational plant,remains unclear.This study compared and analyzed RNA m^(6)A methylation and the transcriptome in floral buds of two varieties with large differences in tepal number at the early stage of development.It was found that the degree of RNA m^(6)A methylation and relative expression levels of MawuAGL6-2,MawuPI-4,and MawuAGL9 in‘Jiaodan’with 36 tepals were significantly higher than those in‘Jiaohong’with 9 tepals during the development of floral organ primordia.Combined with quantitative real-time PCR,the expression levels of MawuAGL6-2,MawuPI-4,and MawuAGL9were positively correlated with the number of tepals.Transgenic experiments showed that MawuAGL6-1/2,and MawuPI-4 can increase the number of petals in Arabidopsis.Moreover,MawuAGL6-2 and MawuPI-4 can restore the missing petal phenotype of mutant Arabidopsis.Yeast two hybrid and yeast three hybrid indicated that MawuAGL6-2,MawuAP3-1/2,and MawuPI-4 could interact with each other under the mediation of the class E protein MawuAGL9.Based on these results,it is hypothesized that m^(6)A methylation influences the multi-petalization of Magnolia wufengensis by affecting the expression levels of MawuAGL6-2,MawuAP3-1/2,MawuPI-4,and MawuAGL9.These findings provide a better understanding of the molecular mechanisms of epigenetic modifications in flower developmental diversity.展开更多
Ferroptosis in combination with immune therapy emerges as a promising approach for cancer therapy.Herein,dual-responsive metal-polyphenol coordinated nanomedicines were developed for pH/glutathione(GSH)-responsive syn...Ferroptosis in combination with immune therapy emerges as a promising approach for cancer therapy.Herein,dual-responsive metal-polyphenol coordinated nanomedicines were developed for pH/glutathione(GSH)-responsive synergistic ferroptosis and immunotherapy.Our innovative strategy involves the development of a manganese-polyphenol coordinated nanostructure,leveraging the biocompatibility of bovine serum albumin(BSA)as a template to encapsulate the anticancer drug sorafenib.The tumor microenvironment(pH/GSH)prompts the disassembly of MnO_(2)and epigallocatechin gallate(EGCG),thereby releases the anticancer payload.Concurrently,MnO_(2)acts to deplete intracellular GSH,which in turn suppresses glutathione peroxidase activity,leading to an accumulation of lipid peroxides with cell ferroptosis.Additionally,the release of Mn^(2+)ions bolster the cyclic guanosine monophosphlic acid(GMP)-adenosine monophosphlic acid(AMP)synthase-stimulator of interferon gene(cGAS-STING)pathway,which,in conjunction with the immunogenic cell death(ICD)effect induced by tumor cell apoptosis,significantly promotes dendritic cell(DC)maturation and enhances the presentation of tumor antigens.This successively ignites a robust innate and adaptive immune response.Both in vitro and in vivo experiments have demonstrated that the concurrent administration of ferroptosis-inducing and immune-stimulating therapies can significantly inhibit tumor growth.展开更多
Recently,the composite of soft conductive substrates,such as carbon fiber(CF),with metal-organic frameworks(MOFs)has been employed in a myriad of applications.The composite material has demonstrated exceptional potent...Recently,the composite of soft conductive substrates,such as carbon fiber(CF),with metal-organic frameworks(MOFs)has been employed in a myriad of applications.The composite material has demonstrated exceptional potential in the realm of electrochemical sensing platforms.However,the rapid growth of MOFs on the surface of CF remains a challenge.Herein,we propose a simple galvanostatic method as an effective strategy for rapidly growing zeolitic imidazolate frameworks(ZIFs)on CF,and obtain nanocaltrop-like ZIFs modified CF(NC-ZIFs/CF)glucose(Glu)sensor platform with distinctive morphology.The prepared NC-ZIFs/CF demonstrated significant electrocatalytic activity towards the oxidation of Glu in alkaline media,characterized by a pronounced augmentation in oxidation current density.At an applied potential of 0.4 V,NC-ZIFs/CF exhibited a remarkably broad detection range(3–30,000μmol/L)and demonstrated outstanding selectivity,repeatability and reproducibility.Additionally,the NC-ZIFs/CF was efficaciously employed for the detection of blood Glu levels in the serum of both normoglycemic and hyperglycemic patients,obtaining highly reliable results.This work demonstrates the feasibility of using galvanostatic method assembly to induce the growth of MOFs on conductive substrates,providing new ideas for electrocatalysis sensors and other electrochemical applications.展开更多
