Marine Chemistry最新文献_第3页

Dynamic organic matter sources drive intact polar lipids recently deposited in surface sediments from the Yangtze River Estuary and adjacent sea 动态有机质源驱动了长江口及邻近海域表层沉积物中近期沉积的完整极性脂质

IF 2.5 3区地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY

Marine Chemistry

Pub Date : 2025-10-29 DOI: 10.1016/j.marchem.2025.104574

Dayu Duan , Ke Xu , Yuxue Yang , Yue Wu , Yasong Wang , Yuli Wei , Wenjie Xiao , Zhixuan Feng , Xueqin Zhao , Yunping Xu , Weichao Wu

Lipids, especially the intact polar lipids, serve as valuable biological information for biogeochemical studies. However, the distributions of sedimentary lipids and their controlling factor in dynamic estuarine systems remain poorly constrained. Here we used an untargeted lipidomics approach to analyze lipid composition in surface sediments across freshwater, turbidity and inner shelf zones in the Yangtze River estuary. A total of 852 lipids from 28,378 molecular features were annotated, covering 35 subclasses based on LIPIDMAPS framework. The most abundant lipids, including subclasses free fatty acids, triacylglycerols, ceramides, diacylglyceryl trimethylhomoserines, and phosphatidylcholines, accounted for up to 71.4 %. Multivariate analysis reveals a significant effect of total organic carbon δ¹³C values (δ¹³C-TOC) and grain size on lipid distribution, suggesting that sedimentary organic matter sources and hydrodynamic conditions are key controlling factors on spatial lipid heterogeneity. An apparent seawards increase in δ¹³C-TOC values (−24.7 − −20.4 ‰) indicates contribution of phytoplankton-derived organic matter to sedimentary TOC from the adjacent sea area. However, most putatively eukaryotic lipids, including phospholipids, glycerolipids and betaine lipids, exhibit no distinct seawards pattern. This pattern is likely attributed to the integrative effect between lipid degradation of riverine phytoplankton and replenishment of marine phytoplankton with the resuspension of sediment. In contrast, most ceramides, especially phytosphingosine-based ceramides, show a substantially decreasing trend seawards and a strongly negative association with δ¹³C-TOC (r < −0.8, p < 0.001), probably indicating a terrestrial origin. This study highlights the lipid diversity under the complex marine dynamics and the potential use of lipids for tracing the biogeochemical cycling of polar lipids in the ocean.

脂质，尤其是完整的极性脂质，是生物地球化学研究的重要生物信息。然而，对动态河口体系中沉积脂类的分布及其控制因素的研究仍然缺乏深入的认识。本文采用非靶向脂质组学方法分析了长江口淡水带、浑浊带和内陆架带表层沉积物的脂质组成。基于LIPIDMAPS框架，共对28378个分子特征中的852个脂类进行了注释，涵盖35个亚类。最丰富的脂类，包括亚类游离脂肪酸、三酰甘油、神经酰胺、二酰甘油三甲基高丝氨酸和磷脂酰胆碱，占71.4%。多变量分析显示，总有机碳δ13C值（δ13C- toc）和颗粒大小对脂质分布有显著影响，表明沉积有机质来源和水动力条件是控制脂质空间异质性的关键因素。δ13C-TOC值（- 24.7‰~ - 20.4‰）向海方向明显增加，表明浮游植物源有机质对邻近海域沉积TOC有贡献。然而，大多数被认为是真核生物的脂质，包括磷脂、甘油脂和甜菜碱脂，并没有明显的海向模式。这种模式可能归因于河流浮游植物的脂质降解和海洋浮游植物的补充与沉积物的再悬浮之间的综合作用。相反，大多数神经酰胺，特别是植物鞘氨醇基神经酰胺，呈现出向海方向显著降低的趋势，与δ13C-TOC呈强负相关（r <−0.8,p < 0.001），可能是陆源的。本研究强调了复杂海洋动态下的脂质多样性，以及脂质在海洋极地脂质生物地球化学循环中的潜在应用。

