Global and Planetary Change最新文献_第7页

From holocene to anthropogenic impact: Surpassing coral's pH up-regulation capacity under ocean acidification 从全新世到人为影响：在海洋酸化下超越珊瑚的pH上调能力

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2025-02-01 DOI: 10.1016/j.gloplacha.2024.104683

Huiling Kang , Xuefei Chen , Guangchao Deng , Jian-xin Zhao , Gangjian Wei

Corals' regulation of internal calcifying fluid (CF or cf) chemistry is crucial for their extraordinary calcification capacity, endowing them with a certain ability to cope with environmental changes such as anthropogenic ocean acidification (OA) and warming. However, it remains unclear whether the impacts of these changes on corals have substantially surpassed their regulation capacity, particularly in comparison to the CF chemistry responses to natural climate variability with minor or no human perturbation. In this study, we reconstructed the pH, dissolved inorganic carbon, and carbonate ion concentrations in coral CF (pH_cf, DIC_cf, and [CO₃²⁻]_cf) during the Mid- to Late-Holocene, by analyzing the skeletal δ¹¹B and B/Ca of 80 Porites spp. from eastern Hainan Island in the South China Sea (SCS). Our records indicate considerable inter-colony variations in CF chemistry, with maximum disparities reaching 0.18 units for pH_cf and 1664 μmol/kg for DIC_cf. With this in mind, we found no clear responses of coral DIC_cf to the climate fluctuations during the past ∼5500 years, nor evident differences in pH_cf and [CO₃²⁻]_cf across pre-industrial natural epochs. However, pH_cf and [CO₃²⁻]_cf of modern corals have significantly declined compared to fossil corals. Further analyzes compiling global data on Porites spp. also confirm this pronounced pH_cf decrease in modern corals, suggesting the limitations of pantropical corals to counteract OA by up-regulating pH_cf. Importantly, these fossil and modern corals reveal a clear long-term pH_cf descending trend parallel to atmospheric CO₂ changes, supporting the reliability of coral δ¹¹B in recording long-term changes in seawater pH (pH_sw).

珊瑚对内部钙化液（CF或CF）化学的调节对其非凡的钙化能力至关重要，使其具有一定的应对人为海洋酸化（OA）和变暖等环境变化的能力。然而，目前尚不清楚这些变化对珊瑚的影响是否大大超过了它们的调节能力，特别是与很少或没有人为扰动的CF化学对自然气候变化的反应相比。本文通过对南海海南岛东部80个Porites sp .的骨骼δ11B和B/Ca的分析，重建了中-晚全新世珊瑚CF （pHcf、DICcf和[CO32−]CF）的pH、溶解无机碳和碳酸盐离子浓度。我们的记录表明，菌落间的CF化学差异很大，pHcf的最大差异为0.18 μmol/kg， DICcf的最大差异为1664 μmol/kg。考虑到这一点，我们发现珊瑚DICcf在过去~ 5500年间对气候波动没有明确的响应，pHcf和[CO32−]cf在工业化前自然时期也没有明显的差异。然而，与化石珊瑚相比，现代珊瑚的pHcf和[CO32−]cf明显下降。进一步分析汇编的Porites spp.的全球数据也证实了现代珊瑚pHcf的显著下降，这表明泛热带珊瑚通过上调pHcf来抵消OA的局限性。重要的是，这些化石和现代珊瑚揭示了与大气CO2变化平行的pHcf长期下降趋势，支持了珊瑚δ11B记录海水pH （pHsw）长期变化的可靠性。

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引用次数: 0

Marine productivity controlled by oceanic circulation in the Northwest Pacific over the last glacial cycle 最后一次冰期旋回期间西北太平洋海洋环流控制的海洋生产力

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2025-02-01 DOI: 10.1016/j.gloplacha.2024.104686

Limin Hu , Hao Fang , Xuefa Shi , Yuying Zhang , Zhifei Duan , Chao Li , Jörg Lippold , Minoru Ikehara , Yiming Luo

The oceanic carbon cycles have a significant effect on the climate transitions by influencing the atmospheric CO₂ levels. As one of the largest carbon sinks, the Northwest Pacific is the key to understand how the carbon cycles react to past and future climate changes. In this study, the marine productivity in Northwest Pacific over the last 25,000 years has been comprehensively reconstructed using ²³⁰Th-normalized biogenic fluxes recorded in a series of sedimentary cores. Our results show contrasting onsets of productivity pulse between cores from the subarctic and the subtropical gyres, while both have been controlled by the nutrient supply related to ocean circulation. Specifically, the wind-driven southward shift of subarctic gyre combined with stronger East Asia winter monsoon during the Last Glacial Maximum and early deglaciation supplied more nutrients to the south and stimulated the subtropical productivity, while this process synchronously limited the subarctic productivity especially with downward extension of the North Pacific Intermediate Water (NPIW). The contraction of subarctic gyre associated with the collapse of the NPIW during the Bølling-Allerød generated the productivity pulse in subarctic region and lowered the subtropical productivity. Terrigenous inputs, reconstructed from ²³²Th fluxes, however, mainly affected the productivity in the subtropical gyre over the last glacial cycle, especially for the marginal region, in contrast to the pelagic subarctic gyre. Our findings reveal an interplay between subarctic and subtropical gyres and their integrated impacts on marine productivity, providing a paleoceanographic perspective to understand the carbon budget across different timescales in the Northwest Pacific.

