Global and Planetary Change最新文献_第7页

High-elevation Qilian Mountains and its inspiration for tectonics and biodiversity during the late Middle Miocene 高海拔祁连山及其对中新世晚期构造和生物多样性的启示

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2024-11-12 DOI: 10.1016/j.gloplacha.2024.104632

Yongheng Yang , Yunfa Miao , Xuelian Wang , Tao Zhang , Liwu Li

The accurate paleoelevation reconstruction of the Qilian Mountains is critical to advancing our understanding the integrity of the Tibetan Plateau (TP) uplift model, its deep structural mechanisms, and corresponding connections with climatic, environmental, and biodiversity changes. Recently, the first quantitative reconstruction of the paleomidrange (i.e., average elevation of the basin and mountains) of the northern Tibetan Plateau (NTP) was completed, using innovative palynological paleoaltimetry-TP/TPAP [(Tsuga% + Podocarpus%) / (Tsuga% + Podocarpus% + Abies% + Picea%)] ratios, which revealed a rapid uplift of the NTP from low to high elevations during the late Middle Miocene. Here, we analyzed the Ebotu Fauna pollen record (13–12 Ma) from the Hongyazi Basin, situated within the Qilian Mountains, to directly infer the paleoelevation of this region. The pollen assemblages were predominantly composed of conifers (average of 64.0 %), including Picea, Cedrus, and Pinus of the Pinaceae, as well as Cupressaceae, with broadleaves and steppes taxa each accounting for <15 %. This pollen composition evidently reflects a vegetation type dominated by high-mountain conifers forest, consistent with Middle Miocene pollen assemblages from the Qaidam Basin. Application TP/TPAP ratios yielded a paleomidrange of 3492 ± 87 m at 13–12 Ma. Combined with the known elevation of the Qaidam Basin during this period (1885 ± 566 m), the elevation of the Qilian Mountains was calculated to be 4338 ± 653 m. In turn, an elevation of 2646 ± 740 m was obtained for the Hongyazi Basin. This high-elevation terrain provides evidence to support the multi-stage convective removal model of the TP caused by crustal shortening and thickening. It also led to the formation of a humid ecosystem dominated by conifers forest in the Qilian Mountains, supporting the diversification of mammalian taxa.

准确重建祁连山的古海拔高度，对于推动我们理解青藏高原隆升模型的完整性、其深层构造机制以及与气候、环境和生物多样性变化的相应联系至关重要。最近，利用创新的古乐彩网学古海拔高度-TP/TPAP[（Tsuga% + Podocarpus%）/（Tsuga% + Podocarpus% + Abies% + Picea%）]比值，首次完成了青藏高原北部古海拔范围（即盆地和山脉的平均海拔）的定量重建，揭示了中新世晚期青藏高原北部从低海拔向高海拔的快速隆升。在此，我们分析了祁连山红崖子盆地的鄂博图动物群花粉记录（13-12 Ma），以直接推断该地区的古海拔高度。花粉组合主要由针叶树类（平均占 64.0%）组成，包括松科的松柏属、杉木属、松属以及濯缨松科，阔叶树类和草原类各占 15%。这种花粉组成明显反映了以高山针叶林为主的植被类型，与柴达木盆地的中新世花粉组合一致。应用TP/TPAP比率得出13-12Ma时的古海拔范围为3492 ± 87 m。结合这一时期柴达木盆地的已知海拔高度（1885 ± 566 米），计算出祁连山的海拔高度为 4338 ± 653 米。这种高海拔地形为地壳缩短和增厚导致的TP多级对流清除模型提供了证据支持。这也导致了祁连山针叶林为主的湿润生态系统的形成，为哺乳动物类群的多样化提供了支持。

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引用次数: 0

Widespread upper-ocean deoxygenation in the Alpine-Mediterranean Tethys during the Toarcian Oceanic Anoxic Event 托阿克洋缺氧事件期间阿尔卑斯-地中海特提斯大范围上层海洋脱氧

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2024-11-10 DOI: 10.1016/j.gloplacha.2024.104631

