Global and Planetary Change最新文献

{"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}

{"title":"Predicting the potential geographical distribution of peatlands in Northeast China based on the ensemble model","authors":"Haobo Wu ,&nbsp;Zhongsheng Zhang ,&nbsp;Zhenshan Xue ,&nbsp;Wenwen Zhao ,&nbsp;Luan Sang ,&nbsp;Haitao Wu ,&nbsp;Wenfeng Wang ,&nbsp;Qiang Guan ,&nbsp;Kangle Lu","doi":"10.1016/j.gloplacha.2025.104866","DOIUrl":"10.1016/j.gloplacha.2025.104866","url":null,"abstract":"<div><div>Peatlands are vital carbon sinks and unique ecosystems which are highly sensitive to global climate change. Predicting their spatial distribution under current and future climate scenarios is essential for effective conservation and management. In this study, we developed an ensemble model using multiple algorithms to predict the dynamic distribution of suitable peatland areas in Northeast China under current and future climate conditions. The ensemble model demonstrated strong performance, achieving Area Under the Curve (AUC) of 0.937 and True Skill Statistic (TSS) of 0.828. Our results indicate that the current suitable peatland area in Northeast China is 97,100 km². These areas are primarily located in the valleys and along the riverbanks of the Greater Khingan Mountain Region and the Changbai Mountains Region, with relatively fewer suitable areas in the Lesser Khingan Mountain Region and the Sanjiang Plain. Under future climate change, peatlands in Northeast China face a significant risk of degradation, especially under the high emission SSP585 scenario. Climate factors, especially the mean diurnal temperature range and the max temperature of the warmest month, have a significant impact on the distribution of suitable peatland areas. Additionally, factors such as soil pH, the freeze-thaw process, topography, and regional water retention capacity also play crucial roles in determining peatland suitability. Our findings provide an important foundation for better management and sustainable development of peatland resources.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"252 ","pages":"Article 104866"},"PeriodicalIF":4.0,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143900340","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":"Stability up until the end: Disruption, recovery and the latest Permian nitrogen cycle at Penglaitan, China","authors":"Shane D. Schoepfer ,&nbsp;Eldridge Machen II ,&nbsp;Hannah Cothren ,&nbsp;Lei Xiang ,&nbsp;Hua Zhang","doi":"10.1016/j.gloplacha.2025.104868","DOIUrl":"10.1016/j.gloplacha.2025.104868","url":null,"abstract":"<div><div>Negative organic sedimentary nitrogen isotope excursions are a common feature of sedimentary records spanning the end-Permian mass extinction (EPME). These excursions likely reflect global-scale perturbations of the marine nitrogen cycle. However, most EPME sections offer too little stratigraphic resolution to assess the timing, nature, and local ecological impacts of these disruptions. The Penglaitan Northern Bank section in Guangxi, China, offers an opportunity to explore the end-Permian nitrogen cycle in over 600 m of Changhsingian strata deposited in marginal marine environments of the Nanpanjiang Basin. The succession contains numerous volcanogenic sandstones and crystalline tuffs, defining a pattern of disruption and recovery on ecological timescales that can be compared to the more impactful biogeochemical changes associated with the EPME.</div><div>Organic carbon and nitrogen isotopes in the Penglaitan Northern Bank section are stable throughout the majority of the Changhsingian, with nitrogen isotope values consistent with a background ‘greenhouse’ climate nitrogen cycle. This stability in the nitrogen cycle is interrupted by the latest Permian transgression, beginning at 252.0 Ma. During the transgression, nitrogen isotope values become considerably more variable, ranging from negative values indicative of N fixation in an oligotrophic environment to more enriched values reflecting the incursion of anoxic, denitrifying waters. Nitrogen isotope values in the earliest Triassic stabilize, but remain lower than the Changhsingian baseline. The negative δ¹⁵N excursions seen in other sections globally likely represent condensed expressions of the more complex nitrogen cycle processes revealed at Penglaitan.</div><div>At Penglaitan, δ¹⁵N instability precedes the paleontologically defined extinction at the EPME and demonstrates that changes to marine biogeochemical cycles were diachronous with respect to local species extinctions, which may have been proximally driven by local volcanism and facies changes. While unstable nutrient cycles may have stressed marine ecosystems in the latest Changhsingian, they did not immediately push these communities beyond their ability to recover from episodic disturbance by volcanism.