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引用次数: 0

pHT measurements of TRIS buffer solutions in artificial seawater matrix in the salinity range 5–40 and temperature range 5–40 °C. Part 2: Uncertainty of pHT values TRIS缓冲溶液在人工海水基质中盐度范围5-40，温度范围5-40°C的pHT测量。第2部分：pHT值的不确定度

IF 2.5 3区地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY

Marine Chemistry

Pub Date : 2025-10-17 DOI: 10.1016/j.marchem.2025.104573

Rieke Schäfer , Gaëlle Capitaine , Frank Bastkowski , Daniela Stoica , Olivier Pellegrino , Raquel Quendera , Eric P. Achterberg , Simon L. Clegg , Paola Fisicaro , Steffen Seitz

In the first part of this study, we determined a fit function which allows the calculation of the total pH (pH

_{T}

) value of an artificial seawater/2-amino-2-(hydroxymethyl)-1,3-propanediol (TRIS) buffer, extrapolated to 0 mol kg⁻¹ H

_{2}

O TRIS molality (i.e. to a true pH

_{T}

scale), in terms of temperature and practical salinity. In this second part, we present a method to quantify the uncertainty of that function. The uncertainty plays an important role in the characterization of the indicator dye used for the routine spectrophotometric pH

_{T}

measurement in seawater. However, it has not been determined previously. We assigned uncertainties to measured input quantities, and propagated them through the calculation steps described in the first part. Both, analytical uncertainty calculation and Monte Carlo simulations have been applied to adequately consider the various steps of the procedure needed to calculate pH

_{T}

values of artificial seawater. The combined standard uncertainty of pH

_{T} (S, T, b (TRIS) = 0 mol kg^{−1} H_{2} O)

for artificial seawater/TRIS buffers was 0.0011 over the practical salinity range 5 to 40 and temperature range 5 °C to 40 °C. This uncertainty can now be used to determine, the uncertainties of the characterization of the indicator dye used for seawater pH

_{T}

measurements.

在本研究的第一部分中，我们确定了一个拟合函数，该函数允许计算人工海水/2-氨基-2-（羟甲基）-1,3-丙二醇（TRIS）缓冲液的总pH （pHT）值，根据温度和实际盐度外推到0 mol kg−1 H2O TRIS质量摩尔浓度（即真正的pHT刻度）。在第二部分中，我们提出了一种量化该函数不确定性的方法。不确定度在常规分光光度法测定海水pHT的指示剂的表征中起着重要的作用。然而，它之前并没有确定。我们将不确定性分配给测量的输入量，并通过第一部分中描述的计算步骤传播它们。分析不确定度计算和蒙特卡罗模拟都被用于充分考虑计算人工海水pHT值所需的程序的各个步骤。人工海水/TRIS缓冲液的pHT（S，T,b(TRIS)=0mol kg−1H2O）在实际盐度5 ~ 40、温度5℃~ 40℃范围内的联合标准不确定度为0.0011。这种不确定度现在可以用来确定用于海水pHT测量的指示剂染料特性的不确定度。

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引用次数: 0

Polyamines as predominant organic basic compounds in the Antarctic Peninsula 多胺是南极半岛主要的有机碱性化合物

IF 2.5 3区地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY

Marine Chemistry

Pub Date : 2025-10-12 DOI: 10.1016/j.marchem.2025.104572

Kentaro Saeki , Daniel P. Zitterbart , Kazuya Ikari , Joseph D. Warren , Kylie Owen , Shin-Ichi Ohira , Kei Toda

Polyamines, such as putrescine, spermidine, and spermine, are vital for marine microorganisms as nutrients and bioactive compounds. While their presence has been studied in various marine regions, they remain unexamined in the Antarctic region, and no study has compared polyamines with monoamines, another class of organic nitrogen compounds. This study quantified polyamines and monoamines in seawater in the West Antarctic Peninsula region using 4-(N,N-dimethylaminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole (DBD-F) derivatization and HPLC-MS/MS. Polyamines were detected in Antarctica for the first time at sub-μM to μM levels, and it was approximately two orders of magnitude higher than reports from lower-latitude regions. Although total polyamine concentrations did not differ significantly among the five sites sampled, distinct patterns in polyamine composition were observed between the sites. In Wilhelmina Bay, total polyamines exhibited a positive but non-significant association with zooplankton backscatter (NASC), while cadaverine alone correlated significantly (r = 0.53, n = 15, p = 0.04). Our results established a baseline for Antarctic polyamines and revealed bay-to-bay differences in species composition. These baseline observations set the stage for tracking how polyamine dynamics respond to environmental change in the Southern Ocean.

