Quantification and characterization of coastal dissolved organic matter by high‐performance size exclusion chromatography with ultraviolet absorption, fluorescence, and total organic carbon analyses

Shimotori, Koichi; Satou, Takayuki; Imai, Akio; Kawasaki, Nobuyuki; Komatsu, Kazuhiro; Kohzu, Ayato; Tomioka, Noriko; Shinohara, Ryuichiro; Miura, Shingo

doi:10.1002/lom3.10118

Cited by 18 publications

(9 citation statements)

References 64 publications

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“…In seawater, inorganic Hg(II) speciation is thought to be mainly controlled by complexation with chloride, bromide, and DOM. Recent studies demonstrated that DOM in coastal water is dominated (≥75%) by low MW (MW ≤ 2 kDa) hydrophilic fulvic-like organic matter. , The size of these predominant DOM, based on their MW, can be estimated to be a few nanometers. Therefore, Hg(II) complexes with these small DOM may diffuse through the gel and contribute to the observed Hg(II) dyn fraction.…”

Section: Resultsmentioning

confidence: 99%

In Situ Voltammetric Sensor of Potentially Bioavailable Inorganic Mercury in Marine Aquatic Systems Based on Gel-Integrated Nanostructured Gold-Based Microelectrode Arrays

et al. 2021

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The development and field validation of newly designed nanostructured gold-plated gelintegrated microelectrode arrays (Au-GIME) applied to the direct in situ Square Wave Anodic Stripping Voltammetry (SWASV) quantification of the potentially bioavailable inorganic mercury (Hg(II)) species in coastal area are presented. The Au-GIME consists of arrays of 100 to 500 interconnected iridium (Ir)-based microdisks that are electroplated with renewable Au nanoparticles (AuNP) or Au nanofilaments (AuNF) and covered with an agarose gel. The gel protects the sensor surface from fouling and ensures that mass transport of analytes toward the sensor surface is by pure diffusion only and therefore independent of the ill-controlled convective conditions of the media. The responses of these sensors to direct SWASV measurements of inorganic Hg(II) at near-neutral pH were investigated first in synthetic media, then in UV irradiated marine samples. The analytical responses were found to be correlated to the number of interconnected microelectrodes and the morphology of the nanostructured Au deposits, and independent of the media composition for chloride concentration  0.2M (salinity S  13) and pH ranging from 7 to 8.5. The AuNF-GIMEs have detection and quantification limits at the low pM level, fulfilling the requirement of sentinel tools for real-time monitoring of the dynamic fraction of Hg(II) in coastal area. The AuNF-GIMEs were incorporated in an in-house advanced multi-channel sensing probe for remote in situ highresolution trace metal monitoring. Field evaluation and validation were successfully performed as 2 part of a field study in the Arcachon Bay (France), from which environmental data are presented. This work marks the first time that an autonomous electrochemical sensing probe successfully measures Hg(II) and its hourly temporal variation in situ without chemical modification of the sample.

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Section: Resultsmentioning

confidence: 99%

In Situ Voltammetric Sensor of Potentially Bioavailable Inorganic Mercury in Marine Aquatic Systems Based on Gel-Integrated Nanostructured Gold-Based Microelectrode Arrays

et al. 2021

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“…Traditional methods focusing on DOM molecular size are typically not capturing the continuous nature of the size distribution, but relying on either operational cutoffs (e.g., tangential ultrafiltration techniques) or simplifying indices of the size spectrum (e.g., averaged molecular weight from size‐exclusion chromatography). However, Shimotori et al (2016) showed that photochemical characteristics of natural DOM depend on molecular sizes. In order to examine the continuous DOM size distribution in more detail, we applied a decomposition method that aims to utilize all the potential information contained in the size‐exclusion chromatograms.…”

Section: Discussionmentioning

confidence: 99%

“…Size‐separated DOM molecules are commonly detected and analyzed with absorbance or fluorescence detectors in size‐exclusion chromatography setups (Shimotori et al 2016). The chosen detector wavelength has also important consequences on the results.…”

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confidence: 99%

“…The few studies that have expanded the analytical window beyond one wavelength, have shown that the molecular size characteristics (such as apparent molecular weight) are wavelengths‐dependent (O'Loughlin and Chin 2001; Yan et al 2012; Wünsch et al 2018). Other detection methods such as DOC detection (Huber and Frimmel 1994; Dittmar and Kattner 2003; Shimotori et al 2016) and mass spectrometry (Minor et al 2002; Wu et al 2004) have been used to analyze the size‐separated molecules. Each size‐exclusion chromatography analysis yields a detailed chromatogram with a wealth of information, which is usually not utilized to its full potential with traditional metrics of, e.g., average molecular weight.…”

