Global and Planetary Change最新文献

{"title":"Dynamics of dunes and climate variability over the last five decades: A remote sensing analysis of regional contrasts on the northeastern Tibetan Plateau and the adjacent Hexi Corridor","authors":"Lukas Dörwald ,&nbsp;Frank Lehmkuhl ,&nbsp;Lucie Delobel ,&nbsp;Xiaoping Yang ,&nbsp;Georg Stauch","doi":"10.1016/j.gloplacha.2025.104873","DOIUrl":"10.1016/j.gloplacha.2025.104873","url":null,"abstract":"<div><div>Dunes react quickly to climatic changes, with the main drivers being the dominating wind regime (e.g. magnitude and direction), precipitation, and temperature. Furthermore, human impact can alter dune movement by fixation of active dunes through greening projects, or reactivation of fixed dunes through overgrazing or neglect of former human structures. The northeastern Tibetan Plateau shows a high variability of climatic parameters like wind, temperature, and precipitation within a high elevation environment, situated between the mid-latitude westerlies and the East Asian Summer monsoon. This study assesses changes in the movement of active barchans and sand sheets in three different regions of the northeastern Tibetan Plateau and additionally the adjacent Hexi Corridor to evaluate the different impact of climate change and anthropogenic activities in the past 54 years. Over 500 active barchan dunes and 46 sand sheets were studied to assess climatic influence on aeolian deposits. Since weather stations on the Tibetan Plateau are rare and their measurements often cover only a short time span, ERA-5 reanalysis data was utilized. Dune migration rates were deduced from different satellite imagery taken from 1968 onwards. The Normalized Difference Vegetation Index was implemented to observe changes in vegetation. As a further metric, dune field density changes were calculated, to investigate dynamics in dune field settings and human impact from agriculture in the Hexi Corridor.</div><div>The results show similar migration rates in the Hexi Corridor and the Gonghe Basin with mean values of 8.54 and 7.33 m y⁻¹, respectively, while in the Source Area of the Yellow River the dunes are migrating slower with a mean of 3.62 m y⁻¹. The Zoige Basin sand sheets show mostly an expansion in size with a mean growth of 65.39 km² y⁻¹ and a sum extension of 3007.95 km² since 1968. The results show the influence of the East Asian Summer Monsoon as a driver for precipitation and subsequent vegetation establishment altering dune movement through fixation. Furthermore, regional dune behavior is influenced by human activities during the past decades, diverting the climatic signal.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"252 ","pages":"Article 104873"},"PeriodicalIF":4.0,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143934680","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":"Using speleothem 87Sr/86Sr variations tracking the controls on trace element (Sr-Mg) compositions","authors":"Rishui Chen ,&nbsp;Shuyu Xue ,&nbsp;Hongbin Zhang ,&nbsp;Michael Griffiths ,&nbsp;Yi Zhou ,&nbsp;Xing Liu ,&nbsp;Zhenli Zhu ,&nbsp;Lin Chen ,&nbsp;Wei Guo ,&nbsp;Shitou Wu ,&nbsp;Hai Cheng ,&nbsp;Junhua Huang ,&nbsp;Zongmin Zhu ,&nbsp;Shucheng Xie","doi":"10.1016/j.gloplacha.2025.104872","DOIUrl":"10.1016/j.gloplacha.2025.104872","url":null,"abstract":"<div><div>Speleothem Sr/Ca and Mg/Ca ratios have emerged as important hydroclimate proxies due to their geochemical responses under uniform hydrological conditions. However, inconsistent Sr/Ca-Mg/Ca patterns in individual or coeval speleothems within cave systems complicate hydroclimate reconstructions, highlighting the complexities in the controls of Sr-Mg compositions. Recent advances in cave monitoring and multiproxy studies demonstrated the potential of ⁸⁷Sr/⁸⁶Sr in discriminating the sources and hydrological processes of Mg and Sr variations. Nevertheless, systematic applications of ⁸⁷Sr/⁸⁶Sr in both modern process studies and paleoclimate reconstructions are lacking.