多胺，如腐胺、亚精胺和精胺，作为营养物质和生物活性化合物对海洋微生物至关重要。虽然在不同的海洋区域对它们的存在进行了研究，但它们在南极地区仍未得到研究，而且没有研究将多胺与单胺（另一类有机氮化合物）进行比较。本研究采用4-（N，N-二甲氨基磺酰基）-7-氟-2,1,3-苯并恶二唑（DBD-F）衍生化和HPLC-MS/MS技术对南极半岛西部地区海水中的多胺和单胺进行了定量分析。在南极首次检测到亚μM ~ μM水平的多胺，比低纬度地区报道的多胺含量高约2个数量级。虽然总多胺浓度在五个采样点之间没有显着差异，但在不同的地点之间观察到不同的多胺组成模式。在Wilhelmina Bay，总多胺与浮游动物反向散射（NASC）呈显著正相关（r = 0.53, n = 15, p = 0.04）。我们的结果建立了南极多胺的基线，并揭示了海湾间物种组成的差异。这些基线观测为跟踪多胺动力学如何响应南大洋环境变化奠定了基础。

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引用次数: 0

Acid-leachability of metals from suspended particles in the Pacific Ocean 太平洋悬浮颗粒中金属的酸浸性

IF 2.5 3区地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY

Marine Chemistry

Pub Date : 2025-10-10 DOI: 10.1016/j.marchem.2025.104571

Yoshiki Sohrin , Linjie Zheng , Cheuk-Yin Chan , Yuzuru Nakaguchi , Shotaro Takano , Rumi Sohrin , Wen-Hsuan Liao , Tung-Yuan Ho

Suspended particles are major carriers of trace metals in seawater, while the cycling mechanisms of particulate trace metals remain largely unclear owing to analytical challenges. In this study, we focused on the acid-leachability of particulate trace metals collected from the Pacific Ocean and investigated their compositional features by measuring the total dissolvable metal (tdM) and dissolved metal (dM) concentrations in unfiltered and filtered seawater samples, respectively. We defined the difference between total dissolvable and dissolved metals as the particulate metal (pM). We investigated the pM time course in acidified bottom waters (pH 1.9) over approximately two years. pM increased in two stages and reached equilibrium within a few years. In the field study, we stored acidified seawater samples at least two years before analysis. We compared pM with total particulate metal (tpM) concentrations in the same samples collected from 11 stations in the subarctic Pacific. The tpM concentrations were determined by particle filtration followed by total digestion using strong acids, including HF. The results indicate that pAl and pFe are nearly equivalent to tpAl and tpFe, respectively. Many metals in the suspended particles, including clay minerals, are highly acid-leachable during long-time storage. By compiling our pM data observed in the Pacific Ocean and its marginal seas (approximately 1500 samples), we found that the average pM/dM ratio across the Pacific is 9 for Al and 4 for Fe. Although pAl and pFe exhibit strong linear correlations, their concentrations and regression slopes are spatially variable, reflecting differences in sources and fluxes.

悬浮颗粒是海水中微量金属的主要载体，但由于分析方面的挑战，颗粒微量金属的循环机制在很大程度上仍不清楚。本研究通过测定未过滤和过滤海水样品中总溶解金属（tdM）和溶解金属（dM）浓度，研究了太平洋海水中颗粒状微量金属的酸浸性，并探讨了其组成特征。我们将总可溶金属和溶解金属的区别定义为颗粒金属（pM）。在大约两年的时间里，我们研究了酸化水底（pH值1.9）的pM时间过程。pM分两个阶段增加，并在几年内达到平衡。在实地研究中，我们在分析前将酸化的海水样本至少保存了两年。我们比较了从亚北极太平洋11个站点收集的相同样品中的pM和总颗粒金属（tpM）浓度。采用颗粒过滤法测定tpM浓度，然后用强酸（包括HF）进行总消解。结果表明，pAl和pFe分别与tpAl和tfe几乎相等。悬浮颗粒中的许多金属，包括粘土矿物，在长期储存期间极易酸浸。通过汇编我们在太平洋及其边缘海域观测到的pM数据（大约1500个样本），我们发现整个太平洋的平均pM/dM比值为Al为9，Fe为4。尽管pAl和pFe表现出很强的线性相关性，但它们的浓度和回归斜率在空间上是可变的，反映了来源和通量的差异。

