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Geochemical characteristics of quaternary sediments in the St.Martin Island,Bangladesh:implication for provenance,weathering and sedimentary processes 被引量:1
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作者 Rahat Khan Sudeb Chandra Das +10 位作者 Ayon Saha Khondaker MdNur Alam Abdullah Al-Amin Saad Aldawood MdAbu Haydar Sudipta Saha MdMasud Karim MdHarunor Rashid Khan Abubakr MIdris AHMSaadat Dhiman Kumer Roy 《Acta Geochimica》 2025年第3期573-598,共26页
The sedimentary geochemistry of St.Martin’s Island is important to determine the origin of the source rock,paleo weathering,tectonic setting,sediment recycling,maturity,sorting,redox condition,and paleo salinity of t... The sedimentary geochemistry of St.Martin’s Island is important to determine the origin of the source rock,paleo weathering,tectonic setting,sediment recycling,maturity,sorting,redox condition,and paleo salinity of the sediments.Major oxides,trace elements,and rare earth elements(REEs)obtained from the INAA technique are presented by analyzing the sediment samples collected from the shoreline of St.Martin’s Island,Bangladesh.The elemental ratios,comparison with average upper continental crust(UCC),binary diagrams(Th/Sc vs.Sc,La/Th vs.Hf,Th/Co vs.La/Sc),and chondrite normalized REE patterns exhibit substantial LREE enrichment,relatively fl at HREE fractionation,considerable negative Eu anomalies(average:0.72),indicates the derivation from a source dominated by felsic rock,with contribution from intermediate source and mafi c component.Sediments from St.Martin’s Island exhibit the deposition of sediments in transitional environments of active and passive continental margin settings.Weathering indices value of CIA,PIA,CIW,CIX,and K 2 O/Rb ratio show moderate chemical weathering,indicating that the sediments are chemically mature.Sedimentary redox indicative proxies,such as U/Th,V/Cr,and V/Sc,show an oxic depositional environment during sediment deposition.The intermediate CIA and other weathering index values of the St.Martin’s sediments show that the area had semiarid and humid climatic conditions throughout the deposition.The Rb/K ratio of the St.Martin’s sediments suggests that the development and deposition of the sedimentary sequence of St.Martin’s Island mainly occurred in a brackish water environment during the geological past. 展开更多
关键词 St.Martin’s Island Geochemistry PROVENANCE Paleo-weathering Tectonic setting
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两栖、爬行动物Rensch法则的研究进展
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作者 梁涛 时磊 《生态学杂志》 北大核心 2025年第7期2408-2416,共9页
体型大小的两性异形(sexual size dimorphism)是指物种雌雄两性体型大小在地理和系统发育尺度上表现出不同程度和方向上的差异。Rensch法则用来描述物种体型大小两性异形的异速增长模式,即小体型物种的雌性体型会比雄性大,而大体型物种... 体型大小的两性异形(sexual size dimorphism)是指物种雌雄两性体型大小在地理和系统发育尺度上表现出不同程度和方向上的差异。Rensch法则用来描述物种体型大小两性异形的异速增长模式,即小体型物种的雌性体型会比雄性大,而大体型物种的雄性体型会大于雌性。性选择、繁殖力选择以及性别特异性的表型可塑性均可导致Rensch法则的实现,以及与之相反模式的产生。两栖、爬行动物广泛分布于除南极洲以外的各个大陆,具有丰富的表型特征,体型表现出多种两性异形模式,非常适宜开展Rensch法则的研究。本文从概念、检验方法、模式、形成机制等方面,综述了两栖、爬行动物Rensch法则的研究现状,并提出未来的研究建议。 展开更多
关键词 体型大小 两性异形 异速增长 Bergmann法则 Island法则
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SCIENCE AND TECHNOLOGY
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《China Today》 2025年第1期69-69,共1页
Long March 12 Makes Debut Flight from New Commercial Spaceport China successfully launched a new carrier rocket into space from the Hainan commercial spacecraft launch site in the southern island province of Hainan on... Long March 12 Makes Debut Flight from New Commercial Spaceport China successfully launched a new carrier rocket into space from the Hainan commercial spacecraft launch site in the southern island province of Hainan on November 30,2024.The Long March-12 carrier rocket sent two experimental satellites into their planned orbits.The launch mission was a complete success,according to Hainan provincial authorities.The mission was the maiden flight of the Long March-12 carrier rocket,and the first launch mission undertaken by the Hainan commercial spacecraft launch site. 展开更多
关键词 HAINAN ISLAND ROCKET
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Habitat fragmentation differentially affects invasive and native plant diversity in a human-dominated wetland island system
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作者 Jinliang Liu Mengyuan Chen +4 位作者 Lu Wang Tengteng Liu Xinjie Jin Fei-Hai Yu Yonghua Zhang 《Plant Diversity》 2025年第5期824-832,共9页