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confidence: 99%

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Identification of dissolved organic matter size components in freshwater and marine environments

Asmala

Massicotte

Carstensen

2021

Limnology & Oceanography

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Dissolved organic matter (DOM) in the transition zone from freshwater to marine systems was analyzed with a new approach for parameterizing the size distribution of organic compounds. We used size‐exclusion chromatography for molecular size analysis and quantified colored DOM (CDOM) on samples from two coastal environments in the Baltic Sea (Roskilde Fjord, Denmark and Gulf of Gdansk, Poland). We applied a Gaussian decomposition method to identify peaks from the chromatograms, providing information beyond bulk size properties. This approach complements methods where DOM is separated into size classes with pre‐defined filtering cutoffs, or methods where chromatograms are used only to infer average molecular weight. With this decomposition method, we extracted between three and five peaks from each chromatogram and clustered these into three size groups. To test the applicability of our method, we linked our decomposed peaks with salinity, a major environmental driver in the freshwater‐marine continuum. Our results show that when moving from freshwater to low‐salinity coastal waters, the observed steep decrease of apparent molecular weight is mostly due to loss of the high‐molecular‐weight fraction (HMW; >2 kDa) of CDOM. Furthermore, most of the CDOM absorbance in freshwater originates from HMW DOM, whereas the absorbing moieties are more equally distributed along the smaller size range (< 2 kDa) in marine samples.

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“…Potassium hydrogen phthalate (Kanto Chemical) was used as a standard. Additionally, molecular size distributions of DOC were measured by high-performance size exclusion chromatography (HPSEC) with total organic carbon detectors in monoplicate, according to Kawasaki et al (2011) and Shimotori et al (2016). In the HPSEC analysis, there were two peaks of weight-averaged molecular sizes (M w ) of 1.3 ± 0.1 × 10 5 Da and 2.2 ± 0.2 × 10 3 Da (n = 117), and we defined them as high-molecular-weight DOC (HMW-DOC) and low-molecular-weight DOC (LMW-DOC), respectively, in the present study.…”

Section: Sample Analysismentioning

confidence: 99%

Horizontal variability and regulation of bacterial production in Lake Biwa, Japan

et al. 2021

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To clarify horizontal variability and regulation of bacterial production (BP), we investigated BP and environmental variables along three east-west transects (lines 12, 15, and 17) covering inshore/offshore stations in Lake Biwa, Japan, during four seasons using 15 N-labeled deoxyadenosine for measuring BP. In winter, surface BP along Line 12 (southern transect) was higher than Lines 15 and 17 (central and northern transects) and reflected the water-temperature distribution. Additionally, any nutrients and dissolved organic carbon did not correlate to BP, suggesting water temperature primarily regulated BP in winter. In spring, surface BP was higher at eastern inshore stations, near large agricultural fields, and was correlated with nutrient concentrations rather than water temperature, suggesting that the limitation shifted to nutrient availability. In summer, surface BP at offshore stations along Lines 15 and 17 was notably lower than the other stations, and the horizontal heterogeneity became largest (maximum to minimum BP ratio = 9.5, compared to 2.8 ~ 4.1 in the other seasons). The BP was also positively correlated to nutrient concentrations, especially phosphorus. Surface BP in autumn also showed higher values at eastern stations as well as spring and positively correlated to phosphorus concentration. Additionally, there was a negative relationship between BP and water temperature, suggesting that bacterial growth was enhanced by groundwater seepage at the eastern stations. The results suggest that the horizontal distribution is characterized by a north-south distribution with a temperature gradient in winter, and allochthonous nutrient loading determines horizontal BP variations in the other seasons in this lake.

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Quantification and characterization of coastal dissolved organic matter by high‐performance size exclusion chromatography with ultraviolet absorption, fluorescence, and total organic carbon analyses

Cited by 18 publications

References 64 publications

In Situ Voltammetric Sensor of Potentially Bioavailable Inorganic Mercury in Marine Aquatic Systems Based on Gel-Integrated Nanostructured Gold-Based Microelectrode Arrays

In Situ Voltammetric Sensor of Potentially Bioavailable Inorganic Mercury in Marine Aquatic Systems Based on Gel-Integrated Nanostructured Gold-Based Microelectrode Arrays

Identification of dissolved organic matter size components in freshwater and marine environments

Horizontal variability and regulation of bacterial production in Lake Biwa, Japan

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