Marine Chemistry最新文献_第7页

Diatom-driven processes lead to the assimilation of elements from silicate minerals into their frustules 硅藻驱动的过程导致硅酸盐矿物中的元素被同化到它们的结晶体中

IF 3 3区地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY

Marine Chemistry

Pub Date : 2025-03-19 DOI: 10.1016/j.marchem.2025.104512

Tasuku Akagi, Sophia Welti, Rei Tajiri, Kazuhiko Shimada

To examine whether diatoms dissolve silicate minerals and incorporate foreign metals into their frustules, culture experiments were performed using Achnanthes kuwaitensis Hendey, Eucampia sp. and Coscinodiscus wailesii. These comprised two comparative experiments: (i) an analysis of diatom activities (population, transparent exopolymer particles (TEP) secretion and the Al/Si of frustules) in the presence/absence of feldspar particles, and (ii) an examination of mineral surfaces in the presence/absence of diatoms. Although the presence/absence of silicate minerals did not incur marked differences in diatom population, TEP secretion increased in the presence of silicate particles. Further, it was observed that the girdles of Coscinodiscus frustules showed double Si peaks and the outer layers of the girdles had significantly higher Al/Si ratios than the inner layers when feldspar particles were present. In the diatom cultures, feldspar particles largely disappeared in extended cultivation, and those still present showed rounded or fractured edges, features that were not seen in the absence of diatoms. The presence of diatoms appeared to have more influence on silicate minerals than the presence of silicate minerals on diatom activities. The C/Si ratios of the rounded feldspar grain edges in the Coscinodiscus cultures were significantly higher than those of stepwise edges, that we interpret to indicate that diatoms secrete TEP to dissolve silicate minerals. Two observations substantiated this hypothesis: pH decreases around diatoms, and incorporation of the mineral particles in TEP coatings.

Nevertheless, the physiological advantage for diatoms to dissolve silicate minerals remains unclear. Given the difference in TEP secretion between two different feldspar minerals, we believe that diatoms actively dissolve silicates in order to incorporate silica. We thus propose a mechanism by which diatoms dissolve silicate minerals. This may explain the inclusion of foreign elements at levels, whose relative concentrations are similar to those in terrigenous matter, in diatom frustules.

为了研究硅藻是否能溶解硅酸盐矿物并将外来金属融入到它们的结壳中，我们用阿克南提（Achnanthes kuwaitensis Hendey）、尤卡皮（Eucampia）和瓦利塞（Coscinodiscus wailesii）进行了培养实验。这些实验包括两个比较实验：(i)在长石颗粒存在/不存在的情况下分析硅藻活性（种群，透明外聚合物颗粒（TEP）分泌和晶体的Al/Si），以及（ii）在硅藻存在/不存在的情况下检查矿物表面。尽管矽酸盐矿物的存在和不存在对硅藻种群没有显著影响，但硅酸盐颗粒存在时，TEP的分泌增加。此外，在长石颗粒存在的情况下，尾盘晶体的环带呈现双Si峰，且环带外层的Al/Si比值明显高于内层。在硅藻培养中，长石颗粒在扩展培养中大部分消失，那些仍然存在的长石颗粒呈现圆形或断裂的边缘，这些特征在没有硅藻的情况下是看不到的。硅藻的存在对硅酸盐矿物的影响似乎大于硅酸盐矿物对硅藻活动的影响。硅藻培养物中圆形长石颗粒边缘的C/Si比值显著高于阶梯边缘，表明硅藻分泌TEP来溶解硅酸盐矿物。两个观察结果证实了这一假设：硅藻周围的pH值降低，以及TEP涂层中矿物颗粒的掺入。然而，硅藻溶解硅酸盐矿物的生理优势尚不清楚。鉴于两种不同长石矿物之间TEP分泌的差异，我们认为硅藻主动溶解硅酸盐以纳入二氧化硅。因此，我们提出了一种硅藻溶解硅酸盐矿物的机制。这也许可以解释硅藻中外来元素的含量，其相对浓度与陆源物质相似。

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引用次数: 0

Regression-based characterization of the marine carbonate system across shelf and nearshore waters of Queen Charlotte Sound 夏洛特女王湾陆架及近岸海域海相碳酸盐体系的回归表征

IF 3 3区地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY

Marine Chemistry

Pub Date : 2025-03-14 DOI: 10.1016/j.marchem.2025.104511

A.A. Hare , W. Evans , H.V. Dosser , J.M. Jackson , S.R. Alin , C. Hannah , T. Ross , J.M. Klymak