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引用次数: 0

Submarine groundwater discharge and gas hydrate dissociation fuel organic matter formation in Arctic fjord sediments 海底地下水排放和天然气水合物解离为北极峡湾沉积物有机质形成提供燃料

IF 2.5 3区地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY

Marine Chemistry

Pub Date : 2025-10-08 DOI: 10.1016/j.marchem.2025.104570

Beata Szymczycha , Magdalena Diak , Wei-Li Hong , Michael Ernst Böttcher , Aivo Lepland , Przemysław Makuch , Sophie ten Hietbrink , Seyed Reza Saghravani , Arunima Sen , Aleksandra Winogradow , Marc J. Silberberger

Arctic fjord sediments store significant amounts of organic matter (OM), contributing to the global carbon cycle, but are increasingly influenced by climate change. This study investigates OM distribution and sources in sediments from 24 stations across three West Spitsbergen fjords (Hornsund, Isfjord, and Kongsfjord-Krossfjord), focusing on relationships with porewater chloride concentrations and stable water isotopes. Freshening of porewater indicated by low chlorinity was detected in Isfjord and Hornsund. In Hornsund and Tempelfjord (Isfjord), water isotope signatures point to a meteoric origin, likely via submarine groundwater discharge (SGD). In contrast, Ekmanfjord (Isfjord) shows isotopic evidence of gas hydrate dissociation as the freshening source. Both Isfjord sites contain OM with low δ¹³C_org < –26.8 ‰) and δ¹⁵N_tot (< 3.1 ‰) values, which are inconsistent with known OM sources in Svalbard fjords. We propose that carbon released from SGD and gas hydrate dissociation, along with methane oxidation and nitrogen assimilation by methanotrophic microbes, contribute to OM formation. These findings suggest that Arctic fjord sediments may help mitigate climate change by supporting microbial processes that consume methane, a potent greenhouse gas.

北极峡湾沉积物储存了大量的有机物（OM），为全球碳循环做出了贡献，但受到气候变化的影响越来越大。本研究调查了西斯皮次卑尔根三个峡湾（Hornsund、Isfjord和kongsjord - krossfjord） 24个站点沉积物中OM的分布和来源，重点研究了孔隙水氯浓度和稳定水同位素的关系。在Isfjord和Hornsund检测到低氯含量的孔隙水变新鲜。在霍恩松德和坦普尔峡湾（Isfjord），水的同位素特征指向大气起源，可能是通过海底地下水排放（SGD）。相比之下，埃克曼峡湾（Isfjord）显示了天然气水合物解离作为新鲜来源的同位素证据。两个Isfjord遗址均含有低δ13Corg （< -26.8‰）和δ15Ntot （< 3.1‰）值的OM，这与斯瓦尔巴峡湾已知的OM来源不一致。研究人员认为，甲烷发酵过程中释放的碳和天然气水合物的解离，以及甲烷氧化和甲烷营养微生物对氮的同化，都有助于有机质的形成。这些发现表明，北极峡湾沉积物可能通过支持消耗甲烷（一种强效温室气体）的微生物过程来帮助减缓气候变化。

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引用次数: 0

Variations in lignin content deposited in the Congo fan and its potential for oxidative degradation 刚果扇沉积木质素含量的变化及其氧化降解的潜力

IF 2.5 3区地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY

Marine Chemistry

Pub Date : 2025-10-04 DOI: 10.1016/j.marchem.2025.104569

Louis C. Bondurant , Megan L. Baker , Sophie Hage , Peter J. Talling , Patrick G. Hatcher