</div><div>In this study, we presented two speleothems (HZZ41B-1 and HZZ11) with similar growing intervals and divergent Sr/Ca and Mg/Ca variations from Haozhu cave in central China. In order to decipher the underlying controls on trace element (Sr-Mg) compositions, we conducted a detailed investigation of ⁸⁷Sr/⁸⁶Sr and trace elements composition of the overlying soil, bedrock, cave sediment, drip water, and the two speleothems. The ⁸⁷Sr/⁸⁶Sr compositions in speleothems are closer to the bedrock end-member, suggesting a dominant bedrock contribution to speleothem Sr compositions. The ⁸⁷Sr/⁸⁶Sr values in speleothem HZZ41B-1 exhibit significant variations and positive correlation with Mg/Ca, which might be caused by the inconsistent dissolution of limestone and dolomite modulated by the varied water-rock interaction (WRI) time in the karst layer. In contrast, ⁸⁷Sr/⁸⁶Sr values in HZZ11 exhibit minimal variability, further supporting the prior calcite precipitation (PCP) control on the Sr-Mg compositions. In short summary, this study offers an approach to understanding the inconsistent variations in speleothem Sr/Ca and Mg/Ca by extra investigation of ⁸⁷Sr/⁸⁶Sr, further conducive to the recognition of the proper proxy for local hydroclimate.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"252 ","pages":"Article 104872"},"PeriodicalIF":4.0,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144070062","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":"Forest and mosaic vegetation cut off savanna corridors during the Last Glacial Maximum in Southeast Asia recorded by marine pollen","authors":"Gang Lin ,&nbsp;Chuanxiu Luo ,&nbsp;Dileep Bandara Herath ,&nbsp;Sui Wan ,&nbsp;Xiang Su ,&nbsp;Yiping Yang ,&nbsp;Mingzhen Zhong ,&nbsp;Zhiying Wang ,&nbsp;Xun Yuan ,&nbsp;Rong Xiang","doi":"10.1016/j.gloplacha.2025.104871","DOIUrl":"10.1016/j.gloplacha.2025.104871","url":null,"abstract":"<div><div>During the Last Glacial Maximum (LGM), Southeast Asia was characterized by the exposure of a vast landmass known as Sundaland, which emerged from the continental shelf. This newly available area may have facilitated the proliferation of vegetation, potentially enhancing carbon dioxide (CO₂) uptake. The ongoing controversy regarding previous interpretations of “savanna corridors (C₄-rich grassland corridors)”, “mosaic vegetation” and “forest” in Southeast Asia demands further evidence to substantiate the existence of forests and grasslands. Pollen serves as a crucial proxy for reconstructing paleovegetation; however, pollen data from the central region of Southeast Asia, specifically the Indo-China Peninsula, are lacking for the LGM period. In this study, we present a new marine pollen record (core NS2007–8) from the western South China Sea, which provides insights into the paleovegetation of the eastern Indo-China Peninsula, including the drainage basins of the paleo-Mekong River and the paleo-Red River. These rivers encompass both ancient rivers on the exposed shelf and modern rivers. We establish a standard for savanna (C₄-rich grassland) by comparing modern pollen data from savanna sediments and soils in Africa and South America. Our findings indicate that Poaceae-dominant tropical grasslands experienced a rapid decline in the eastern Indo-China Peninsula during the broad LGM (28 ka BP – 17 ka BP), coinciding with the expansion of <em>Pinus</em> and evergreen <em>Quercus</em>-dominant lower montane rainforest and lowland rainforest. The abrupt reduction in herbaceous vegetation may further correlate with rapid events, such as rapid warm cycle between Heinrich events 1 and 2 (H1−H2), potentially corresponding to Dansgaard-Oeschger (D-O) event 2, which occurred near the onset of the LGM. Furthermore, by applying the established savanna standard, we find that the exposed northern Sundaland during the LGM supported an incomplete savanna mixed forest, resulting in a landscape characterized by forest-seasonal savanna mosaics. These findings provide support for the concepts of “forest” and “mosaic vegetation”, challenging the hypothesis of “savanna corridors”.