Marine carbonate system measurements are essential for understanding ocean acidification and CaCO₃ saturation states, and their response to oceanographic and anthropogenic processes. Acquiring such measurements in remote coastal areas is limited by challenges in the development and deployment of autonomous sensors for these parameters, and by the complexity and costs of directly measuring them. We address this challenge by extending an established method of estimating carbonate system parameters through proxy variables to the remote waters of Queen Charlotte Sound, British Columbia. Paired regressions are developed from bottle samples and common hydrographic measurements for both offshore and coastal waters that intersect in this region but retain distinct relationships between total alkalinity and salinity. Application of these regression models to regional autonomous glider data demonstrates that established features of this shelf system can be characterized from a carbonate system perspective along a contiguous transect from land to the shelf break, despite greater regression uncertainties in coastal water. These results also provide new insight into the dynamics of aragonite saturation on the shelf in relation to regional winds. This approach extends a tool to gain knowledge of the marine carbonate system to a coastal region of the northeast Pacific Ocean where hydrographic data used as proxies are more commonly available.

海洋碳酸盐系统测量对于了解海洋酸化和CaCO3饱和状态及其对海洋和人为过程的响应至关重要。在偏远沿海地区获取此类测量数据受到开发和部署这些参数的自主传感器的挑战，以及直接测量这些参数的复杂性和成本的限制。为了应对这一挑战，我们将一种通过代理变量估计碳酸盐岩系统参数的既定方法扩展到不列颠哥伦比亚省夏洛特女王湾的偏远水域。配对回归是根据瓶子样品和在该地区相交的近海和沿海水域的常见水文测量结果开发的，但总碱度和盐度之间保留了明显的关系。将这些回归模型应用于区域自主滑翔机数据表明，尽管沿海水域的回归不确定性较大，但从碳酸盐岩体系的角度来看，从陆地到陆架断裂的连续样带可以表征该陆架体系的既定特征。这些结果也为大陆架文石饱和度与区域风的关系提供了新的见解。这种方法将一种获取海相碳酸盐体系知识的工具扩展到东北太平洋沿海地区，在那里，水文数据更常用作代用。

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引用次数: 0

Copper speciation in a tropical mangrove forest of Southeast Asia 东南亚热带红树林中的铜物种分化

IF 3 3区地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY

Marine Chemistry

Pub Date : 2025-03-11 DOI: 10.1016/j.marchem.2025.104510

Ying Ping Lee , Kuo Hong Wong , Hajime Obata , Mohd Zaki Kamsah , Mohd Hisyam Rasidi

Mangrove forests are vital ecosystems that protect coastlines, sequester carbon, and support diverse food webs. Elucidation of the behaviors of nutrients, trace elements, and organic matters in these regions is crucial to understand the impact of human activities and the potential effects of climate change. In this study, we revealed the distributions and bioavailability of a trace metal, copper (Cu), and conducted the first study of Cu speciation in a mangrove region in Southeast Asia. Dissolved Cu (dCu) concentrations ranged from 0.3 to 2.3 nmol L⁻¹ in the study region, which are relatively low compared to most other coastal regions globally. Two classes of Cu-binding organic ligands with average conditional stability constants, log K, of 15.5 and 13.2, respectively, were detected in mangrove waters. Complexing capacities of the ligands generally decrease in low salinity waters with low dCu concentrations. Concentrations of the stronger-binding class of organic ligand (L₁) were higher than those of dCu, reducing the bioavailable Cu²⁺ concentration to less than femtomolar levels, potentially inducing Cu-limitation to microorganism growth. To further understand the biogeochemical processes of trace metals in mangrove regions, future studies should prioritize obtaining baseline data using standardized sampling and analytical techniques to ensure consistent and reliable results.

红树林是保护海岸线、固碳和支持多样化食物网的重要生态系统。阐明这些地区的营养物质、微量元素和有机物的行为对了解人类活动的影响和气候变化的潜在影响至关重要。在这项研究中，我们揭示了微量金属铜（Cu）的分布和生物利用率，并首次对东南亚红树林地区的铜标本进行了研究。研究区域的溶解铜（dCu）浓度介于 0.3 至 2.3 nmol L-1 之间，与全球大多数其他沿海地区相比相对较低。在红树林水域检测到两类铜结合有机配体，其平均条件稳定常数 log K 分别为 15.5 和 13.2。配体的络合能力在 dCu 浓度较低的低盐度水域中普遍下降。结合力较强的一类有机配体（L1）的浓度高于 dCu 的浓度，使生物可利用的 Cu2+ 浓度降低到飞摩尔水平以下，从而可能导致 Cu 限制微生物的生长。为进一步了解红树林地区痕量金属的生物地球化学过程，今后的研究应优先使用标准化的采样和分析技术获取基线数据，以确保结果的一致性和可靠性。