The deposition of terrigenous organic carbon (tOC) in offshore deep-marine settings has traditionally been viewed as inconsequential for organic carbon burial. However, it has been shown that deep-sea sediment flows, turbidity currents, can contribute significantly to the burial of tOC. Elemental, isotopic, and molecular data were obtained on sediment samples from three areas within and adjacent to the Congo Deep-Sea Fan. The elemental, organic geochemical, and isotopic data agree well with previous studies from the Congo Fan, which show that terrigenous organic matter from the Congo River extends seaward in the axis of the submarine canyon to abyssal depths. Using advanced solid-state ¹³C NMR and TMAH thermochemolysis data we verify that a significant amount of lignin is exported to the canyon (∼14 % wt. lignin) and the distal lobe (∼16 % wt. lignin) sediments. The basin plain contains no detectable lignin but does show the presence of terrigenous long-chain fatty acids having an even carbon number predominance. Following a laboratory oxidation experiment on sediments from the distal lobe for 6 d there was an organic carbon mass loss of 59.8 % and the solid-state ¹³C NMR spectrum shows a major reduction in peaks associated with carbohydrate-like and lignin molecules and a relative increase in aliphatic molecules. This shows that terrigenous lignin molecules can be remineralized to CO₂ and/or altered to structures that no longer resemble that of lignin through oxidative degradation processes. This would have a potentially significant implication on what is traditionally viewed as autochthonous marine organic matter.

传统上认为，近海深海环境中陆源有机碳（tOC）的沉积与有机碳埋藏无关。然而，已有研究表明，深海沉积物流动，即浊度流，对tOC的埋藏有重要贡献。元素、同位素和分子数据来自刚果深海扇内部和邻近的三个区域的沉积物样本。元素、有机地球化学和同位素数据与刚果扇的研究结果一致，表明来自刚果河的陆源有机质沿海底峡谷轴线向海洋延伸至深海深处。使用先进的固态13C NMR和TMAH热化学分解数据，我们验证了大量的木质素被出口到峡谷（~ 14% wt.木质素）和远叶（~ 16% wt.木质素）沉积物。盆地平原不含可检测到的木质素，但确实显示出具有偶数碳数优势的陆源长链脂肪酸的存在。在对来自远叶的沉积物进行6天的实验室氧化实验后，有机碳质量损失了59.8%，固态13C核磁共振光谱显示与碳水化合物和木质素分子相关的峰大幅减少，脂肪分子相对增加。这表明陆源木质素分子可以通过氧化降解过程再矿化为CO2和/或改变为不再类似木质素的结构。这将对传统上被视为原生海洋有机物的物质产生潜在的重大影响。

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引用次数: 0

Mapping of dissolved black carbon in the Atlantic Ocean 大西洋中溶解的黑碳的地图

IF 2.5 3区地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY

Marine Chemistry

Pub Date : 2025-10-01 DOI: 10.1016/j.marchem.2025.104568

Nina Davtian , Nuria Penalva , Oriol Teruel , Pau Comes , Antoni Rosell-Melé , Joan Villanueva

Oceanic dissolved black carbon (DBC) is the subject of a conundrum between the dominant riverine inputs in terms of mass flux and its stable and radiogenic carbon isotope composition inconsistent with a predominant riverine origin. Here, we analyzed seawater samples within specific and contrasting water masses along several latitudinal and longitudinal transects across the Atlantic Ocean to quantify DBC and map its latitudinal and water depth changes in this ocean. After comparing latitudinal changes in surface water DBC properties with those in atmospheric pyrogenic carbon inputs from seasonal, massive grass burning events in the African Savanna, we could not demonstrate the significance of atmospheric deposition as a non-riverine source of DBC in the Atlantic Ocean, likely due to the balance by DBC photo-bleaching. We found constant DBC concentrations and increasing trends in the condensation degree of DBC (i.e., B6CA:B5CA molar ratio) from surface to deep Atlantic waters and from the South Atlantic to the North Atlantic within individual shallow to deep water masses. Overall, our mapping of DBC in the Atlantic Ocean highlights the need to explore the following alternative hypotheses in the future to better understand the cycling of oceanic DBC: 1) enhanced regional atmospheric BC deposition from African savanna grassland fires impact particulate rather than dissolved BC in the Atlantic Ocean, 2) oceanic DBC has a predominantly non-pyrogenic origin, and 3) exports of terrigenous DBC across the Atlantic Ocean accompany those of terrigenous humic-like compounds from the North Atlantic via meridional circulation.

