Continental Shelf Research最新文献

Assessing the conservation status of Mediterranean coastal ponds: Checklist, ecological and functional diversity of diatom communities 评估地中海沿岸池塘的保护状况：硅藻群落的清单、生态和功能多样性

IF 2.1 3区地球科学 Q2 OCEANOGRAPHY

Continental Shelf Research

Pub Date : 2024-11-14 DOI: 10.1016/j.csr.2024.105359

Davide Taurozzi , Massimiliano Scalici

Coastal ponds are peculiar and threatened habitats, considered biodiversity hotspots. In many ecosystems ponds can be a valuable resource for the conservation of freshwater biodiversity. The Castelporziano Presidential Estate is a Mediterranean protected area hosting numerous ponds which are suffering severe droughts and a general decline in number and hydroperiod length. Hydroperiod changes can be particularly relevant for biodiversity inhabiting ponds, in particular diatom communities. Here, for the first time, we evaluate the conservation status of Mediterranean ponds inside the Castelporziano Reserve. The aims of this research are to i) investigate the influence of environmental variables on diatom communities of ponds; (ii) analyse diatom community structure in function of species richness and competitive interactions; (iii) highlight the potential and effectiveness of diatom ecological guilds in supporting the interpretation of the ecological status of threatened small waterbodies. Overall, 122 diatom taxa in the 29 ponds were described. Nitzschia (18 species) was the most species-rich genus, followed by Gomphonema (14) and Navicula (13). 17 species were included in the Red List of endangered species. Intra-pond distance and anthropogenic impacts didn't influence diatom assemblages. On the contrary, diatom communities were influenced by altitude and the distance from the sea. Furthermore, temporary ponds showed the lowest values for Shannon, evenness and Simpson indexes Considering Beta-diversity, both Bray-Curtis and Jaccard dissimilarity matrices highlighted a large dissimilarity between sampling sites. Inter-variability between sites and intra-variability within the sites resulted both very low. Our results highlight that diatom species are not influenced by hydroperiod length. Moreover, a structured diatom community emerged, where segregation processes predominating over aggregation ones. Finally, the average water quality of the ponds, calculated using the EPI-D index, was described as “good”. This study represents the most complete checklist of diatom communities inside coastal ponds of Castelporziano, providing valuable insights into the effects of natural and anthropogenic influences on ponds conservation and management activities. However, spatial-temporal changes and anthropogenic impacts should be deeply investigated.

沿海池塘是一种奇特且濒临灭绝的栖息地，被视为生物多样性的热点。在许多生态系统中，池塘都是保护淡水生物多样性的宝贵资源。卡斯特波齐亚诺总统庄园是一个地中海保护区，这里有许多池塘，但由于严重干旱，池塘数量和水文周期长度普遍下降。水文周期的变化对栖息在池塘中的生物多样性尤其重要，特别是硅藻群落。在此，我们首次对卡斯特波齐亚诺保护区内地中海池塘的保护状况进行了评估。这项研究的目的是：(i) 调查环境变量对池塘硅藻群落的影响；(ii) 分析硅藻群落结构对物种丰富度和竞争性相互作用的作用；(iii) 强调硅藻生态区系在支持解释受威胁小水体生态状况方面的潜力和有效性。29 个池塘中共有 122 个硅藻分类群被描述。Nitzschia（18 种）是物种最丰富的属，其次是 Gomphonema（14 种）和 Navicula（13 种）。有 17 个物种被列入濒危物种红色名录。塘内距离和人为影响对硅藻群落没有影响。相反，硅藻群落受到海拔高度和离海距离的影响。考虑到 Beta 多样性，Bray-Curtis 和 Jaccard 差异矩阵都突出显示了采样点之间的巨大差异。取样点之间的差异和取样点内部的差异都非常小。我们的研究结果表明，硅藻物种不受水文周期长度的影响。此外，硅藻群落出现了结构化现象，其中分离过程比聚集过程占主导地位。最后，根据 EPI-D 指数计算，池塘的平均水质为 "良好"。这项研究是卡斯特波齐亚诺沿海池塘硅藻群落最完整的清单，为了解自然和人为因素对池塘保护和管理活动的影响提供了宝贵的信息。然而，时空变化和人为影响还需要深入研究。