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引用次数: 0

Surface macro- and micro-nutrients within the Copper River plume region respond to along-shore winds 铜河羽流区域的表层宏量和微量营养物质对沿岸风有响应

IF 3 3区地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY

Marine Chemistry

Pub Date : 2025-02-21 DOI: 10.1016/j.marchem.2025.104508

E.L.S. Ortega, I. Reister, S.L. Danielson, A.M. Aguilar-Islas

The Copper River is a major source of freshwater to the Northern Gulf of Alaska (NGA) shelf with a seasonal cycle that reaches peak discharge in summer. This glacially-fed river also provides a large input of dissolved chemicals to the NGA, and because of its large particle load, it impacts the distribution of particle-reactive elements. Summertime sampling of shelf water properties was carried out within the Copper River plume region during two years: first during a period of upwelling-favorable winds and higher river discharge (4–7 July 2019) and later during lower river discharge and more typical downwelling conditions (11–13 July 2020). Although these wind conditions were observed in separate years, both can occur over the course of a single summer. We found that the export of most nutrients to surface shelf waters was enhanced under upwelling-favorable winds accompanied by higher river discharge compared to downwelling conditions and lower discharge. For example, greater cross-shelf plume transport in 2019 resulted in higher mid-shelf surface inventories for nitrate + nitrite (N + N), silicic acid (H₄SiO₄), phosphate (PO₄³⁻), dissolved Fe (dFe), and dissolved Cu (dCu) compared to 2020. Entrainment of relatively macronutrient-rich subsurface waters under upwelling conditions may also have contributed to the enhancement of these mid-shelf nutrient inventories. The observed high N:P ratios in plume waters were likely driven by the scavenging of P within particle-laden plume waters. Similarly, we observed lower than expected [dFe] (1.58 to 6.12 nM) in particle-laden plume waters, likely a result of enhanced scavenging combined with low concentrations of dissolved Fe-binding ligands. Although dNi and dZn have a river source, we observed lower concentrations in surface shelf waters under upwelling conditions, suggesting enhanced dilution by relatively micronutrient-poor subsurface waters. Results highlight the influence of sub-seasonal variations in atmospheric forcing on nutrient distributions and suggest that this forcing also impacts the location and timing of primary production hotspots during summer, adding to the ecological mosaic of the NGA across a range of temporal and spatial scales.

铜河是阿拉斯加北部海湾（NGA）大陆架的主要淡水来源，其季节性循环在夏季达到峰值。这条冰川补给的河流也为NGA提供了大量的溶解化学物质输入，并且由于其大颗粒负荷，它影响了颗粒活性元素的分布。夏季对铜河羽流区域的陆架水性质进行了为期两年的采样：首先是在上升流有利的风向和较高的河流流量期间（2019年7月4日至7日），然后是在较低的河流流量和更典型的下行条件下（2020年7月11日至13日）。虽然这些风况是在不同的年份观察到的，但它们都可能在一个夏天发生。研究发现，在上升流有利的条件下，大多数营养物质向陆架表层水的输出都比下升流有利的条件下和低流量的条件下增强。例如，与2020年相比，2019年更大的跨大陆架羽流运输导致硝酸盐+亚硝酸盐（N + N）、硅酸（H4SiO4）、磷酸盐（PO43−）、溶解铁（dFe）和溶解铜（dCu）的中大陆架表面库存增加。在上升流条件下，相对丰富的大量营养物质的地下水的夹带也可能有助于这些中陆架营养物质库存的增加。烟柱水体的高氮磷比可能是由烟柱水体对磷的清除作用引起的。同样，我们观察到，在颗粒富集的羽流水中，[dFe]（1.58至6.12 nM）低于预期，这可能是由于清除能力增强以及低浓度溶解的铁结合配体的结果。虽然dNi和dZn有河流来源，但我们观察到在上升流条件下，陆架表层水体中dNi和dZn的浓度较低，这表明相对微量营养素贫乏的地下水增强了它们的稀释作用。研究结果强调了大气强迫的亚季节变化对养分分布的影响，并表明这种强迫还影响夏季初级生产热点的位置和时间，从而增加了NGA在不同时空尺度上的生态马赛克。

