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Microplastics in wild Saccostrea cucullata oysters in Sri Lanka: Pollution status and risk assessment 斯里兰卡野生 Saccostrea cucullata 牡蛎中的微塑料:污染状况和风险评估
IF 3 3区 地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY Pub Date : 2024-09-24 DOI: 10.1016/j.marchem.2024.104457
K.P.G.K.P. Guruge , K.M.S.N. Abeysinghe , Tharindu Bandara , P.B.T.P. Kumara
Microplastics (MPs) have widely been reported in many marine organisms that cause significant environmental concern. Oysters are known to accumulate MPs through their filter-feeding mechanism yet studies focused on MPs pollution in oysters along with ecological risk assessment are scarce. In this study, we investigated MPs pollution in wild Saccostrea cucullata oysters and assessed the ecological risk of MPs pollution in oysters and their habitats along the southern and western coasts of Sri Lanka. Oyster MPs abundance varied from 0.63 to 2.20 particles g−1 wet weight (ww), which showed a significant positive correlation with MPs abundances in surrounding surface seawater and surface sediment. The average MPs abundances in oysters, surface seawater and surface sediment showed significant spatial differences where high MPs abundances were reported in areas that had high anthropogenic activities. Size classification of MPs revealed that small size (100 μm-1 mm) blue fibres were dominant in oysters, surface seawater and surface sediment likely due to the high abundance of discarded fishing nets in studied areas. The abundance of various polymer types indicated that low-density polyethene polymers were most abundant (oysters, 45.74 %; surface seawater, 42.91 % and surface sediment, 39.62 %). Results of the ecological risk assessment indicated that MPs pollution in the environment was low (Level I). However, MPs pollution in oysters ranged from low to moderate risk levels (Level I-II), where moderate risk was reported in the areas with high MPs contamination. Therefore, our study highlights that mitigation of MPs pollution on the southern and western coast of Sri Lanka is important to alleviate the increasing ecological risk of MPs pollution in Saccostrea cucullata.
微塑料(MPs)在许多海洋生物中被广泛报道,引起了重大的环境问题。众所周知,牡蛎会通过其滤食机制积累 MPs,但有关牡蛎中 MPs 污染以及生态风险评估的研究却很少。在这项研究中,我们调查了斯里兰卡南部和西部海岸野生 Saccostrea cucullata 牡蛎中的 MPs 污染情况,并评估了 MPs 污染对牡蛎及其栖息地造成的生态风险。牡蛎的 MPs 丰度在 0.63 至 2.20 微粒 g-1 湿重(ww)之间变化,与周围表层海水和表层沉积物中的 MPs 丰度呈显著正相关。牡蛎、表层海水和表层沉积物中 MPs 的平均丰度显示出明显的空间差异,在人为活动频繁的地区 MPs 丰度较高。MPs的尺寸分类显示,在牡蛎、表层海水和表层沉积物中,小尺寸(100 μm-1 mm)蓝色纤维占主导地位,这可能是由于研究地区存在大量废弃渔网。各类聚合物的含量表明,低密度聚乙烯聚合物含量最高(牡蛎,45.74%;表层海水,42.91%;表层沉积物,39.62%)。生态风险评估结果表明,环境中的多溴联苯醚污染程度较低(I 级)。然而,牡蛎中的 MPs 污染程度从低到中度不等(I-II 级),其中 MPs 污染程度较高的地区报告了中度风险。因此,我们的研究强调,斯里兰卡南部和西部沿海地区必须减轻 MPs 污染,以缓解 Saccostrea cucullata 不断增加的 MPs 污染生态风险。
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引用次数: 0
Tracking suspended particulate organic matter biochemistry from glacial meltwater runoff to coastal waters of an Antarctic fjord 跟踪从冰川融水径流到南极峡湾沿岸水域的悬浮颗粒有机物生物化学过程
IF 3 3区 地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY Pub Date : 2024-09-22 DOI: 10.1016/j.marchem.2024.104455
Claudia Parodi , Luis Cerpa , Zhuoyi Zhu , Jing Zhang , Pablo Muniz , Natalia Venturini
Increased glacier melting runoff in Antarctica involves intensification of freshwater, nutrients, sediments and organic matter inputs from land to the sea, which is impacting coastal ecosystems. Basic environmental characteristics of water and biochemical composition of suspended particulate organic matter (POM) both in the proglacial melting runoff system (PROGLARS) of Collins Glacier and marine surface waters of Collins Bay was studied based on organic biopolymers and molecular level analysis of amino acids (AAs), to discern among sources and degradation state in the two environments. Hierarchical Clustering Analysis revealed that PROGLARS stations and marine stations form two distinct groups in terms of water physicochemical characteristics and suspended POM biochemical composition. These differences are the consequence of low restricted contribution of freshwater from Collins Glacier runoff into the coastal-marine environment. Our results evidenced low concentrations of terrestrial suspended POM in marine waters of Collins Bay mainly attributed to low meltwater inputs between the 1st and 7th of February 2018. In terms of macromolecular composition, the predominance of proteins, denote the labile nature of suspended POM in the two environments. Suspended POM in Collins Bay is labile, poorly degraded, representing a protein supplemented food resource, with high energetic value and easily assimilated by heterotrophic marine organism. AAs composition supported less degraded suspended POM derived from marine phytoplankton in surface waters of Collins Bay, whereas, great degradation of suspended POM in the proglacial runoff system of Collins Glacier. Changes in the biochemistry of suspended POM caused by glacial melting and retreat, may affect food features and availability, the productivity of ecosystems, and ultimately, the capacity of Antarctic fjords to act as carbon sinks and climate regulators. Considering low influence of Collins Glacier meltwater in coastal marine waters of Collins Bay, due to the relatively slow retreat of Collins Glacier and low development of its meltwater runoff system, the results of our work are relevant as baseline information for comparison with other Antarctic fjords. Further knowledge about meltwater runoff and suspended POM input dynamics in Antarctic coastal ecosystems, is critical, particularly in areas prone to undergo increased glacier melting in the following decades.