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引用次数: 0

A century of tidal evolution around the Panama Canal 巴拿马运河周边一个世纪的潮汐演变

IF 2.1 3区地球科学 Q2 OCEANOGRAPHY

Continental Shelf Research

Pub Date : 2024-11-10 DOI: 10.1016/j.csr.2024.105357

Haidong Pan , Min Gan , Tengfei Xu , Zexun Wei

As one of the most vital passageways worldwide, the Panama Canal plays essential roles in global trade and maritime logistics. Sea levels around the Panama Canal are dominated by ocean tides but local tidal evolution is still unexplored to date, which motivates present study. Two secular tide gauges longer than 110 years (Cristobal and Balboa) around the Panama Canal are analyzed to explore multi-time scale tidal variability. It is found that observed nodal modulations of major constituents are generally consistent with the equilibrium tidal theory. M₄ and Mf nodal modulations notably deviate from the theory possibly due to non-linear processes. Long-term trends exist in main semi-diurnal tides, while main diurnal tides do not have significant secular trends. It is worth mentioning that M₄ and MS₄ amplitudes at Cristobal have halved in the past century. Moreover, tidal parameters of major constituents at Cristobal and Balboa show abnormal mutations in 1908, 1990–1998, and 2013–2018. As a result of changing tides, tidal asymmetries at Cristobal are significantly weakened while the number of high tides per year is notably decreased. Tides at Balboa are almost symmetric. Tidal regimes at Cristobal can periodically shift between mixed diurnal tides and mixed semi-diurnal tides following the 18.61-year nodal cycle. However, such regime shift has disappeared since 1997 due to secular negative trends in M₂ amplitudes. In general, the findings of this study can be helpful for ships navigating in the Panama Canal.

作为全球最重要的通道之一，巴拿马运河在全球贸易和海运物流中发挥着至关重要的作用。巴拿马运河附近的海平面主要受海洋潮汐的影响，但当地潮汐的演变至今仍未得到探索，这也是本研究的动机所在。本研究分析了巴拿马运河周围两个超过 110 年的常规验潮仪（克里斯托巴尔验潮仪和巴尔博亚验潮仪），以探索多时间尺度的潮汐变化。研究发现，观测到的主要成分的节点模态与平衡潮汐理论基本一致。M4 和 Mf 节点调制明显偏离理论，可能是由于非线性过程造成的。主半日潮存在长期趋势，而主日潮没有明显的世俗趋势。值得一提的是，克里斯托巴尔的 M4 和 MS4 振幅在上个世纪减小了一半。此外，克里斯托巴尔和巴尔博亚主要成分的潮汐参数在 1908 年、1990-1998 年和 2013-2018 年出现异常突变。由于潮汐的变化，克里斯托巴尔的潮汐不对称性明显减弱，同时每年的高潮次数显著减少。巴尔博亚的潮汐几乎是对称的。克里斯托巴尔的潮汐系统会根据 18.61 年的交点周期在混合日潮和混合半日潮之间周期性地转换。然而，自 1997 年以来，由于 M2 振幅的长期负值趋势，这种潮汐机制的转变已经消失。总之，这项研究的结果对在巴拿马运河航行的船只很有帮助。

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引用次数: 0

Flow characterization and turbulence in the eastern section of the Strait of Magellan, Southern Chile 智利南部麦哲伦海峡东段的水流特征和湍流情况

IF 2.1 3区地球科学 Q2 OCEANOGRAPHY

Continental Shelf Research

Pub Date : 2024-11-09 DOI: 10.1016/j.csr.2024.105344

Leandro Suarez , Maricarmen Guerra , Megan E. Williams , Cristián Escauriaza , Iossif Lozovatsky , Ronald Coppersmith , Harindra Joseph S. Fernando

The Strait of Magellan connects the Pacific and Atlantic oceans in South America’s southern region, and it has been recognized for centuries as an important transoceanic navigation route as well as a unique marine environment with a rich ecological diversity. Evaluations of the impact of human activities in the channel and multiple potential future developments require a better understanding of the physical environment to design sustainable strategies aimed at preserving these characteristics. In this investigation, we study the flow near the Atlantic inlet of the Strait where the dynamics is characterized by the interactions of the tide propagation within two narrows, which are the predominant features of the channel morphology. Tides amplified by the Patagonian shelf generate strong currents through these narrows and control the exchange between the Atlantic and central regions of the Strait. We employ bottom-mounted and vessel-mounted Acoustic Doppler Current Profilers (ADCPs) with tide gauges to analyze the mean flow, tidal propagation, and turbulence, complementing the data with previous available measurements. The analysis reveals residual flows directed toward ebb flow at the channel center and flood near the edges, showing a significant spring-neap variation. Turbulence statistics in the second narrows exhibit a significant variability between ebb and flood, with a balance between production and dissipation observed only during ebb phases.