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引用次数: 0

Dissolved iron release by sediment and dust particles in Antarctic seawater greater than glacial flour and sea-ice particles 南极海水中沉积物和尘埃颗粒释放的溶解铁大于冰川粉和海冰颗粒

IF 3 3区地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY

Marine Chemistry

Pub Date : 2025-02-21 DOI: 10.1016/j.marchem.2025.104509

Matthew Corkill , Klaus Martin Meiners , Pat Wongpan , Pier van der Merwe , Layla Creac'h , Sandrin Feig , Talitha Nelson , Abigail Jessica Rose Smith , Ashley T. Townsend , Samantha Twiname , Delphine Lannuzel

Primary productivity by phytoplankton in the Southern Ocean can be limited by low iron concentrations. Iron limitation in the surface ocean around Antarctica may be alleviated by particle dissolution of dust from exposed rock, glacial flour, resuspended marine sediment, and sea ice. Ligands, which are ubiquitous in seawater, chelate some metals and keep them in solution. Ligands are thereby thought to increase metal solubility, including iron. Leaching studies of Antarctic particles from various sources are rare but important due to observed and predicted changes occurring around Antarctica, e.g., changes in sea ice and ice-free areas on the continent. Here, we quantified the solubility of iron in different particle types using vertical flow-through leaching experiments that simulated sinking through the water column and ran for 78 min of flow at 4 °C under trace metal-clean conditions. Both unaltered and ultraviolet-irradiated seawater leaching solution treatments were used to test the effect of organic ligands on iron dissolution, which was found to be non-significant. Sediment and dust released the most dissolved iron to seawater, followed by glacial flour, and then sea-ice particles (9.00 ± 9.92 × 10⁻² and 3.18 ± 3.79 × 10⁻², 1.97 ± 1.79 × 10⁻⁴, 1.37 ± 0.90 × 10⁻⁹ g DFe/100 g material, respectively). We discuss these laboratory results in relation to particle availability and how this may affect the supply of dissolved iron to Antarctic surface waters.

南大洋浮游植物的初级生产力可能受到低铁浓度的限制。由于暴露的岩石、冰川粉、再悬浮的海洋沉积物和海冰中粉尘的颗粒溶解，南极洲周围海洋表面的铁限制可能会得到缓解。配体在海水中无处不在，它能螯合一些金属并使其保持在溶液中。因此，配体被认为可以增加金属的溶解度，包括铁。对来自各种来源的南极颗粒进行浸出研究是罕见的，但由于南极周围发生的观测和预测变化，例如南极大陆海冰和无冰区的变化，研究很重要。在这里，我们通过垂直流动浸出实验来量化铁在不同颗粒类型中的溶解度，模拟通过水柱下沉，在4°C的微量金属清洁条件下运行78分钟的流动。在未改变和紫外线照射的海水浸出液处理下，测试了有机配体对铁溶解的影响，发现有机配体对铁溶解的影响不显著。沉积物和粉尘向海水释放的溶解铁最多，其次是冰川粉，其次是海冰颗粒（分别为9.00±9.92 × 10−2和3.18±3.79 × 10−2,1.97±1.79 × 10−4,1.37±0.90 × 10−9 g DFe/100 g材料）。我们将讨论这些实验室结果与颗粒有效性的关系，以及这可能如何影响南极地表水中溶解铁的供应。

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引用次数: 0

Comparative study of dissolved copper speciation using DGT and CLE-AdSV in a contaminated urban river estuary and marina DGT法和cl - adsv法在污染城市河口和码头中溶解铜形态的比较研究

