Global and Planetary Change最新文献

{"title":"Westerlies migrations and volcanic records over the past 4000 years from the Azores lacustrine sequences. Exploring correlations and impacts on Western Europe","authors":"Alberto Sáez ,&nbsp;Armand Hernández ,&nbsp;Adriano Pimentel ,&nbsp;Mariana Andrade ,&nbsp;Roberto Bao ,&nbsp;Pedro M. Raposeiro ,&nbsp;Vitor Gonçalves ,&nbsp;Mario Benavente ,&nbsp;Sergi Pla-Rabes ,&nbsp;Ricardo Ramalho ,&nbsp;Santiago Giralt","doi":"10.1016/j.gloplacha.2025.104698","DOIUrl":"10.1016/j.gloplacha.2025.104698","url":null,"abstract":"<div><div>The Azores region plays a crucial role as a pathway for precipitation fronts traversing the North Atlantic from west to east, driven by the prevailing westerly winds. Variations in the strength of the Azores High affect the dynamics of the North Atlantic Oscillation (NAO), leading to latitudinal shifts in the trajectory of the westerlies and jet stream current over time.</div><div>Throughout the Holocene and Late Pleistocene, the Azores islands experienced numerous highly explosive eruptions. Volcanic ash from these events was primarily dispersed to the east, carried by the North Atlantic Jet Stream, with cryptotephras being found across the British Isles and Northern-Central Europe.</div><div>To investigate how NAO variations influenced the latitudinal position of the westerlies and in the ash dispersal towards Europe during the Late Holocene, we analysed the stratigraphy and sedimentology from 20 lake sediment sequences across five islands of Azores and revise highstand/lowstand periods in several lakes in Europe. Our facies analysis of Azorean lakes revelated three long-term phases highstand at 0–0.6, 2.6–1.5 and &gt; 4.2–3.4 cal ka BP and two lowstand phases at 1.5–0.6 and 2.6–3.3 cal ka BP which are ultimately related to paleo-NAO intensity and signal variations. By modelling spatial and temporal climate variability between Azores and Europe, we tracked changes in the westerlies' latitudinal position over the last 4200 years.</div><div>Additionally, we characterised tephra deposits in Azorean lakes, creating a preliminary database to support future tephrostratigraphic and tephrochronological research. This framework can also be useful for recognising distal cryptotephra layers in Europe and North Africa.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"246 ","pages":"Article 104698"},"PeriodicalIF":4.0,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143020024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Basin-scale spatio-temporal development of glacial lakes in the Hindukush-Karakoram-Himalayas","authors":"Atul Kumar ,&nbsp;Suraj Mal ,&nbsp;Udo Schickhoff ,&nbsp;A.P. Dimri","doi":"10.1016/j.gloplacha.2024.104656","DOIUrl":"10.1016/j.gloplacha.2024.104656","url":null,"abstract":"<div><div>Glacial lakes are expanding exponentially in the cryospheric environment of the Hindukush-Karakoram-Himalayas (HKH). Rapid glacier melting due to an above mean global annual temperature increase in HKH is attributed as the main reason for the expansion of the glacial lakes. The rapid expansion of glacial lakes increases the risk of future Glacial Lake Outburst Floods (GLOFs) events in the HKH.</div><div>In the present study, glacial lake inventories for the Indus, Ganga and Brahmaputra (IGB) river basins in the HKH were generated for 1990, 2000, 2010 and 2020 using Landsat (TM &amp; OLI) at the sub-basin level to understand the spatio-temporal and regional patterns of glacial lakes dynamics, elevational evolution, and changes in the typology. We mapped 17,641 glacial lakes (area: 1082.57 ± 192.601 km²) in 1990, 18,206 (area: 1120.95 ± 198.49 km²) in 2000, 18,399 (area: 1147.12 ± 201.26 km²) in 2010, and 19,284 (area: 1191.81 ± 209.21 km²) in 2020. Between 1990 and 2020, IGB basins showed an increase of 9.31 % in total number and 10.09 % in total area of glacial lakes. In 2020, the Brahmaputra basin had the maximum total area (area: 763.59 ± 132.14 km²), followed by Indus basin (area: 217.47 ± 43.39 km²) and the Ganga basin (area: 210.74 ± 33.66 km²). However, between 1990 and 2020, glacial lakes in the Ganga basin (n: 22.08 %) had the highest growth rate, followed by the Indus basin (n: 14.73 %) and the Brahmaputra basin (n: 4.41 %). In 2020, 76.11 % of glacial lakes were end-moraine-dammed M(e) lakes, followed by other bedrock-dammed B(o) lakes (16.45 %), supraglacial lakes (2.79 %), lateral moraine-dammed M(l) lakes (2 %), cirque B(c) lakes (1.06 %), other moraine-dammed M(o) lakes (0.38 %), and other glacial (O) lakes (1.18 %). Given the rapid growth of glacial lakes in the region along with their likely flood volumes and damage potential in case of their failures, the present study will be of importance for disaster management authorities, an important input for detection of potentially hazardous glacial lakes and for development of mitigation strategies to minimize the impact of potential future GLOF events.