KHALED S. Sinoussy, Hiroshi Naraoka, Osamu Seki, MAHMOUD A. Hassaan, Yusuke Okazaki
{"title":"过去 2.3 万年间北非的水文和植被变化:利用遥感技术和来自东地中海的特定化合物 δ2H 和 δ13C 对尼罗河流域进行的比较研究","authors":"KHALED S. Sinoussy, Hiroshi Naraoka, Osamu Seki, MAHMOUD A. Hassaan, Yusuke Okazaki","doi":"10.1002/jqs.3649","DOIUrl":null,"url":null,"abstract":"<div>\n \n <p>Hydroclimate variation and vegetation changes of the Nile River watershed area in northeast Africa since the Last Glacial Maximum (LGM) were reconstructed based on n-alkanes, their carbon isotope ratios (δ<sup>13</sup>C<sub>n-alkanes</sub>), and their hydrogen isotope ratios (δ<sup>2</sup>H<sub>n-alkanes</sub>) in sediments from ODP Site 967 in the Eastern Mediterranean Sea. The results were compared with the present vegetation cover in the watershed areas using ArcGIS. The average proportion of current grassland in the Equatorial Lake and Ethiopian Highland Plateaus watershed areas was 45.8 and 64.7%, respectively. δ<sup>2</sup>H<sub>n-alkanes</sub> ranged from −199 to −127‰ and co-varied with insolation change response to orbital forcing. Depleted δ<sup>2</sup>H<sub>n-alkanes</sub> were found from deglaciation to the middle Holocene, suggesting increased precipitation during the African Humid Period (AHP) from 15 to 5 ka caused by northward migration of the Intertropical Convergence Zone. However, lower precipitation was inferred by enriched δ<sup>2</sup>H<sub>n-alkanes</sub> during the LGM and late Holocene. δ<sup>13</sup>C<sub>n-alkanes</sub> at Site 967 did not show a trend in harmony with δ<sup>2</sup>H<sub>n-alkanes</sub> and instead exhibited millennial-scale variations ranging from –25.9 to –33.2‰. These δ<sup>13</sup>C<sub>n-alkanes</sub> values consistently indicated a C4 grass-dominated environment in the watershed areas of the River Nile since the LGM, persisting through the AHP and into the present. Reconstructions demonstrated orbital and abrupt forcing of hydroclimate variability while maintaining generally grass-dominated vegetation with weak precipitation feedback over the late Quaternary.</p>\n </div>","PeriodicalId":16929,"journal":{"name":"Journal of Quaternary Science","volume":null,"pages":null},"PeriodicalIF":1.9000,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Hydrological and vegetation changes in North Africa over the past 23 000 years: a comparative study of watershed areas of the Nile River using remote sensing and compound-specific δ2H and δ13C from the Eastern Mediterranean Sea\",\"authors\":\"KHALED S. Sinoussy, Hiroshi Naraoka, Osamu Seki, MAHMOUD A. Hassaan, Yusuke Okazaki\",\"doi\":\"10.1002/jqs.3649\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div>\\n \\n <p>Hydroclimate variation and vegetation changes of the Nile River watershed area in northeast Africa since the Last Glacial Maximum (LGM) were reconstructed based on n-alkanes, their carbon isotope ratios (δ<sup>13</sup>C<sub>n-alkanes</sub>), and their hydrogen isotope ratios (δ<sup>2</sup>H<sub>n-alkanes</sub>) in sediments from ODP Site 967 in the Eastern Mediterranean Sea. The results were compared with the present vegetation cover in the watershed areas using ArcGIS. The average proportion of current grassland in the Equatorial Lake and Ethiopian Highland Plateaus watershed areas was 45.8 and 64.7%, respectively. δ<sup>2</sup>H<sub>n-alkanes</sub> ranged from −199 to −127‰ and co-varied with insolation change response to orbital forcing. Depleted δ<sup>2</sup>H<sub>n-alkanes</sub> were found from deglaciation to the middle Holocene, suggesting increased precipitation during the African Humid Period (AHP) from 15 to 5 ka caused by northward migration of the Intertropical Convergence Zone. However, lower precipitation was inferred by enriched δ<sup>2</sup>H<sub>n-alkanes</sub> during the LGM and late Holocene. δ<sup>13</sup>C<sub>n-alkanes</sub> at Site 967 did not show a trend in harmony with δ<sup>2</sup>H<sub>n-alkanes</sub> and instead exhibited millennial-scale variations ranging from –25.9 to –33.2‰. These δ<sup>13</sup>C<sub>n-alkanes</sub> values consistently indicated a C4 grass-dominated environment in the watershed areas of the River Nile since the LGM, persisting through the AHP and into the present. Reconstructions demonstrated orbital and abrupt forcing of hydroclimate variability while maintaining generally grass-dominated vegetation with weak precipitation feedback over the late Quaternary.