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"252 ","pages":"Article 104871"},"PeriodicalIF":4.0,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144089561","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":"Deep-sea rare earth element-rich sediments: A review of distribution, carriers and petrogenesis","authors":"Yu Fu ,&nbsp;Zhengkun Li ,&nbsp;David Chew ,&nbsp;Pete Hollings ,&nbsp;Jinzhou Peng ,&nbsp;Jieyun Chen ,&nbsp;Bojue Tan ,&nbsp;Gaowen He ,&nbsp;Yongjia Liang ,&nbsp;Fei Huang ,&nbsp;Yayue Tang ,&nbsp;Rui Wang ,&nbsp;Dengfeng Li ,&nbsp;Xiaoming Sun","doi":"10.1016/j.gloplacha.2025.104870","DOIUrl":"10.1016/j.gloplacha.2025.104870","url":null,"abstract":"<div><div>Rare earth elements and yttrium (REY) enriched deep-sea sediments are promising mineral resources that are associated with apatite and Fe-Mn (hydro)oxides. With terrestrial REY resources dwindling, attention has shifted towards these essential elements within the deep-sea sediment. Here, we review existing literatures on the REY data from deep-sea sediments of all oceans. Based on the average REY content exceeding 700 μg/g, there are five major REY enrichment belts located in the Western, Central, Northeast, Southeast Pacific and the Central Indian Ocean, respectively. The water depth of five belts range from 3380 m to 5792 m, with the vast majority of depths exceeding 4000 m. The Western Pacific REY-rich layers mainly occurred at ∼5–6 m below seafloor (mbsf), with one to three REY-rich layers occurring in the topmost 10 mbsf. The deepest layer recognized in the Western Pacific occurred at around 171–172 mbsf. As such, this belt is probably the best-endowed REY-rich sedimentary region in the oceans. The REY contents of deep-sea sediment in Central Pacific are lower than that in Western Pacific, and most REY-rich layers extend to depths greater than 30 m. The Northeast Pacific REY-rich sediment lies within the Clarion-Clipperton Fault Zone (CCFZ), which is featured by Fe-Mn nodules in surface sediment and REY-rich sediment at greater depths. The REY-rich sediment in Southeast Pacific shows evidence of submarine hydrothermal origin with the depth of the layers varying significantly from 0.26 to 69.5 mbsf. The Central Indian Ocean exhibits similarities in REY content and thickness to the Pacific. The REY-rich sediment layers are shallow (mostly 0–5 mbsf) and occur near the surface of Central Indian Ocean Basin. Whereas, in the Wharton Basin, the layers tend to be deeper and are frequently found below 100 mbsf. Although the bioapatite, Fe-Mn (hydr)oxides, zeolites and clay minerals are the primary mineral components of REY-rich sediment, REY might be mainly hosted by apatite. Fe-Mn (hydro)oxide is a temporary carrier for REY that scavenges REY from seawater, and then transports REY to bioapatite during the early diagenesis. The genesis of these REY-rich deep-sea sediments can be traced to hydrogenetic, diagenetic and hydrothermal processes. Effective utilization of REY-rich deep-sea sediments requires systematic characterization of their spatial distribution, carrier phases, formation chronology and petrogenesis, as well as reconciling economic viability with ecological preservation.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"252 ","pages":"Article 104870"},"PeriodicalIF":4.0,"publicationDate":"2025-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143943131","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":"Study on typical dust aerosol transport processes and radiative effects in Central Asia using EOF decomposition","authors":"Ying Gan ,&nbsp;Zhe Zhang ,&nbsp;Yuechen Yang ,&nbsp;Yuxin Ren","doi":"10.1016/j.gloplacha.2025.104869","DOIUrl":"10.1016/j.gloplacha.2025.104869","url":null,"abstract":"<div><div>Dust aerosols in Central Asia significantly shape global climate change through their optical, microphysical, and radiative properties. This study uses MERRA-2 and CALIPSO data from 2007 to 2021 to examine the dust budget and vertical