IF 3 3区地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY

Marine Chemistry

Pub Date : 2025-02-20 DOI: 10.1016/j.marchem.2025.104500

Billie G.B. Benedict , Rebecca Zitoun , Keith A. Hunter , Sylvia G. Sander

A comprehensive study was conducted in a river estuary and marina in Auckland, New Zealand, to examine the in-situ speciation of copper (Cu) complexes across freshwater, estuarine, and marine environments using the diffusive gradient in thin films (DGT) technique. The study employed both open-pore (OP) and restrictive-pore (RP) diffusive gels of varying thicknesses to assess the effectiveness of DGT hydrogels and the role of the apparent diffusive boundary layer (ADBL) in determining the lability of Cu complexes in natural waters. The DGT findings were compared with results from competing ligand exchange–adsorptive stripping voltammetry (CLE-AdSV) and a speciation prediction model (WHAM/Model-VII). The study highlighted the critical importance of accounting for the ADBL, as its exclusion led to an average underestimation of Cu-complex lability by approximately 50 %. Given the minimal difference in outcomes between DGT-OP and DGT-RP, the use of standard DGT-OP is recommended. Further analysis revealed a strong correlation between DGT-labile Cu (CuDGT-lab), the weaker Cu-L₂ complexes detected by CLE-AdSV, and the inorganic Cu species predicted by WHAM/Model-VII, the latter two based on discrete samples. A strong relationship was also noted between Cu_DGT-lab and the inorganic Cu measured by CLE-AdSV. The study provided compelling evidence that the in-situ ligand pool consists of a mixture of terrestrial humic substances and marine-derived organic ligands. These marine ligands form highly stable Cu-L₁ complexes along the salinity gradient, which were mostly DGT-inert. The DGT results indicated that the lability of in-situ Cu complexes decreased with increasing salinity, with over 60 % of Cu in freshwater being DGT-labile. Overall, the study demonstrates that the DGT technique is a robust and straightforward method for environmental monitoring and risk assessment across diverse physico-chemical water conditions.

在新西兰奥克兰的河口和码头进行了一项综合研究，利用薄膜扩散梯度（DGT）技术检查淡水、河口和海洋环境中铜（Cu）配合物的原位形态。该研究采用不同厚度的开孔（OP）和限制孔（RP）扩散凝胶来评估DGT水凝胶的有效性，以及表观扩散边界层（ADBL）在确定天然水体中Cu配合物稳定性中的作用。DGT结果比较了竞争配体交换吸附溶出伏安法（cl - adsv）和物种形成预测模型（WHAM/ model - vii）的结果。该研究强调了考虑ADBL的重要性，因为它的排除导致对cu复合物稳定性的平均低估约50%。鉴于DGT-OP和DGT-RP之间的结果差异很小，建议使用标准DGT-OP。进一步分析表明，dgt -不稳定Cu （CuDGT-lab）、CLE-AdSV检测到的较弱Cu- l2配合物和WHAM/Model-VII预测的无机Cu物种之间存在很强的相关性，后两者基于离散样本。CuDGT-lab与CLE-AdSV测量的无机Cu之间也存在很强的关系。该研究提供了令人信服的证据，表明原位配体池由陆地腐殖质物质和海洋来源的有机配体组成。这些海洋配体沿盐度梯度形成高度稳定的Cu-L1配合物，这些配合物大多是dgt惰性的。DGT结果表明，原位Cu配合物的稳定性随着盐度的增加而降低，淡水中超过60%的Cu是DGT不稳定的。总体而言，该研究表明，DGT技术是一种强大而直接的方法，可用于各种物理化学水条件下的环境监测和风险评估。

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引用次数: 0

Excess alkalinity and its impacts on pCO2 estimation in coastal and estuarine waters of the Yellow Sea 黄海沿岸和河口过量碱度及其对pCO2估算的影响

IF 3 3区地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY

Marine Chemistry

Pub Date : 2025-02-11 DOI: 10.1016/j.marchem.2025.104499

Young Ho Ko , Seung-Hee Shin , Seong-Gil Kim , Mi-Ok Park , Min-Woo Seok , Min-Soo Kim , Kitack Lee , Tae-Wook Kim

Excess alkalinity (TA_EX) represents an uncharacterized component of total alkalinity (TA), which can introduce significant uncertainty in the estimation of other carbonate parameters. This effect is particularly pronounced in productive coastal regions, where the use of measured TA as an input parameter may lead to inaccurate assessment. In this study, we evaluated the seasonal variability of TA_EX along the western coast of South Korea by applying an overdetermination method, which allows for the quantification of discrepancies (i.e., TA_EX) between measured TA and values calculated from pH and dissolved inorganic carbon (DIC). Samples with salinity below 20 were excluded due to difficulties in accurately quantifying uncertainties in TA_EX calculations, which increase significantly below this threshold. Elevated TA_EX concentrations were found in waters with salinity below 25, with some instances exhibiting TA_EX values reaching up to 50 μmol kg⁻¹, suggesting riverine influence. Additionally, elevated TA_EX values (> 20 μmol kg⁻¹) were also observed in locations markedly undersaturated with respect to atmospheric CO₂, indicating contributions from in-situ biological production. The high TA_EX values associated with increased water transparency during autumn and winter months suggested that light penetration may significantly enhance biological activity, subsequently increasing TA_EX levels. These findings highlight the importance of riverine inputs and biological processes in shaping the spatial and temporal distribution of TA_EX. In the study area, TA_EX should be accounted for in seawater partial pressure of CO₂ (pCO₂) calculations using the DIC–TA pair, as TA_EX significantly influences these calculations compared to the pH–TA and pH–DIC pair.