Wenhan Chen , David B. Kemp , Hugh C. Jenkyns , Stuart A. Robinson , Shouyi Jiang , Chengrong Pan , Chao Li

The early Toarcian (∼183 Ma) was characterized by pronounced climate warming associated with massive release of ¹³C-depleted carbon to the exogenic system, as evidenced by globally recognized negative carbon-isotope excursions (N-CIE) in biospheric carbon reservoirs. Global warming during this interval triggered a variety of environmental perturbations, of which large-scale marine deoxygenation (as indicated by the presence of widespread organic carbon-rich deposits) is arguably diagnostic and led to the naming of the interval in question as the Toarcian Oceanic Anoxic Event (T-OAE). Nevertheless, the spatial variability of water-column redox during the T-OAE is unclear because most sedimentological and geochemical methods used to infer marine redox are likely reflective of bottom-water and/or pore-water conditions. Here we report new I/(Ca + Mg) and Cerium (Ce)-anomaly data from two carbonate successions from northern Italy that encompass the T-OAE interval. Both successions were deposited in the Alpine-Mediterranean Tethys; one in a shallow-water platform setting and the other within a pelagic environment. Both successions record an abrupt drop in I/(Ca + Mg) values, coupled with positive excursions in Ce-anomaly records at the onset of the T-OAE N-CIE. The synchronized changes in marine iodate depletion and Ce enrichment suggest widespread and significant upper-ocean deoxygenation in the Alpine-Mediterranean Tethys. This redox pattern is attributed to an expanded oxygen minimum zone (OMZ) formed as a result of sluggish oceanic circulation under climate warming, augmented by enhanced dissolved oxygen consumption due to increased nutrient availability and the consequent eutrophication in both proximal and distal settings. Because reduced seawater dissolved oxygen [O₂] would increase the ecological stress and constrict any potentially hospitable habitats, the broad synchroneity between biotic turnovers and upper-ocean deoxygenation in the Alpine-Mediterranean Tethys is compatible with a potential causal link.

托阿尔早期（183 Ma ∼）的特点是气候明显变暖，同时向外源系统大量释放 13C 贫化碳，全球公认的生物圈碳库负碳同位素偏移（N-CIE）就是证明。在这一时期，全球变暖引发了各种环境扰动，其中大规模的海洋脱氧（如广泛存在的富含有机碳的沉积物所示）可以说是诊断性的，并导致将这一时期命名为托阿尔西元海洋缺氧事件（T-OAE）。然而，T-OAE 期间水柱氧化还原作用的空间变化尚不清楚，因为大多数用于推断海洋氧化还原作用的沉积学和地球化学方法可能反映的是底层水和/或孔隙水条件。在此，我们报告了来自意大利北部两个碳酸盐岩组的新的 I/（Ca + Mg）和铈（Ce）异常数据，这些数据涵盖了 T-OAE 时段。这两个演替都沉积在阿尔卑斯-地中海特提斯地区；一个在浅水平台环境中，另一个在浮游环境中。两个演替都记录了 I/（Ca + Mg）值的突然下降，同时在 T-OAE N-CIE 开始时，Ce-异常记录出现了正偏移。海洋碘酸盐耗竭和铈富集的同步变化表明，阿尔卑斯-地中海特提斯大范围的上层海洋严重脱氧。这种氧化还原模式是由于气候变暖导致大洋环流缓慢而形成的最小含氧区（OMZ）扩大，而营养物质供应的增加又加剧了溶解氧的消耗，从而导致近海和远海富营养化。由于海水溶解氧[O2]的减少会增加生态压力，并限制任何潜在的宜居生境，阿尔卑斯-地中海特提斯的生物转化与上层海洋脱氧之间的广泛同步性与潜在的因果关系相吻合。

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引用次数: 0

Nutrient changes from Zhoushan coastal upwelling fluctuations since 1900 and its implications for fisheries 1900 年以来舟山沿海上升流波动引起的营养物质变化及其对渔业的影响

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2024-11-09 DOI: 10.1016/j.gloplacha.2024.104630