南极洲冰川融化径流的增加加剧了淡水、营养物、沉积物和有机物从陆地向海洋的输入,对沿岸生态系统产生了影响。根据有机生物聚合物和氨基酸(AAs)的分子水平分析,研究了科林斯冰川的冰川融化径流系统(PROGRARS)和科林斯湾海洋表层水的水的基本环境特征和悬浮颗粒有机物(POM)的生物化学组成,以区分两种环境的来源和降解状态。分层聚类分析(Hierarchical Clustering Analysis)显示,PROGRLARS 站和海洋站在水理化特征和悬浮 POM 生物化学组成方面形成了两个不同的群体。这些差异是柯林斯冰川径流淡水进入沿岸-海洋环境受限程度低的结果。我们的研究结果表明,柯林斯湾海水中陆地悬浮 POM 浓度较低,主要归因于 2018 年 2 月 1 日至 7 日期间融水输入量较低。在大分子组成方面,蛋白质占主导地位,这表明两种环境中的悬浮 POM 都具有易变性。柯林斯湾的悬浮POM易变、降解性差,是补充蛋白质的食物资源,具有高能量价值,易被海洋异养生物同化。在柯林斯湾表层水域,来自海洋浮游植物的 AAs 成分支持降解程度较低的悬浮 POM,而在柯林斯冰川的冰川径流系统中,悬浮 POM 降解程度很高。冰川融化和后退引起的悬浮 POM 生物化学变化可能会影响食物特征和供应、生态系统的生产力,并最终影响南极峡湾作为碳汇和气候调节器的能力。考虑到柯林斯冰川融水对柯林斯湾沿岸海域的影响较小,因为柯林斯冰川退缩相对较慢,其融水径流系统开发程度较低,我们的研究结果可作为与其他南极峡湾进行比较的基线信息。进一步了解南极沿岸生态系统的融水径流和悬浮 POM 输入动态至关重要,尤其是在未来几十年冰川融化加剧的地区。
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引用次数: 0
Spatial distribution of dissolved free amino acids in three Iberian Atlantic estuaries 伊比利亚大西洋三个河口溶解游离氨基酸的空间分布
IF 3 3区 地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY Pub Date : 2024-09-18 DOI: 10.1016/j.marchem.2024.104456
Valentina Amaral , Jesús Forja , Barbara Steger-Mähnert , Gerhard J. Herndl , Cristina Romera-Castillo

Rivers and estuaries are the main link between land and ocean, transferring significant amounts of dissolved organic carbon. These ecosystems receive large amount of dissolved organic matter (DOM) from diverse sources, both allochthonous and autochthonous. Within this pool, dissolved free amino acids (DFAA) represent the most labile fraction, offering valuable insights into DOM composition and diagenetic processes. Our study focused on three Iberian Atlantic estuaries—Guadalquivir, Guadiana, and Tinto-Odiel— that differ in hydrology, land use and DOM sources. We studied the longitudinal distribution of DFAA and their response to tidal cycles across these estuaries. Despite similar DFAA concentrations between estuaries (176.6 nM to 1770 nM) were found, variations in specific amino acids like glutamic acid, taurine, and aspartic acid pointed to a substantial influence of terrestrial inputs in Guadalquivir and Guadiana estuaries and an anthropogenic influence in Tinto-Odiel. Predominant amino acids—serine, glycine, ornithine, and asparagine —comprised more than 50 mol% of the estuarine DFAA pool. The dominance of serine, glycine, and ornithine indicated substantial DOM degradation, possibly associated with the loss of labile DOM during estuarine transport. Concurrently, asparagine prevalence was linked to allochthonous DOM input particularly associated with terrestrial runoff, lateral input, and anthropogenic activities at estuarine margins. Our results underscore the impact of tidal cycles on DFAA distribution and emphasize the potential of DFAA in unraveling estuarine DOM dynamics and their role as indicators of reactivity and composition in estuarine biogeochemistry.