过量碱度（TAEX）是总碱度（TA）的一个未表征成分，它会给其他碳酸盐参数的估计带来很大的不确定性。这种影响在沿海生产地区尤其明显，在这些地区，使用测量的热饱和度作为输入参数可能导致不准确的评估。在这项研究中，我们通过应用超测定方法评估了韩国西海岸TAEX的季节性变化，该方法允许量化测量TA与pH和溶解无机碳（DIC）计算值之间的差异（即TAEX）。由于难以准确量化TAEX计算中的不确定度，盐度低于20的样品被排除在外，TAEX计算中的不确定度在此阈值以下显着增加。在盐度低于25的水中发现TAEX浓度升高，某些情况下TAEX值高达50 μmol kg - 1，表明河流的影响。此外，TAEX值升高(>；在相对于大气CO2明显不饱和的位置也观察到20 μmol kg−1)，表明原位生物生产的贡献。高TAEX值与秋冬季节水透明度的增加有关，这表明光的穿透可能显著增强生物活性，从而增加TAEX水平。这些发现强调了河流输入和生物过程在形成TAEX时空分布中的重要性。在研究区，使用DIC-TA对计算海水CO2分压（pCO2）时应考虑TAEX，因为与pH-TA和pH-DIC对相比，TAEX对这些计算有显著影响。

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引用次数: 0

Achieving measurement comparability in mercury speciation analysis in seawater: Key requirements and best practices 实现海水中汞形态分析的测量可比性：关键要求和最佳做法

IF 3 3区地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY

Marine Chemistry

Pub Date : 2025-02-04 DOI: 10.1016/j.marchem.2025.104498

Igor Živković , Lars-Eric Heimbürger-Boavida , Mariia V. Petrova , Aurélie Dufour , Ermira Begu , Milena Horvat

The comparability of measurement results is an important issue in contemporary mercury (Hg) speciation in seawater. Sampling campaigns must be properly designed to determine significant differences on spatial and temporal scales, considering two major parameters: the variability of expected data at a given sampling point/transect and variability in the results due to the intrinsic properties of specific analytical methods, particularly the measurement uncertainty. This study assessed the required sample size, considering several aspects of data variability when determining total Hg, dissolved gaseous Hg, and methylated Hg species in seawater. The required sample sizes were calculated using (1) the measurement uncertainty of a single-laboratory measurement of analytical methods used; (2) performance of the laboratories in interlaboratory comparison exercises; and (3) natural variability in Hg species/fractions in a selected case study in the Central Adriatic Sea. It was shown that the measurement uncertainty of a particular method and interlaboratory variability among laboratories have significant influence on data interpretation in case natural variability of Hg fractions is relatively small, such as for example the open seawater depth profiles. In contrary, in areas with large natural variability of Hg contractions, such as coastal and contaminated sites, their influence on data interpretation is negligible. The present paper introduces the importance of proper estimation of measurement uncertainty in international programs, such as GEOTRACES, where data comparability is of fundamental importance to assess temporal and spatial trends of Hg measurements in the marine environment.

测量结果的可比性是当代海水中汞形态形成的一个重要问题。必须适当地设计抽样活动，以确定空间和时间尺度上的显著差异，同时考虑两个主要参数：给定采样点/样条上预期数据的可变性，以及由于特定分析方法的内在特性，特别是测量不确定性而导致的结果的可变性。本研究评估了所需的样本量，在确定海水中总汞、溶解气态汞和甲基化汞的种类时，考虑了数据可变性的几个方面。所需的样本量使用(1)所用分析方法的单实验室测量的测量不确定度计算；(2)实验室在实验室间比较活动中的表现；(3)亚得里亚海中部汞种类/组分的自然变异。结果表明，在自然变异相对较小的情况下，例如开放海水深度剖面，特定方法的测量不确定度和实验室间的变异对数据解释有显著影响。相反，在汞收缩自然变异性较大的地区，如沿海和污染场地，它们对数据解释的影响可以忽略不计。本文介绍了在GEOTRACES等国际项目中正确估计测量不确定性的重要性，这些项目中数据的可比性对于评估海洋环境中汞测量的时空趋势至关重要。