Meiqun Xiao , Bing Deng , Guosen Zhang , Hui Wu , Yuanyuan Chen , Lijun Hou

This study aims to elucidate the environmental changes signified by biogenic components, assess fluctuations in upwelling over the past century, and evaluate the potential risks associated with variations in coastal upwelling intensity on the degradation of fisheries within the Zhoushan Fishing Ground. High-resolution sediment records were established to reveal long-term variations in Zhoushan coastal upwelling. Results showed a significant reduction in nutrient components between 1900s and 1950s, suggesting a decline in upwelling strength. Since the 1960s, lightened δ¹⁵N and the incline of nutrients suggests an increase in anthropogenic nutrients influx, and increased OP and CUI_SST (SST-based coastal upwelling index) indicates strengthening of upwelling during the 1950s to 1980s. A positive correlation between organic phosphorus (OP) and δ¹³C has been observed since the 1960s, implying that P is a limiting nutrient due to increasing anthropogenic N influx, and the change in CUI_SST coincides well with our OP records. OP is a potential indicator of upwelling strength because upwelling contributes to over 90 % of the P on the East China Sea shelf. A prominent decline in the nutrient composition occurred from the 1980s to 2010s, despite substantially increased anthropogenic nutrients influx and eutrophication in adjoining Changjiang delta regions in the past decades. Weakening upwelling and the consequent decreasing nutrients influx has presumably hindered recovery and thus contributed to the degradation of fishery resources in recent decades.

本研究旨在阐明生物成份所代表的环境变化，评估近一个世纪以来上升流的波动，并评估沿岸上升流强度变化对舟山渔场渔业退化的潜在风险。为揭示舟山沿岸上升流的长期变化，建立了高分辨率沉积物记录。结果表明，1900 年代至 1950 年代，营养成分明显减少，表明上升流强度下降。自 20 世纪 60 年代以来，δ15N 变浅和营养盐倾斜表明人为营养盐流入增加，而 OP 和 CUISST（基于 SST 的沿岸上升流指数）增加表明 20 世纪 50 年代至 80 年代上升流增强。自 20 世纪 60 年代以来，有机磷（OP）和δ13C 之间出现了正相关，这意味着由于人为营养盐流入量的增加，磷成为限制性营养盐，而 CUISST 的变化与我们的 OP 记录非常吻合。OP 是上升流强度的一个潜在指标，因为东海大陆架上 90% 以上的 P 来自于上升流。尽管过去几十年来长江三角洲邻近地区人为营养物质流入量和富营养化程度大幅增加，但从20世纪80年代到2010年代，营养物质组成出现了显著下降。近几十年来，上升流减弱以及随之而来的营养物质流入量减少可能阻碍了营养物质的恢复，从而导致渔业资源退化。

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引用次数: 0

Clustered slumping in the northern South China Sea: Implications for chronology and geohazards 中国南海北部的集群坍塌：对年代学和地质灾害的影响

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2024-11-08 DOI: 10.1016/j.gloplacha.2024.104623

Yin Lu , Ed L. Pope , Qiliang Sun , Michael Strasser

Seismic facies analysis is the most widely used method to identify event deposits from subaqueous environments. However, the internal structures of a chaotic or transparent seismic unit that represent event deposits are usually poorly imaged. This is primarily due to the limited resolution (usually <10 m) of commonly available multi-channel seismic reflection data. As a consequence, potential (sub)meter-thick, interbedded background sediments that may divide the chaotic layer cannot be discerned on such a seismic profile. The result of this, is that a complex of multiple moderate-thickness event layers can be misinterpreted as a single, thick event layer and this can greatly impact age-depth model reconstruction and geohazard assessment. One approach to resolve the problem is to correlate seismic data with high-resolution sediment core analysis. To address the problem in the South China Sea, we combine multiple methods to identify event deposits in the IODP holes U1499A and U1432C. Our dataset reveals that: (1) the previously interpreted ∼50 m-thick slumping unit in the region is a complex of multiple moderately sized units; (2) the slumping events are clustered between 0.6 and 0.4 Ma. Using our new understanding of event emplacement, we define event-free age models for mass wasting on the margin of the South China Sea, improving our understanding of local geohazards. Our methods here represent a sedimentological approach which could be used in other subaqueous environments to reconstruct event-free age models and geohazard histories.