海洋碳循环通过影响大气CO2水平对气候变化具有重要影响。作为最大的碳汇之一，西北太平洋是了解碳循环如何对过去和未来气候变化作出反应的关键。本文利用一系列沉积岩心记录的230度标准化生物源通量，对西北太平洋近25000年来的海洋生产力进行了全面重建。研究结果表明，亚北极和副热带环流核心区的生产力脉动出现了明显的差异，但两者都受到与海洋环流有关的养分供应的控制。具体而言，末次盛冰期和消冰期早期，亚北极环流的南移与东亚冬季风的增强相结合，为南方提供了更多的营养物质，促进了亚热带生产力的增长，但这一过程同时限制了亚北极生产力，特别是北太平洋中间水（NPIW）的向下延伸。在b ølling- allerd期间，亚北极环流的收缩和NPIW的崩溃产生了亚北极地区的生产力脉冲，降低了副热带生产力。然而，根据232Th通量重建的陆源输入主要影响了末次冰旋回期间副热带环流的生产力，特别是边缘区域的生产力，与远洋亚北极环流形成对比。我们的研究结果揭示了亚北极和亚热带环流之间的相互作用及其对海洋生产力的综合影响，为了解西北太平洋不同时间尺度的碳收支提供了古海洋学视角。

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引用次数: 0

About 868 cal. yr BP tsunami event at the northern South China Sea revealed from offshore sediments 南海北部近海沉积物揭示了约868 cal. yr BP海啸事件

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2025-02-01 DOI: 10.1016/j.gloplacha.2024.104685

Yuming Wang , Xiaohong Chen , Adam D. Switzer , Linlin Li , Yang Xu , Yukun Wang , Elaine Tan , Peizhen Zhang

The northern coast of the South China Sea (SCS) is a densely populated and economically important area. Despite the absence of any tsunamigenic events in the last century in this region, their occurrence on a much longer timescale remains largely unknown. Given the catastrophic consequences a potential tsunami event could bring, we aim to bridge this research gap by conducting high-resolution sedimentological, geochemical, and geochronological analyses on two well-preserved offshore sedimentary columns, B01 and D02, from the northern SCS, at depths of −27 and − 46 m, respectively. Using statistical methods, we identified two anomalous sediment units, each ∼30 to 40 cm thick, in both columns. These units are dominated by coarse-grained, poorly sorted sediments with a normally graded sequence. Each unit is rich in biogenic debris, devoid of parallel or cross-bedding, and has a unique set of elemental and isotopic signatures. They contain allochthonous biological species and record a disordered age-depth pattern. Such observations are indicative of the sudden input of marine components, suggesting an instantaneous high-energy event. The median calibrated ages, measured by accelerator mass spectrometry (AMS), from shell and foraminifera in the anomalous units, return the mixed ages of 4454–842 cal. yr BP and 2098–840 cal. yr BP, respectively. Shell and foraminifera above and below the anomalous units define AMS ¹⁴C ages of 951–779 cal. yr BP, with a median age of ∼868 cal. yr BP. Our data collectively point to a tsunami event at ∼868 cal. yr BP, equivalent to the North-Song Dynasty of ∼1000 years ago. This age pattern is consistent with reported tsunami events in and around the SCS, also compatible with historical accounts describing a “tidal overflow in Eastern Guangdong and Eastern Fujian at AD1067–1068” in Chinese documents. Combined with available data, the ca 868 cal. yr BP tsunami event in the SCS likely originated from the joint interaction of earthquakes induced by the Manila Subduction Zone and the Littoral Fault Zone, along with related landslide activities within the northern SCS.

南中国海（SCS）北岸是一个人口稠密、经济重要的地区。尽管该地区在上个世纪没有发生过任何海啸事件，但在更长的时间尺度上发生海啸的情况在很大程度上仍然是未知的。鉴于潜在海啸事件可能带来的灾难性后果，我们对南中国海北部水深分别为-27 米和-46 米的两个保存完好的近海沉积柱 B01 和 D02 进行了高分辨率沉积学、地球化学和地质年代分析，旨在弥补这一研究空白。利用统计方法，我们在这两个沉积柱中发现了两个异常沉积单元，每个单元的厚度在 30 至 40 厘米之间。这些单元以粗粒、分选差的沉积物为主，序列分级正常。每个单元都富含生物碎屑，没有平行或交叉层理，具有独特的元素和同位素特征。它们含有同生生物物种，并记录了无序的年龄-深度模式。这些观察结果表明海洋成分的突然输入，表明这是一个瞬时高能事件。通过加速器质谱法（AMS）测量异常单元中贝壳和有孔虫的校准年龄中值，得出的混合年龄分别为公元前 4454-842 年和公元前 2098-840 年。异常单元上下的贝壳和有孔虫确定的 AMS 14C 年龄为 951-779 大元前，中位年龄为 868 大元前。我们的数据共同表明，海啸发生在公元前 868 年，相当于距今 1000 年的北宋时期。这一年代模式与所报道的南中国海及其周边地区的海啸事件相吻合，也与中国文献中描述的 "公元1067-1068年粤东、闽东潮溢 "的历史记载相吻合。结合现有数据，约公元前 868 年发生在南中国海的海啸事件可能源于马尼拉俯冲带和沿岸断裂带诱发的地震的共同作用，以及南中国海北部的相关滑坡活动。