Managing invasive species requires identifying the factors that determine alien species invasion success.This study investigates how anthropogenic and biogeographical factors influence alien plant invasion in the Sany... Managing invasive species requires identifying the factors that determine alien species invasion success.This study investigates how anthropogenic and biogeographical factors influence alien plant invasion in the Sanyang Wetlands,a human-dominated island system in Wenzhou City,China.Specifically,we analyzed whether human activities(e.g.,habitat heterogeneity,proportion of road area,and cultivation)and island characteristics(e.g.,island area,isolation)affect the diversity of native and invasive plant species similarly.We also assessed the applicability of the equilibrium theory of island biogeography to invasive plant species diversity and examined how these factors affect invasive plant species with different dispersal syndromes(anemochore,zoochore,and autochore).We found that both invasive and native species richness positively correlate with island area,habitat heterogeneity,and proportion of road area.However,although native species richness was negatively correlated with isolation,invasive species richness was not.The diversity and composition of invasive species with different dispersal syndromes were determined by different variables;for example,the composition and diversity of zoochores was increased by habitat heterogeneity,while anemochore species richness was increased by the proportion of road area,whereas anemochore species composition was influenced by distance to the nearest island.We conclude that habitat fragmentation differentially affects invasive and native plant diversity,aligning with the predictions of the equilibrium theory of island biogeography only for native species but not for invasive species.Our findings indicate that tailoring habitat attributes and regulating human activities could be effective strategies for mitigating the spread of invasive species in fragmented landscapes. 展开更多
关键词 Alien species invasion Dispersal strategies Human disturbance Island attributes Island biogeography theory WETLAND
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Edge States and Enhanced Superconducting Gaps in Bi Islands on FeTe_(0.55)Se_(0.45)
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作者 Chuanhao Wen Zhiyong Hou +2 位作者 Zhiyuan Shang Huan Yang Hai-Hu Wen 《Chinese Physics Letters》 2025年第8期195-200,共6页
By measuring scanning tunneling spectroscopy on some large Bi islands deposited on FeTe_(0.55)Se_(0.45)superconductors,we observe clear in-gap edge states with double peaks at about±1.0 me V on the spectra measur... By measuring scanning tunneling spectroscopy on some large Bi islands deposited on FeTe_(0.55)Se_(0.45)superconductors,we observe clear in-gap edge states with double peaks at about±1.0 me V on the spectra measured near the perimeter of the islands.This feature is very different from the single zero-energy peak observed on some other small Bi islands.The edge states spread towards the inner side of the islands over a width of 2-3 nm.The two edge-state peaks at positive and negative energies move to higher values with the increase of the magnetic field,and they disappear near the transition temperature of FeTe_(0.55)Se_(0.45).Meanwhile,enhanced superconducting gaps are observed in the central regions of these Bi islands,which may be induced by the enhanced pair potential of the topological surface state.Our observations provide a valuable message for the edge state and the proximity-induced superconductivity on specific Bi islands grown on FeTe_(0.55)Se_(0.45)substrate. 展开更多
关键词 FETE SE scanning tunneling spectroscopy Bi islands superconducting gaps positive negative energies bi islands edge states bi islandsthe
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Path of Enhancing the Sense of Gain Among Community Residents in Island Tourism Destinations in the Context of Culture and Tourism Integration:A Case Study of Weizhou Island
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作者 FANG Changgan CAO Yang 《Journal of Landscape Research》 2025年第1期74-80,84,共8页
Weizhou Island,located in Beihai,Guangxi Province,is recognized as the largest paleovolcanic island in China,characterized by its relatively young geological age.The development of island tourism has progressively est... Weizhou Island,located in Beihai,Guangxi Province,is recognized as the largest paleovolcanic island in China,characterized by its relatively young geological age.The development of island tourism has progressively established it as a significant tourist attraction within Beihai,transforming the area into a prominent leisure and tourism resort.As tourism on Weizhou Island continues to develop both in scope and in depth,it has increasingly influenced the sense of gain among the local community residents.Currently,in alignment with the strategic objective of achieving common prosperity,it is crucial to comprehend and enhance the sense of gain experienced by residents in island tourism destinations,as this is vital for the achievement of this overarching goal.Taking the residents of Weizhou Island in Beihai as the subjects,this paper constructs their sense of gain related to tourism,employing grounded theory.It posits that the residents’sense of gain comprises four primary dimensions:sense of economic gain,sense of social gain,sense of cultural gain,and sense of environmental gain.Additionally,the paper examines the factors that influence these dimensions.Based on this foundation,effective strategies are proposed to enhance the sense of gain among community residents in island tourism destinations,thereby promoting the sustainable development of island tourism. 展开更多