海洋溶解黑碳（DBC）在质量通量方面的主要河流输入与其稳定的放射性碳同位素组成与主要河流来源不一致之间是一个难题。在这里，我们分析了大西洋上几个纬度和纵向断面上特定和对比水团的海水样本，以量化DBC并绘制其在该海洋中的纬度和水深变化。在比较了非洲热带稀树草原季节性大规模烧草事件引起的地表水DBC特性的纬度变化与大气热原碳输入的纬度变化后，我们无法证明大气沉积作为大西洋中DBC的非河流来源的重要性，这可能是由于DBC光漂白的平衡。结果表明，从大西洋表层到大西洋深层，从南大西洋到北大西洋，各个浅水到深水水体中，DBC浓度保持不变，其凝结度（即B6CA:B5CA摩尔比）呈增加趋势。总的来说，我们对大西洋DBC的映射强调了未来探索以下替代假设的必要性，以更好地理解海洋DBC的循环：1)来自非洲热带稀树草原大火的区域大气BC沉积增强，影响了大西洋中颗粒而不是溶解的BC； 2)海洋DBC主要是非热成因的；3)陆源DBC通过经向环流与北大西洋的陆源腐殖质样化合物一起通过大西洋出口。

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引用次数: 0

Dissolved iron distribution and budget in the Solomon Sea 所罗门海溶解铁的分布与收支

IF 2.5 3区地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY

Marine Chemistry

Pub Date : 2025-09-29 DOI: 10.1016/j.marchem.2025.104567

Géraldine Sarthou , Eva Bucciarelli , Fabien Quéroué , François Lacan , Hélène Planquette , Viet Q. Pham , Maxime Grand , Catherine Pradoux , Martine Rodier , Sophie Bonnet , Gérard Eldin , Sophie Cravatte , Catherine Jeandel , Alexandre Ganachaud

As part of the PANDORA cruise (GEOTRACES GP12), concentrations of dissolved iron (dFe) were measured at 11 stations inside and outside the Solomon Sea, a semi-enclosed sea in the western tropical Pacific, with complex topography and straits, and strong western boundary currents supplying the equatorial current system. These measurements aimed to better assess the various sources of dFe in our study area and the Solomon Sea's potential as a source of dFe for the Equatorial Undercurrent (EUC). A simple box model allows calculating and discussing the fate of the dFe in the different water layers flowing through the Solomon Sea and suggests that the amount of dFe enrichment within the enclosed sea was not significant for the lower thermocline and intermediate waters, indicating that most of the dFe was acquired prior to reaching the Solomon Sea at the entrance and/or that inputs are approximately balanced by scavenging within the basin for these two layers. In contrast, dFe enrichment was significant for the upper thermocline layer and the deep waters, highlighting enrichments from external sources, as well as combination of internal processes, such as scavenging and/or organic complexation. The relative dFe contribution of the Solomon Sea to EUC was 20 %, on average. Other sources might thus provide dFe to the EUC, along the water transport downstream of the Solomon Sea (e.g. Bismarck Sea) or from the northern hemisphere. Diazotrophs such as Trichodesmium might also contribute to the dFe enrichment of the EUC after export and remineralization at depth outside the Solomon Sea.

作为潘多拉巡航（GEOTRACES GP12）的一部分，在所罗门海内外的11个站点测量了溶解铁（dFe）的浓度。所罗门海位于热带太平洋西部的半封闭海域，地形复杂，海峡狭窄，有强大的西部边界流提供赤道流系统。这些测量旨在更好地评估我们研究区域中dFe的各种来源，以及所罗门海作为赤道潜流（EUC） dFe来源的潜力。一个简单的箱形模型可以计算和讨论流经所罗门海的不同水层中dFe的命运，并表明封闭海中dFe的富集量对于下温跃层和中间水域来说并不显著，这表明大部分dFe是在进入所罗门海之前获得的，并且/或者这两个水层的输入通过盆地内的清除大致平衡。相反，dFe在上层温跃层和深水中富集显著，突出来自外部来源的富集，以及内部过程的组合，如清除和/或有机络合作用。所罗门海对欧盟的相对铁贡献平均为20%。因此，其他来源可能沿着所罗门海（如俾斯麦海）下游的水运或从北半球向欧盟提供dFe。重氮营养体（如Trichodesmium）也可能有助于出口后的EUC的dFe富集和所罗门海以外深度的再矿化。