河流和河口是连接陆地和海洋的主要通道,可传输大量溶解有机碳。这些生态系统从不同来源(包括同源和自源)接收大量溶解有机物(DOM)。其中,溶解游离氨基酸(DFAA)是最易变的部分,可为了解 DOM 的组成和成岩过程提供有价值的信息。我们的研究重点是伊比利亚大西洋的三个河口--瓜达尔基维尔河、瓜迪亚纳河和廷托-奥迪尔河,这三个河口在水文、土地利用和 DOM 来源方面各不相同。我们研究了这些河口的 DFAA 纵向分布及其对潮汐周期的响应。尽管发现各河口之间的 DFAA 浓度相似(176.6 nM 至 1770 nM),但谷氨酸、牛磺酸和天冬氨酸等特定氨基酸的变化表明,陆地输入对瓜达尔基维尔河和瓜迪亚纳河口的影响很大,而对 Tinto-Odiel 的影响则是人为的。占主导地位的氨基酸--丝氨酸、甘氨酸、鸟氨酸和天冬酰胺--占河口 DFAA 库的 50 摩尔%以上。丝氨酸、甘氨酸和鸟氨酸占主导地位表明存在大量的 DOM 降解,这可能与河口迁移过程中可溶性 DOM 的损失有关。同时,天门冬酰胺的流行与外源 DOM 输入有关,特别是与陆地径流、横向输入和河口边缘的人为活动有关。我们的研究结果强调了潮汐周期对 DFAA 分布的影响,并强调了 DFAA 在揭示河口 DOM 动态方面的潜力,以及它们作为河口生物地球化学中反应性和组成指标的作用。
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引用次数: 0
A comparative study of optical and size properties of dissolved organic matter in the lower Mississippi River and Pearl River 密西西比河下游和珠江溶解有机物的光学和粒度特性比较研究
IF 3 3区 地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY Pub Date : 2024-09-14 DOI: 10.1016/j.marchem.2024.104453
Zhengzhen Zhou , Hui Lin , Eurico J. D'Sa , Laodong Guo

Monthly water samples were collected from the lower Mississippi and Pearl Rivers between January 2009 and August 2011 to investigate the heterogeneity in the dynamic variations of dissolved organic carbon (DOC), colloidal organic carbon, chromophoric and fluorescence dissolved organic matter (CDOM and FDOM), PARAFAC-derived fluorescent components, and other optical properties including spectral slope, specific UV absorbance (SUVA), and fluorescence indices between the two contrasting river systems. The lower Mississippi River exhibits relatively lower concentrations of DOC (306 ± 41 μM C) and CDOM (27.9 ± 5.7 m−1 at 254 nm), featuring lower aromaticity (indicated by SUVA254) and apparent molecular weight (or higher spectral slope) with weak seasonal variability. The Pearl River, in contrast, has elevated levels of DOC (537 ± 212 μM C) and CDOM (66.4 ± 31.4 m−1), characterized by higher aromaticity, higher molecular weight, and significant seasonality, primarily originating from soil-derived allochthonous sources. The abundance of the >1 kDa colloidal DOC was, on average, 58 ± 3 % of the bulk DOC in the lower Mississippi River and 68 ± 6 % in the lower Pearl River. The >1 kDa high-molecular weight DOM (HMW-DOM) consistently had lower spectral slope and biological index (BIX) values, but higher humification index (HIX) values compared to both bulk DOM and low-molecular-weight DOM (LMW-DOM) counterparts. These trends could be representative of other similar large and small rivers. Four PARAFAC-derived fluorescent components (three humic-like and one protein-like) were identified for both rivers. A positive correlation between discharge and terrestrial humic-like fluorescent components indicated their dominant allochthonous sources, while the protein-like component decreased with increasing discharge, consistent with its autochthonic source and a dilution effect during high flow seasons. The occurrence of large flood events during the sampling period contributed to large DOC pulses, with DOM of higher aromaticity and HMW-DOM. This has important implications for coastal ocean ecosystems, which are increasingly impacted by river flooding events under changing climate conditions. Our results also provide an improved understanding of DOM dynamics in two representative rivers and establish a baseline dataset for future studies to assess changes in sources and composition of DOM and their impacts on the coastal ocean in response to climate, hydrological, and anthropogenic influences.