diffusion patterns via empirical orthogonal function (EOF) analysis. The clear sky aerosol radiative forcing (ADRF) of dust aerosol is also investigated to evaluate the performance of climate models. The research results indicate that specific dust source regions correspond to the primary pattern of dust activity in Central Asia. The spatial distribution of dust exhibits an east–west oscillation, while the temporal distribution displays an alternating annual cycle. The major sources of dust emissions include the southern margin of the Tarim Basin in Xinjiang, the Gobi Desert, and areas surrounding the Aral Sea. Dust activity over the Tarim Basin peaks in spring, with concentrations typically observed at altitudes between 2 and 6 km. In autumn, as dust spreads, its altitude gradually increases, reaching a maximum of 5–8 km<em>.</em> Under clear-sky conditions, dust aerosol direct radiative forcing rises steadily in spring but decreases through fall and winter, with a minimum of +0.90 W/m² in December. Under clear-sky conditions, seasonal net shortwave forcing at the top of the atmosphere and surface shows negative values, indicating a net cooling effect. In contrast, atmospheric shortwave ADRF and surface longwave ADRF exhibit positive values. These peak in spring at +6.10 W/m² and +1.40 W/m², respectively, and minimize in winter at +1.20 W/m² and +0.33 W/m².</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"252 ","pages":"Article 104869"},"PeriodicalIF":4.0,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143924890","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":"Impacts of climate extremes on variations in evergreen forest ecosystem carbon–water fluxes across Southern China","authors":"Wanqiu Xing ,&nbsp;Zhiyu Feng ,&nbsp;Jia Wei ,&nbsp;Shiqin Xu ,&nbsp;Quanxi Shao ,&nbsp;Weiguang Wang ,&nbsp;Xiaonan Shi","doi":"10.1016/j.gloplacha.2025.104867","DOIUrl":"10.1016/j.gloplacha.2025.104867","url":null,"abstract":"<div><div>Climate extremes exert detrimental influences on the water retention capacity and carbon sequestration functions of forest ecosystems. However, the response mechanisms of carbon–water cycles and their coupling relationships to climate extremes remain unclear. To address these issues, we investigated in an evergreen forest ecosystem located in Southern China, with comprehensive datasets and machine learning (ML) algorithms, where water–use efficiency (WUE) is defined as the ratio of gross primary production (GPP) to evapotranspiration (ET). The spatial–temporal distribution characteristics of GPP, ET, and WUE, as well as their responses to observed extreme weather events (torrential rains, drought, heat wave and cold wave) and climate extreme indices (CEIs) during 1979–2017 were investigated. We evaluated the accuracy of 8 types of ML algorithms in modelling observed GPP and ET, and the extreme gradient boosting model showed the best performance (GPP: R² = 0.91–0.98, ET: R² = 0.84–0.98). Regionally averaged annual values indicated significant increasing (<em>p</em> &lt; 0.01) trends for GPP (3.28 gC m⁻² a⁻²), ET (0.62 mm a⁻²), and WUE (0.0023 gC m⁻² mm⁻¹ a⁻¹), with mean annual values exhibiting a gradient increase from the northwest to southeast. Across the 21 CEIs, the precipitation–related indices showed positive correlations with GPP and ET, and the warm (cold)–related temperature indices showed positive (negative) correlations with these fluxes. These fluxes were more sensitive to torrential rains and cold wave, during which the response of ET was more immediate, while the negative impact of cold wave on GPP gradually intensified over time. As a result, WUE initially remained stable but then declined sharply during cold period. Overall, the carbon–water fluxes for evergreen forests on Southern China were most likely to exhibit high risk during cold events. Our findings provide valuable references for the response of evergreen forests to climate extremes.