关键词 Sense of gain Island tourism Weizhou Island Beihai Sustainable development
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Tourism-driven Commodification of Island Landscapes:An Actor-Network Analysis of Dynamic Mechanisms in Guanglu Island,China
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作者 LIU Tianbao ZHAO Shan PENG Fei 《Chinese Geographical Science》 2025年第4期867-881,共15页
The complex relationship between humans and nature plays a key role in shaping geographic landscapes.This study examines how tourism transforms island landscapes into marketable commodities,focusing on Guanglu Island ... The complex relationship between humans and nature plays a key role in shaping geographic landscapes.This study examines how tourism transforms island landscapes into marketable commodities,focusing on Guanglu Island in China from 2002–2025 through the lens of Actor-Network Theory(ANT).The findings reveal three main insights:1)commodification involves reimagining natural landscapes,digitizing them for broader appeal,and integrating them into tourist consumption.2)This process reshapes original landscapes into four interconnected forms:material landscapes,fluid landscapes,virtual landscapes,and psychological landscapes.3)Multiple actors drive commodification:the island’s natural conditions provide foundation and influence concrete ways of commodification,local government is deeply involved through planning and regulating tourism development,tourism practitioners adapt services to market demands,and tourist preferences guide the direction of commercialization.By analyzing the roles of both human and non-human actors,this research highlights how tourism redefines island landscapes while emphasizing the active influence of nature itself in these transformations.The findings reveal the geographical attributes of landscape commodification process and the multidimensionality and complexity of its impacts,thereby providing valuable insights for the sustainable development of island tourism. 展开更多
关键词 island tourism commodification Actor-Network Theory(ANT) Guanglu Island China
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Fragmentation effects onβ-diversity:The role of abundance and intraspecifictrait variation in shaping taxonomic,functional,and phylogenetic patterns
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作者 Aiying Zhang Xiaofei Wei +3 位作者 Donghao Wu Zhonghan Wang Mingjian Yu Lingfeng Mao 《Plant Diversity》 2025年第6期981-990,共10页
Habitat fragmentation dramatically reshapes species richness and community composition.However,most estimates ofβ-diversity rely on incidence-based metrics,which consider only species presence/absence.Here,we introdu... Habitat fragmentation dramatically reshapes species richness and community composition.However,most estimates ofβ-diversity rely on incidence-based metrics,which consider only species presence/absence.Here,we introduce a novel framework that explicitly incorporates species abundance and intraspecifictrait variation(ITV)into the quantificationof taxonomic,functional,and phylogeneticβ-diversity,allowing a more nuanced understanding of community differentiation.To demonstrate the utility of this framework,we quantifiedthe effects of island area and isolation onβ-diversity across plant communities in China's Thousand Island Lake.Abundance-weighted taxonomic multiple-site/pairwiseβ-diversity showed substantially higher nestedness and stronger nestedness-area relationship than incidence-based metrics,indicating that species-poor communities are not only subsets of richer ones but share similar abundance hierarchies,highlighting strong environmental filteringand hierarchical species sorting.We also found that the turnover component was less sensitive to isolation,suggesting limited dispersal effects.Incidence-based functional and phylogenetic distances increased with differences in island area,but these associations weakened or disappeared in abundance-weighted measures,suggesting stronger environmental filteringand functional/phylogenetic clustering among larger islands.Only abundance-weighted standardized effect sizes increased with island area differences.Additionally,ITV further amplifiedfunctional nestedness and buffered the influenceof isolation on turnover,emphasizing its role in mitigating dispersal limitations.By jointly considering abundance and ITV,two often-overlooked but critical dimensions,this study advances our understanding of how fragmentation shapesβ-diversity.These findingshighlight the importance of integrating abundanceweighted and trait-based metrics into conservation strategies to better detect functionally important species,prioritize larger habitat patches,and design biodiversity monitoring that captures withinspecies variation. 展开更多