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引用次数: 0

Physical-biological processes regulating summer sea-air CO2 exchanges along the Drake Passage and northern Antarctic Peninsula 调节夏季德雷克海峡和南极半岛北部海气二氧化碳交换的物理-生物过程

IF 3 3区地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY

Marine Chemistry

Pub Date : 2025-02-01 DOI: 10.1016/j.marchem.2025.104497

Rodrigo Kerr , Thiago Monteiro , Matheus S. Batista , Brendon Yuri Damini

We determined the sea-air carbon dioxide (CO₂) exchanges and investigated the main physical-biological processes responsible for regulating the sea surface partial pressure of CO₂. This was done through the analysis of continuous and discrete measurements of oceanographic and atmospheric variables measured during the NAUTILUS V cruise (January 2019) crossing the main fronts along the Drake Passage and several distinct biogeochemical provinces along the northern Antarctic Peninsula. The main findings indicated that the Drake Passage acted as a weak net CO₂ outgassing area (∼0.1 mmol m⁻² d⁻¹), although contrasting regions with close sea-air CO₂ fluxes magnitudes of ∼3 mmol m⁻² d⁻¹ were identified north (a net CO₂ sink zone regulated by net photosynthesis) and south (a net CO₂ source zone regulated by net respiration) of the Polar Front. On the other hand, the northern Antarctic Peninsula areas demonstrated a more heterogeneous sea-air CO₂ exchanges behaviour varying from moderate net CO₂ outgassing of ∼1.3 mmol m⁻² d⁻¹ (Bransfield Strait, western Antarctic Peninsula and Weddell Sea continental shelves) to a moderate (∼ −2.4 mmol m⁻² d⁻¹) or weak (∼ −0.1 mmol m⁻² d⁻¹) net CO₂ ingassing in Antarctic Sound surroundings and Gerlache Strait, respectively. It is interesting to note that a huge intensification of the net CO₂ outgassing of ∼5 mmol m⁻² d⁻¹ was identified in the area under the influence of the Antarctic Slope Front bifurcation eddy south of Clarence Island. The CO₂ outgassing is expected in this stationary and anticyclonic feature, but its magnitude was ∼75 % higher than the known estimate, which was associated with strengthen winds and eddy dynamics. Net respiration was the leading biological process occurring in the study area, except north of Polar Front where net photosynthesis prevailed. The patchy distribution of sea-air CO₂ exchanges behaviour along the Drake Passage and northern Antarctic Peninsula reinforced the needs for better understanding and focus on finer resolution of the CO₂ chemistry and processes at regional and local investigations, especially in a region suffering with multiple climate stressors, located in a transition zone of warm and cold environments, and key to connect the Southern Ocean ecosystems in a circumpolar way.

我们测定了海气二氧化碳交换，并研究了调节海面二氧化碳分压的主要物理-生物过程。这是通过分析鹦鹉螺号V号巡航（2019年1月）穿越德雷克海峡主要锋面和南极半岛北部几个不同的生物地球化学省期间测量的连续和离散海洋和大气变量的测量结果来完成的。主要研究结果表明，尽管北极锋北部（净光合作用调节的净CO2汇区）和南部（净呼吸调节的净CO2源区）的海气CO2通量值接近于~ 3 mmol m−2 d−1，但德雷克通道是一个弱的净CO2放出区（~ 0.1 mmol m−2 d−1）。另一方面，南极半岛北部地区表现出更不均匀的海气CO2交换行为，从中度的CO2净排放（~ 1.3 mmol m−2 d−1）（布兰斯菲尔德海峡、南极半岛西部和威德尔海大陆架）到中度（~−2.4 mmol m−2 d−1）或弱（~−0.1 mmol m−2 d−1）的CO2净排放（南极海峡周围和Gerlache海峡）。值得注意的是，在克拉伦斯岛以南的南极坡锋分岔涡的影响下，该地区的净CO2释放量大幅增加了~ 5 mmol m−2 d−1。预计在这一静止和反气旋特征中会出现二氧化碳脱气，但其量级比已知的估计高出约75%，这与加强的风和涡流动力学有关。除极锋以北以净光合作用为主外，净呼吸作用是研究区主要的生物过程。德雷克海峡和南极半岛北部海气二氧化碳交换行为的不均匀分布，加强了在区域和地方调查中更好地理解和关注二氧化碳化学和过程的精细分辨率的需求，特别是在一个遭受多种气候压力的地区，位于温暖和寒冷环境的过渡地带，以及以环极地方式连接南大洋生态系统的关键。