在 2009 年 1 月至 2011 年 8 月期间,每月从密西西比河下游和珠江采集水样,研究这两条对比强烈的河流水系之间溶解有机碳 (DOC)、胶体有机碳、发色和荧光溶解有机物(CDOM 和 FDOM)、PARAFAC 衍生荧光成分以及光谱斜率、特定紫外线吸收率 (SUVA) 和荧光指数等其他光学特性的动态变化的异质性。密西西比河下游的 DOC(306 ± 41 μM C)和 CDOM(254 纳米波长下为 27.9 ± 5.7 m-1)浓度相对较低,芳香度(用 SUVA254 表示)和表观分子量(或光谱斜率较高)较低,季节变化较小。相比之下,珠江的 DOC(537 ± 212 μM C)和 CDOM(66.4 ± 31.4 m-1)含量较高,芳香度较高,分子量较大,季节性明显,主要来源于土壤异源物。在密西西比河下游,1 kDa 胶体 DOC 的丰度平均为总量 DOC 的 58 ± 3 %,在珠江下游为 68 ± 6 %。与块状 DOM 和低分子量 DOM 相比,1 kDa 高分子量 DOM(HMW-DOM)的光谱斜率和生物指数(BIX)值一直较低,但腐殖化指数(HIX)值较高。这些趋势可能在其他类似的大小河流中具有代表性。在这两条河流中发现了四种 PARAFAC 衍生的荧光成分(三种类腐殖质和一种类蛋白质)。排水量与陆生腐殖质类荧光成分之间呈正相关,表明其主要来源于同源物,而蛋白质类荧光成分则随着排水量的增加而减少,这与其自生来源和大流量季节的稀释效应相一致。采样期间发生的大洪水事件导致了大量 DOC 的产生,其中包括芳香度较高的 DOM 和高分子量 DOM。这对沿岸海洋生态系统具有重要意义,因为在不断变化的气候条件下,河流洪水事件对沿岸海洋生态系统的影响越来越大。我们的研究结果还加深了对两条代表性河流中 DOM 动态变化的了解,并为今后评估 DOM 来源和组成的变化及其对沿岸海洋在气候、水文和人为影响下的影响建立了基线数据集。
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引用次数: 0
Two-dimensional determination of dissolved manganese in sediment porewaters 沉积物孔隙水中溶解锰的二维测定
IF 3 3区 地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY Pub Date : 2024-09-14 DOI: 10.1016/j.marchem.2024.104454
Aurélia Mouret , Constance Choquel , Aubin Thibault de Chanvalon , Florian Cesbron , Thierry Jauffrais , Didier Jézéquel , Patrick Launeau , Anthony Barbe , Romain Levrard , Alan Nicol , Céline Charbonnier , Edouard Metzger

We present a new method for imaging dissolved manganese at millimeter scale by coupling DET (diffusive equilibrium in thin film) and colorimetric techniques. The method is an adaptation of the porphyrin approach for the measurement of dissolved Mn by substitution of Mn(II) and Mn(III) to Cd in the Cd(II)–POR complex. Optimization of the Cd-POR concentrations was required for transposition to 2D-DET. A commercial flatbed scanner and a hyperspectral camera were used for imaging. Using the hyperspectral camera, detection limit is about 5 μM and measuring range is up to 520 μM. The method was applied on the field in a tidal mudflat of the French Atlantic coast and in sediments inhabited by polychaetes. These first images allowed to precisely describe two-dimensional millimeter features such as burrows and highlighted the role of bioirrigation in benthic Mn fluxes. This new technique offers the possibility to investigate the reactivity of microenvironments towards dissolved Mn in two dimensions in a wide range of laboratory and in situ studies using a non-destructive tool.

我们介绍了一种通过将 DET(薄膜中的扩散平衡)和比色技术相结合,在毫米尺度上对溶解的锰进行成像的新方法。该方法是通过在 Cd(II)-POR 复合物中用锰(II)和锰(III)取代镉来测量溶解锰的卟啉方法的改良。在转用二维 DET 时需要优化 Cd-POR 的浓度。使用商用平板扫描仪和高光谱照相机进行成像。使用高光谱照相机,检测限约为 5 μM,测量范围可达 520 μM。该方法已在法国大西洋沿岸的潮汐泥滩和多毛目动物栖息的沉积物中实地应用。这些首批图像能够精确描述洞穴等二维毫米特征,并突出了生物灌溉在底栖锰通量中的作用。这项新技术提供了一种可能性,可以利用一种非破坏性工具,在广泛的实验室和现场研究中调查微环境对二维溶解锰的反应性。
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引用次数: 0
Vanadium redox speciation in the acid-extractable phase of Krka River estuary surface sediment 克尔卡河河口表层沉积物酸萃取相中钒的氧化还原分型
IF 3 3区 地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY Pub Date : 2024-09-13 DOI: 10.1016/j.marchem.2024.104452
Lucija Knežević , Nuša Cukrov , Elvira Bura Nakić

This study investigated the redox speciation and mobility of V in the acid-extractable fraction of surface sediments from the Krka River estuary using an optimized IC-UV/Vis analytical method. The separation of V(IV) and V(V) redox species was done using anion-exchange based chromatographic method, while pseudo-total V concentrations were measured using HR ICP-MS analytical instrumentation. Extracted V concentrations from the sediment fraction (pH = 5, HCl) and determined pseudo-total V concentrations were used to calculate the Enrichment Factor (EF) and Risk Assessment Code (RAC), indicating potential anthropogenic influence and environmental risk. A simple PHREEQC model was developed to asses V speciation in the oxic bottom seawater layer simulating possible remobilization of the leached sediment phase. The results of the study show that minor fraction of V is present in the acid-extractable phase across the surface sediment of Krka River estuary. Higher V mobility is mostly observed at locations rich with clay minerals, terrigenous input, and carbonates. Anthropogenic influence was linked to higher enrichment but lower mobility, suggesting binding to less mobile sediment phases (reducible, organic and residual fractions). The predominance of reduced V(IV) species in the acid-extractable sediment fraction indicates a potentially low V toxicity risk in the sediments of Krka River estuary, even in cases of high potential remobilization of V. However, the model predicted complete oxidation of V(IV) to V(V) upon remobilization into the oxic bottom water layer. This highlights the complexity of V behavior in natural estuarine systems, where the toxicity risks of possible V remobilization still remain unclear. Results of this study demonstrate the need for the strengthening efforts in speciation of V in the mobile sediment phase to obtain a cohesive outlook on its potential toxicity and biogeochemical cycling.

