1,721,258 research outputs found
Expanding the Limits of Structural Characterization of Marine Dissolved Organic Matter Using Nonuniform Sampling Frequency-Reversed Edited HSQC NMR
Full text linkThe multiplicity-edited heteronuclear single quantum correlation (ME-HSQC) NMR method is widely used for the structural characterization of marine dissolved organic matter (DOM), which is a complex molecular mixture comprising millions of individual compounds. However, the standard ME-HSQC suffers from significant signal cancellation and subsequent loss of crucial structural information due to the overlap between CH3/CH (positive) and CH2 (negative) cross-peaks in overcrowded regions. This study introduces nonuniform sampling in frequency-reversed ME-HSQC (NUS FR-ME-HSQC), highlighting its remarkable potential for the comprehensive structural characterization of marine DOM. By reversing the frequency of CH2 cross-peaks into an empty region, the FR-ME-HSQC method effectively simplifies the spectra and eliminates signal cancellation. We demonstrate that nonuniform sampling enables the acquisition of comparable spectra in half the time or significantly enhances the sensitivity in time-equivalent spectra. Comparative analysis also identifies vulnerable CH2 cross-peaks in the standard ME-HSQC that coincide with CH3 and CH cross-peaks, resulting in the loss of critical structural details. In contrast, the NUS FR-ME-HSQC retains these missing correlations, enabling in-depth characterization of marine DOM. These findings highlight the potential of NUS FR-ME-HSQC as an advanced NMR technique that effectively addresses challenges such as signal overcrowding and prolonged experimental times, enabling the thorough investigation of complex mixtures with implications in several fields, including chemistry, metabolomics, and environmental sciences. The advantages of NUS FR-ME-HSQC are experimentally demonstrated on two solid-phase-extracted DOM (SPE-DOM) samples from the surface and deep ocean. With this new technology, differences in the composition of DOM from various aquatic environments can be assigned to individual molecules
Molecular formulae assignments and compound category classifications from the 58th Japanese Antarctic Research Expedition
No full textThe sampling campaign was conducted during the austral summer between December 2016 and February 2017 as a part of the 58th Japanese Antarctic Research Expedition. On Sôya Coast (Lützow-Holm Bay, East Dronning Maud Land, East Antarctica), there are hundreds of lakes with variable water chemistry which were formed during the last 7,000 years under the glacier retreat and iso-static uplifts that occurred after the Last Glacial Maximum. Water samples were collected either at the center of the lakes or at the shore into 550-mL PET bottles after rinsing more than three times with the collected water. Within a few hours after sampling, samples were filtered through pre-combusted (450dc, >3 h) glass-fiber filters (nominal pore size 0.3mm, GF-75, Advantec, Tokyo, Japan) into pre-combusted glass bottles (see doi:10.1016/J.WATRES.2019.114901). The filtered samples were immediately spiked with sodium azide (final concentration of 0.02%) for preservation, stored dark at 5dc, and shipped back to Japan. DOM was extracted and desalted prior to FT-ICR MS analysis following an established method using cartridges filled with a styrene-divinylbenzene copolymer (Agilent Bond Elut PPL, 100 mg). Depending on the DOC concentration, the volume used for extraction was adjusted such that 4 µmol C was applied to each cartridge. We performed a mass spectrometric analysis of DOM extracts via FT-ICR MS on a 15 Tesla solariX XR Fourier-transform ion cyclotron resonance mass spectrometer (Bruker Daltonik GmbH, Bremen, Germany). The system was equipped with an electrospray ionization source (ESI, Bruker Apollo II) applied in negative ionization mode. Methanol extracts were mixed with ultrapure water (50:50 v/v) for FT-ICR MS analysis and diluted to a final DOC concentration of 2.5 mg C/L. 200 single scans with an ion accumulation time of 0.1 s were recorded over a mass range of m/z 92 to 2,000 Da and added to one spectrum. Data processing, molecular formulae assignments, and compound category classifications were done with the software package ICBM-OCEAN