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"245 ","pages":"Article 104656"},"PeriodicalIF":4.0,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142746654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Zooplankton fecal pellet flux and carbon export: The South China Sea record and its global comparison","authors":"Jiaying Li,&nbsp;Zhifei Liu,&nbsp;Baozhi Lin,&nbsp;Yulong Zhao,&nbsp;Xiaodong Zhang,&nbsp;Junyuan Cao,&nbsp;Jingwen Zhang,&nbsp;Hongzhe Song","doi":"10.1016/j.gloplacha.2024.104657","DOIUrl":"10.1016/j.gloplacha.2024.104657","url":null,"abstract":"<div><div>Zooplankton fecal pellets constitute a major component of passively sinking particles in the ocean. The sinking of zooplankton fecal pellets provides an efficient vehicle for the transfer and sequestration of particulate organic carbon (POC) in the deep sea, which has been widely reported in different regions. However, most existing studies focus on the sinking flux of fecal pellets within the upper ocean, while lower mesopelagic and bathypelagic zones are rarely investigated. Here, we report the spatiotemporal flux variation of zooplankton fecal pellets collected by two sediment traps deployed in mesopelagic and bathypelagic zones (500 m and 2190 m, respectively) of the South China Sea from June 2020 to May 2022, and compare it with deep-sea (&gt;500 m) fecal pellet flux data reported in the global ocean. In the South China Sea, fecal pellet fluxes display distinct seasonal patterns due to the control of the East Asian monsoon system, with higher fluxes in winter and spring, and lower fluxes in summer and autumn. Small fecal pellets (width &lt; 100 μm) dominate the overall pellet numerical flux (more than 98 %), while rare large pellets (width &gt; 100 μm) account for averaging 20 % of fecal pellet carbon flux. Both large and small pellet fluxes appear to be higher at 2190 m, mainly due to the in-situ reworking and repackaging of deep-dwelling zooplankton communities, as well as the input of lateral advection from high productive continental coasts and shelves. Identifiable zooplankton fecal pellets constitute approximately 10 % to the total POC flux in the deep South China Sea. Comparing the eutrophic polar and upwelling regions with mesotrophic and oligotrophic regions, we find a good correlation between marine primary production and fecal pellet carbon export. On the global scale, carbon fluxes through zooplankton fecal pellets to the deep sea are mainly constrained by the grazing impacts of zooplanktons, influenced by temperature, zooplankton biomass, and zooplankton size spectrum.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"245 ","pages":"Article 104657"},"PeriodicalIF":4.0,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142746655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Radium fingerprinting traces hydrology of the global cryosphere under climate warming","authors":"Zhe Zhang,&nbsp;Lixin Yi,&nbsp;Ruotong Li,&nbsp;Tianxue Lyu,&nbsp;Chenyi Liu,&nbsp;Yingchun Dong","doi":"10.1016/j.gloplacha.2024.104654","DOIUrl":"10.1016/j.gloplacha.2024.104654","url":null,"abstract":"<div><div>Dynamic changes in the cryosphere have profound implications for global warming. This study, through case studies of seasonal ice lakes and glacier-originated rivers, complemented by global data, offers novel insights into radium (Ra) isotopes' characteristic in the cryosphere. It elucidates the quantification of the “Ra quartet” as tracers in frozen hydrological processes across various timescales. (1) Theoretical case studies. Significant differences in water chemistry and Ra activities were observed, highlighting distinct Ra supply and depletion mechanisms. The improved Ra mass model was utilized to estimate the freezing duration of the lakes and the groundwater discharge beneath the ice, while also elucidating the recharge dynamics of groundwater along glacial rivers. (2) Global scale theoretical discoveries. The low ²²⁴Ra/²²⁸Ra ratio, including the case studies presented, may be a significant characteristic of the non-subterranean cryosphere. This phenomenon can be attributed to various processes, including decay, particulate scavenging, groundwater discharge, upwelling, and glacial meltwater. In contrast, the ratio observed in permafrost is more complex, potentially influenced by diverse hydrogeological conditions and intricate sampling protocols. While Ra isotopes are well-traced in the ocean cryosphere—covering groundwater discharge, water exchange, and composition-particle interactions—their application in terrestrial and atmospheric cryospheric studies remains underexplored. Our study provides novel perspectives on Ra isotopes in the cryosphere, offering crucial theoretical and practical implications for addressing ongoing climate warming.