Ferroustherapy has gained great attention for anti-cancer treatment in recent years. Enlightened by temperature-mediated Fenton reaction in industrial waste water removal, we designed a iron-based polyphenol-coordinat...Ferroustherapy has gained great attention for anti-cancer treatment in recent years. Enlightened by temperature-mediated Fenton reaction in industrial waste water removal, we designed a iron-based polyphenol-coordinated nanomedicines for mild hyperthermia-assisted anti-cancer ferroustherapy. In brief, Fe-GA@BSA nanoparticles was synthesized by self-assembly and sorafenib(SRF) was loaded into Fe-GA@BSA to establish Fe-GA@BSA-SRF nanomedicines. The result nanomedicines can induce ferroptosis in cancer cells by accelerating Fenton reaction. And the photothermal effect of Fe-GA@BSA-SRF was used for mild hyperthermia-assisted ferroustherapy. The nanomedicines performs good anti-cancer therapeutic efficacy by inducing the production of ROS and inhibiting glutathione peroxidase 4(GPX4) expression in vitro and in vivo. Besides, the broad absorption of Fe-GA@BSA-SRF in near infrared region endows it with photoacoustic imaging ability. This study provides ideas about rational design on iron-based nanoparticles for anti-cancer ferroustherapy.展开更多
Recently,Wu et al.[1]suggested an earthquake-induced landslide dam outburst flood on the eastern Tibetan Plateau at 1920BCE(3870 a BP,BP denotes year before 1950 CE)caused the Great Flood in the middle-lower Yellow Ri...Recently,Wu et al.[1]suggested an earthquake-induced landslide dam outburst flood on the eastern Tibetan Plateau at 1920BCE(3870 a BP,BP denotes year before 1950 CE)caused the Great Flood in the middle-lower Yellow River reaches,and resulted in the founding of Xia Dynasty at 3850 a BP.This age is$150–300younger than the previously estimated age of the Xia Dynasty[2].While the geological evidence of the outburst flood。展开更多
Arid Central Asia(ACA), with its diverse landscapes of high mountains, oases, and deserts, hosted the central routes of the Silk Roads that linked trade centers from East Asia to the eastern Mediterranean.Ecological p...Arid Central Asia(ACA), with its diverse landscapes of high mountains, oases, and deserts, hosted the central routes of the Silk Roads that linked trade centers from East Asia to the eastern Mediterranean.Ecological pockets and ecoclines in ACA are largely determined by local precipitation. However, little research has gone into the effects of hydroclimatic changes on trans-Eurasian cultural exchange. Here,we reconstruct precipitation changes in ACA, covering the mid-late Holocene with a U-Th dated, ~3 a resolution, multi-proxy time series of replicated stalagmites from the southeastern Fergana Valley,Kyrgyzstan. Our data reveal a 640-a megadrought between 5820 and 5180 a BP, which likely impacted cultural development in ACA and impeded the expansion of cultural traits along oasis routes. Instead,it may have diverted the earliest transcontinental exchange along the Eurasian steppe during the 5 th millennium BP. With gradually increasing precipitation after the megadrought, settlement of peoples in the oases and river valleys may have facilitated the opening of the oasis routes, ‘‘prehistoric Silk Roads", of trans-Eurasian exchange. By the 4 th millennium BP, this process may have reshaped cultures across the two continents, laying the foundation for the organized Silk Roads.展开更多
Application of X-ray fluorescence core-scanning(XRF-CS) on both marine and lake sediments has achieved remarkable results. However, its application has not been widely extended to the research on speleothems. In this ...Application of X-ray fluorescence core-scanning(XRF-CS) on both marine and lake sediments has achieved remarkable results. However, its application has not been widely extended to the research on speleothems. In this study, we measure the Sr abundance and the Sr/Ca ratios of three stalagmites(two aragonite stalagmites, one calcite stalagmite) using the state-of-the-art fourth-generation Avaatech high-resolution XRF core scanner. Through comparisons among different scan paths and among different scan resolutions, as well as comparisons with inductively coupled plasma optical emission spectrometer(ICP-OES), Itrax XRF, and Artax XRF results, we confirm that the Avaatech XRF core scanner could precisely, quickly, and nondestructively analyze the high-resolution Sr abundance of speleothems. Furthermore, we combine the stalagmite δ^(18)O records to explore the paleoclimatic significance of the measured stalagmite Sr/Ca.展开更多