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"252 ","pages":"Article 104867"},"PeriodicalIF":4.0,"publicationDate":"2025-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143904593","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":"Accelerated Pleistocene exhumation and isostatic uplift along the Himalaya","authors":"Yi Wang ,&nbsp;Yang Wang ,&nbsp;Lindsay M. Schoenbohm ,&nbsp;Weitao Wang ,&nbsp;Matthew Fox ,&nbsp;Peizhen Zhang","doi":"10.1016/j.gloplacha.2025.104861","DOIUrl":"10.1016/j.gloplacha.2025.104861","url":null,"abstract":"<div><div>The Himalayan Mountains exhibit extreme topography, with the highest peaks and most incised rivers on earth. Rapid uplift, surface erosion and geomorphological changes have been taking place in the Himalaya throughout the late Cenozoic. Although the interactions among tectonics, climate, and surface erosion have been intensively studied over the past several decades, the landscape evolution and formation of extreme topography in the Himalaya are still unclear. Here, we present low-temperature thermochronology and thermal history modeling results that reveal the Makalu massif (∼87°E) in the central part of the Himalayan orogen may have experienced over 4 km of exhumation since 2 Ma. Combined with 1442 previously published cooling ages, we derive temporal and spatial variation in exhumation rates since 10 Ma for the entire Himalaya and reveal rapid cooling and exhumation since the Pleistocene. The isostatic response to this erosional unloading exhumation is quantified using a two-dimensional flexural model. Calculated results show that vertical uplift reached nearly 3200 m in the highest parts of the Himalaya orogen, suggesting that the isostatic response may play an important role in the building of relief and extreme topographic elevations since the Pleistocene.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"252 ","pages":"Article 104861"},"PeriodicalIF":4.0,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143912448","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":"Carbonate weathering-related carbon sink fluxes in Chinese Loess Plateau with rich carbonate content: Insights from three little catchments","authors":"Hailong Sun ,&nbsp;Mingyu Shao ,&nbsp;Zaihua Liu ,&nbsp;Chaowei Lai ,&nbsp;Zhen Ma ,&nbsp;Xuejun He ,&nbsp;Qinong Chai ,&nbsp;Yan Fang","doi":"10.1016/j.gloplacha.2025.104864","DOIUrl":"10.1016/j.gloplacha.2025.104864","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Continental rock weathering exerts negative feedback on global warming by removing atmospheric CO&lt;sub&gt;2&lt;/sub&gt;, with carbonate weathering being an important component of terrestrial carbon sinks. The fast kinetics of carbonate weathering leads the Chinese Loess Plateau (CLP), which is rich in carbonate minerals, to contribute greater HCO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;−&lt;/sup&gt; loads as the karst area. Therefore, carbonate weathering-related carbon sink fluxes (&lt;em&gt;CCSFs&lt;/em&gt;) in the CLP are of great significance to the global carbon cycle. However, few studies have focused on the CLP, and the variations, mechanisms, and accurate estimates of &lt;em&gt;CCSFs&lt;/em&gt; in loess areas with rich carbonate content remain unclear. To address this knowledge gap, we combined measurements of hydrochemistry (concentrations of HCO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;−&lt;/sup&gt;, SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2−&lt;/sup&gt;, Ca&lt;sup&gt;2+&lt;/sup&gt; and Mg&lt;sup&gt;2+&lt;/sup&gt;), isotopic composition (δ&lt;sup&gt;13&lt;/sup&gt;C&lt;sub&gt;DIC&lt;/sub&gt; and δ&lt;sup&gt;34&lt;/sup&gt;S-SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2−&lt;/sup&gt;), and theoretical models to elucidate the temporal variations in riverine hydrochemistry and their controlling mechanisms. Our study focused on the Hong, Wuli, and Bainiu Rivers in Xi'an city, located on the southern margin of the CLP, during the hydrological years from November 2020 to May 2022. Our results show that seasonal variations in