地震剖面分析是用于识别水下环境事件沉积的最广泛方法。然而，代表事件沉积的混沌或透明地震单元的内部结构通常很难成像。这主要是由于常用的多道地震反射数据分辨率有限（通常为 10 米）。因此，在这种地震剖面图上无法辨别可能分割混沌层的（亚）米厚的夹层背景沉积物。其结果是，由多个中等厚度的事件层组成的复合层可能会被误解为单一的厚事件层，这会极大地影响年龄-深度模型的重建和地质灾害评估。解决这一问题的方法之一是将地震数据与高分辨率沉积岩芯分析相关联。为了解决南海的这一问题，我们结合多种方法来识别 IODP U1499A 和 U1432C 孔中的事件沉积。我们的数据集显示(1) 该地区以前解释的厚度为 50 米的坍塌单元是由多个中等大小的单元组成的复合体；(2) 坍塌事件集中在 0.6 至 0.4 Ma 之间。利用我们对事件置换的新认识，我们定义了南海边缘大规模侵蚀的无事件年龄模型，从而提高了我们对当地地质灾害的认识。我们的方法代表了一种沉积学方法，可用于其他水下环境，重建无事件年龄模型和地质灾害历史。

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引用次数: 0

Unraveling lead sources in a tropical urban Swamp Forest: Insights and challenges 揭示热带城市沼泽森林中的铅源：见解与挑战

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2024-11-08 DOI: 10.1016/j.gloplacha.2024.104629

Canh Tien Trinh Nguyen , Mengli Chen , Chris Gouramanis , Gonzalo Carrasco , Robert J. Wasson , Alan D. Ziegler

We investigate the contributions of natural (geogenic) and anthropogenic sources of lead (Pb) to the Nee Soon Swamp Forest, a relatively undisturbed catchment in Singapore. Using a Bayesian statistical source tracking approach with Pb isotopes preserved in sediment sections, our findings reveal a predominance of geogenic Pb in contemporary sediments, despite the significant presence of anthropogenic Pb in aerosols from local and distant sources. However, the geogenic Pb isotope signatures of the two main soil types in the catchment overlap with those of anthropogenic sources, introducing considerable uncertainty in using Pb isotopes as tracers within this catchment and potentially across larger areas. This uncertainty raises concerns about past interpretations of Pb contamination in both terrestrial and aquatic environments in Singapore and the broader region. To address these challenges, we emphasize the importance of accurately determining the signatures of all natural sources before using Pb isotopes as tracers in future studies. We also suggest that incorporating additional Pb isotope ratios or other stable isotope ratios (e.g., Ba, Cu, Sr, Zn) could enhance our ability to distinguish between natural and anthropogenic Pb sources. Ultimately, our study highlights the complexity of Pb sources in the environment and underscores the need for more comprehensive approaches to assessing their impacts.

Synopsis

This paper highlights insights and challenges in lead (Pb) source tracing studies conducted in urban catchments. These challenges primarily stem from the inadequate identification of all Pb isotope sources. We address these challenges by employing a Bayesian statistical approach to effectively identify, discriminate, and quantify Pb sources within a wetland ecosystem in Singapore.

我们调查了新加坡一个相对未受干扰的集水区--尼顺沼泽森林--的铅（Pb）的自然（地质）和人为来源。利用贝叶斯统计源追踪方法和沉积物切片中保存的铅同位素，我们的研究结果表明，尽管来自本地和远方的气溶胶中存在大量人为铅，但在当代沉积物中，地生铅占主导地位。然而，集水区两种主要土壤类型的地生铅同位素特征与人为来源的特征重叠，这给在该集水区以及可能在更大范围内使用铅同位素作为示踪剂带来了相当大的不确定性。这种不确定性引起了人们对新加坡及更广泛地区陆地和水生环境中铅污染的过去解释的担忧。为了应对这些挑战，我们强调在未来的研究中使用铅同位素作为示踪剂之前，准确确定所有自然来源特征的重要性。我们还建议，纳入更多的铅同位素比值或其他稳定同位素比值（如钡、铜、锶、锌）可提高我们区分自然和人为铅来源的能力。最终，我们的研究突出了环境中铅来源的复杂性，并强调了采用更全面的方法来评估其影响的必要性。这些挑战主要源于对所有铅同位素来源的识别不足。我们采用贝叶斯统计方法有效地识别、区分和量化了新加坡湿地生态系统中的铅源，从而应对了这些挑战。