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引用次数: 0

Astronomically forced dynamics of Late Devonian (Famennian) sea level and biotic recovery in western Junggar, Northwest China 准噶尔西部晚泥盆世（法门世）海平面的天文强迫动态与生物恢复

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2025-02-01 DOI: 10.1016/j.gloplacha.2024.104677

Kunyuan Ma , Linda Hinnov , Zhihong Wang , Kai Wang , Ruiwen Zong , Xinsong Zhang , Junjun Song , Yang Bai , Yiming Gong

The Hongguleleng Formation in western Junggar, northwest China preserves a rich variety of fossils and was previously regarded as a “refugium” during the Late Devonian biotic crisis. Uncertainty in the age of the Hongguleleng Formation has persisted for a considerable time. In this study, cyclostratigraphic analysis was carried out on the Upper Devonian Bulongguoer and Wulankeshun sections from western Junggar, northwest China. Time series analysis and modeling of iron (Fe) concentration proxy data reveal variations with frequencies comparable to those of the Earth's long and short orbital eccentricity, obliquity, and precession index in both successions. Interpreted 405-kyr long orbital eccentricity cycles were used to establish floating astronomical time scales (FATs) for the two successions. From these FATs the depositional duration of the Hongguleleng Formation is calculated as 11.5 ± 0.58 Myr. The Devonian-Carboniferous boundary age of 359.3 ± 0.3 Ma was chosen as a time “anchor”, resulting in an astronomically determined age of 370.2 ± 0.66 Ma for the base of the Hongguleleng Formation. Combined with conodont biostratigraphy, this age indicates that the Hongguleleng Formation in western Junggar does not reach down to the Frasnian-Famennian boundary. Sedimentary noise modeling of the reconstructed Fe concentration time series provides an interpretation of sea-level variations in the Paleo-Asian Ocean controlled by astronomical forcing from very long orbital eccentricity cycles (g₄–g₃) throughout the Late Devonian period. Intensified monsoonal climates during these orbital eccentricity cycle maxima led to elevated terrigenous input and strengthened upwelling, which enhanced primary productivity in the western Junggar. We propose an “astronomical climate change” model as a driving mechanism that led to biotic recovery in the Famennian Hongguleleng Formation.

位于中国西北部准噶尔西部的红古楞地层保存了丰富的化石，曾被视为晚泥盆世生物危机时期的 "避难所"。红古楞地层的年代一直存在不确定性。本研究对中国西北准噶尔西部的上泥盆统布隆郭尔段和乌兰克顺段进行了旋回地层分析。通过对铁（Fe）浓度代用数据的时间序列分析和建模，发现这两个层位的变化频率与地球长短轨道偏心率、斜度和前向指数的变化频率相当。通过对 405 千年长轨道偏心率周期的解释，为两个演替建立了浮动天文时间尺度（FAT）。根据这些浮动天文时间尺度，计算出红古冷构造的沉积时间为 11.5 ± 0.58 Myr。泥盆纪-石炭纪的边界年龄为 359.3 ± 0.3 Ma，被选为时间 "锚"，从而得出红古楞地层底部的天文年龄为 370.2 ± 0.66 Ma。结合锥齿类生物地层学，这一年龄表明准噶尔西部的红古楞地层并没有到达新生代-新生代边界。通过对重建的铁元素浓度时间序列进行沉积噪音建模，可以解释整个晚泥盆世时期古亚洲洋的海平面变化受来自超长轨道偏心率周期（g4-g3）的天文作用的控制。在这些轨道偏心周期最大值期间，季风气候加剧，导致土著输入量增加，上升流增强，从而提高了准噶尔西部的初级生产力。我们提出的 "天文气候变化 "模型是导致法门寺红古楞地层生物恢复的驱动机制。