麦哲伦海峡位于南美洲南部地区，连接太平洋和大西洋，数百年来一直被认为是重要的跨洋航道，也是具有丰富生态多样性的独特海洋环境。要评估人类活动对航道的影响以及未来的多种潜在发展，就必须更好地了解物理环境，以设计旨在保护这些特征的可持续战略。在这项调查中，我们研究了海峡大西洋入口附近的水流，其动态特征是潮汐在两个狭长地带内传播的相互作用，这是海峡形态的主要特征。经巴塔哥尼亚大陆架放大的潮汐通过这些狭窄处产生强大的水流，控制着海峡大西洋和中部地区之间的水流交换。我们利用安装在海底和船上的声学多普勒海流剖面仪（ADCP）和验潮仪来分析平均流、潮汐传播和湍流，并将这些数据与之前的测量数据进行补充。分析结果显示，残余水流在水道中心为退潮流，在边缘为洪峰流，显示出显著的春-夏变化。第二窄河道的湍流统计在退潮和洪水之间表现出明显的变化，只有在退潮阶段才能观察到产生和消散之间的平衡。

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引用次数: 0

Machine learning reveals biological activities as the dominant factor in controlling deoxygenation in the South Yellow Sea 机器学习揭示生物活动是控制南黄海脱氧的主导因素

IF 2.1 3区地球科学 Q2 OCEANOGRAPHY

Continental Shelf Research

Pub Date : 2024-11-07 DOI: 10.1016/j.csr.2024.105348

Qingyi Liu , Chunli Liu , Qicheng Meng , Bei Su , Haijun Ye , Bingzhang Chen , Wei Li , Xinyu Cao , Wenlong Nie , Nina Ma

Dissolved oxygen (DO) is a crucial element for both biotic and abiotic processes in marine ecosystems, but has declined globally in recent decades. Therefore, there is an urgent need for solid large-scale and continuous estimation of DO concentration in vital ecosystems, such as coastal areas. A random forest (RF) model for DO in South Yellow Sea (SYS) was developed by integrating satellite data and simulation data during 2011–2019. The root mean squared error (RMSE) for the training and test sets were 0.514 mg/L and 0.732 mg/L, respectively. Spatiotemporal distributions of DO of multiple layers in the study area during 2011–2019 were very well reproduced by the RF model and showed a slight decline trend in most SYS areas, while more intense decline occurred in the deep central SYS. The analysis of the mechanisms of DO decline in the South Yellow Sea cold water mass (SYSCWM), located in the deep central SYS, indicates that the deoxygenation here is largely due to biological activities. This finding may have implications for studies on drivers of deoxygenation in coastal areas. Furthermore, integrating satellite data with machine learning models can offer a powerful approach to capturing the continuous spatiotemporal characteristics of ocean parameters over large spatial scales.

溶解氧（DO）是海洋生态系统中生物和非生物过程的关键元素，但近几十年来，全球溶解氧浓度都在下降。因此，迫切需要对沿海地区等重要生态系统的溶解氧浓度进行大规模、连续的可靠估算。通过整合 2011-2019 年期间的卫星数据和模拟数据，建立了南黄海溶解氧随机森林（RF）模型。训练集和测试集的均方根误差（RMSE）分别为 0.514 mg/L 和 0.732 mg/L。射频模型很好地再现了 2011-2019 年期间研究区多层溶解氧的时空分布，大部分 SYS 区域的溶解氧呈轻微下降趋势，而中部深层 SYS 区域的溶解氧下降更为剧烈。对位于 SYS 中部深层的南黄海冷水团溶解氧下降机理的分析表明，这里的脱氧主要是由生物活动引起的。这一发现可能会对沿岸地区脱氧驱动因素的研究产生影响。此外，将卫星数据与机器学习模型相结合，可以为捕捉大空间尺度上海洋参数的连续时空特征提供一种强有力的方法。