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引用次数: 0

Quantitative contributions of different atmospheric circulation systems to Holocene aeolian activity in northwestern China: Evidence from a closed interdune lake in the Tengger Desert hinterland 不同大气环流系统对中国西北全新世风化活动的定量贡献：来自腾格里沙漠腹地封闭沙丘间湖泊的证据

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2024-11-07 DOI: 10.1016/j.gloplacha.2024.104621

Bing Liu , Yongtao Zhao , Aimin Liang , Aijun Sun , Zhengcai Zhang , Jianhui Ge , Hui Zhao , Fahu Chen

The aeolian deserts of northwestern China are major landscape types in the arid regions of the Northern Hemisphere, and collectively they are one of the largest dust source regions on Earth. However, owing to occurrence of sedimentary hiatuses within aeolian deposits in the deserts, we lack clear knowledge of the history of Holocene aeolian activity and the interaction between aeolian processes and their potential drivers. In this study, we extracted an environmentally sensitive grain-size component from the sediments of a closed interdune lake in the hinterland of the Tengger Desert. Our methodology included the application of End Member Analysis (EMA) of different modern sediment types from catchment to regional scales. We reconstructed aeolian activity over the past 13 cal ka BP and quantified the contributions of environmental factors. The results indicated that the EM 2 fraction of the interdune lake sediments is mainly transported by local winds and reflects changes in the intensity of aeolian activity. Based on EM 2 the strongest aeolian activity occurred during 13.0–7.0 cal ka BP, especially during 8.0–7.0 cal ka BP, and the weakest activity occurred during 7.0–3.5 cal ka BP. Aeolian activity increased after 3.5 cal ka BP, but with a gradually weakening trend. The occurrence of the weakest aeolian activity in the Tengger Desert during the Middle Holocene differs from that on the Asian Summer Monsoonal Boundary and in the area influenced by the Westerlies-dominated climate regime. Thus, there was a clearly defined spatio-temporal differentiation of Holocene aeolian activity across the deserts and dune fields of northern China. Quantitative analysis of the contributions of the potential drivers indicated that wind activity forced by different atmospheric circulation systems, rather than changes in vegetation cover, were the most important driver of regional aeolian activity, although their relative effects varied during the Holocene.

中国西北部的风化沙漠是北半球干旱地区的主要地貌类型，也是地球上最大的尘源区之一。然而，由于沙漠中的风化沉积出现了沉积间断，我们对全新世风化活动的历史以及风化过程与其潜在驱动因素之间的相互作用缺乏清晰的认识。在这项研究中，我们从腾格里沙漠腹地一个封闭沙丘间湖泊的沉积物中提取了对环境敏感的粒度成分。我们的研究方法包括从流域到区域尺度对不同的现代沉积物类型进行末端成分分析（EMA）。我们重建了过去 13 cal ka BP 的风化活动，并量化了环境因素的贡献。结果表明，沙丘间湖泊沉积物中的EM 2部分主要由当地风力搬运，反映了风化活动强度的变化。根据 EM 2，最强的风化活动发生在 13.0-7.0 cal ka BP，尤其是 8.0-7.0 cal ka BP，最弱的活动发生在 7.0-3.5 cal ka BP。风化活动在 3.5 cal ka BP 之后有所增加，但有逐渐减弱的趋势。中全新世时期腾格里沙漠的风化作用最弱，这与亚洲夏季季风边界和受西风带气候影响地区的情况不同。因此，全新世风化活动在华北沙漠和沙丘地带存在明显的时空分异。对潜在驱动因素贡献的定量分析表明，不同大气环流系统驱动的风活动，而不是植被变化，是区域风化活动的最重要驱动因素，尽管它们在全新世期间的相对影响各不相同。