本研究采用优化的 IC-UV/Vis 分析方法,研究了克尔卡河口地表沉积物酸萃取部分中 V 的氧化还原分型和迁移率。使用基于阴离子交换的色谱法分离了 V(IV) 和 V(V) 氧化还原物种,同时使用 HR ICP-MS 分析仪器测量了假总 V 浓度。从沉积物部分(pH = 5,盐酸)提取的 V 浓度和确定的假总 V 浓度用于计算富集因子(EF)和风险评估代码(RAC),以显示潜在的人为影响和环境风险。开发了一个简单的 PHREEQC 模型,以模拟沥滤沉积物相可能的再移动,评估氧底层海水中的钒分 子。研究结果表明,在克尔卡河口的表层沉积物中,酸萃取相中存在少量的钒。在富含粘土矿物、陆相沉积物和碳酸盐的地方,主要观察到较高的钒迁移率。受人类活动影响,富集程度较高,但流动性较低,这表明与流动性较低的沉积物相(可还原、有机和残留组分)结合。在酸性可萃取沉积物组分中,还原型 V(IV)物种占主导地位,这表明克尔卡河口沉积物中 V 的潜在毒性风险较低,即使在 V 的潜在再移动性较高的情况下也是如此。这凸显了 V 在自然河口系统中行为的复杂性,V 在自然河口系统中可能的再移动所带来的毒性风险仍不明确。这项研究的结果表明,有必要加强对流动沉积物相中 V 的标本分析,以便对其潜在毒性和生物地球化学循环有一个全面的认识。
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引用次数: 0
Tidal scale dissolved inorganic and particulate organic carbon dynamics in a tropical estuary 热带河口潮汐尺度的溶解无机碳和颗粒有机碳动力学
IF 3 3区 地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY Pub Date : 2024-09-06 DOI: 10.1016/j.marchem.2024.104451
Mohammad Atif Khan , Sanjeev Kumar , Rajdeep Roy , Satya Prakash , Aneesh A. Lotliker , Sanjiba Kumar Baliarsingh

Dissolved inorganic carbon (DIC) and particulate organic carbon (POC) dynamics in the world's estuaries have been studied extensively at monthly, seasonal, and annual time scales with particular focus on their concentrations and export fluxes to the coastal oceans. However, given the dynamic nature of the estuaries, the effect of tidal and diel cycles on the processes modulating DIC and POC dynamics remains obscure. To decipher the biogeochemical processes at tidal scale, DIC and POC concentrations and their carbon and nitrogen isotopic compositions were measured across the salinity gradient at every high and low tide for nine consecutive days (14–23 October 2019) in the Mahanadi estuary, a tropical estuary at the east coast of India. Showing contrasting differences across salinity gradient in DIC, POC and their isotopic compositions, DIC and POC were significantly different during high and low tide in the mixing zone only during spring duration. This showed the effect of spring-neap tidal cycle owing to water level fluctuations and mixing intensity in the estuarine mixing zone. Linear least-squares regression models indicated carbonate and/or silicate weathering by biogenic CO2 to be the probable DIC source in the freshwater region of the estuary. Deviations of observed DIC concentrations and δ13CDIC from the conservative mixing values suggested pronounced alteration of DIC source signature in the mixing zone. A process-based model approach aimed at delineating possible biogeochemical processes affecting DIC dynamics indicated calcite dissolution during low tide and calcite precipitation during high tide to be dominant processes in the mixing zone. Additionally, signatures of more than one simultaneous biogeochemical process modulating the DIC dynamics were also observed. POC pool in the mixing zone was largely influenced by its removal through rapid remineralization during both high and low tides. Graphical plots also showed that POC in the mixing zone and at the saline location was significantly affected by processes such as degradation, whereas it was only slightly affected in the freshwater region of the estuary. δ13CPOC, along with the C/N ratio of POM, indicated that C3 plants and/or their derived soil were the major source of POM in the freshwater, whereas the higher contribution of riverine POM and marine phytoplankton was observed in the mixing zone and saline location, respectively.