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引用次数: 0

Groundwater modulates nutrient dynamics in a freshened saltmarsh tidal creek 地下水调节新鲜盐沼潮汐溪的营养动态

IF 2.5 3区地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY

Marine Chemistry

Pub Date : 2025-09-27 DOI: 10.1016/j.marchem.2025.104566

Jianan Liu , Xueqing Yu , Tong Peng , Xinyi Lin , Jinzhou Du

Saltmarsh tidal creeks play a critical role in coastal nutrient cycling, yet submarine groundwater discharge (SGD), as a key driver, remains poorly understood. Research on SGD-derived outwelling of multiple nutrient species is notably scarce in low-salinity estuarine saltmarshes influenced by large rivers. Utilizing long-lived radium isotopes (²²⁶Ra and ²²⁸Ra) combined with high-frequency monitoring encompassing the most comprehensive species of dissolved nutrient to date during both spring and neap tides, we quantified SGD fluxes and their contribution to nutrient outwelling in a low-salinity saltmarsh tidal creek system of the Yangtze River Estuary. Results showed that driven by tidal pumping, SGD flux during spring tides (12 ± 5.9 cm d⁻¹) was significantly greater than during neap tides (0.77 ± 0.42 cm d⁻¹), along with corresponding differences in nutrient transport fluxes. SGD served as a source of dissolved inorganic nitrogen (DIN) and dissolved silicate (DSi) to the tidal creek system. Specifically, NH₄-N contributed approximately 93 % of the outwelling flux, while SGD-derived DSi accounted for 31–36 % of the DSi outwelling. Conversely, SGD functioned as a sink for dissolved phosphorus (inorganic + organic), capable of removing phosphorus in the tidal creek waters. More importantly, due to nitrogen input via SGD and its retention of phosphorus, both groundwater and ebbing tidal creek waters exhibited nitrogen-to‑phosphorus (N/P) ratios significantly exceeding the Redfield ratio. Although the saltmarshes partially mitigated the elevated N/P ratio during the outwelling process, the imbalanced N/P ratio in SGD-driven outwelling still poses risks of inducing coastal eutrophication and harmful algal blooms. This study unveils the crucial regulatory role of SGD in nutrient dynamics within low-salinity saltmarshes, emphasizing the necessity to incorporate groundwater-surface water interactions into coastal nutrient management and ecological conservation.

盐沼潮汐溪在沿海养分循环中起着关键作用，但作为关键驱动因素的海底地下水排放（SGD）仍然知之甚少。在受大河影响的低盐度河口盐沼中，对sgd衍生的多种营养物质外溢的研究尤其缺乏。利用长寿命镭同位素（226Ra和228Ra），结合迄今为止春潮和小潮期间最全面的溶解营养物种类的高频监测，我们量化了长江口低盐度盐沼潮汐溪系统的SGD通量及其对营养物外移的贡献。结果表明，在潮汐泵送的驱动下，春潮期间的SGD通量（12±5.9 cm d - 1）显著大于小潮期间的SGD通量（0.77±0.42 cm d - 1），同时营养物运输通量也存在相应差异。SGD是潮汐溪系统中溶解无机氮（DIN）和溶解硅酸盐（DSi）的来源。具体而言，NH4-N贡献了约93%的外溢通量，而sgd衍生的DSi占DSi外溢的31 - 36%。相反，SGD作为溶解磷（无机+有机）的汇，能够去除潮溪水体中的磷。更重要的是，由于SGD的氮输入及其对磷的滞留，地下水和退潮溪水的氮磷比（N/P）显著超过Redfield比。尽管盐沼在外溢过程中部分缓解了氮磷比的升高，但sgd驱动的外溢中氮磷比的不平衡仍然存在诱发沿海富营养化和有害藻华的风险。本研究揭示了SGD在低盐度盐沼营养动态中的重要调节作用，强调了将地下水-地表水相互作用纳入沿海营养管理和生态保护的必要性。