HCO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;−&lt;/sup&gt; concentrations in the three spring-river systems presented chemostatic behavior, which is also found in the karst areas of South China. Therefore, the variation in runoff depth (river discharge) may play a more important role in controlling &lt;em&gt;CCSFs&lt;/em&gt; than variation in HCO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;−&lt;/sup&gt; for catchments in the CLP. The average concentrations of HCO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;−&lt;/sup&gt; in the spring sites of the Hong, Wuli, and Bainiu River catchments were 5.18 mmol/L, 6.2 mmol/L and 6.92 mmol/L, respectively, which are higher than the equilibrium concentrations of HCO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;−&lt;/sup&gt; at the local annual mean temperature of 13.1 °C under the given soil CO&lt;sub&gt;2&lt;/sub&gt; concentration. The higher HCO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;−&lt;/sup&gt; concentrations indicate that the HCO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;−&lt;/sup&gt; is derived not only from the dissolution of carbonate minerals by carbonic acid but also by strong weathering acids (H&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt; or HNO&lt;sub&gt;3&lt;/sub&gt;). After deducting the effect of strong acids, the net &lt;em&gt;CCSFs&lt;/em&gt; of Hong, Wuli, and Bainiuhe Rivers were estimated to be 5.03 t C km&lt;sup&gt;−2&lt;/sup&gt; a&lt;sup&gt;−1&lt;/sup&gt;, 4.61 t C km&lt;sup&gt;−2&lt;/sup&gt; a&lt;sup&gt;−1&lt;/sup&gt;, and 5.39 t C km&lt;sup&gt;−2&lt;/sup&gt; a&lt;sup&gt;−1&lt;/sup&gt;, respectively. Furthermore, we estimated that the CO&lt;sub&gt;2&lt;/sub&gt; consumption of major rivers originating from or flowing through the loess region of the world could reach approximately 2.09 × 10&lt;sup&gt;7&lt;/sup&gt; t C a&lt;sup&gt;−1&lt;/sup&gt;, accounting for 9.86 % of the total carbonate weathering-related carbon flux from rivers to the ocean. Considering the extensive global distribution of loess (approximately 6 % of the t","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"252 ","pages":"Article 104864"},"PeriodicalIF":4.0,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143924891","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":"Lithium isotope fractionation in Weinan loess and implications for pedogenic processes and groundwater impact","authors":"Mao-Yong He ,&nbsp;Ji-Bao Dong ,&nbsp;Xingxing Liu ,&nbsp;Shugang Kang ,&nbsp;Youbin Sun ,&nbsp;Li Deng ,&nbsp;Ning Zhang ,&nbsp;Xiaolin Zhang","doi":"10.1016/j.gloplacha.2025.104865","DOIUrl":"10.1016/j.gloplacha.2025.104865","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The water-rock interaction has a significant impact on reconstructing climatic and environmental changes using loess deposits. Lithium isotopes (δ&lt;sup&gt;7&lt;/sup&gt;Li) are important tracers to track this process. This study examined the Li contents and δ&lt;sup&gt;7&lt;/sup&gt;Li values of different phases (water, weak acid leachate and residue were recorded as [Li]&lt;sub&gt;water&lt;/sub&gt;, [Li]&lt;sub&gt;leachate&lt;/sub&gt;, [Li]&lt;sub&gt;residue&lt;/sub&gt;, δ&lt;sup&gt;&lt;strong&gt;7&lt;/strong&gt;&lt;/sup&gt;Li&lt;sub&gt;water&lt;/sub&gt;, δ&lt;sup&gt;&lt;strong&gt;7&lt;/strong&gt;&lt;/sup&gt;Li&lt;sub&gt;leachate&lt;/sub&gt; and δ&lt;sup&gt;&lt;strong&gt;7&lt;/strong&gt;&lt;/sup&gt;Li&lt;sub&gt;residue&lt;/sub&gt;) within the upper 22 m Weinan loess-paleosol sediment located on the southeastern margin of the Chinese Loess Plateau. Significant variations were observed in both the [Li] and δ&lt;sup&gt;7&lt;/sup&gt;Li values of different fractions within the loess. The water fraction samples have the lowest [Li]&lt;sub&gt;water&lt;/sub&gt; with less than 0.05 μg/g. The leachate samples show relatively low [Li]&lt;sub&gt;leachate&lt;/sub&gt; levels ranging from 0.67 μg/g to 2.45 μg/g. In comparison, the residue samples exhibit higher [Li] values than the leachate samples, with the concentrations varying from approximately 