关键词 Functional traits Island biogeography Isolation ITV NESTEDNESS TURNOVER
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A miracle on Santa Bárbara Island
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作者 谭婷 《疯狂英语(新读写)》 2025年第8期50-51,78,共3页
Activity 1 Think about the following questions and write down your answers before reading the text.1.What are some possible ways animals can survive without access to fresh water sources?2.What other factors besides w... Activity 1 Think about the following questions and write down your answers before reading the text.1.What are some possible ways animals can survive without access to fresh water sources?2.What other factors besides water could contribute to the thriving(茁壮成长)of a herd of goats on an isolated island? 展开更多
关键词 isolated island thriving factors SURVIVAL fresh water herd goats THINK
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冰湖救援女英雄
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作者 孙启禄 《疯狂英语(新悦读)》 2025年第6期30-33,76,77,共6页
1 On December 26,2024,a remarkable act of heroism took place at Poospatuck Creek.Kayla Masotto,a 28⁃year⁃old resident of Mastic,Long Island,stepped into the role of a life⁃saver when she witnessed a man fall through t... 1 On December 26,2024,a remarkable act of heroism took place at Poospatuck Creek.Kayla Masotto,a 28⁃year⁃old resident of Mastic,Long Island,stepped into the role of a life⁃saver when she witnessed a man fall through the ice on the lake.2 At about 6 pm,Kayla was washing vegetables in the kitchen when her attention was suddenly caught by a boy skating alone on the lake.In a split second,she witnessed the ice beneath him break,and the boy fell into the water.Without any hesitation,Kayla immediately grabbed her paddleboard(桨叶式冲浪板)and ran across her backyard,reaching the edge of the lake in seconds. 展开更多
关键词 ice rescue washing vegetables HEROISM paddleboard Lake Long Island
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Prevalence and Potential Risk Predictors of Undernutrition Among Under-Five Children in Island Areas of Bangladesh
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作者 Md.Abdul Aziz Mohammad Mozibul Haque +3 位作者 Afia Nawar Kazi Nazira Sharmin Md.Altaf Hossain Suvanker Saha 《Health Care Science》 2025年第6期381-391,共11页
Background:Undernutrition poses a major threat for the growth and development of children in remote island regions of Bangladesh.Methods:This study investigated the prevalence and risk predictors of undernutrition amo... Background:Undernutrition poses a major threat for the growth and development of children in remote island regions of Bangladesh.Methods:This study investigated the prevalence and risk predictors of undernutrition among children under five in the island regions of Bangladesh.A cross‐sectional study was conducted in 13 unions across two islands,with a random sample of 549 children.Results:Descriptive analyses showed that underweight(Z‐score<−2),wasting(Z‐score<−2),and stunting(Z‐score<−2)were prevalent,with rates of 36.80%,24.60%,and 47.20%,respectively.Significant predictors of underweight included a history of diarrhea(AOR=2.24,p<0.001),acute respiratory infection(ARI)(AOR=1.84,p<0.01),anemic caregivers(AOR=1.52,p<0.05),and belonging to day labor families(AOR=0.29,p<0.01).Childhood wasting was significantly associated with partial vaccination(AOR=2.84,p<0.001),large family size(AOR=1.79,p<0.05),higher birth order(AOR=0.58,p<0.05),diarrhea(AOR=3.09,p<0.001),anemic mothers(AOR=1.89,p<0.05),primary(AOR=3.35,p<0.05)and secondary(AOR=4.11,p<0.01)maternal education,and fathers working abroad(AOR=0.42,p<0.05)or as daily laborers(AOR=0.17,p<0.001).Stunting was more common among children with partial vaccination,diarrhea,and ARI,and less common among those with a history of fever or those from day laborer families.Conclusion:Overall,undernutrition among children in the island areas of Bangladesh is influenced by multiple factors,necessitating a multisectoral approach to improve their nutritional status. 展开更多
关键词 child health island area risk factor under-five-children UNDERNUTRITION
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Population Genetics Study of Saccostrea malabonensis(Bivalvia:Ostreidae)in Hainan Island
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作者 XIE Dansheng LI Fengping +8 位作者 LIU Mingjie HENG Xin FAN Likai GUO Xingchen DONG Qingqiu AN Qianying WANG Aimin LIU Chunsheng YANG Yi 《Journal of Ocean University of China》 2025年第6期1728-1736,共9页