{"title":"Astronomically forced dynamics of Late Devonian (Famennian) sea level and biotic recovery in western Junggar, Northwest China","authors":"Kunyuan Ma , Linda Hinnov , Zhihong Wang , Kai Wang , Ruiwen Zong , Xinsong Zhang , Junjun Song , Yang Bai , Yiming Gong","doi":"10.1016/j.gloplacha.2024.104677","DOIUrl":"10.1016/j.gloplacha.2024.104677","url":null,"abstract":"<div><div>The Hongguleleng Formation in western Junggar, northwest China preserves a rich variety of fossils and was previously regarded as a “refugium” during the Late Devonian biotic crisis. Uncertainty in the age of the Hongguleleng Formation has persisted for a considerable time. In this study, cyclostratigraphic analysis was carried out on the Upper Devonian Bulongguoer and Wulankeshun sections from western Junggar, northwest China. Time series analysis and modeling of iron (Fe) concentration proxy data reveal variations with frequencies comparable to those of the Earth's long and short orbital eccentricity, obliquity, and precession index in both successions. Interpreted 405-kyr long orbital eccentricity cycles were used to establish floating astronomical time scales (FATs) for the two successions. From these FATs the depositional duration of the Hongguleleng Formation is calculated as 11.5 ± 0.58 Myr. The Devonian-Carboniferous boundary age of 359.3 ± 0.3 Ma was chosen as a time “anchor”, resulting in an astronomically determined age of 370.2 ± 0.66 Ma for the base of the Hongguleleng Formation. Combined with conodont biostratigraphy, this age indicates that the Hongguleleng Formation in western Junggar does not reach down to the Frasnian-Famennian boundary. Sedimentary noise modeling of the reconstructed Fe concentration time series provides an interpretation of sea-level variations in the Paleo-Asian Ocean controlled by astronomical forcing from very long orbital eccentricity cycles (<em>g</em><sub>4</sub>–<em>g</em><sub>3</sub>) throughout the Late Devonian period. Intensified monsoonal climates during these orbital eccentricity cycle maxima led to elevated terrigenous input and strengthened upwelling, which enhanced primary productivity in the western Junggar. We propose an “astronomical climate change” model as a driving mechanism that led to biotic recovery in the Famennian Hongguleleng Formation.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"245 ","pages":"Article 104677"},"PeriodicalIF":4.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142841257","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}

引用次数: 0

Sedimentary responses to climatic variations and Kuroshio intrusion into the northern South China Sea since the last deglaciation 末次冰期以来南海北部对气候变化和黑潮入侵的沉积响应

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2025-02-01 DOI: 10.1016/j.gloplacha.2024.104671

Chao Huang , Liyuan Wu , Jiansen Cheng , Xiaoxu Qu , Yongyi Luo , Huiling Zhang , Feng Ye , Gangjian Wei

The terrigenous sediment source-to-sink processes in marginal seas are governed by intricate interactions among climate, sea level, and ocean currents. The continental slope of the northern South China Sea (SCS) provides an excellent setting to examine these processes due to its substantial terrigenous influx and continuous sedimentation. In this study, we present a high-resolution sedimentary record from the northern SCS continental slope covering the last deglaciation. Analyses of Rare Earth Elements (REEs) and Sr–Nd isotopic compositions in the NH07 core indicate that the predominant source of terrigenous sediment was Taiwan. Grain size-standard deviation analysis identified two sensitive grain size components, with the sensitive component 2 used as a marker of the Kuroshio intrusion into the northern SCS through Luzon Strait. The intensity of the Kuroshio intrusion into the northern SCS was found to be inversely related to that of the open Pacific. The Asian monsoon and El Niño-Southern Oscillation (ENSO) significantly influenced the variability of the Kuroshio Current throughout the deglaciation period. During the interval 16, 000–11, 700 cal yr BP, variations in terrigenous influx were collectively driven by sea level changes and the intensity of the Kuroshio intrusion, while chemical weathering intensity was affected by the reworking of previously exposed shelf sediments due to sea level fluctuations. During the Holocene, however, the East Asian summer monsoon intensity became the primary factor influencing variations in terrigenous influx and chemical weathering.

边缘海的土著沉积物从源到汇过程受气候、海平面和洋流之间错综复杂的相互作用的支配。南中国海（SCS）北部的大陆坡因其大量的陆相沉积和持续的沉积作用，为研究这些过程提供了极佳的环境。在本研究中，我们展示了南中国海北部大陆坡涵盖末次脱冰期的高分辨率沉积记录。对NH07岩芯中稀土元素（REEs）和Sr-Nd同位素组成的分析表明，陆相沉积的主要来源是台湾。粒度标准偏差分析确定了两个敏感粒度分量，其中敏感分量 2 是黑潮通过吕宋海峡侵入南中国海北部的标志。研究发现，黑潮侵入南中国海北部的强度与开阔太平洋的强度成反比。亚洲季风和厄尔尼诺-南方涛动（ENSO）对黑潮在整个降冰期的变化有显著影响。在公元前16,000-11,700年期间，海平面变化和黑潮入侵强度共同驱动了土著涌入量的变化，而化学风化强度则受到海平面波动导致的先前裸露陆架沉积物再加工的影响。然而，在全新世期间，东亚夏季季风强度成为影响土著流入量和化学风化作用变化的主要因素。

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引用次数: 0

Testing and improving brGMGTs-based paleotemperature estimates in peat sediments: Evidence from global surface peat samples and two well-dated Holocene peat cores in far Northwest China 基于brgmgts的泥炭沉积物古温度估算的检验与改进：来自全球地表泥炭样品和中国西北远地区两个全新世泥炭岩心的证据