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引用次数: 0

Unraveling sedimentary organic matter in the Oiapoque estuarine-marine ecosystem: Insights from elemental composition and isotopic fingerprints on the Amazon coast 揭示Oiapoque河口-海洋生态系统中的沉积有机质：来自亚马逊海岸元素组成和同位素指纹的见解

IF 2.5 3区地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY

Marine Chemistry

Pub Date : 2025-09-15 DOI: 10.1016/j.marchem.2025.104565

Yasmym Schütz de Vincenzi Weirich , Carlos Eduardo de Rezende , Fernanda Maria de Souza , Valdenira Ferreira dos Santos , César C. Martins

The Oiapoque River estuary, located on the border between Brazil and French Guiana, is an understudied Amazon region characterized by intense discharge of fluvial sediment and terrestrial organic matter (OM). Influenced by environmental factors such as temperature, salinity, tides, and currents, the sedimentary OM composition reflects both autochthonous production and adjacent land biomass. This study aimed to identify and differentiate primary sources of sedimentary OM in the Amazon coastal zone using geochemical parameters such as total organic carbon (TOC), total nitrogen (TN), their relative atomic ratio (expressed as C/N), and carbon and nitrogen isotopic ratios (δ¹³C and δ¹⁵N). Two surface sediment sampling campaigns were conducted in 2018 during the wet and dry seasons. The sediments showed a strong correlation between TOC and TN across both campaigns (R² = 0.98 and 0.94); however, results suggested the contribution of inorganic nitrogen forms (e.g., NH₄⁺). The C/N ratio indicated predominant OM from terrigenous input (∼24) at upstream sites and marine input (∼5 and ∼ 9) at downstream ones. The δ¹³C analysis revealed low variability along the estuary, with values around −27 ‰ upstream and near the mouth (typical of land or C3 plant contributions), intermediate values around −24 ‰ in the central portion (mixed sources), and higher values around −22 ‰ near the mouth (marine inputs). The δ¹⁵N values (∼3 ‰) were primarily found in the inner region, at the center of the estuary, and near the mouth where river discharges occur, associated with terrestrial plants. The elemental and isotopic composition of the sedimentary OM indicates a predominance of terrigenous OM, particularly near areas influenced by the Uáça and Ouanary rivers, reflecting land use and human occupation. Estuarine dynamics, influenced by rainfall and tidal currents, affect the distribution of marine inputs and the mixture of allochthonous and autochthonous sources throughout the estuary.

Oiapoque河河口位于巴西和法属圭亚那之间的边界，是一个未被充分研究的亚马逊地区，其特点是河流沉积物和陆相有机质（OM）的大量排放。受温度、盐度、潮汐和海流等环境因素的影响，沉积物有机质组成既反映了本地生产，也反映了邻近陆地生物量。利用总有机碳（TOC）、总氮（TN）及其相对原子比（以C/N表示）、碳氮同位素比（δ13C和δ15N）等地球化学参数，对亚马孙海岸带沉积有机质的主要来源进行了识别和区分。2018年在干湿季节进行了两次地表沉积物采样活动。在两个运动中，沉积物TOC与TN具有较强的相关性（R2 = 0.98和0.94）；然而，结果表明无机氮形式（如NH₄+）的贡献。C/N比值表明，上游的OM主要来自陆源输入（~ 24），下游的OM主要来自海洋输入（~ 5和~ 9）。δ13C沿河口变化较小，上游和河口附近（典型的陆地或C3植物贡献）的δ13C值在- 27‰左右，中部（混合源）的δ13C值在- 24‰左右，河口附近（海洋输入）的δ13C值在- 22‰左右。δ15N值（~ 3‰）主要分布在河口内、河口中心和河口附近，与陆生植物有关。沉积有机质的元素和同位素组成表明陆源有机质占主导地位，特别是在受Uáça和Ouanary河影响的地区附近，反映了土地利用和人类活动。受降雨和潮流影响的河口动力学影响了整个河口的海洋输入分布以及外来和本地源的混合。

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引用次数: 0