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"244 ","pages":"Article 104654"},"PeriodicalIF":4.0,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Late Cretaceous ecosystem dynamics in the southern incipient Arctic Ocean: A micropaleontological and geochemical perspective","authors":"J.F. Diaz ,&nbsp;L. Schwark ,&nbsp;P.K. Pedersen ,&nbsp;J.M. Galloway ,&nbsp;M. Bringué ,&nbsp;S.E. Grasby","doi":"10.1016/j.gloplacha.2024.104643","DOIUrl":"10.1016/j.gloplacha.2024.104643","url":null,"abstract":"<div><div>Micropaleontological and geochemical analyses in samples from the Coniacian-Maastrichtian-aged Smoking Hills and Mason River formations in the Anderson Basin of the northern mainland coast of Arctic Canada provide a refined picture of the environmental conditions occurring in the incipient southern Arctic Ocean at the end of the Cretaceous. These units were deposited within a 22 myr time span in an outer shelf setting characterized by relatively stable tectonic conditions and low sedimentation rates. The Coniacian-middle Campanian Smoking Hills Formation was deposited during times of marine transgression and water column stratification. Surface waters were highly productive and dominated by dinoflagellates, red algae, green algae and likely diatoms and silicoflagellates. Bottom waters were predominantly anoxic-euxinic, but the presence of benthic foraminifera and variations of geochemical signatures in some intervals indicate episodic ventilation. The deposition of the Smoking Hills Formation is temporally consistent with the Oceanic Anoxic Event 3 (OAE3), but the duration of these anoxic conditions is much longer in the Anderson Basin. During the middle Campanian, relative sea level reached a highstand, fostering the expansion of planktic siliceous microorganisms, including diatoms, silicoflagellates and radiolarians. During the late Campanian to at least the Maastrichtian, sediments of the Mason River Formation were deposited during a regressive sedimentation phase characterized by high productivity fueled by river run-off and the proliferation of diatoms, red and green algae. Despite high productivity, bottom waters were oxygenated. This study highlights the importance of data integration to reconstruct the environmental conditions of the past as many, if not all, of the proxies utilized to this end are subjected to preservational and diagenetic bias.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"244 ","pages":"Article 104643"},"PeriodicalIF":4.0,"publicationDate":"2024-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Molybdenum isotopic evidence for linked changes in North Pacific Intermediate Water and subtropical Northwest Pacific redox conditions over the last 200 k.y","authors":"Yanguang Dou ,&nbsp;Chenghui Sun ,&nbsp;Shouye Yang ,&nbsp;Xuefa Shi ,&nbsp;Yonghua Wu ,&nbsp;Jingyi Cong ,&nbsp;Yong Zhang ,&nbsp;Fengmei Wang ,&nbsp;Feng Cai ,&nbsp;Peter D. Clift","doi":"10.1016/j.gloplacha.2024.104637","DOIUrl":"10.1016/j.gloplacha.2024.104637","url":null,"abstract":"<div><div>Through biological productivity and ocean-atmosphere CO₂ exchange, North Pacific mid-depth ventilation has the potential to regulate regional climate over glacial timescales. Nevertheless, the subtropical Northwest Pacific currently lacks continuous long redox records that would enable us to evaluate this process. In this instance, we present δ^98/95Mo and redox-sensitive trace element data derived from Okinawa Trough sediments to reconstruct redox conditions and assess their possible significance in regulating atmospheric CO₂ in the subtropical Northwest Pacific over the last 200 k.y. Enhanced oxic conditions induced by a strengthened Kuroshio Current during Marine Isotope Stage (MIS) 1 suggest the presence of enhanced deep water ventilation and upwelling in the Okinawa Trough, which likely contributed to high atmospheric CO₂ concentrations during interglacial periods. The Okinawa Trough may have been oxic and served as a regional net carbon sink during MIS2 and MIS6, due to glacial North Pacific Intermediate Water (GNPIW) and a weak Kuroshio Current. During interglacials, high productivity brought on by the stronger East Asian Summer Monsoon (EASM) leads to an increase in organic matter burial and oxygen consumption. This substantial positive excursion in δ^98/95Mo values during MIS4 and early MIS3 can be linked to the anaerobic oxidation of methane (AOM) and the release of methane-rich fluids from methane hydrate decomposition. Our findings highlight potential links between higher upwelling, GNPIW expansion, and the underlying processes regulating the atmospheric CO₂ budget in the subtropical North Pacific during the late Quaternary.