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"252 ","pages":"Article 104868"},"PeriodicalIF":4.0,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143900294","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":"The proportion of labile REEs in the river sediments serves as an index for silicate weathering intensity","authors":"Yulong Guo ,&nbsp;Yalong Li ,&nbsp;Shouye Yang","doi":"10.1016/j.gloplacha.2025.104863","DOIUrl":"10.1016/j.gloplacha.2025.104863","url":null,"abstract":"<div><div>Weathering indices derived from bulk sediment geochemistry are inevitably affected by inherited signatures from recycled sedimentary rocks. Therefore, characterizing and evaluating the impacts of sedimentary recycling becomes critically important. The proportion of labile REEs in river sediments holds promise in meeting this requirement. This is because the presence of labile REEs are primarily influenced by processes associated with present-cycle weathering, including the release of REEs through the dissolution of primary REE-bearing minerals, the formation of secondary minerals, and the simultaneous adsorption of REEs. Sediments from small catchments in Southeast China, featuring diverse climatic, geological settings, and weathering regimes, are utilized to establish and validate this potential weathering index.The chemical labile fractions of sediment samples were separated by 1 N HCl leaching. For sediments from catchments in Southeast mainland China, characterized by Mesozoic granitoid source rocks, the proportions of labile REEs are notably high, ranging from 32 % to 82 %, and show a significant positive correlation with CIA values. The main hosts for the labile REEs in these sediments are absorbed phase by clay minerals and/or Fe<img>Mn (hydro)oxides. In contrast, for sediments from the Zhuoshuixi catchment in Taiwan, which originate from recycled sedimentary and metasedimentary rocks, the proportions of labile REEs are much lower, around 8 %, and exhibit a negative correlation with CIA values. In these sediments, the dissolution of MREE-bearing minerals is likely the main source of labile REEs. Compared to weathering indices based on bulk sediment geochemistry, the proportion of labile REEs can indicate weathering intensity over a broader range of W/D values and can largely avoid interference from sedimentary recycling. Overall, our results reaffirm that earth surface processes, including chemical weathering and hydrodynamic sorting, may effect the REE distribution in the labile phase and even the bulk sediment. This factor must be fully considered when using REEs as sediment provenance tracers.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"252 ","pages":"Article 104863"},"PeriodicalIF":4.0,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143894702","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":"Benzo[ghi]fluoranthene and benz[a]anthracene as potentially useful wildfire temperature indicators","authors":"Leszek Marynowski ,&nbsp;Dorota Staneczek ,&nbsp;Maria Barbacka ,&nbsp;Grzegorz Pacyna","doi":"10.1016/j.gloplacha.2025.104846","DOIUrl":"10.1016/j.gloplacha.2025.104846","url":null,"abstract":"<div><div>Polycyclic aromatic hydrocarbons (PAHs), along with charcoal, are key indicators of wildfires in the geological record. This study explores the distribution of PAHs in charcoal and fusinite-rich sedimentary rocks from the Late Triassic and Early Jurassic periods. During the Upper Triassic, conifers were the main source of biomass for forest fires. In contrast, in the Lower Jurassic, almost all main plant groups could provide fuel for wildfires including lycopsids, horsetails, ferns, cycads, bennettitaleans, ginkgoaleans, and conifers. For the Upper Triassic, fire temperatures ranged widely from 272 °C to 742 °C, which includes ground, surface, and crown fires. Regarding the Lower Jurassic fires, the range of measured temperatures was smaller, from 251 °C to 451 °C, corresponding to ground and surface fires. As expected, the reflectance of fusinite correlates well with total organic carbon for charcoals (R² = 0.52) apart from a few outliers that lower the correlation. By analysing the correlation between the benzo[<em>ghi</em>]fluoranthene (B[<em>ghi</em>]Fl) to benz[<em>a</em>]anthracene (B[<em>a</em>]A) ratio and fusinite reflectance, a new method for estimating wildfire temperatures was developed. The B[<em>ghi</em>]Fl/(B[<em>ghi</em>]Fl + B[<em>a</em>]A) ratio exhibits a robust correlation (R² = 0.62) with fire temperatures calculated from fusinite reflectance. A novel formula for calculating wildfire temperatures was proposed, offering a valuable proxy complementary to fusinite reflectance. The results obtained are related to the higher thermal stability of B[<em>ghi</em>]Fl compared to B[<em>a</em>]A, making this ratio a reliable indicator of combustion temperature. The use of PAHs to determine the temperature of wildfires should be limited to unweathered rocks, as B[<em>a</em>]A is rapidly oxidised. Further research is needed to verify the application of this indicator in other sedimentary basins.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"252 ","pages":"Article 104846"},"PeriodicalIF":4.0,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143904592","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}