Hainan Island is one of the largest islands in China and is located in the Indo-Burma biodiversity hotspot region.Despite its ecological significance,comprehensive population genetic studies of key marine organisms al... Hainan Island is one of the largest islands in China and is located in the Indo-Burma biodiversity hotspot region.Despite its ecological significance,comprehensive population genetic studies of key marine organisms along the entire coastline of Hainan Island have not been reported.This study examined the genetic diversity and population structure of the widely distributed oyster Saccostrea malabonensis around Hainan Island with analyzing mitochondrial COI gene sequences.The impacts of geographical,environmental and anthropogenic factors on genetic differentiation were also investigated.The results revealed a significant AT bias in the COI gene sequences,with transitions as the main mutation type.A total of 103 variable sites and 107 haplotypes were identified from480 COI sequences,with haplotype diversities from 0.067 to 0.782,and nucleotide diversities between 0.00011 and 0.00278.AMOVA analysis indicated that 86.65%of the variation occurred within one population while 13.35%among different populations.The average genetic distance across 16 populations was 0.00169,and the average genetic differentiation index was 0.13353.Distinct population patterns can be observed.The populations of Tonghai Village(THV)and Gangmen Mountain(GMM)in Lingshui showed similar genetic structures while those of Wanquan River Estuary(WQRE,Qionghai)and Wuzhizhou Island(WZZI,Sanya)displayed divergent evolutionary trends.Cluster analysis grouped the 480 individuals of S.malabonensis into six subpopulations.These findings are helpful for developing conservation strategies and genetic breeding programs,and are also helpful for understanding the evolutionary history of this oyster species in Hainan Island. 展开更多
关键词 Hainan Island OYSTER Saccostrea malabonensis genetic diversity COI
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无车之境,马语春秋
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作者 李云祥 《疯狂英语(新悦读)》 2025年第12期51-52,79,共3页
In Michigan,the US“car capital of the world”where major automakers first started,there's a special island called Mackinac Island.This small island,only 9.8 square kilometers in size,has a strict rule:no cars are... In Michigan,the US“car capital of the world”where major automakers first started,there's a special island called Mackinac Island.This small island,only 9.8 square kilometers in size,has a strict rule:no cars are allowed here—not even golf carts.Around 600 people live on the island all year round,and horses are the real“kings”that keep daily life running. 展开更多
关键词 Mackinac Island horses automakers mackinac islandthis MICHIGAN car free zone
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Remote sensing monitoring for impact of island on chloro-phyll a in the water near the Diaoyu Island(Diaoyu Dao)and its affiliated islands,China
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作者 Lina Cai Ruohao Xin +3 位作者 Xiaomin Ye Rong Tang Jie Yin Leichao Cheng 《Acta Oceanologica Sinica》 2025年第2期24-36,共13页
The Diaoyu Island(Diaoyu Dao)and its affiliated islands(DAA)have abundant fishery resources,and chlorophyll a(Chl a)concentration is an important marine color element and an important indicator of primary productivity... The Diaoyu Island(Diaoyu Dao)and its affiliated islands(DAA)have abundant fishery resources,and chlorophyll a(Chl a)concentration is an important marine color element and an important indicator of primary productivity in the ocean.Therefore,it is meaningful to understand the distribution and variation characteristics of Chl a concentration in the waters near the DAA.The distribution details of Chl a concentration in the adjacent waters of DAA were revealed by high-resolution satellite GF-1 Wide Field View(WFV)data with 16 m spatial resolution.The results indicate that:(1)The Chl a concentration is between 0.06μg/L and 0.38μg/L throughout the year and the concentration of Chl a in the northeast and east directions of the island(downstream)is significantly higher than that in the west(upstream),and there are observed vortexes with high Chl a concentration in the downstream of DAA.This phenomenon continues to persist in the waters surrounding the DAA all year.(2)The vortex induced by the interaction between the current and island results in the vorticity change of water,inducing the replenishment of a large number of nutrients to the surface,thereby promoting the growth of plankton in the downstream of DAA on the east.In addition,the DAA also plays a significant role in regulating the downstream mix layer depth(MLD).The MLD in the northeast downstream is considerably deeper than the upstream in winter and spring;it is deeper in the east downstream in summer and autumn,and the range of influence for the MLD is greatly larger than the size of the island itself.This shows that the disruption of the DAA on the current is substantial.In addition,the combined effects of SST and wind also play a significant role in modifying Chl a distribution.(3)Based on the analysis above,this study proposes the conception of building fishing pastures downstream of the DAA,and proposes a general migration plan in different seasons to scientifically and rationally utilize and protect the surrounding waters of DAA. 展开更多