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"244 ","pages":"Article 104637"},"PeriodicalIF":4.0,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Possible influence of low latitude wetland area changes on the Holocene global atmospheric methane concentration trend","authors":"Yunping Song ,&nbsp;Hai Xu ,&nbsp;Kevin M. Yeager","doi":"10.1016/j.gloplacha.2024.104655","DOIUrl":"10.1016/j.gloplacha.2024.104655","url":null,"abstract":"<div><div>Understanding the causes of variations in global atmospheric methane concentration (GAMC) is an important issue in the study of global climatic changes. Long-term GAMC varied rhythmically on glacial-interglacial timescales, and broadly followed the orbital/suborbital cycles in northern hemisphere solar insolation. Yet the late Holocene has witnessed an increasing GAMC trend since the mid-Holocene, which decouples with the global atmospheric CO₂ concentration trend and the northern hemisphere solar insolation trend. The causes of this decoupling have been extensively studied, but remain highly debated. Here we show that the Holocene GAMC trend closely follows the long-term trend in global low latitude wetland extent as inferred from our lake-level reconstruction and from other existing hydroclimate records. We contend that changes in low latitude wetland extent play an important role in shaping the GAMC trend. We propose that reduced low latitude wetland areas during the mid-Holocene, which were likely due to the submersion of tropical wetlands by rising sea levels, and reduced low latitude wetland areas inferred from lower lake levels, could be responsible for the observed mid-Holocene GAMC drop. Increasing global low latitude wetland areas during the late Holocene are likely responsible for the contemporary increasing GAMC trend.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"244 ","pages":"Article 104655"},"PeriodicalIF":4.0,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721908","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Iron isotope fractionation during granite weathering under different climates","authors":"Meng Qi ,&nbsp;Chengshuai Liu ,&nbsp;Ting Gao ,&nbsp;Zhengrong Wang ,&nbsp;Yuhui Liu ,&nbsp;Yafei Xia","doi":"10.1016/j.gloplacha.2024.104653","DOIUrl":"10.1016/j.gloplacha.2024.104653","url":null,"abstract":"<div><div>Climate controls chemical weathering of silicate rocks on the transport of iron (Fe) and its isotopes from continent to the ocean, impacting the global Fe geochemical cycle. However, it's elusive if Fe isotope fractionation during silicate weathering reflects variations in climate factors. This study examines two granite-derived regolith profiles; one in Beijing (BJ), representing a temperate climate, and the other in Guangdong (GD), representing a tropical climate, to investigate their mineralogy, Fe-bearing phases, element concentrations, and Fe isotope compositions. Our results show that, despite climate differences, the two granite weathering profiles have average δ⁵⁶Fe_{bulk regolith} values within analytical uncertainty (0.09 ± 0.02 ‰ vs. 0.12 ± 0.04 ‰, 2SD). The δ⁵⁶Fe_{bulk regolith} values of temperate and tropical regolith are similar to or slightly higher than those of their respective bedrocks and remain steady along the entire weathering profile. The limited variation of Fe isotope composition in weakly weathered temperate regolith likely reflects the dissolution of primary minerals rather than the formation of secondary minerals. The Rayleigh fractionation calculations also show a Δ⁵⁶Fe_{pore solution-regolith} value of ∼0 ‰ between pore solution and regolith. In contrast, in the tropical profile, despite the abundance of secondary minerals and the differences in δ⁵⁶Fe values among the extracted Fe-pools exceeding 0.68 ‰, only limited Fe isotope fractionation is observed in the bulk regolith (0.01 ‰ to 0.24 ‰). These variations are likely driven by the formation of Fe oxides, relying on the atomic distribution of Fe in hematite and goethite. The linear regression analysis estimates the apparent Fe isotope fractionation factor between hematite and goethite as 0.46 ± 0.07 ‰ (Δ⁵⁶Fe_{hematite-goethite}, 1SE). These findings indicate that the sensitivity of Fe isotope fractionation in bulk regolith to variations in climate factors is relatively limited. However, combined with results from other weathering profiles in different climate zones, two models suggest that changes in δ⁵⁶Fe values of easily leachable and silicate-bound Fe pools are likely influenced by climate factors such as temperature and precipitation. This work advances our understanding of the Fe isotope fractionation during silicate weathering and its potential climate connection on Earth's surface.