The Asian summer monsoon(ASM) is a vast climate system, whose variability is critical to the livelihoods of billions of people across the Asian continent. During the past half-century, much progress has been made in u...The Asian summer monsoon(ASM) is a vast climate system, whose variability is critical to the livelihoods of billions of people across the Asian continent. During the past half-century, much progress has been made in understanding variations on a wide range of timescales, yet several significant issues remain unresolved. Of note are two long-standing problems concerning orbital-scale variations of the ASM.(1) Chinese loess magnetic susceptibility records show a persistent glacial-interglacial dominated ~100 kyr(thousand years) periodicity, while the cave oxygen-isotope(δ18 O) records reveal periodicity in an almost pure precession band(~20 kyr periodicity)—the "Chinese 100 kyr problem".(2) ASM records from the Arabian Sea and other oceans surrounding the Asian continent show a significant lag of 8–10 kyr to Northern Hemisphere summer insolation(NHSI), whereas the Asian cave δ18 O records follow NHSI without a significant lag—a discrepancy termed the "sea-land precession-phase paradox". How can we reconcile these differences? Recent and more refined model simulations now provide spatial patterns of rainfall and wind across the precession cycle, revealing distinct regional divergences in the ASM domain, which can well explain a large portion of the disparities between the loess, marine, and cave proxy records. Overall, we also find that the loess, marine, and cave records are indeed complementary rather than incompatible, with each record preferentially describing a certain aspect of ASM dynamics. Our study provides new insight into the understanding of different hydroclimatic proxies and largely reconciles the "Chinese 100 kyr problem" and "sea-land precession-phase paradox".展开更多
Evaluating anthropogenic impacts on regional vegetation changes during historical time is not only important for a better understanding of the Anthropocene but also valuable in improving the vegetation-climate models....Evaluating anthropogenic impacts on regional vegetation changes during historical time is not only important for a better understanding of the Anthropocene but also valuable in improving the vegetation-climate models.In this study,we analyzed stable isotopes(δ^18O,δ^13C)and trace elements(Mg/Ca,Sr/Ca)of a stalagmite from Huangchao Cave in central Shandong,northern China.230Th and AMS14C dating results indicate the stalagmite deposited during 174BC and AD1810,with a hiatus between AD638 and 1102.Broad similarities of theδ^18O and trace elements in the stalagmite suggest they are reliable precipitation indexes.Theδ^13C of the stalagmite,a proxy of vegetation change,was generally consistent with local precipitation and temperature variations on a centennial-scale before the 15th century.It typically varied from–9.6‰to–6.3‰,indicating climate controlled C3 type vegetation during this period.However,a persistent and marked increasing trend in theδ^13C record was observed since the 15th century,resulting inδ^13C values from–7.7‰to–1.6‰in the next four centuries.This unprecedentedδ^13C change caused by vegetation deterioration cannot be explained by climate change but is fairly consistent with the dramatically increasing population and farmland in Shandong.We suggest that the increasing deforestation and reclamation in central Shandong began to affect vegetation in the mountain region of central Shandong since the 15th century and severely destroyed or even cleared the forest during the 16th–18th century.展开更多