29.45 μg/g to 41.28 μg/g. The δ&lt;sup&gt;&lt;strong&gt;7&lt;/strong&gt;&lt;/sup&gt;Li&lt;sub&gt;water&lt;/sub&gt; values are all higher than those of the corresponding leachate and residue, ranging from 14.7 ‰ to 28.2 ‰. Additionally, the δ&lt;sup&gt;&lt;strong&gt;7&lt;/strong&gt;&lt;/sup&gt;Li&lt;sub&gt;water&lt;/sub&gt; values vary from −8.4 ‰ to 8.7 ‰. The δ&lt;sup&gt;7&lt;/sup&gt;Li of residue samples are relatively stable, ranging from −0.6 ‰ to 1.7 ‰, with an average δ&lt;sup&gt;&lt;strong&gt;7&lt;/strong&gt;&lt;/sup&gt;Li&lt;sub&gt;residue&lt;/sub&gt; = 0.5 ± 1.3 ‰. The results indicate that the [Li]&lt;sub&gt;leachate&lt;/sub&gt; in Weinan Loess-paleosol sediments has excellent potential to indicate the variations of East East Asian summer monsoons during the last glacial-interglacial cycle, compared to the values of grain size, magnetic susceptibility, and CaCO&lt;sub&gt;3&lt;/sub&gt; content. Meanwhile, the δ&lt;sup&gt;7&lt;/sup&gt;Li&lt;sub&gt;leachate&lt;/sub&gt; of loess not only can be utilized for tracing the pedogenic processes of weathering, eluviation, and migration, as well as for tracing groundwater impact. In the upper 15 m, the δ&lt;sup&gt;7&lt;/sup&gt;Li&lt;sub&gt;leachate&lt;/sub&gt; can be employed to track soil water migration processes and the magnitude of pedogenic processes in loess at various time periods. Below the calcium carbonate accumulation layer (CAA, &gt;15 m), there is groundwater, and CAA has impeded the flow of groundwater, making it difficult for the influence of groundwater to penetrate the CAA layer. Due to the prolonged exposure to capillary water, the acid-soluble phase lithium represents the lithium adsorbed by loess continuously absorbed from groundwater. δ&lt;sup&gt;&lt;strong&gt;7&lt;/strong&gt;&lt;/sup&gt;Li&lt;sub&gt;leachate&lt;/sub&gt; and δ&lt;sup&gt;&lt;strong&gt;7&lt;/strong&gt;&lt;/sup&gt;Li&lt;sub&gt;water&lt;/sub&gt; had basically reached equilibrium, with values of α ranging from 0.98 to 0.99 and an average value of α at 0.98. Our work thus shows that the δ&lt;sup&gt;&lt;strong&gt;7&lt;/strong&gt;&lt;/sup&gt;Li&lt;sub&gt;leachate&lt;/s","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"252 ","pages":"Article 104865"},"PeriodicalIF":4.0,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143907794","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":"Temperature dependent evaporite-sourced Li isotopic seasonality in the upper Yellow River","authors":"Long-Fei Gou ,&nbsp;Jiayuan Ren ,&nbsp;Zheng Chen ,&nbsp;Jianqi Man ,&nbsp;Wenqi Zhang ,&nbsp;Zhengjie Chen ,&nbsp;Jun Xiao ,&nbsp;Zhangdong Jin","doi":"10.1016/j.gloplacha.2025.104862","DOIUrl":"10.1016/j.gloplacha.2025.104862","url":null,"abstract":"<div><div>Silicate weathering sustains the habitability of the Earth via regulating atmospheric CO₂ concentrations and nutrient supply over geological time scales. So far, it lacks an effective tracer for silicate weathering. Riverine Li isotopes are proposed as a promising tracer as silicate weathering intensity, but the evaporite contribution to riverine Li⁺ remains poorly constrained, shaking its root as a such tracer. Here, we collected river water samples weekly at the Toudaoguai hydrological station at the end of the upper Yellow River to address this issue. We found that more than 80 % (up to 100 %) of riverine Li⁺ is sourced from evaporite dissolution within the upper Yellow River catchment, where distributed a large amount of salt lakes and old marine stratum. Even though, the seasonal variation in the riverine Li isotopes still supports that the long residence time in large rivers facilitates the low temperature Li isotopic fractionation and thus temperature dependency. The sources and isotopic variation of terrestrial Li⁺ input to oceans should therefore be carefully reevaluated.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"252 ","pages":"Article 104862"},"PeriodicalIF":4.0,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143916388","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}