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引用次数: 0

Can wood harvest followed by forest regrowth enhance carbon sequestration of the forest sector in China? 森林采伐后再生长能否提高中国林业部门的碳汇能力？

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2024-11-07 DOI: 10.1016/j.gloplacha.2024.104626

Mengyu Wang , Chao Yue , Junhao He , Pengyi Zhang , Mengyang Xu , Yu Li , Jiaming Wang , Lele Wang , Can Xu

Forest management policies play a crucial role in enhancing the carbon sequestration capacities of forests. China's current harvest-prohibitive policies may result in the development of old-growth forests and the eventual saturation of their carbon stocks. This study combines empirically derived forest biomass growth models, spatially explicit information on forest age and live biomass carbon stock, and life cycle analysis to explore whether wood harvesting followed by forest regrowth can enhance carbon sequestration in the forest sector for 2021–2060 in China, by accounting for carbon stock changes in both live biomass and harvested wood products (HWP). The results showed that the net effect of wood harvesting on carbon sequestration, compared to that without any harvesting, is crucially dependent on the half-life of HWP and, secondarily, on harvest intensity. The ‘no-harvest’ scenario will enable 9.58 Pg more carbon to be stored in the forest live biomass by 2060 compared to that in 2020. Wood harvesting under the current average half-life of HWP in China (12.5 years) will enhance the forest sector's capability to sequester carbon with a light harvest intensity and diminish it with an intensive harvest intensity. However, the carbon sequestration capacity of the forest sector would increase, irrespective of the harvest intensity, if the HWP half-life could be doubled (25 years) or even quadrupled (50 years). Our findings highlighted the potential positive role of wood harvesting in increasing the carbon sequestration capacity of the forest sector in China and provide useful perspectives for drafting national forest management policies.

森林管理政策在提高森林固碳能力方面发挥着至关重要的作用。中国目前的禁伐政策可能会导致老龄林的发展及其碳储量的最终饱和。本研究结合经验得出的森林生物量增长模型、森林年龄和活体生物量碳储量的空间显式信息以及生命周期分析，通过考虑活体生物量和伐木制品（HWP）的碳储量变化，探讨在 2021-2060 年期间，木材采伐后森林再生长能否提高中国森林部门的碳封存能力。研究结果表明，与不采伐相比，采伐木材对碳封存的净影响主要取决于伐木制品的半衰期，其次取决于采伐强度。与 2020 年相比，到 2060 年，"无采伐 "方案将使森林活生物质中的碳储存量增加 9.58 Pg。在中国目前的活立木平均半衰期（12.5 年）下采伐木材，轻度采伐强度将提高森林部门的碳封存能力，而密集采伐强度将降低碳封存能力。然而，无论采伐强度如何，如果 HWP 的半衰期能翻一番（25 年）甚至翻两番（50 年），林业部门的固碳能力都会提高。我们的研究结果凸显了木材采伐在提高中国林业固碳能力方面的潜在积极作用，并为起草国家森林管理政策提供了有益的视角。

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引用次数: 0

Multi-proxy reconstructions of paleotemperature in the southern South China Sea since the last deglaciation 末次冰期以来南海南部古温度的多代重建

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2024-11-07 DOI: 10.1016/j.gloplacha.2024.104620