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"244 ","pages":"Article 104653"},"PeriodicalIF":4.0,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of ENSO on extreme precipitation in Southwest Asia","authors":"Omid Alizadeh ,&nbsp;Morteza Mousavizadeh","doi":"10.1016/j.gloplacha.2024.104645","DOIUrl":"10.1016/j.gloplacha.2024.104645","url":null,"abstract":"<div><div>The El Niño-Southern Oscillation (ENSO) is a primary driver of interannual variability in extreme precipitation in many regions worldwide. Understanding the relationship between ENSO and extreme precipitation is crucial, as it has implications for understanding the interannual variability of flood risk. We investigated the frequency of extreme daily precipitation in Southwest Asia across different seasons during El Niño and La Niña using the daily GPCP and ERA5 precipitation datasets for the period 1997–2022. Extreme precipitation at each grid point is defined as daily accumulated precipitation exceeding the 95th percentile on wet days, where a wet day is defined as one with at least 0.1 mm rainfall. El Niño is associated with an overall increase in the frequency of extreme precipitation in Southwest Asia during autumn, winter, and spring, whereas La Niña shows the opposite effect. To explore the dynamics of El Niño and La Niña teleconnections to Southwest Asia, we applied a feature tracking method on the ERA5 relative velocity at 850 hPa in different seasons. Overall, the storm track density and the mean intensity of storms increase in Southwest Asia during El Niño and decrease during La Niña in autumn, winter, and spring. In summer, El Niño favors less frequent extreme precipitation in the southern parts of Southwest Asia, where the tropical summer monsoon circulation is dominated, while La Niña is associated with more frequent extreme precipitation in this region. This pattern is expected, as the monsoon circulation is weaker during El Niño and stronger during La Niña. In line with this, we identified a decrease in the mean intensity of storms in the southern parts of Southwest Asia during El Niño, with the opposite occuring during La Niña. Our findings have important implications for understanding interannual variability of extreme precipitation in Southwest Asia and providing a framework for predicting such events.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"244 ","pages":"Article 104645"},"PeriodicalIF":4.0,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of climate change and methane-rich fluid activity on sedimentary sulfur geochemical records in the northern South China Sea since mid-Pleistocene","authors":"Junxi Feng ,&nbsp;Yufei Zhang ,&nbsp;Niu Li ,&nbsp;Jianhou Zhou ,&nbsp;Jinqiang Liang ,&nbsp;Qianyong Liang ,&nbsp;Shengxiong Yang ,&nbsp;Duofu Chen ,&nbsp;Harunur Rashid","doi":"10.1016/j.gloplacha.2024.104644","DOIUrl":"10.1016/j.gloplacha.2024.104644","url":null,"abstract":"<div><div>Microbial sulfate reduction (MSR) and associated pyritic sulfide formation are important diagenetic processes in marine sediments. The sulfur isotopic composition of pyrite (δ³⁴S_pyr) is proven to be sensitive to changes in sedimentation rates and the content and reactivity of organic carbon, especially on the continental shelves and upper slopes (water depth &lt; 350 m). However, the diagenetic responses of sulfur to variations in climatic and depositional conditions in the deep-sea sediments are still poorly understood. This study combines element contents and isotopes to characterize diagenetic interplays of sulfur, organic carbon, and methane in the continental slope sediments of the northern South China Sea since the mid-Pleistocene. Our data suggest that the total organic carbon (TOC) increased during glacial times, implying enhanced primary productivity due to increased nutrient supply by the East Asian Winter Monsoon, in addition to efficient transfer of organic carbon and better preservation of organic carbon due to reduced bottom water oxygen. Total sulfur and chromium reduction sulfur contents varied concomitantly with the TOC, suggesting an increased burial of organic carbon that enhanced the organoclastic sulfate reduction (OSR) and the formation of authigenic pyrite. The environmental changes did not induce a significant shift in δ³⁴S_pyr, due most likely to relatively low sedimentation rates and large fractionation in sulfur isotope through OSR during the glacial-interglacial cycles. Instead, it is hypothesized that the sulfate-driven anaerobic methane oxidation promoted the formation of a higher amount of authigenic pyrite. Consequently, it created a closed diagenetic system leading to positive excursions in δ³⁴S_pyr at the sulfate-methane transition zone. Our results suggest the vulnerability of pyrite formation and its sulfur isotopic composition to the changes in monsoon-driven primary productivity and the methane-rich fluid migrations in the continental margin sediments. This study complements the growing evidence for the local diagenetic controls on sedimentary sulfur geochemical records by highlighting the importance of early diagenesis in paleoenvironment reconstruction based on the content and sulfur isotopic composition of pyrite.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"244 ","pages":"Article 104644"},"PeriodicalIF":4.0,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}