关键词 Diaoyu Island and its affiliated islands high-resolution satellite chlorophyll a
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Long Island's rainbow campaign
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作者 严丽华 《疯狂英语(新悦读)》 2025年第7期51-52,78,79,共4页
Rainbows-symbolizing peace,hope,promise and endurance(忍耐力)in hard times-are springing up in neighborhoods throughout Long Island in an effort to color the future road with optimism.The campaign,Rainbows over Nassau... Rainbows-symbolizing peace,hope,promise and endurance(忍耐力)in hard times-are springing up in neighborhoods throughout Long Island in an effort to color the future road with optimism.The campaign,Rainbows over Nassau and Suffolk Counties and Beyond,started on March 21 and spread through a group.It's a campaign that encourages participants to make rainbows to display outside their homes,anywhere from their front windows and doors to lawns and sidewalks.It follows another similar project,Chalk Your Walk,which promotes writing hopeful messages in chalk on driveways and sidewalks. 展开更多
关键词 your walkwhich Chalk Your Walk peace rainbow campaign Long Island OPTIMISM PROMISE endurance
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A Fun Trip to Nan'ao Island,Shantou
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作者 关璟骏 姚明婉(指导) 《疯狂英语(双语世界)》 2025年第4期73-74,共2页
Last summer holiday,I went to Nan'ao Island in Shantou with my family.It was a wonderful trip,and I enjoyed it very much.The island is very beautiful.The sea was clear and blue,and the beach had soft golden sand.W... Last summer holiday,I went to Nan'ao Island in Shantou with my family.It was a wonderful trip,and I enjoyed it very much.The island is very beautiful.The sea was clear and blue,and the beach had soft golden sand.We spent the whole morning at Qing'ao Bay.I played frisbee with my brother,built a little sand house,and even collected some pretty seashells.The waves were small and gentle,so I ran into the water and felt very excited.Later,we visited the Nan'ao Island Museum,where we learned many interesting stories about the island's history,the fishermen's lives,and the animals in the sea. 展开更多
关键词 fishing life history summer holiday sand houseand Shantou nanao island BEACH MUSEUM
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Geologic methane emissions from the Daginsky thermo-mineral springs in the northeast of Sakhalin Island: 2024 expedition and remote sensing data
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作者 Nadezhda Syrbu Andrei Kholmogorov +4 位作者 Aleksey Legkodimov Igor Stepochkin Rafael Zharkov Anatoly Salyuk Vyacheslav Kantalin 《Geoscience Frontiers》 2025年第5期471-484,共14页
The paper deals with the urgent problem of gas-geochemical parameters in the seas and shelf transit zones based on a comparison of field studies and remote sensing data.The results of complex gas-geochemical studies o... The paper deals with the urgent problem of gas-geochemical parameters in the seas and shelf transit zones based on a comparison of field studies and remote sensing data.The results of complex gas-geochemical studies of the Daginsky gas-hydrothermal system are presented,as well as an assessment of methane emissions from the studied area.The Daginsky gas-hydrothermal system is located on the northeastern coast of Sakhalin Island,and is a unique object due to a combination of a number of factors:from zonality due to the proximity of the Okhotsk Sea and the geological structure,to the interaction of deep and surface processes manifested in the presence of biogenic and thermogenic methane,as well as mantle helium.Tectonic faults and oil and gas bearing structures of the northeastern shelf of Sakhalin,which determine the direction of natural gas flows and facilitate its migration to the surface,make a significant contribution to the gas appearance of thermal springs.The main gas is methane up to 90%,homologues of methane up to and including pentane have been established,and isolated high concentrations of helium and hydrogen,both dissolved and in the free gas of bubbles,have also been noted.The conducted isotope studies allow to speak about the complex genesis of the gas.δ^(13)C isotopic composition,ranging from−49.4‰to−60.2‰shows the dominance of biogenic methane with an admixture of thermogenic component.This is also confirmed by the presence of a fraction of mantle helium.The flow of methane into the atmosphere from the Daginsky area is 963757.5 mol/(km^(2)·day),or about 15.4 t/(km^(2)·year),which indicates the importance of this region for the regional and global carbon cycle.The dynamics of methane emissions can vary depending on various factors,such as seasonal fluctuations and geological activity,which further complicates the understanding of processes in the region. 展开更多
关键词 Methane emission HELIUM Geothermal systems Sakhalin Island Cold seeps
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