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引用次数: 0

Echoes of a Cold War 冷战的回声

IF 2.1 3区地球科学 Q2 OCEANOGRAPHY

Continental Shelf Research

Pub Date : 2024-11-06 DOI: 10.1016/j.csr.2024.105347

Valeriy Y. Rusakov , Ruslan A. Lukmanov , Bulat R. Soktoev , Andrey Y. Mishan'kin

The Kara Sea was an area of radionuclide contamination as a result of nuclear weapons testing, since it is located in close proximity to the nuclear test site on the Novaya Zemlya archipelago. The vertical distribution of ¹³⁷Cs and ²¹⁰Pb in 15 sediment cores from the sea made it possible to reconstruct the chronology of ¹³⁷Cs entry into marine sediments. The reconstruction was based on the age-depth model RUS2023 (Rusakov et al., 2024) for ²¹⁰Pb_ex, taking into account the grain-size composition and sorption capacity of sediments. Our study showed that higher ¹³⁷Cs concentrations in sediments of the Novaya Zemlya Trough correspond to the time of active nuclear weapons testing in 1961–63 (about 9.0 ± 1.6 Bq kg^‒1), as well as in estuarine sediments of the Yenisei Bay in 1986 (85.2 ± 3.2 Bq kg^‒1). The abnormally high flux in 1980s represents the superposition of ¹³⁷Cs fluxes as a result of global fallout (Chernobyl trace) and as a result of the release of radionuclide from regional source located in the Yenisei River catchment. Both of these events are associated with increased the sedimentation and mass accumulation rates of marine sediments. In 1961‒63, this was a consequence of the release of sediment into the atmosphere due to nuclear explosions, and in the 1980s, as a result of an increase in sediment supply with river runoff. Currently, against the backdrop of a decrease in sediment fluxes into the sea, Novaya Zemlya and Yenisei River remain the main sources of ¹³⁷Cs supply to marine sediments. Background values for recent sediments in the Kara Sea are <2.0 Bq kg^‒1.

卡拉海是核武器试验造成放射性核素污染的地区，因为它毗邻新泽姆利亚群岛上的核试验场。根据该海域 15 个沉积岩芯中 137Cs 和 210Pb 的垂直分布情况，可以重建 137Cs 进入海洋沉积物的时间顺序。重建是基于 210Pbex 的年龄深度模型 RUS2023（Rusakov 等人，2024 年），并考虑了沉积物的粒度组成和吸附能力。我们的研究表明，新泽姆利亚海槽沉积物中较高的 137Cs 浓度与 1961-63 年核武器试验活跃时期（约 9.0 ± 1.6 Bq kg-1）以及 1986 年叶尼塞湾河口沉积物中较高的 137Cs 浓度（85.2 ± 3.2 Bq kg-1）相对应。20 世纪 80 年代异常高的通量是 137Cs 通量的叠加，它是全球尘降（切尔诺贝利痕量）的结果，也是位于叶尼塞河流域的区域源释放放射性核素的结果。这两个事件都与海洋沉积物的沉积和堆积速度加快有关。1961-63 年，这是核爆炸导致沉积物释放到大气中的结果；20 世纪 80 年代，则是河流径流导致沉积物供应增加的结果。目前，在入海沉积物通量减少的背景下，新谢姆利亚和叶尼塞河仍然是海洋沉积物中 137Cs 的主要供应来源。喀拉海近期沉积物的背景值为 2.0 Bq kg-1。

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引用次数: 0

Storms can increase beach resilience on a low-energy coast in the proximity of a harbor 风暴可增强港口附近低能量海岸的海滩复原力