Liping Tian , Yingxue Yang , Li Li, Yanming Ruan, Juan He, Guodong Jia

The accuracy of paleothermometers is a prerequisite for understanding the past sea surface temperature (SST) changes in the tropical seas. Here, we analyzed the SST estimates reconstructed by four lipid proxies with common linear and newly advanced models in parallel in a sediment core collected from the southern South China Sea (SCS). After excluding the impact of terrestrial input, all of the four proxies-inferred SSTs displayed a gradually warming pattern since 18.3 ka. Our long-chain alkenones-derived annual SST at seawater depth of 0–30 m (SST _{0–30 m}) record closely matched the regional synthetic SST record from the entire southern SCS, corresponding to high-latitude climate events during the deglaciation. The temperatures reconstructed by long-chain diols (LCDs) showed an upper limit of 27 °C, and we thus proposed that they reflected the optimal survival temperature for organisms producing LCDs when SST was higher than 27 °C. Isoprenoid and hydroxy glycerol dialkyl glycerol tetraethers (iGDGTs and OH-GDGTs)-derived temperatures likely reflected the subsurface temperature (subT) at seawater depth of 30–125 m and SST towards the warm season in the tropical sea, respectively.

古温度计的准确性是了解热带海洋过去海表温度（SST）变化的先决条件。在此，我们分析了在中国南海南部采集的沉积岩芯中，四种脂质代用指标用普通线性模型和新的先进模型平行重建的海表温度估算值。在排除陆地输入的影响后，四种代用指标推断的海温均显示出自18.3 ka以来逐渐变暖的模式。我们的长链烯酮推导出的海水深度0-30米的年海温（SST 0-30米）记录与整个南中国海南部的区域合成海温记录非常吻合，与脱冰期的高纬度气候事件相对应。长链二元醇（LCDs）重建的温度上限为27 °C，因此我们认为它们反映了当海温高于27 °C时产生长链二元醇的生物的最佳生存温度。异戊二烯和羟基甘油二烷基甘油四醚（iGDGTs和OH-GDGTs）重建的温度可能分别反映了30-125米海水深度的次表层温度（subT）和热带海洋暖季的SST。

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引用次数: 0

An improved instantaneous gross primary productivity model considering the difference in contributions of sunlit and shaded leaves to canopy sun-induced chlorophyll fluorescence 一种改进的瞬时总初级生产力模型，它考虑到了阳光照射叶片和阴影叶片对树冠阳光诱导的叶绿素荧光贡献的差异

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2024-11-05 DOI: 10.1016/j.gloplacha.2024.104627

Xiaoping Wang , Zhi Li , Fei Zhang

Sun-induced chlorophyll fluorescence (SIF) from plants offers an effective proxy for estimating gross primary productivity (GPP) by modeling SIF-GPP relationships, a widely used method to evaluate the global carbon sink. However, most SIF-GPP models ignore SIF differences between shaded and sunlit leaves, resulting in GPP underestimation, particularly in dense vegetation. This study aims to partition the contributions of sunlit and shaded leaves to canopy SIF and GPP to refine the SIF-GPP estimation model. Data from 40 eddy covariance (EC) sites representing eight major biomes and TROPOMI SIF satellite data were used for site-specific and global-scale analyses. Our results showed that the contributions of sunlit and shaded leaves to canopy SIF were 80 % and 20 %, and to canopy GPP were 55 % and 45 %, respectively. For site-specific or satellite data, the SIF-GPP relationships were the strongest for sunlit leaves (R² > 0.51, RMSE = 4.03 μmol m⁻² s⁻¹, p < 0.001). The new SIF-GPP model, including sunlit-shaded SIF separation, can improve the accuracy of GPP estimation (R² = 0.53, RMSE = 4.38 μmol m⁻² s⁻¹, p < 0.001). Compared with the model established with observed data, R² was increased by 0.1, and RMSE decreased by 13.26 μmol m⁻² s⁻¹, indicating that the ‘two-leaf’ model could notably improve the SIF-GPP model. This study confirms the different contributions of sunlit and shaded leaves to canopy SIF and GPP, and ignoring this disparity would induce systematic bias in GPP estimation. Our methods and findings on sunlit-shaded SIF separation can be referenced by other studies to enhance GPP estimation accuracy.

