High-field NMR spectroscopy and FTICR mass spectrometry: powerful discovery tools for the molecular level characterization of marine dissolved organic matter

Biogeosciences - Tập 10 Số 3 - Trang 1583-1624
Norbert Hertkorn1, Mourad Harir1, Boris Koch2, Bernhard Michalke1, Philippe Schmitt‐Kopplin1
1Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Research Unit Analytical Biogeochemistry (BGC), Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany
2Alfred Wegener Institute, AWI, Am Handelshafen 12, 27570 Bremerhaven, (Building Co-5), Germany

Tóm tắt

Abstract. High-performance, non-target, high-resolution organic structural spectroscopy was applied to solid phase extracted marine dissolved organic matter (SPE-DOM) isolated from four different depths in the open South Atlantic Ocean off the Angola coast (3° E, 18° S; Angola Basin) and provided molecular level information with extraordinary coverage and resolution. Sampling was performed at depths of 5 m (Angola Current; near-surface photic zone), 48 m (Angola Current; fluorescence maximum), 200 m (still above Antarctic Intermediate Water, AAIW; upper mesopelagic zone) and 5446 m (North Atlantic Deep Water, NADW; abyssopelagic, ~30 m above seafloor) and produced SPE-DOM with near 40% carbon yield and beneficial nuclear magnetic resonance (NMR) relaxation properties, a crucial prerequisite for the acquisition of NMR spectra with excellent resolution. 1H and 13C NMR spectra of all four marine SPE-DOM showed smooth bulk envelopes, reflecting intrinsic averaging from massive signal overlap, with a few percent of visibly resolved signatures and variable abundances for all major chemical environments. The abundance of singly oxygenated aliphatics and acetate derivatives in 1H NMR spectra declined from surface to deep marine SPE-DOM, whereas C-based aliphatics and carboxyl-rich alicyclic molecules (CRAM) increased in abundance. Surface SPE-DOM contained fewer methyl esters than all other samples, likely a consequence of direct exposure to sunlight. Integration of 13C NMR spectra revealed continual increase of carboxylic acids and ketones from surface to depth, reflecting a progressive oxygenation, with concomitant decline of carbohydrate-related substructures. Aliphatic branching increased with depth, whereas the fraction of oxygenated aliphatics declined for methine, methylene and methyl carbon. Lipids in the oldest SPE-DOM at 5446 m showed a larger share of ethyl groups and methylene carbon than observed in the other samples. Two-dimensional NMR spectra showed exceptional resolution and depicted resolved molecular signatures in excess of a certain minimum abundance. Classical methyl groups terminating aliphatic chains represented ~15% of total methyl in all samples investigated. A noticeable fraction of methyl (~2%) was bound to olefinic carbon. Methyl ethers were abundant in surface marine SPE-DOM, and the chemical diversity of carbohydrates was larger than that of freshwater and soil DOM. In all samples, we identified sp2-hybridized carbon chemical environments with discrimination of isolated and conjugated olefins and α,β-unsaturated double bonds. Olefinic proton and carbon atoms were more abundant than aromatic ones; olefinic unsaturation in marine SPE-DOM will be more directly traceable to ultimate biogenic precursors than aromatic unsaturation. The abundance of furan, pyrrol and thiophene derivatives was marginal, whereas benzene derivatives, phenols and six-membered nitrogen heterocycles were prominent; a yet unassigned set of six-membered N-heterocycles with likely more than one single nitrogen occurred in all samples. Various key polycyclic aromatic hydrocarbon substructures suggested the presence of thermogenic organic matter at all water depths. Progressive NMR cross-peak attenuation from surface to deep marine SPE-DOM was particularly strong in COSY NMR spectra and indicated a continual disappearance of biosignatures as well as entropy gain from an ever increased molecular diversity. Nevertheless, a specific near-seafloor SPE-DOM signature of unsaturated molecules recognized in both NMR and Fourier transform ion cyclotron mass spectrometry (FTICR/MS) possibly originated from sediment leaching. The conformity of key NMR and FTICR/MS signatures suggested the presence of a large set of identical molecules throughout the entire ocean column even though the investigated water masses belonged to different oceanic regimes and currents. FTICR/MS showed abundant CHO, CHNO, CHOS and CHNOS molecular series with slightly increasing numbers of mass peaks and average mass from surface to bottom SPE-DOM. The proportion of CHO and CHNO negative ions increased from surface to depth, whereas CHOS and especially CHNOS molecular series markedly declined. While certain rather aliphatic CHOS and CHNOS ions were observed solely in the surface, deep marine SPE-DOM was enriched in unique unsaturated and rather oxygenated CHO and CHNO molecular series. With the exception of abyssopelagic SPE-DOM at 5446 m, which showed a peculiar CHOS chemistry of unsaturated carbon and reduced sulphur (black sulphur), CHO and CHNO molecular series contributed ~87% to total positive electrospray ionization FTICR mass peak integral, with a near constant ratio of CHNO / CHO molecular compositions near 1.13 ± 0.05. In case of all four marine SPE-DOM, remarkably disparate average elemental compositions as determined from either MS and NMR spectra were observed, caused by a pronounced ionization selectivity in electrospray ionization FTICR/MS. The study demonstrates that the exhaustive characterization of complex unknowns in marine DOM will enable a meaningful classification of individual marine biogeosignatures. Future in-depth functional biodiversity studies with a clear understanding of DOM structure and function might eventually lead to a novel, unified perception of biodiversity and biogeochemistry.