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2025-02-01 DOI: 10.1016/j.gloplacha.2025.104700

Zhongwei Shen , Minghua Zhao , Tianyan Lin , Xiaoxu Qu , Haichun Guo , Jiantao Cao , Guodong Jia , Zhiguo Rao

BrGMGTs (branched glycerol monoalkyl glycerol tetraethers) are proposed as potential proxies for temperature estimation due to their constrained and consistent biological origin. However, discrepancies observed between brGMGTs-based proxies and MAAT (mean annual air temperature) have raised concerns about their applicability. Here, we analyzed surface samples from three peatlands across China, and two well-dated Holocene peat cores. We found: 1) surface peat samples showed that %brGMGTs (abundance of brGMGTs relative to brGMGTs and brGDGTs; brGDGTs: branched glycerol dialkyl glycerol tetraethers) and H-MBT (methylation degree of brGMGTs) were ineffective to represent temperature. 2) Holocene records of %brGMGTs and H-MBT were uncorrelated with MBT’_5ME records (previously established as reliable temperature records) in the same cores, as well as with regional other proxy temperature records. Our data, along with the global peat dataset, indicated that brGMGTs are ineffective for temperature estimation under cold conditions (MAAT <10 °C). This ineffectiveness may be due to unfavorable temperature niches, changes in aerobic/anaerobic conditions and microbial communities. By setting a threshold (%brGMGTs >4 %), we found that H-MBT showed a higher positive correlation with MAAT (R² = 0.50, p < 0.01, n = 26), compared to all samples (R² = 0.47, p < 0.01, n = 72). Although this improvement in correlation is modest, it helps exclude samples with MAAT <10 °C. Our revised method for temperature estimation using brGMGTs could potentially be applied to peat sediments with MAAT ranging from 10 °C to 27 °C, enhancing their application for paleotemperature reconstruction in future research.

BrGMGTs（支链甘油单烷基甘油四醚）由于其受约束和一致的生物来源而被提出作为温度估计的潜在代理。然而，基于brgmgts的代用物与MAAT（年平均气温）之间观测到的差异引起了人们对其适用性的担忧。在这里，我们分析了来自中国三个泥炭地的地表样本，以及两个年代确定的全新世泥炭岩心。结果表明：1)表层泥炭样品中brGMGTs（相对于brGMGTs和brGMGTs的丰度）%；brGMGTs：支化甘油二烷基甘油四醚)和H-MBT （brGMGTs的甲基化程度）不能代表温度。2)全新世的% brgmgt和H-MBT记录与同一岩心的MBT’5ME记录（以前建立的可靠温度记录）以及区域其他代理温度记录不相关。我们的数据以及全球泥炭数据表明，在寒冷条件下（MAAT <10°C）， brGMGTs对温度估计无效。这种无效可能是由于不利的温度生态位，好氧/厌氧条件和微生物群落的变化。通过设置阈值（%brGMGTs > 4%），我们发现H-MBT与MAAT有较高的正相关(R2 = 0.50, p <；0.01, n = 26)，与所有样本相比(R2 = 0.47, p <；0.01, n = 72)。虽然这种相关性的改善是适度的，但它有助于排除MAAT <；10°C的样品。修正后的brGMGTs温度估算方法可应用于MAAT范围为10 ~ 27℃的泥炭沉积物，增强了其在未来研究中古温度重建的应用价值。

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引用次数: 0

Glacial-interglacial changes in Antarctic Intermediate Water advection in the Southeast Pacific during the last 787 kyr 过去787年东南太平洋南极中水平流的冰期-间冰期变化

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2025-02-01 DOI: 10.1016/j.gloplacha.2025.104695

Karol O. Duarte , Igor M. Venancio , Rodrigo A. Nascimento , Ana Luiza S. Albuquerque , Thiago P. Santos , Stefano Crivellari , Cristiano M. Chiessi , IODP Expedition 383 Shipboard Scientists

Southern-sourced intermediate waters play a central role in global ocean oxygenation and nutrient transport to low latitudes. However, the glacial-interglacial variability in their formation rate and geometry are not well constrained. Here we present a new ca. 787 thousand years-long benthic foraminifera stable carbon isotopic record from the Southeast Pacific, near the main formation region of Antarctic Intermediate Water (AAIW), which allows the investigation of changes in the formation rate and transport of AAIW over the last 787 kyr. Our results show glacial-interglacial changes in AAIW transport, with more AAIW being exported towards the Atlantic Ocean during interglacials, and to the low-latitude Pacific Ocean during glacials. We hypothesize that the AAIW exportation from the Pacific to the Atlantic Ocean is controlled by transport through the Drake Passage, which is reduced (increased) during glacial (interglacial) periods. The observed pattern is probably related to a combination of factors, including reduced (increased) sea-ice extent and southward (northward) shift of oceanic fronts and/or the westerlies during interglacials (glacials). Our mechanism reconciles the greater influence of AAIW in the northern Chilean margin during glacial periods, concurrent with the previously suggested decrease in formation rate and shallowing of this water mass. Ultimately, the glacial-interglacial variability in AAIW exportation to the Atlantic Ocean may be closely linked with changes in the stability of Atlantic Meridional Overturning Circulation during these distinct climate background states.