植物的太阳诱导叶绿素荧光（SIF）是通过模拟 SIF-GPP 关系估算总初级生产力（GPP）的有效替代物，这是一种广泛用于评估全球碳汇的方法。然而，大多数 SIF-GPP 模型都忽略了阴影叶片和阳光叶片之间的 SIF 差异，导致 GPP 被低估，尤其是在茂密植被中。本研究旨在区分日照叶和遮光叶对冠层 SIF 和 GPP 的贡献，以完善 SIF-GPP 估算模型。研究使用了代表八个主要生物群落的 40 个涡度协方差（EC）站点的数据和 TROPOMI SIF 卫星数据，进行站点和全球尺度分析。结果表明，阳光照射叶片和阴影叶片对冠层 SIF 的贡献率分别为 80% 和 20%，对冠层 GPP 的贡献率分别为 55% 和 45%。对于特定地点或卫星数据，阳光照射叶片的 SIF-GPP 关系最强（R2 > 0.51, RMSE = 4.03 μmol m-2 s-1, p <0.001）。新的 SIF-GPP 模型包括日照-阴影 SIF 分离，可提高 GPP 估计的准确性（R2 = 0.53，RMSE = 4.38 μmol m-2 s-1，p <0.001）。与利用观测数据建立的模型相比，R2 增加了 0.1，RMSE 减少了 13.26 μmol m-2 s-1，表明 "双叶 "模型能显著改善 SIF-GPP 模型。这项研究证实了日照叶片和遮光叶片对冠层 SIF 和 GPP 的贡献是不同的，忽视这种差异会导致 GPP 估算的系统性偏差。我们关于阳光-阴影 SIF 分离的方法和发现可供其他研究参考，以提高 GPP 估算的准确性。

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引用次数: 0

Ecosystem water limitation shifts driven by soil moisture in the Loess Plateau, China 中国黄土高原土壤水分导致的生态系统水分限制变化

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2024-11-05 DOI: 10.1016/j.gloplacha.2024.104625

Xiaoru Liang , Jianwu Yan , Wei Liang , Boyan Li , Xiaohong Liu , Fulai Feng , Jia Wei

In the context of climate change, the functionality of ecosystems is primarily influenced by the availability of water and energy supply. However, there is limited research that comprehensively uses energy indicators to explore how climate change affects the water and energy limiting states of ecosystems. Here we evaluated the historical and future water and energy limitations using the Ecosystem Limitation Index (ELI) derived from evapotranspiration (ET), soil moisture (SM), net radiation (Rn), and air temperature (Ta), and conducted an in-depth analysis of the dominant factors. The results indicate that: (1) The degree of water limitation deepened initially and then weakened. Over 68 % of the region became drier initially, while over 83 % became wetter later. (2) In terms of area, soil moisture emerged as a critical factor influencing the variations in water and energy constraints within the Loess Plateau. Further research revealed the range of critical soil moisture (CSM) for the transition of water-energy limitation state is 0.286 mm³mm⁻³, and it varies with changes in temperature, soil texture, vegetation cover, and season. (3) Future projections suggest a transition towards heightened water limitations across the Loess Plateau. These findings underscore the efficacy of ELI in assessing and predicting dynamic ecosystem changes, offering valuable insights into the impacts of climate change on water and energy cycles within semi-arid ecosystems.

在气候变化的背景下，生态系统的功能主要受水和能源供应的影响。然而，全面使用能源指标来探讨气候变化如何影响生态系统的水和能源限制状态的研究却很有限。在此，我们利用由蒸散量（ET）、土壤湿度（SM）、净辐射（Rn）和气温（Ta）得出的生态系统限制指数（ELI）对历史和未来的水和能量限制进行了评估，并对主导因素进行了深入分析。结果表明(1) 水分限制程度先加深后减弱。超过 68% 的区域最初变得较干，而超过 83% 的区域后来变得较湿。(2) 就面积而言，土壤湿度是影响黄土高原水和能量限制变化的关键因素。进一步研究发现，水能限制状态过渡的临界土壤湿度（CSM）范围为 0.286 mm3mm-3，它随温度、土壤质地、植被覆盖和季节的变化而变化。(3）未来预测表明，整个黄土高原的水限制将向加剧过渡。这些发现强调了 ELI 在评估和预测生态系统动态变化方面的功效，为了解气候变化对半干旱生态系统中水和能量循环的影响提供了宝贵的见解。

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引用次数: 0