Dissolved organic matter composition in Antarctic streams (Sôya Coast, Lützow-Holm Bay, East Dronning Maud Land, East Antarctica) derived from FT-ICR-MS analyses during JARE58
No full textThe sampling campaign was conducted during the austral summer in January 2017 as a part of the 58th Japanese Antarctic Research Expedition. There are several ice-free areas on Sôya Coast with hundreds of lakes and several streams, which were formed during the last 7,000 years under the glacier retreat and iso-static uplifts that occurred after the Last Glacial Maximum. The Langhovde ice-free area is located ~25 km away from Japan's Syowa Station. The Yukidori and Yatsude Valleys in Langhovde run from the edge of the continental ice sheet to Lutzow-Holm Bay. At each stream of the valleys, water samples were directly collected into 550-mL volume polyethylene terephthalate bottles after rinsing more than three times with the collected water. The collected waters were filtered in a field laboratory within a few hours after sampling. Samples were filtered through pre-combusted (450dc, >3 h) glass-fiber filters (nominal pore size 0.3mm, GF-75, Advantec, Tokyo, Japan) into pre-combusted glass bottles (see doi:10.1016/J.WATRES.2019.114901). The filtered samples were immediately spiked with sodium azide (final concentration of 0.02%) for preservation, stored dark at 5dc, and shipped back to Japan. DOM was extracted and desalted prior to FT-ICR MS analysis following an established method using cartridges filled with a styrene-divinylbenzene copolymer (Agilent Bond Elut PPL, 100 mg). Depending on the DOC concentration, the volume used for extraction was adjusted such that 4 µmol C was applied to each cartridge. We performed a mass spectrometric analysis of DOM extracts via FT-ICR MS on a 15 Tesla solariX XR Fourier-transform ion cyclotron resonance mass spectrometer (Bruker Daltonik GmbH, Bremen, Germany). The system was equipped with an electrospray ionization source (ESI, Bruker Apollo II) applied in negative ionization mode. Methanol extracts were mixed with ultrapure water (50:50 v/v) for FT-ICR MS analysis and diluted to a final DOC concentration of 2.5 mg C/L. 200 single scans with an ion accumulation time of 0.1 s were recorded over a mass range of m/z 92 to 2,000 Da and added to one spectrum. Data processing, molecular formulae assignments, and compound category classifications were done with the software package ICBM-OCEAN
(Table 1) Normalized peak intensities from solid phase extracted dissolved organic matter from porewater and overlying bottom water collected during Maria S. Merian cruise MSM29 and Polarstern cruise PS85 to the Fram Strait
No full textDissolved organic matter molecular analyses were performed on a Solarix FT-ICR-MS equipped with a 15 Tesla superconducting magnet (Bruker Daltonic) using a an electrospray ionization source (Bruker Apollo II) in negative ion mode. Molecular formula calculation for all samples was performed using an Matlab (2010) routine that searches, with an error of < 0.5 ppm, for all potential combinations of elements including including the elements C∞, O∞, H∞, N = 4; S = 2 and P = 1. Combination of elements NSP, N2S, N3S, N4S, N2P, N3P, N4P, NS2, N2S2, N3S2, N4S2, S2P was not allowed. Mass peak intensities are normalized relative to the total molecular formulas in each sample according to previously published rules (Rossel et al., 2015; doi:10.1016/j.marchem.2015.07.002). The final data contained 7400 molecular formulae
(Table S2) Contribution of formulas and elemental ratios of solid phase extracted dissolved organic matter from porewater and overlying bottom water collected during Maria S. Merian cruise MSM29 and Polarstern cruise PS85 to the Fram Strait
No full textContribution of different molecular categories, H/Cwa and O/Cwa elemental ratios, aromaticity index (Aimodwa) and double bond equivalents (DBEwa) and indices of degradation (Ideg) and lability (MLBwl; Ibioprod). The contribution of each molecular category is expressed as a percentage of the total formulas in each sample obtained after normalization. Molecular formulas were additionally associated with different molecular categories because less than 6% of the DOM has been identified on a molecular level. Molecular categories are defined as follow: 1) condensed aromatics, with an AImod ≥ 0.67 (Koch and Dittmar, 2006, doi:10.1002/rcm.2386) was separated in 3 different subgroups, either 0.5 but 2, O/C 0.9 and with either no (sugars) or with heteroatoms (sugars-CHOx) and 7)unsaturated with N (unsaturated-N) molecular formulas, with 1.5 0. Additionally, polyphenols, highly unsaturated and unsaturated aliphatics were further separated in oxygen rich (-O-rich) and oxygen poor (-O-poor) if the element ratio O/C was > 0.5 or < 0.5 respectively