南源中间水在全球海洋含氧和向低纬度地区输送营养物质的过程中发挥着核心作用。然而，它们的形成速度和几何形状在冰川-冰川间的变化并没有得到很好的解释。在此，我们从南极中层水（AAIW）的主要形成区域附近的东南太平洋地区获得了长达约 78.7 万年的新的底栖有孔虫稳定碳同位素记录，从而可以研究过去 78.7 万年中南极中层水的形成速率和传输的变化。我们的研究结果显示了冰期-间冰期AAIW迁移的变化，在间冰期有更多的AAIW向大西洋输出，而在冰期则向低纬度太平洋输出。我们假设，从太平洋向大西洋输出的 AAIW 受控于通过德雷克海峡的传输，而在冰川期（间冰期），德雷克海峡的传输会减少（增加）。观测到的模式可能与多种因素有关，包括海冰范围缩小（增大）、大洋锋面和/或西风在间冰期南移（北移）。在冰川期，AAIW 对智利北部边缘的影响更大，与此同时，之前提出的该水团的形成率下降和变浅的情况也得到了调和。最终，冰川-间冰期向大西洋输出 AAIW 的变化可能与这些不同气候背景状态下大西洋经向翻转环流稳定性的变化密切相关。

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引用次数: 0

Changes in surface conditions and associated hypoxia since the late Marine Isotope Stage 3, eastern Arabian Sea

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2025-01-31 DOI: 10.1016/j.gloplacha.2025.104734

Jeet Majumder , Anil K. Gupta , Prasanta Sanyal , Rudra Narayan Mohanty

This study presents multiproxy record of benthic foraminiferal assemblages, relative abundances of planktic foraminifer Globigerina bulloides, stable isotope ratios in benthic foraminifer Uvigerina peregrina, and signature of pyritization from Core SK291/GC17, located at a water depth of 182 m in the eastern Arabian Sea (EAS). The sediment core covers an age from ∼40,000 to 3500 calibrated years before present (cal yr BP). Distinctly high abundance of G. bulloides, suggests strong upwelling and high productivity driven by intense Indian summer monsoon (ISM) winds in the EAS during ∼40,000–29,000 cal yr BP, corresponding to the late Marine Isotope Stage 3 (MIS3). As the sea level was lower than the recent time in the MIS3, closer proximity of the core to the coast aided high continental influx, which led to eutrophic, oxygen deficient condition at the sediment-water interface. This hypoxic condition is evident from the subjugation of oxic benthic foraminifera and their very low species diversity. Framboidal pyrite aggregates were observed during the MIS 3, suggesting iron-rich continental influx to the study core followed by pyritization in the anoxic environment. During the Last Glacial Maximum (LGM), a lower sea level and weak ISM caused relatively mesotrophic (and better oxygenated) condition over Core SK291/GC17. The extreme eutrophic and associated hypoxic condition in the late MIS 3 at Core SK291/GC17 was never experienced in the younger intervals, with G. bulloides percentages showing continuous decrease.

本研究介绍了位于东阿拉伯海（EAS）水深 182 米处的岩芯 SK291/GC17 中的底栖有孔虫组合、浮游有孔虫 Globigerina bulloides 的相对丰度、底栖有孔虫 Uvigerina peregrina 的稳定同位素比值以及黄铁矿化特征的多代理记录。该沉积物岩芯的年代为距今 ∼ 40,000 年至 3500 年（公元前）。G. bulloides 的明显高丰度表明，在公元前 4 万至 2.9 万卡年（相当于海洋同位素阶段 3（MIS3）晚期），东阿拉伯海在强烈的印度夏季季风（ISM）驱动下出现了强烈的上升流和高生产力。由于 MIS3 阶段的海平面低于近代，岩芯与海岸的距离更近，有助于大量大陆流入，从而导致沉积物-水界面的富营养化和缺氧状态。这种缺氧状态从含氧底栖有孔虫及其极低的物种多样性中可见一斑。在 MIS 3 期间，观察到褶皱黄铁矿聚集体，这表明富含铁的大陆物质流入研究岩芯，然后在缺氧环境中发生黄铁矿化。在末次冰川极盛时期（LGM），较低的海平面和较弱的 ISM 使岩心 SK291/GC17 处于相对中营养（含氧量较高）的状态。核心区 SK291/GC17 在 MIS 3 晚期的极度富营养化及相关缺氧条件在较年轻的区间从未经历过，G. bulloides 的百分比持续下降。