The widely accepted“Milankovitch theory”explains insolation-induced waxing and waning of the ice sheets and their effect on the global climate on orbital timescales.In the past half century,however,the theory has of...The widely accepted“Milankovitch theory”explains insolation-induced waxing and waning of the ice sheets and their effect on the global climate on orbital timescales.In the past half century,however,the theory has often come under scrutiny,especially regarding its“100-ka problem.”Another drawback,but the one that has received less attention,is the“monsoon problem,”which pertains to the exclusion of monsoon dynamics in classic Milankovitch theory even though the monsoon prevails over the vast low-latitude(30N to30S)region that covers half of the Earth’s surface and receives the bulk of solar radiation.In this review,we discuss the major issues with the current form of Milankovitch theory and the progress made at the research forefront.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.31570651)。
文摘N^(6)-Methyladenosine(m^(6)A)is the most common modification in the transcriptome of biological RNA and plays roles that include maintaining the stability and transportation of mRNA,mRNA precursor shearing,polyadenylation,and the initiation of translation.With the improving understanding of RNA methylation,m^(6)A modification is known to play vital roles in plant development and growth.The multi-petalization of flowering plants has high ornamental and research value in horticultural landscapes.However,the mechanism of RNA methylation in flower formation in Magnolia wufengensis,a classical multi-petalizational plant,remains unclear.This study compared and analyzed RNA m^(6)A methylation and the transcriptome in floral buds of two varieties with large differences in tepal number at the early stage of development.It was found that the degree of RNA m^(6)A methylation and relative expression levels of MawuAGL6-2,MawuPI-4,and MawuAGL9 in‘Jiaodan’with 36 tepals were significantly higher than those in‘Jiaohong’with 9 tepals during the development of floral organ primordia.Combined with quantitative real-time PCR,the expression levels of MawuAGL6-2,MawuPI-4,and MawuAGL9were positively correlated with the number of tepals.Transgenic experiments showed that MawuAGL6-1/2,and MawuPI-4 can increase the number of petals in Arabidopsis.Moreover,MawuAGL6-2 and MawuPI-4 can restore the missing petal phenotype of mutant Arabidopsis.Yeast two hybrid and yeast three hybrid indicated that MawuAGL6-2,MawuAP3-1/2,and MawuPI-4 could interact with each other under the mediation of the class E protein MawuAGL9.Based on these results,it is hypothesized that m^(6)A methylation influences the multi-petalization of Magnolia wufengensis by affecting the expression levels of MawuAGL6-2,MawuAP3-1/2,MawuPI-4,and MawuAGL9.These findings provide a better understanding of the molecular mechanisms of epigenetic modifications in flower developmental diversity.
基金supported by the National Key R&D Program of China(No.2022YFC2304205)National Natural Science Foundation of China(Nos.51903062,52273128)the Plan on Enhancing Scientific Research in GMU(No.02-410-2405033).
文摘Ferroptosis in combination with immune therapy emerges as a promising approach for cancer therapy.Herein,dual-responsive metal-polyphenol coordinated nanomedicines were developed for pH/glutathione(GSH)-responsive synergistic ferroptosis and immunotherapy.Our innovative strategy involves the development of a manganese-polyphenol coordinated nanostructure,leveraging the biocompatibility of bovine serum albumin(BSA)as a template to encapsulate the anticancer drug sorafenib.The tumor microenvironment(pH/GSH)prompts the disassembly of MnO_(2)and epigallocatechin gallate(EGCG),thereby releases the anticancer payload.Concurrently,MnO_(2)acts to deplete intracellular GSH,which in turn suppresses glutathione peroxidase activity,leading to an accumulation of lipid peroxides with cell ferroptosis.Additionally,the release of Mn^(2+)ions bolster the cyclic guanosine monophosphlic acid(GMP)-adenosine monophosphlic acid(AMP)synthase-stimulator of interferon gene(cGAS-STING)pathway,which,in conjunction with the immunogenic cell death(ICD)effect induced by tumor cell apoptosis,significantly promotes dendritic cell(DC)maturation and enhances the presentation of tumor antigens.This successively ignites a robust innate and adaptive immune response.Both in vitro and in vivo experiments have demonstrated that the concurrent administration of ferroptosis-inducing and immune-stimulating therapies can significantly inhibit tumor growth.