对全球河口的溶解无机碳(DIC)和颗粒有机碳(POC)动力学进行了月度、季节和年度时间 尺度的广泛研究,重点是它们的浓度和向沿岸海洋的输出通量。然而,鉴于河口的动态性质,潮汐和昼夜周期对 DIC 和 POC 动态调节过程的影响仍不明显。为了破译潮汐尺度下的生物地球化学过程,研究人员在印度东海岸的热带河口马哈纳迪河口连续九天(2019 年 10 月 14-23 日)的涨潮和退潮时测量了不同盐度梯度的 DIC 和 POC 浓度及其碳和氮同位素组成。不同盐度梯度的 DIC、POC 及其同位素组成呈现出截然不同的差异。这表明由于水位波动和河口混合区的混合强度,春-夏潮汐周期产生了影响。线性最小二乘回归模型表明,碳酸盐和/或硅酸盐风化产生的生物源二氧化碳可能是河口淡水区域的 DIC 来源。观测到的 DIC 浓度和 δ13CDIC 与保守混合值的偏差表明,混合区的 DIC 来源特征发生了明显变化。为确定影响 DIC 动态的可能生物地球化学过程,采用了基于过程的模型方法,结果表明,退潮时的方解石溶解和涨潮时的方解石沉淀是混合区的主要过程。此外,还观察到多个生物地球化学过程同时调节 DIC 动态。混合区的 POC 池主要受涨潮和退潮期间通过快速再矿化去除 POC 的影响。图表还显示,混合区和盐水区的 POC 受降解等过程的影响较大,而河口淡水区的 POC 仅受轻微影响。δ13CPOC以及POM的C/N比表明,C3植物和/或其衍生土壤是淡水中POM的主要来源,而在混合区和盐碱地,河流POM和海洋浮游植物的贡献率分别较高。
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引用次数: 0
A protocol for the synthesis of [35S]-labeled 3-dimethylsulfoniopropionate and dimethylsulfide from L-methionine for use in biogeochemical studies 从 L-蛋氨酸合成[35S]标记的 3-二甲基硫代丙酸酯和二甲基硫醚以用于生物地球化学研究的方案
IF 3 3区 地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY Pub Date : 2024-09-01 DOI: 10.1016/j.marchem.2024.104440
Alexandra M. Smith , Daniela A. del Valle , Alison N. Rellinger , Jeffrey W. Krause , Ronald P. Kiene

Radiotracers are highly sensitive tools for quantifying the rates of important biogeochemical processes and the fates of specific atoms and/or compounds within major global elemental cycles, especially those that are requisite for life. Important radiolabeled organosulfur compounds, like dimethylsulfide (DMS) and its precursor 3-dimethylsulfoniopropionate (DMSP), are not commercially available, but their well-documented use has been key in furthering our understanding of the marine sulfur cycle. [35S]-DMSP obtained by chemical synthesis has been used extensively in radiotracer studies involving DMS and DMSP, but its synthesis has been restricted to 2 research groups. Presented here is a protocol for the chemical synthesis of [35S]-DMSP from [35S]-L-methionine, though the method could be used for other radiolabels (e.g. [14C], [3H]). The synthesis consists of 2 reaction steps, (1) the sequential oxidative deamination and decarboxylation of [35S]-L-methionine to [35S]-3-methylmercaptopropionate and (2) the methylation of [35S]-methylmercaptopropionate to yield the product [35S]-DMSP. The product is purified by liquid chromatography and two cation-resin exchanges. Average final [35S]-DMSP yield was 5.34% (n = 16; range: 1.26% to 14.84%, excluding failures), although updated instrumentation could likely improve final yields. The objective of this work is to standardize the synthesis of [35S]-DMSP to widen its availability and use among the community and hence facilitate increased understanding of the reduced sulfur and carbon cycles.