{"title":"Changes in surface conditions and associated hypoxia since the late Marine Isotope Stage 3, eastern Arabian Sea","authors":"Jeet Majumder , Anil K. Gupta , Prasanta Sanyal , Rudra Narayan Mohanty","doi":"10.1016/j.gloplacha.2025.104734","DOIUrl":"10.1016/j.gloplacha.2025.104734","url":null,"abstract":"<div><div>This study presents multiproxy record of benthic foraminiferal assemblages, relative abundances of planktic foraminifer <em>Globigerina bulloides</em>, stable isotope ratios in benthic foraminifer <em>Uvigerina peregrina</em>, and signature of pyritization from Core SK291/GC17, located at a water depth of 182 m in the eastern Arabian Sea (EAS). The sediment core covers an age from ∼40,000 to 3500 calibrated years before present (cal yr BP). Distinctly high abundance of <em>G. bulloides</em>, suggests strong upwelling and high productivity driven by intense Indian summer monsoon (ISM) winds in the EAS during ∼40,000–29,000 cal yr BP, corresponding to the late Marine Isotope Stage 3 (MIS3). As the sea level was lower than the recent time in the MIS3, closer proximity of the core to the coast aided high continental influx, which led to eutrophic, oxygen deficient condition at the sediment-water interface. This hypoxic condition is evident from the subjugation of oxic benthic foraminifera and their very low species diversity. Framboidal pyrite aggregates were observed during the MIS 3, suggesting iron-rich continental influx to the study core followed by pyritization in the anoxic environment. During the Last Glacial Maximum (LGM), a lower sea level and weak ISM caused relatively mesotrophic (and better oxygenated) condition over Core SK291/GC17. The extreme eutrophic and associated hypoxic condition in the late MIS 3 at Core SK291/GC17 was never experienced in the younger intervals, with <em>G. bulloides</em> percentages showing continuous decrease.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"246 ","pages":"Article 104734"},"PeriodicalIF":4.0,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143124536","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}

引用次数: 0

Significant contribution of groundwater to the basalt weathering flux in an inactive volcanic field: Evidence from radiogenic uranium isotope

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2025-01-29 DOI: 10.1016/j.gloplacha.2025.104728

Laifeng Li , Shenghui Ouyang , Gen K. Li , David William Hedding

Chemical weathering of basalt plays a vital role in the long-term carbon cycle and Earth's habitability. Quantifying the magnitude and controlling factors of basalt weathering requires assessing the contribution to weathering solutes from groundwater, which has remained challenging. In this work, we apply radiogenic uranium isotope activity ratios (²³⁴U/²³⁸U) to trace groundwater input to riverine weathering solutes in an inactive volcanic field from East China. Dissolved (²³⁴U/²³⁸U) is closely tied to the residence time of water bodies on the Earth's surface, allowing us to separate surface weathering solutes and groundwater characterized by distinct flow paths and residence time. We constrain the surface-weathering and groundwater end-members using hillslope-weathering solutes and spring waters, respectively. Based on the (²³⁴U/²³⁸U) ratios of the collected end-member samples, we developed a mass balance model and determined that groundwater contributes significantly to riverine solutes (∼41.5 %) but only has a minor contribution (∼10 %) to the water in man-made reservoirs in the study area. The estimated basalt weathering rates based on the alkalinity of river water may deviate from the global trend between basalt weathering rates and temperature if the contribution of groundwater is not corrected. Overall, our findings highlight the necessity to account for the influence of groundwater when estimating basalt weathering rates using river water, whereas man-made reservoirs may be less prone to groundwater inputs.

{"title":"Significant contribution of groundwater to the basalt weathering flux in an inactive volcanic field: Evidence from radiogenic uranium isotope","authors":"Laifeng Li , Shenghui Ouyang , Gen K. Li , David William Hedding","doi":"10.1016/j.gloplacha.2025.104728","DOIUrl":"10.1016/j.gloplacha.2025.104728","url":null,"abstract":"<div><div>Chemical weathering of basalt plays a vital role in the long-term carbon cycle and Earth's habitability. Quantifying the magnitude and controlling factors of basalt weathering requires assessing the contribution to weathering solutes from groundwater, which has remained challenging. In this work, we apply radiogenic uranium isotope activity ratios (<sup>234</sup>U/<sup>238</sup>U) to trace groundwater input to riverine weathering solutes in an inactive volcanic field from East China. Dissolved (<sup>234</sup>U/<sup>238</sup>U) is closely tied to the residence time of water bodies on the Earth's surface, allowing us to separate surface weathering solutes and groundwater characterized by distinct flow paths and residence time. We constrain the surface-weathering and groundwater end-members using hillslope-weathering solutes and spring waters, respectively. Based on the (<sup>234</sup>U/<sup>238</sup>U) ratios of the collected end-member samples, we developed a mass balance model and determined that groundwater contributes significantly to riverine solutes (∼41.5 %) but only has a minor contribution (∼10 %) to the water in man-made reservoirs in the study area. The estimated basalt weathering rates based on the alkalinity of river water may deviate from the global trend between basalt weathering rates and temperature if the contribution of groundwater is not corrected. Overall, our findings highlight the necessity to account for the influence of groundwater when estimating basalt weathering rates using river water, whereas man-made reservoirs may be less prone to groundwater inputs.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"246 ","pages":"Article 104728"},"PeriodicalIF":4.0,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143124541","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}