Từ khóa


Tài liệu tham khảo

Aihara, J. I., Sekine, R., and Ishida, T.: Electronic and magnetic characteristics of polycyclic aromatic hydrocarbons with factorizable Kekulé structure counts, J. Phys. Chem. A., 115, 9314–9321, 2011.

Aluwihare, L. I., Repeta, D. J., and Chen, R. F.: Chemical composition and cycling of dissolved organic matter in the mid-atlantic bight, Deep-Sea Res. Pt. II, 49, 4421–4437, 2002.

Amrani, A., Turner, J. W., Ma, Q. S., Tang, Y. C., and Hatcher, P. G.: Formation of sulfur and nitrogen cross-linked macromolecules under aqueous conditions, Geochim. Cosmochim. Ac., 71, 4141–4160, 2007.

Andreae, M. O. and Crutzen, P. J.: Atmospheric aerosols: Biogeochemical sources and role in atmospheric chemistry, Science, 276, 1052-1058, 1997.

Battin, T. J., Luyssaert, S., Kaplan, L. A., Aufdenkampe, A. K., Richter, A., and Tranvik, L. J.: The boundless carbon cycle, Nat. Geosci., 2, 598–600, 2009.

Bauschlicher, C. W., Peeters, E., and Allamandola, L. J.: The infrared spectra of very large irregular polycyclic aromatic hydrocarbons (PAHs): Observational probes of astronomical pah geometry, size, and charge, Astrophys. J., 697, 311–327, 2009.

Benner, R.: Chemical composition and reactivity, in: Biogeochemistry of marine dissolved organic matter, edited by: Hansell, D. A. and Carlson, C. A., Academic Press, 59–90, 2002.

Bertini, I., Luchinat, C., Parigi, G., and Pierattelli, R.: Perspectives in paramagnetic NMR of metalloproteins, Dalton T., 2008, 3782–3790, 2008.

Blunt, J. W., Copp, B. R., Munro, M. H. G., Northcote, P. T., and Prinsep, M. R.: Marine natural products, Nat. Prod. Rep., 27, 165–237, 2010.

Buddrus, J., Burba, P., Lambert, J., and Herzog, H.: Quantification of partial structures of aquatic humic substances by one- and two-dimensional solution 13C nuclear magnetic resonance spectroscopy, Anal. Chem., 61, 628–631, 1989.

Burdige, D. J., Berelson, W. M., Coale, K. H., McManus, J., and Johnson, K. S.: Fluxes of dissolved organic carbon from California continental margin sediments, Geochim. Cosmochim. Ac., 63, 1507–1515, 1999.

Cane, D. E. and Ikeda, H.: Exploration and mining of the bacterial terpenome, Acc. Chem. Res., 45, 463–472, 2011.

Carlson, C. A., Del Giorgio, P. A., and Herndl, G. J.: Microbes and the Dissipation of Energy and Respiration: From Cells to Ecosystems, Oceanography, 20, 89–100, 2007.

Cavanagh, J., Fairbrother, W. J., Palmer III, A. G., Rance, M., and Skelton, N. J.: Protein NMR Spectroscopy, Elsevier, Burlington, USA, 2007.

Cheng, C. H., Lehmann, J., Thies, J. E., Burton, S. D., and Engelhard, M. H.: Oxidation of black carbon by biotic and abiotic processes, Org. Geochem., 37, 1477–1488, 2006.