基金supported by the National Natural Science Foundation of China(No.51903062)Special Fund Project for Science and Technology Innovation Strategy of Guangdong Province,China(No.pdjh2022b0426)the Plan on Enhancing Scientific Research in GMU(No.02-410-2302330XM).
文摘Recently,the composite of soft conductive substrates,such as carbon fiber(CF),with metal-organic frameworks(MOFs)has been employed in a myriad of applications.The composite material has demonstrated exceptional potential in the realm of electrochemical sensing platforms.However,the rapid growth of MOFs on the surface of CF remains a challenge.Herein,we propose a simple galvanostatic method as an effective strategy for rapidly growing zeolitic imidazolate frameworks(ZIFs)on CF,and obtain nanocaltrop-like ZIFs modified CF(NC-ZIFs/CF)glucose(Glu)sensor platform with distinctive morphology.The prepared NC-ZIFs/CF demonstrated significant electrocatalytic activity towards the oxidation of Glu in alkaline media,characterized by a pronounced augmentation in oxidation current density.At an applied potential of 0.4 V,NC-ZIFs/CF exhibited a remarkably broad detection range(3–30,000μmol/L)and demonstrated outstanding selectivity,repeatability and reproducibility.Additionally,the NC-ZIFs/CF was efficaciously employed for the detection of blood Glu levels in the serum of both normoglycemic and hyperglycemic patients,obtaining highly reliable results.This work demonstrates the feasibility of using galvanostatic method assembly to induce the growth of MOFs on conductive substrates,providing new ideas for electrocatalysis sensors and other electrochemical applications.
基金supported by grants from the National Natural Science Foundation of China (No. 51903062)Guangdong Basic and Applied Basic Research Foundation (No.2020A1515011320)+1 种基金Science and Technology Projects of Guangzhou(No. 202102020757)Subject Construction Project of Basic Medical Sciences of Guangzhou Medical University (Nos.JCXKJS2021B07, JCXKJS2021D09)。
文摘Ferroustherapy has gained great attention for anti-cancer treatment in recent years. Enlightened by temperature-mediated Fenton reaction in industrial waste water removal, we designed a iron-based polyphenol-coordinated nanomedicines for mild hyperthermia-assisted anti-cancer ferroustherapy. In brief, Fe-GA@BSA nanoparticles was synthesized by self-assembly and sorafenib(SRF) was loaded into Fe-GA@BSA to establish Fe-GA@BSA-SRF nanomedicines. The result nanomedicines can induce ferroptosis in cancer cells by accelerating Fenton reaction. And the photothermal effect of Fe-GA@BSA-SRF was used for mild hyperthermia-assisted ferroustherapy. The nanomedicines performs good anti-cancer therapeutic efficacy by inducing the production of ROS and inhibiting glutathione peroxidase 4(GPX4) expression in vitro and in vivo. Besides, the broad absorption of Fe-GA@BSA-SRF in near infrared region endows it with photoacoustic imaging ability. This study provides ideas about rational design on iron-based nanoparticles for anti-cancer ferroustherapy.