IF 2.1 3区地球科学 Q2 OCEANOGRAPHY

Continental Shelf Research

Pub Date : 2024-11-01 DOI: 10.1016/j.csr.2024.105343

Gabriela Medellín , Gemma L. Franklin , Alec Torres-Freyermuth

Storms drive energetic waves and induce high water levels on the nearshore. Hence, they are commonly associated with negative effects on the coast (i.e., beach erosion and coastal flooding). Beach resilience, the capability to resist and recover from storms, relies on the beach width and elevation. This study investigates the subaerial beach morphological response to storms on a micro-tidal, low-energy tropical beach located in the proximity of a harbor. The study area, situated on a barrier island on the northwestern coast of the Yucatan Peninsula, is prone to winter, tropical, and local storms. Beach surveys were carried out over the 2015–2023 period, with a high spatial and temporal resolution, along a 4-km stretch of coast, comprising beach transects located downstream (erosive beach) and upstream (accretive and stable beach) of the harbor jetties. Moreover, offshore wave conditions and water levels were measured to identify storm events. Pre- and post-storm beach surveys are employed to estimate beach geoindicators to assess the impact of 66 storms. Consistent with prior studies, field observations suggest that the beach response (accretive or erosive) is dependent on the water level and pre-storm beach morphology. Furthermore, a net subaerial sediment volume gain, correlated with seasonal changes on the dimensionless fall velocity parameter and water level, occurs during the winter storm season on the prograding/stable beach section. On the other hand, storms induced subaerial sand volume losses on the receding beach section exposed to the same forcing conditions. Thus, our observations suggest that moderate winter and tropical storms can contribute to increasing beach resilience in this region.

暴风雨会掀起高能波浪，导致近岸水位升高。因此，风暴通常会对海岸造成负面影响（如海滩侵蚀和海岸洪水）。海滩的恢复能力，即抵御风暴和从风暴中恢复的能力，取决于海滩的宽度和海拔。本研究调查了位于港口附近的微潮汐、低能量热带海滩上的海滩形态对风暴的响应。研究区域位于尤卡坦半岛西北海岸的一个屏障岛上，冬季易受热带风暴和局部风暴的影响。在 2015-2023 年期间，以较高的空间和时间分辨率，沿着 4 公里长的海岸线进行了海滩调查，包括位于港口码头下游（侵蚀海滩）和上游（增生和稳定海滩）的海滩横断面。此外，还测量了近海波浪状况和水位，以确定风暴事件。风暴前和风暴后的海滩调查用于估算海滩地质指标，以评估 66 次风暴的影响。与之前的研究一致，实地观察表明，海滩反应（增生或侵蚀）取决于水位和风暴前的海滩形态。此外，在冬季风暴季节，前进/稳定的海滩地段会出现海下沉积物量净增加，这与无量纲下降速度参数和水位的季节性变化相关。另一方面，在相同的受力条件下，风暴会导致沙滩后退区段的海沙量减少。因此，我们的观测结果表明，适度的冬季风暴和热带风暴有助于提高该地区海滩的恢复能力。

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引用次数: 0

The Dnipro-Buh plume: A tale of high-volume freshwater discharge in a non-tidal sea 第聂伯河-布赫河羽流：非潮汐海域大量淡水排放的故事

IF 2.1 3区地球科学 Q2 OCEANOGRAPHY

Continental Shelf Research

Pub Date : 2024-10-28 DOI: 10.1016/j.csr.2024.105345

Alexander E. Yankovsky , Yuriy P. Ilyin

The Dnipro River has the second-largest annually-averaged discharge among European rivers and together with the Pivdennyi Buh River runs off on the Black Sea northwestern shelf, forming the Dnipro-Buh coastal buoyant plume. This study presents shipboard observations of the Dnipro-Buh plume in May of 1992 and 1994, when the freshwater discharge was lower and higher, respectively, than its climatological value for May, while the wind forcing was light and variable. In-situ data are complemented with satellite images obtained under similar forcing conditions at later times. Weak mixing in the Dnipro-Buh estuary leads to the formation of a thin, 1.5–3 m deep surface-advected plume. The estuarine outflow runs off parallel with the coastline, but with downstream distance it rapidly expands offshore over multiple baroclinic Rossby radii. On synoptic to monthly time scales, the Dnipro-Buh plume spreads in bimodal fashion, both upstream and downstream from the estuarine mouth. The downstream geostrophic transport of freshwater in the plume is a small fraction of the freshwater discharge feeding the plume. Also, as salinity anomaly decreases offshore, the freshwater content remains near-constant or even increases. This implies that the freshwater spreading is sustained by cross-frontal “diffusion” to a greater extent than through the advection by geostrophic circulation associated with the plume. Meso- and submesoscale instabilities are likely to play a major role in mixing and offshore spreading of the Dnipro-Buh plume.