Dissolved organic carbon and total dissolved nitrogen in sediment porewater and overlying bottom water collected during Maria S. Merian cruise MSM29 and Polarstern cruise PS85 to the Fram Strait
No full textThis data shows concentrations of dissolved organic carbon and total dissolved nitrogen measured in overlying bottom water and sediment porewaters via catalytic oxidation at high temperature with a TOC-VCPH Shimadzu instrument (Stubbins and Dittmar, 2012; doi:10.4319/lom.2012.10.347)
Dissolved organic carbon and solid-phase extracted DOC, and Fourier Transform Ion Cyclotron Resonance Mass Spectrometry results for bottom water and porewater samples collected from the German Bight, during RV Heincke cruises HE582 and HE595
No full textThis dataset presents detailed information on the sampling sites, dissolved organic carbon (DOC) concentrations, and molecular characteristics of solid-phase extracted DOC (SPE-DOC) from bottom water (BW) and porewater (PW) samples collected in the German Bight, North Sea, during RV Heincke cruises HE582 and HE595. The data include average elemental compositions (C, H, O, N, S, P) and relative abundances of major compound classes and structural groups derived from FT-ICR-MS analysis. These molecular-level results provide insights into compositional differences between BW and PW DOM and reveal the selective preservation and transformation processes governing organic matter across the sediment–water interface
Structural fingerprints of individual molecular formulae in DOM from fragmentation experiments on a set of four marine and one freshwater environments
No full textEVENTS:
Antarctic Bottom Water AABW (pooled sample) * LATITUDE: 30° 60' S; 25° 60' S * LONGITUDE: 30° 60' W; 39° 0' W * DEPTH: 4100 m; 4000 m * DATE: 2012-04-18; 2012-04-20 * CRUISE: ANT XXVIII/5 RV Polarstern * DEVICE: rosette sampler
Eurafrican Mediterranean Water EMW (pooled sample) * LATITUDE: 35° 14' N; 38° 45' N * LONGITUDE: 12° 54' W; 12° 37' W * DEPTH: 1000 m; 1000 m * DATE: 2012-05-08; 2012-05-09 * CRUISE: ANT XXVIII/5 RV Polarstern * DEVICE: rosette sampler
North Atlantic Deep Water NADW (pooled sample) * LATITUDE: 9° 24' N; 9° 24' N; 9° 24' N * LONGITUDE: 22° 46' W; 22° 46' W; 22° 46' W * DEPTH: 4000 m; 3000 m; 2500 m* DATE: 2012-04-30; 2012-04-30; 2012-04-30 * CRUISE: ANT XXVIII/5 RV Polarstern * DEVICE: rosette sampler
North Sea * LATITUDE: 54° 11' N * LONGITUDE: 7° 54' E * DATE: 2009-04-09 * DEPTH: 0m * LOCATION: Helgoland, North Sea * DEVICE: bucket
Lake * LATITUDE: 53° 12' N * LONGITUDE: 8° 1' E * DEPTH: 0 m * DATE: 2011-01-11 * LOCATION: Footbridge in Meyerhausen, Germany * DEVICE: Niskin Bottl
Dissolved organic matter (DOM) composition from a set of four marine and one freshwater environments
No full textEVENTS:
Antarctic Bottom Water AABW (pooled sample) * LATITUDE: 30° 60' S; 25° 60' S * LONGITUDE: 30° 60' W; 39° 0' W * DEPTH: 4100 m; 4000 m * DATE: 2012-04-18; 2012-04-20 * CRUISE: ANT XXVIII/5 RV Polarstern * DEVICE: rosette sampler
Eurafrican Mediterranean Water EMW (pooled sample) * LATITUDE: 35° 14' N; 38° 45' N * LONGITUDE: 12° 54' W; 12° 37' W * DEPTH: 1000 m; 1000 m * DATE: 2012-05-08; 2012-05-09 * CRUISE: ANT XXVIII/5 RV Polarstern * DEVICE: rosette sampler
North Atlantic Deep Water NADW (pooled sample) * LATITUDE: 9° 24' N; 9° 24' N; 9° 24' N * LONGITUDE: 22° 46' W; 22° 46' W; 22° 46' W * DEPTH: 4000 m; 3000 m; 2500 m* DATE: 2012-04-30; 2012-04-30; 2012-04-30 * CRUISE: ANT XXVIII/5 RV Polarstern * DEVICE: rosette sampler
North Sea * LATITUDE: 54° 11' N * LONGITUDE: 7° 54' E * DATE: 2009-04-09 * DEPTH: 0m * LOCATION: Helgoland, North Sea * DEVICE: bucket
Lake * LATITUDE: 53° 12' N * LONGITUDE: 8° 1' E * DEPTH: 0 m * DATE: 2011-01-11 * LOCATION: Footbridge in Meyerhausen, Germany * DEVICE: Niskin Bottl
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