基金funded by the National Key Research and Development Program of China (2017YFA0603401)National Natural Science Foundation of China (41372192)+2 种基金Science Foundation for Distinguished Young Scholars of Shaanxi Province, ChinaYouth Innovation Promotion Association of Chinese Academy of SciencesWest Light Foundation of Chinese Academy of Sciences
文摘Recently,Wu et al.[1]suggested an earthquake-induced landslide dam outburst flood on the eastern Tibetan Plateau at 1920BCE(3870 a BP,BP denotes year before 1950 CE)caused the Great Flood in the middle-lower Yellow River reaches,and resulted in the founding of Xia Dynasty at 3850 a BP.This age is$150–300younger than the previously estimated age of the Xia Dynasty[2].While the geological evidence of the outburst flood。
基金supported by the National Key Research and Development Program of China (2018YFA0606400)he Strategic Priority Research Program of Chinese Academy of Sciences (XDB40000000)+5 种基金the 2nd Tibetan Plateau Scientific Expedition and Research (2019QZKK0101)the Youth Innovation Promotion Association of Chinese Academy of Sciences (Y201681)partly supported by the National Natural Science Foundation of China (41888101)the National Social Science Foundation of China (18ZDA172)the National Science Foundation of United States (NSF 1702816, EAR-0908792, and EAR-1211299)a part of the ‘‘Belt & Road” Project of the Institute of Earth Environment, Chinese Academy of Sciences (IEECAS)。
文摘Arid Central Asia(ACA), with its diverse landscapes of high mountains, oases, and deserts, hosted the central routes of the Silk Roads that linked trade centers from East Asia to the eastern Mediterranean.Ecological pockets and ecoclines in ACA are largely determined by local precipitation. However, little research has gone into the effects of hydroclimatic changes on trans-Eurasian cultural exchange. Here,we reconstruct precipitation changes in ACA, covering the mid-late Holocene with a U-Th dated, ~3 a resolution, multi-proxy time series of replicated stalagmites from the southeastern Fergana Valley,Kyrgyzstan. Our data reveal a 640-a megadrought between 5820 and 5180 a BP, which likely impacted cultural development in ACA and impeded the expansion of cultural traits along oasis routes. Instead,it may have diverted the earliest transcontinental exchange along the Eurasian steppe during the 5 th millennium BP. With gradually increasing precipitation after the megadrought, settlement of peoples in the oases and river valleys may have facilitated the opening of the oasis routes, ‘‘prehistoric Silk Roads", of trans-Eurasian exchange. By the 4 th millennium BP, this process may have reshaped cultures across the two continents, laying the foundation for the organized Silk Roads.
基金supported by the National Key Research and Development Program of China (Grant No. 2017YFA0603401)Shaanxi Science Fund for Distinguished Young Scholars (Grant No. 2018JC-023)+2 种基金Youth Innovation Promotion Association (Grant No. 2012295)West Light Foundation of Chinese Academy of Sciencesa part of The "Belt & Road" Project of the Institute of Earth Environment, Chinese Academy of Sciences
文摘Application of X-ray fluorescence core-scanning(XRF-CS) on both marine and lake sediments has achieved remarkable results. However, its application has not been widely extended to the research on speleothems. In this study, we measure the Sr abundance and the Sr/Ca ratios of three stalagmites(two aragonite stalagmites, one calcite stalagmite) using the state-of-the-art fourth-generation Avaatech high-resolution XRF core scanner. Through comparisons among different scan paths and among different scan resolutions, as well as comparisons with inductively coupled plasma optical emission spectrometer(ICP-OES), Itrax XRF, and Artax XRF results, we confirm that the Avaatech XRF core scanner could precisely, quickly, and nondestructively analyze the high-resolution Sr abundance of speleothems. Furthermore, we combine the stalagmite δ^(18)O records to explore the paleoclimatic significance of the measured stalagmite Sr/Ca.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41888101 & 41731174)。