放射性示踪剂是一种高度灵敏的工具,可用于量化重要生物地球化学过程的速率以及全球主要元素循环中特定原子和/或化合物的命运,特别是那些生命必需的元素。重要的放射性标记有机硫化合物,如二甲基硫醚(DMS)及其前体 3-二甲基硫代丙酸酯(DMSP),目前还不能在市场上买到,但它们的使用已得到充分证明,是我们进一步了解海洋硫循环的关键。通过化学合成获得的[35S]-DMSP 已广泛用于涉及 DMS 和 DMSP 的放射性示踪剂研究,但其合成仅限于两个研究小组。这里介绍的是一种从[35S]-L-蛋氨酸化学合成[35S]-DMSP的方法,不过该方法也可用于其他放射性标记(如[14C]、[3H])。合成过程包括两个反应步骤:(1)[35S]-L-蛋氨酸依次氧化脱氨和脱羧成[35S]-3-甲硫基丙酸酯;(2)[35S]-甲硫基丙酸酯甲基化生成产物[35S]-DMSP。产物通过液相色谱法和两次阳离子-树脂交换进行纯化。平均最终[35S]-DMSP 收率为 5.34%(n = 16;范围:1.26% 至 14.84%,不包括失败),尽管更新仪器有可能提高最终收率。这项工作的目的是使[35S]-DMSP 的合成标准化,以扩大其在社区中的可用性和使用范围,从而促进对还原硫和碳循环的进一步了解。
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引用次数: 0
Effect of temperature on the production and degradation of bromoform and other brominated methanes by marine microorganisms 温度对海洋微生物生产和降解溴甲烷及其他溴化甲烷的影响
IF 3 3区 地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY Pub Date : 2024-08-22 DOI: 10.1016/j.marchem.2024.104443
Yuki Okuda, Hayato Yamashita, Shinya Hashimoto
<div><p>Brominated methanes such as bromoform (CHBr<sub>3</sub>) are known to be important carriers of bromine from the ocean to the atmosphere. Bromine released from brominated methanes by photolysis has been shown to catalyze ozone depletion. Marine phytoplankton has been reported as a source of CHBr<sub>3</sub> and marine bacteria as a sink for CHBr<sub>3</sub>. The effects of temperature on both CHBr<sub>3</sub> production by phytoplankton and CHBr<sub>3</sub> degradation by bacteria have yet to be investigated. We investigated the effects of temperature on CHBr<sub>3</sub> production and CHBr<sub>3</sub> degradation by marine microorganisms. The marine diatom <em>Ditylum brightwellii</em> (CCMP358) was cultured at 15 °C, 20 °C, 24 °C, and 30 °C. The maximum CHBr<sub>3</sub> production rate at 24 °C was 1.57–2.39 pmol (μg chlorophyll <em>a</em>)<sup>−1</sup> d<sup>−1</sup>, several times higher than that at 15 °C (0.25–0.41 pmol (μg chlorophyll <em>a</em>)<sup>−1</sup> d<sup>−1</sup>). Higher rates of CHBr<sub>3</sub>, CHBr<sub>2</sub>Cl, and CHBrCl<sub>2</sub> production were observed in the late exponential phase (and stationary phase) than in the early exponential phase at each temperature. These results suggest that temperature affects the rate of CHBr<sub>3</sub> production during plankton growth. We then cultured the marine α-proteobacterium <em>Phaeobacter gallaeciensis</em> (JCM 21319) and the γ-proteobacterium <em>Pseudomonas</em> sp. HKF-4 at 10 °C, 15 °C, 20 °C, and 25 °C for up to 15 days to analyze temperature effects on spiked <sup>13</sup>CHBr<sub>3</sub> degradation. The degradation rate of <sup>13</sup>CHBr<sub>3</sub> by <em>P. gallaeciensis</em> increased with increasing temperature from 10 °C to 25 °C. The half-life of <sup>13</sup>CHBr<sub>3</sub> at 25 °C was about 1.1 d, which is about 6 times shorter than the half-life at 10 °C (about 6.9 d). On the other hand, the change in the half-life of the degradation of <sup>13</sup>CHBr<sub>3</sub> by HKF-1 was relatively small as the temperature increased from 10 °C (half-life: about 5.5 d) to 25 °C (half-life: about 1.8 d). Considering the rate of CHBr<sub>3</sub> production and degradation at each temperature, we estimated how much of the CHBr<sub>3</sub> produced by <em>D. brightwellii</em> for 7 days was degraded by the coexisting bacteria and how much remained after 7 days at each temperature. When coexisting with <em>P. gallaeciensis</em>, the residual CHBr<sub>3</sub> concentration in the culture was relatively higher at 20–25 °C. Similarly, when coexisting with HKF-4, it was relatively higher at 20–25 °C. To estimate the impact of future warming on CHBr<sub>3</sub> concentrations in the oceans, we assume a 5 °C increase in sea surface temperature, with two sea surface temperatures, 15 °C and 20 °C, changing to 20 °C and 25 °C, respectively. Under this assumption, the residual concentration of CHBr<sub>3</sub> produced by <em>D. brightwellii</em> in seawater would be “i