引用次数: 0

Size-fractionated C:N:P:Si stoichiometry of particulate matter in the subtropical Western North Pacific

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2025-01-28 DOI: 10.1016/j.gloplacha.2025.104732

Chaoyong Wang , Kan Zhang , Zhimian Cao , Kuanbo Zhou , Zhongwei Yuan , Junhui Chen , Yifan Ma , Bei Zhou , Xin Liu , Yihua Cai , Dalin Shi , Minhan Dai

Particulate C:N:P:Si ratios and their variations in the upper ocean are crucial for understanding carbon export and its coupling with nutrient dynamics and phytoplankton community composition associated with nutrient limitation. Here, we present the first dataset of size-fractionated biogenic particle concentrations and their elemental ratios, including particulate organic carbon (POC), particulate nitrogen (PN), particulate phosphorus (PP), and biogenic silica (BSi), in the upper 500 m of the water column in the subtropical western North Pacific. The highest POC, PN, and PP concentrations consistently occurred in surface water and then decreased with increasing depth, whereas BSi concentration was frequently highest in the subsurface chlorophyll maximum layer at ∼ 120 m. The small size fraction (SSF, 0.8 or 1–51 μm) dominated the total pool of POC, PN, and PP but contributed less to the total BSi pool than the large size fraction (LSF, >51 μm). This feature was accompanied by lower C:N, C:P, and N:P ratios and higher C:Si ratios in the SSF than in the LSF. In the euphotic zone, total particulate C:N, C:P, N:P, and C:Si ratios averaged 8 ± 1, 146 ± 30, 17 ± 3, and 120 ± 48 mol:mol respectively, and exceeded the canonical Redfield and Brzezinski ratio. The three former ratios aligned with cellular C:N:P ratios of Prochlorococcus and Synechococcus. Moreover, these ratios exhibited observable latitudinal gradients; they were generally higher in the gyre center than in its southern boundary occupied by the North Equatorial Current. Below the euphotic zone down to 500 m, there was a distinct increase in SSF molar C:N, C:P, and N:P ratios with depth, while total particulate molar C:Si ratios remained relatively constant. Combined with data collected in the subtropical eastern South Pacific and North Atlantic, our results demonstrate that the composition of the phytoplankton community primarily controls particulate molar C:N:P:Si stoichiometry in the euphotic zone of ocean gyres, in particular in the SSF, below which preferential remineralization of various bioelements plays an important role.

{"title":"Size-fractionated C:N:P:Si stoichiometry of particulate matter in the subtropical Western North Pacific","authors":"Chaoyong Wang , Kan Zhang , Zhimian Cao , Kuanbo Zhou , Zhongwei Yuan , Junhui Chen , Yifan Ma , Bei Zhou , Xin Liu , Yihua Cai , Dalin Shi , Minhan Dai","doi":"10.1016/j.gloplacha.2025.104732","DOIUrl":"10.1016/j.gloplacha.2025.104732","url":null,"abstract":"<div><div>Particulate C:N:P:Si ratios and their variations in the upper ocean are crucial for understanding carbon export and its coupling with nutrient dynamics and phytoplankton community composition associated with nutrient limitation. Here, we present the first dataset of size-fractionated biogenic particle concentrations and their elemental ratios, including particulate organic carbon (POC), particulate nitrogen (PN), particulate phosphorus (PP), and biogenic silica (BSi), in the upper 500 m of the water column in the subtropical western North Pacific. The highest POC, PN, and PP concentrations consistently occurred in surface water and then decreased with increasing depth, whereas BSi concentration was frequently highest in the subsurface chlorophyll maximum layer at ∼ 120 m. The small size fraction (SSF, 0.8 or 1–51 μm) dominated the total pool of POC, PN, and PP but contributed less to the total BSi pool than the large size fraction (LSF, >51 μm). This feature was accompanied by lower C:N, C:P, and N:P ratios and higher C:Si ratios in the SSF than in the LSF. In the euphotic zone, total particulate C:N, C:P, N:P, and C:Si ratios averaged 8 ± 1, 146 ± 30, 17 ± 3, and 120 ± 48 mol:mol respectively, and exceeded the canonical Redfield and Brzezinski ratio. The three former ratios aligned with cellular C:N:P ratios of <em>Prochlorococcus</em> and <em>Synechococcus</em>. Moreover, these ratios exhibited observable latitudinal gradients; they were generally higher in the gyre center than in its southern boundary occupied by the North Equatorial Current. Below the euphotic zone down to 500 m, there was a distinct increase in SSF molar C:N, C:P, and N:P ratios with depth, while total particulate molar C:Si ratios remained relatively constant. Combined with data collected in the subtropical eastern South Pacific and North Atlantic, our results demonstrate that the composition of the phytoplankton community primarily controls particulate molar C:N:P:Si stoichiometry in the euphotic zone of ocean gyres, in particular in the SSF, below which preferential remineralization of various bioelements plays an important role.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"246 ","pages":"Article 104732"},"PeriodicalIF":4.0,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143349945","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}

引用次数: 0