第聂伯河是欧洲河流中年平均排水量第二大的河流，它与 Pivdennyi Buh 河一起流向黑海西北大陆架，形成第聂伯河-Buh 沿岸浮力羽流。本研究介绍了 1992 年和 1994 年 5 月对第聂伯河-布赫河羽流的船上观测结果，当时淡水排放量分别低于和高于 5 月份的气候值，而风力较小，且变化不定。后来在类似条件下获得的卫星图像补充了现场数据。第聂伯河-布河口的弱混合导致形成了一个 1.5-3 米深的薄表面对流羽流。河口流出的气流与海岸线平行，但随着下游距离的增加，它迅速向近海扩展，形成多个巴氏罗斯比半径。在同步到月度时间尺度上，第聂伯河-布赫河羽流在河口的上游和下游都以双峰方式扩散。羽流中淡水的下游地转输送量仅占哺育羽流的淡水排放量的一小部分。此外，随着近海盐度异常的减小，淡水含量几乎保持不变，甚至有所增加。这意味着淡水扩散在更大程度上是通过跨锋面 "扩散 "来维持的，而不是通过与羽流相关的地转环流的吸附。中尺度和次中尺度的不稳定性很可能在第聂伯河-布赫河羽流的混合和离岸扩散过程中发挥了重要作用。

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引用次数: 0

Sedimentation characteristics of surficial sediments in Baiyun Canyon area, Northern South China Sea 南海北部白云峡谷地区表层沉积物的沉积特征

IF 2.1 3区地球科学 Q2 OCEANOGRAPHY

Continental Shelf Research

Pub Date : 2024-10-20 DOI: 10.1016/j.csr.2024.105342

Qingjie Zhou , Youkou Dong , Lejun Liu , Xishuang Li

The Baiyun Canyon area on the Northern Slope of the South China Sea is a potential hotspot for oil and gas resource development, but the sediment characteristics and sedimentary environment in this region present challenges for offshore engineering. This study comprehensively analyzed the physical, and mechanical properties of sediments in the area using geophysical exploration, engineering geological investigation, fixed-point sampling and hydrological observation. The engineering geological characteristics and sedimentary environment of surface sediments in the Baiyun Canyon area were studied, and the relationship between physical and mechanical properties and sedimentary environment was explored. The study revealed that the sediments in this area consist mainly of organic soft clay with high water content, low density, high pore ratio, high liquid limit, high plasticity and low strength. The physical and mechanical properties of the sediments vary, with the mechanical properties exhibiting higher variability than the physical properties. The research findings offer a scientific basis for understanding the seabed soil properties for designing submarine engineering structures in the deep waters of the northern South China Sea. This study holds significant theoretical and practical implications for oil and gas exploration and offshore engineering construction.

南海北坡白云峡谷地区是潜在的油气资源开发热点，但该地区的沉积特征和沉积环境给海洋工程带来了挑战。本研究采用地球物理勘探、工程地质调查、定点取样和水文观测等方法，全面分析了该地区沉积物的物理力学性质。研究了白云峡谷地区表层沉积物的工程地质特征和沉积环境，探讨了物理力学性质与沉积环境之间的关系。研究表明，该地区沉积物主要由有机软粘土组成，具有高含水率、低密度、高孔隙比、高液限、高塑性和低强度等特点。沉积物的物理和机械特性各不相同，其中机械特性的变异性高于物理特性。研究结果为了解海底土壤性质提供了科学依据，有助于设计南海北部深海水域的海底工程结构。这项研究对油气勘探和海洋工程建设具有重要的理论和实践意义。

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引用次数: 0

Analysis of the annual number of tropical cyclones over Japan using the extreme value theory 利用极值理论分析日本热带气旋的年度数量