</p>\\n </div>\",\"PeriodicalId\":16929,\"journal\":{\"name\":\"Journal of Quaternary Science\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":1.9000,\"publicationDate\":\"2024-07-25\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Quaternary Science\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://onlinelibrary.wiley.com/doi/10.1002/jqs.3649\",\"RegionNum\":3,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"GEOGRAPHY, PHYSICAL\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Quaternary Science","FirstCategoryId":"89","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/jqs.3649","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"GEOGRAPHY, PHYSICAL","Score":null,"Total":0}
Hydrological and vegetation changes in North Africa over the past 23 000 years: a comparative study of watershed areas of the Nile River using remote sensing and compound-specific δ2H and δ13C from the Eastern Mediterranean Sea
Hydroclimate variation and vegetation changes of the Nile River watershed area in northeast Africa since the Last Glacial Maximum (LGM) were reconstructed based on n-alkanes, their carbon isotope ratios (δ13Cn-alkanes), and their hydrogen isotope ratios (δ2Hn-alkanes) in sediments from ODP Site 967 in the Eastern Mediterranean Sea. The results were compared with the present vegetation cover in the watershed areas using ArcGIS. The average proportion of current grassland in the Equatorial Lake and Ethiopian Highland Plateaus watershed areas was 45.8 and 64.7%, respectively. δ2Hn-alkanes ranged from −199 to −127‰ and co-varied with insolation change response to orbital forcing. Depleted δ2Hn-alkanes were found from deglaciation to the middle Holocene, suggesting increased precipitation during the African Humid Period (AHP) from 15 to 5 ka caused by northward migration of the Intertropical Convergence Zone. However, lower precipitation was inferred by enriched δ2Hn-alkanes during the LGM and late Holocene. δ13Cn-alkanes at Site 967 did not show a trend in harmony with δ2Hn-alkanes and instead exhibited millennial-scale variations ranging from –25.9 to –33.2‰. These δ13Cn-alkanes values consistently indicated a C4 grass-dominated environment in the watershed areas of the River Nile since the LGM, persisting through the AHP and into the present. Reconstructions demonstrated orbital and abrupt forcing of hydroclimate variability while maintaining generally grass-dominated vegetation with weak precipitation feedback over the late Quaternary.
期刊介绍:
The Journal of Quaternary Science publishes original papers on any field of Quaternary research, and aims to promote a wider appreciation and deeper understanding of the earth''s history during the last 2.58 million years. Papers from a wide range of disciplines appear in JQS including, for example, Archaeology, Botany, Climatology, Geochemistry, Geochronology, Geology, Geomorphology, Geophysics, Glaciology, Limnology, Oceanography, Palaeoceanography, Palaeoclimatology, Palaeoecology, Palaeontology, Soil Science and Zoology. The journal particularly welcomes papers reporting the results of interdisciplinary or multidisciplinary research which are of wide international interest to Quaternary scientists. Short communications and correspondence relating to views and information contained in JQS may also be considered for publication.