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引用次数: 0

Vertical biochemical composition of particulate organic matter in the Seychelles-Chagos Thermocline Ridge (SCTR), southwestern Indian Ocean 西南印度洋塞舌尔-查戈斯温跃层脊（SCTR）颗粒有机质垂直生化组成

IF 3 3区地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY

Marine Chemistry

Pub Date : 2025-01-19 DOI: 10.1016/j.marchem.2025.104496

Sanghoon Park , Yejin Kim , Jaesoon Kim , Jae Ha Jeon , Inhee Lee , Doshik Hahm , Dong-Jin Kang , Sang Heon Lee

The Seychelles-Chagos Thermocline Ridge (SCTR) in the southwestern Indian Ocean is characterized by upwelling-driven nutrient enrichment and enhanced biological activity compared to adjacent non-SCTR regions. This study investigated the vertical distribution and biochemical composition of particulate organic matter (POM) within these contrasting environments. The SCTR featured a shallower thermocline and cooler sea surface temperatures, indicative of upwelling, which correlated with significantly higher chlorophyll-a concentrations (t-test, p < 0.05). A notable dominance of micro-sized phytoplankton was observed in the SCTR, contributing 13.6 ± 3.0 % of the total phytoplankton biomass, compared to 5.6 ± 1.6 % in the non-SCTR. CHEMTAX analysis revealed distinct phytoplankton communities, with diatoms being approximately four times more abundant in the SCTR (16.5 ± 4.5 %) than in the non-SCTR (4.2 ± 1.2 %). Meanwhile, Prochlorococcus dominated both regions but contributed less in the SCTR (25.2 ± 3.9 %) than non-SCTR (46.8 ± 7.1 %). The biological macromolecular composition of POM showed clear regional differences, with lipid concentrations in the SCTR's photic layer significantly higher (61.3 μg L⁻¹) than in the non-SCTR (23.4 μg L⁻¹). Total biological macromolecule concentrations in the SCTR's photic zone was more than double that of the non-SCTR (96.3 μg L⁻¹ vs. 40.9 μg L⁻¹), reflecting enhanced biological productivity. Elevated macromolecule concentrations were also detected in the aphotic layer of the SCTR. Notably, the less pronounced decline in the protein-to-carbohydrate ratio from photic to aphotic layers in the SCTR suggests that POM sinking to the deep ocean in this region is relatively fresher and less degraded, indicating a more efficient biological carbon pump and enhanced potential for carbon sequestration. These findings highlight the SCTR as a key region of elevated biological productivity and distinct environmental mechanisms driving biogeochemical cycling, providing critical insights into organic matter preservation and carbon export processes in tropical upwelling systems and their role in global marine ecosystems.

与邻近的非塞舌尔-查戈斯温跃层脊区相比，西南印度洋塞舌尔-查戈斯温跃层脊区具有上升流驱动的营养物质富集和生物活性增强的特征。本研究研究了不同环境下颗粒物有机质（POM）的垂直分布和生化组成。SCTR具有较浅的温跃层和较低的海面温度，表明上升流，这与叶绿素-a浓度显著升高相关(t检验，p <；0.05)。微细浮游植物在SCTR中占明显优势，占总浮游植物生物量的13.6±3.0%，而在非SCTR中为5.6±1.6%。CHEMTAX分析揭示了不同的浮游植物群落，硅藻在SCTR中的丰度（16.5±4.5%）大约是非SCTR的4倍（4.2±1.2%）。原绿球藻在两个区域均占主导地位，但在SCTR中所占比例（25.2±3.9%）低于非SCTR（46.8±7.1%）。POM的生物大分子组成存在明显的区域差异，SCTR光化学层的脂质浓度（61.3 μg L−1）显著高于非SCTR光化学层（23.4 μ L−1）。SCTR光区生物大分子总浓度（96.3 μg L−1 vs. 40.9 μg L−1）是非SCTR光区生物大分子浓度的两倍多，反映出生物生产力的增强。在SCTR的凋亡层中也检测到大分子浓度升高。值得注意的是，SCTR中从光层到光层的蛋白质与碳水化合物比率下降不太明显，这表明该地区下沉到深海的POM相对较新鲜，降解程度较低，表明生物碳泵更有效，碳固存潜力增强。这些发现强调了SCTR是生物生产力提高和驱动生物地球化学循环的独特环境机制的关键区域，为热带上升流系统的有机质保存和碳输出过程及其在全球海洋生态系统中的作用提供了重要见解。

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引用次数: 0