IF 2.1 3区地球科学 Q2 OCEANOGRAPHY

Continental Shelf Research

Pub Date : 2024-10-18 DOI: 10.1016/j.csr.2024.105341

Fumio Maruyama

We predicted the extreme value of the annual number of typhoons, tropical cyclones over the western North Pacific, approaching typhoons, and landing typhoons for 1951–2019 over Japan and the minimum central pressure for 1987–2020 using the extreme value theory. The generalized extreme value (GEV) distribution was used to fit the extreme indices. Various diagnostic plots for assessing the accuracy of the GEV model fitted to the annual number of typhoons, approaching typhoons, and landing typhoons are shown, and all four diagnostic plots support the fitted GEV model. The shape parameter ξ for the annual number of typhoons and approaching typhoons is negative, and the number of typhoons has a finite upper limit. The calculated upper limits were 44.5 and 23.2 for the annual number of typhoons and approaching typhoons, respectively. However, ξ in the number of landing typhoons was zero; therefore, the number of landing typhoons did not have a finite upper limit, and there was a possibility that a significant risk would occur. The number of typhoons increased for 1951–2019. The minimum central pressure of typhoons estimated using geostationary satellite images decreased for 1987–2020, and the number of strong typhoons increased. The annual number of violent typhoons (

\geq

54 m/s) increased in the 2010s. The calculated limit of the minimum central pressure of the typhoon is 877 hPa. When the Pacific Decadal Oscillation (PDO) index is positive, more violent typhoons tend to occur.

我们利用极值理论预测了 1951-2019 年日本上空台风、北太平洋西部热带气旋、接近台风和登陆台风的年数量极值，以及 1987-2020 年最低中心气压的极值。采用广义极值（GEV）分布拟合极端指数。图中显示了各种诊断图，用于评估与年度台风数、临近台风数和登陆台风数拟合的 GEV 模型的准确性，所有四个诊断图都支持拟合的 GEV 模型。年台风数和台风逼近数的形状参数ξ为负值，台风数有一个有限的上限。计算得出的台风年数和台风逼近数上限分别为 44.5 和 23.2。然而，登陆台风数的ξ为零；因此，登陆台风数没有有限上限，存在发生重大风险的可能性。1951-2019 年台风数量增加。利用地球静止卫星图像估算的 1987-2020 年台风最低中心气压有所下降，强台风数量有所增加。暴台风（≥ 54 m/s）的年数量在 2010 年代有所增加。台风最低中心气压的计算极限为 877 hPa。当太平洋十年涛动（PDO）指数为正值时，往往会出现更多的强台风。

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引用次数: 0

Phosphorus fractions and their vertical distribution in seabed sediments of the eastern Baltic Sea 波罗的海东部海底沉积物中的磷组分及其垂直分布

IF 2.1 3区地球科学 Q2 OCEANOGRAPHY

Continental Shelf Research

Pub Date : 2024-10-09 DOI: 10.1016/j.csr.2024.105340

Markus Ausmeel , Martin Liira , Päärn Paiste , Aivo Lepland , Sten Suuroja

Phosphorus fractions and their vertical distribution in seabed sediments were studied in short cores from four coastal sites of western Estonia (Western Gulf of Finland, Väinameri Sea, Suur Strait, and Gulf of Riga) representing accumulation and erosion/transport settings. As a result of recent large-scale discharges of nutrients into the marine environment, abundant phosphorus has accumulated in the seabed sediments, from where it can, under the expansion of hypoxic or anoxic conditions, be remobilized and released back into the water column. A sequential extraction method with a neutral, a reducing, a basis, and an acidic solution was used to evaluate the distribution of phosphorous in pools of five different carrier fractions. Potentially mobile phosphorus is mostly associated with redox-sensitive iron- and manganese oxyhydroxides, and this fraction is significant in the Western Gulf of Finland and the Gulf of Riga. As oxygen conditions gradually deteriorate, the remobilization of a considerable amount of potentially mobile phosphorus from sediments can affect the entire Baltic Sea ecosystem.

对爱沙尼亚西部四个沿海地点（西芬兰湾、韦纳梅里海、苏尔海峡和里加湾）的短岩心进行了研究，这些地点代表了积累和侵蚀/迁移环境，研究了海底沉积物中的磷组分及其垂直分布。由于最近向海洋环境大规模排放营养物质，大量磷在海床沉积物中积累，在缺氧或缺氧条件下，磷会从海床沉积物中重新移动并释放回水体。采用中性溶液、还原性溶液、碱性溶液和酸性溶液的顺序萃取法评估了磷在五种不同载体馏分池中的分布情况。潜在的移动磷主要与对氧化还原反应敏感的铁和锰氧氢氧化物有关，这部分磷在芬兰湾西部和里加湾的含量很高。随着氧气条件逐渐恶化，沉积物中大量潜在移动磷的再移动会影响整个波罗的海生态系统。

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引用次数: 0