文摘The Asian summer monsoon(ASM) is a vast climate system, whose variability is critical to the livelihoods of billions of people across the Asian continent. During the past half-century, much progress has been made in understanding variations on a wide range of timescales, yet several significant issues remain unresolved. Of note are two long-standing problems concerning orbital-scale variations of the ASM.(1) Chinese loess magnetic susceptibility records show a persistent glacial-interglacial dominated ~100 kyr(thousand years) periodicity, while the cave oxygen-isotope(δ18 O) records reveal periodicity in an almost pure precession band(~20 kyr periodicity)—the "Chinese 100 kyr problem".(2) ASM records from the Arabian Sea and other oceans surrounding the Asian continent show a significant lag of 8–10 kyr to Northern Hemisphere summer insolation(NHSI), whereas the Asian cave δ18 O records follow NHSI without a significant lag—a discrepancy termed the "sea-land precession-phase paradox". How can we reconcile these differences? Recent and more refined model simulations now provide spatial patterns of rainfall and wind across the precession cycle, revealing distinct regional divergences in the ASM domain, which can well explain a large portion of the disparities between the loess, marine, and cave proxy records. Overall, we also find that the loess, marine, and cave records are indeed complementary rather than incompatible, with each record preferentially describing a certain aspect of ASM dynamics. Our study provides new insight into the understanding of different hydroclimatic proxies and largely reconciles the "Chinese 100 kyr problem" and "sea-land precession-phase paradox".
基金supported by the National Natural Science Foundation of China(Grant No.41991252)the Strategic Priority Research Program(Grant No.XDB40000000)+4 种基金the International Partnership Program(Grant No.132B61KYSB20170005)of Chinese Academy of Sciencesthe National Natural Science Foundation of China(Grant No.41888101)partly supported by the USA National Science Foundation(Grant Nos.0908792,1211299&1702816 to R.Lawrence EDWARDS and Hai CHENG)the 111 Program of China(Grant No.D19002)the Belt&Road Center for Climate and Environment Studies of IEECAS。
文摘Evaluating anthropogenic impacts on regional vegetation changes during historical time is not only important for a better understanding of the Anthropocene but also valuable in improving the vegetation-climate models.In this study,we analyzed stable isotopes(δ^18O,δ^13C)and trace elements(Mg/Ca,Sr/Ca)of a stalagmite from Huangchao Cave in central Shandong,northern China.230Th and AMS14C dating results indicate the stalagmite deposited during 174BC and AD1810,with a hiatus between AD638 and 1102.Broad similarities of theδ^18O and trace elements in the stalagmite suggest they are reliable precipitation indexes.Theδ^13C of the stalagmite,a proxy of vegetation change,was generally consistent with local precipitation and temperature variations on a centennial-scale before the 15th century.It typically varied from–9.6‰to–6.3‰,indicating climate controlled C3 type vegetation during this period.However,a persistent and marked increasing trend in theδ^13C record was observed since the 15th century,resulting inδ^13C values from–7.7‰to–1.6‰in the next four centuries.This unprecedentedδ^13C change caused by vegetation deterioration cannot be explained by climate change but is fairly consistent with the dramatically increasing population and farmland in Shandong.We suggest that the increasing deforestation and reclamation in central Shandong began to affect vegetation in the mountain region of central Shandong since the 15th century and severely destroyed or even cleared the forest during the 16th–18th century.
基金supported by the NationalNatural Science Foundation ofChina(41888101 and 42150710534).
文摘The widely accepted“Milankovitch theory”explains insolation-induced waxing and waning of the ice sheets and their effect on the global climate on orbital timescales.In the past half century,however,the theory has often come under scrutiny,especially regarding its“100-ka problem.”Another drawback,but the one that has received less attention,is the“monsoon problem,”which pertains to the exclusion of monsoon dynamics in classic Milankovitch theory even though the monsoon prevails over the vast low-latitude(30N to30S)region that covers half of the Earth’s surface and receives the bulk of solar radiation.In this review,we discuss the major issues with the current form of Milankovitch theory and the progress made at the research forefront.