众所周知,溴化甲烷(如溴甲烷(CHBr3))是溴从海洋进入大气的重要载体。溴化甲烷通过光解释放出的溴已被证明会催化臭氧消耗。据报道,海洋浮游植物是 CHBr3 的来源,而海洋细菌则是 CHBr3 的吸收汇。温度对浮游植物产生 CHBr3 和细菌降解 CHBr3 的影响尚待研究。我们研究了温度对海洋微生物产生 CHBr3 和降解 CHBr3 的影响。海洋硅藻 Ditylum brightwellii (CCMP358) 在 15 ℃、20 ℃、24 ℃ 和 30 ℃ 下培养。24 °C时的最大CHBr3产生率为1.57-2.39 pmol (μg chlorophyll a)-1 d-1,是15 °C时(0.25-0.41 pmol (μg chlorophyll a)-1 d-1)的数倍。在每种温度下,指数期后期(和静止期)的 CHBr3、CHBr2Cl 和 CHBrCl2 生成速率均高于指数期早期。这些结果表明,温度会影响浮游生物生长过程中 CHBr3 的产生速率。然后,我们在 10 °C、15 °C、20 °C 和 25 °C下培养海洋α-proteobacterium phaeobacter gallaeciensis (JCM 21319) 和 γ-proteobacterium Pseudomonas sp. HKF-4 长达 15 天,分析温度对 13CHBr3 降解的影响。从 10 ℃ 到 25 ℃,随着温度的升高,P. gallaeciensis 对 13CHBr3 的降解率也随之升高。13CHBr3 在 25 °C 下的半衰期约为 1.1 d,比 10 °C 下的半衰期(约 6.9 d)短约 6 倍。另一方面,HKF-1 降解 13CHBr3 的半衰期随着温度从 10 ℃(半衰期:约 5.5 d)升至 25 ℃(半衰期:约 1.8 d)的变化相对较小。考虑到 CHBr3 在每个温度下的产生和降解速率,我们估算了在每个温度下,D. brightwellii 7 天产生的 CHBr3 被共存细菌降解的数量以及 7 天后剩余的数量。当与 P. gallaeciensis 共存时,20-25 °C时培养物中残留的 CHBr3 浓度相对较高。同样,当与 HKF-4 共存时,20-25 °C时的残余 CHBr3 浓度也相对较高。为了估计未来气候变暖对海洋中 CHBr3 浓度的影响,我们假设海面温度上升 5 °C,15 °C 和 20 °C 两种海面温度分别变为 20 °C 和 25 °C。根据这一假设,当 P. gallaeciensis 在这些区域共存时,海水中 D. brightwellii 产生的 CHBr3 的残余浓度将 "增加"(或者,不太可能是 "不变")。同样,在 HKF-4 共存的海水区域,当温度升高 5 °C,D. brightwellii 产生的 CHBr3 残留物总量也会增加。如果如本研究结果所示,温度对海洋中微生物 CHBr3 的产生和降解有影响,那么未来表层海水温度的升高可能会导致开阔洋中 CHBr3 浓度呈上升趋势,尽管这种影响会受到浮游植物物种和共存细菌物种的很大影响。
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引用次数: 0
Radiocarbon research on meltwater and carbon cycling in the polar oceans in a changing climate 气候变化中极地海洋融水和碳循环的放射性碳研究
IF 3 3区 地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY Pub Date : 2024-08-17 DOI: 10.1016/j.marchem.2024.104442
Ling Fang , Hojung Kim , DongHui Shangguan , Minkyoung Kim

Radiocarbon (14C) is a widely used tool with applications that transcend disciplinary boundaries, including the marine chemistry field. The development of 14C measurement techniques and icebreaking research vessels especially encourage and support polar research using 14C. Research examining 14C in polar oceans in the context of climate change has led to considerable insight into the marine carbon cycle. A comprehensive review of the principles, applications, progress, and challenges of 14C will undoubtedly advance related polar research. This review compiled available literature on 14C in the polar oceans and summarizes current progresses in carbon cycling, glacial and ice sheet dynamics, water circulation, and ventilation. The impact of warming induced melting sea ice and glaciers on marine biogeochemical cycles, future environmental challenges and research directions have also been summarized. The limitations of existing 14C research in polar regions can be addressed through well-designed and continuous investigation, data and sample sharing, and the development of state-of-the-art 14C measurement techniques.

放射性碳(14C)是一种应用广泛的工具,其应用超越了学科界限,包括海洋化学领域。14C 测量技术和破冰研究船的发展尤其鼓励和支持利用 14C 进行极地研究。在气候变化背景下对极地海洋中 14C 进行的研究使人们对海洋碳循环有了更深入的了解。对 14C 的原理、应用、进展和挑战进行全面回顾,无疑将推动相关的极地研究。本综述汇编了有关极地海洋中 14C 的现有文献,并总结了当前在碳循环、冰川和冰盖动力学、水循环和通风方面取得的进展。还总结了气候变暖导致海冰和冰川融化对海洋生物地球化学循环的影响、未来环境挑战和研究方向。通过精心设计和持续调查、数据和样本共享以及开发最先进的 14C 测量技术,可以解决极地地区现有 14C 研究的局限性。
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引用次数: 0
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Marine Chemistry
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