Cho, Y., Kim, Y. H., and Kim, S.: Planar limit-assisted structural interpretation of saturates/aromatics/resins/asphaltenes fractionated crude oil compounds observed by fourier transform ion cyclotron resonance mass spectrometry, Anal. Chem., 83, 6068–6073, 2011.

Coble, P. G.: Marine optical biogeochemistry: The chemistry of ocean color, Chem. Rev., 107, 402–418, 2007.

Crouch, R. C., Llanos, W., Mehr, K. G., Hadden, C. E., Russell, D. J., and Martin, G. E.: Applications of cryogenic NMR probe technology to long-range 1H-15N 2-D NMR studies at natural abundance, Magn. Reson. Chem., 39, 555–558, 2001.

Del Giorgio, P. A., Cole, J. J., and Cimbleris, A.: Respiration rates in bacteria exceed phytoplankton production in unproductive aquatic systems, Nature, 385, 148–151, 1997.

Dickens, A. F., Gelinas, Y., Masiello, C. A., Wakeham, S., and Hedges, J. I.: Reburial of fossil organic carbon in marine sediments, Nature, 427, 336–339, 2004.

Dittmar, T. and Kattner, G.: Recalcitrant dissolved organic matter in the ocean: Major contribution of small amphiphilics, Mar. Chem., 82, 115–123, 2003a.

Dittmar, T. and Kattner, G.: The biogeochemistry of the river and shelf ecosystem of the arctic ocean: A review, Mar. Chem., 83, 103–120, 2003b.

Dittmar, T. and Koch, B. P.: Thermogenic organic matter dissolved in the abyssal ocean, Mar. Chem., 102, 208–217, 2006.

Dittmar, T. and Paeng, J.: A heat-induced molecular signature in marine dissolved organic matter, Nat. Geosci., 2, 175–179, 2009.

Dittmar, T., Koch, B., Hertkorn, N., and Kattner, G.: A simple and efficient method for the solid-phase extraction of dissolved organic matter (spe-DOM) from seawater, Limnol. Oceanogr.-Meth., 6, 230–235, 2008.

Dittmar, T., Rezende, C. E., Manecki, M., Niggemann, J., Ovalle, A. R. C., and Bernardes, M. C.: Continuous flux of dissolved black carbon from a vanished tropical forest biome, Nat. Geosci., 5, 618–622, 2012.

Einsiedl, F., Hertkorn, N., Wolf, M., Frommberger, M., Schmitt-Kopplin, P., and Koch, B. P.: Rapid biotic molecular transformation of fulvic acids in a karst aquifer, Geochim. Cosmochim. Ac., 71, 5474–5482, 2007.

Falco, C., Caballero, F. P., Babonneau, F., Gervais, C., Laurent, G., Titirici, M.-M., and Baccile, N.: Hydrothermal Carbon from Biomass: Structural Differences between Hydrothermal and Pyrolyzed Carbons via Solid State NMR, Langmuir, 27, 14460–14471, 2011.

Flerus, R., Koch, B. P., Schmitt-Kopplin, P., Witt, M., and Kattner, G.: Molecular level investigation of reactions between dissolved organic matter and extraction solvents using FT-ICR MS, Mar. Chem., 124, 100–107, 2011.

Flerus, R., Lechtenfeld, O. J., Koch, B. P., McCallister, S. L., Schmitt-Kopplin, P., Benner, R., Kaiser, K., and Kattner, G.: A molecular perspective on the ageing of marine dissolved organic matter, Biogeosciences, 9, 1935–1955, https://doi.org/10.5194/bg-9-1935-2012, 2012.

Friedline, C. J., Franklin, R. B., McCallister, S. L., and Rivera, M. C.: Bacterial assemblages of the eastern Atlantic Ocean reveal both vertical and latitudinal biogeographic signatures, Biogeosciences, 9, 2177–2193, https://doi.org/10.5194/bg-9-2177-2012, 2012.

Gaspar, A., Harir, M., Hertkorn, N., and Schmitt-Kopplin, P.: Preparative free-flow electrophoretic offline ESI-Fourier transform ion cyclotron resonance/MS analysis of Suwannee River fulvic acid, Electrophoresis, 31, 2070–2079, 2010.

Geider, R. J., Delucia, E. H., Falkowski, P. G., Finzi, A. C., Grime, J. P., Grace, J., Kana, T. M., La Roche, J., Long, S. P., Osborne, B. A., Platt, T., Prentice, I. C., Raven, J. A., Schlesinger, W. H., Smetacek, V., Stuart, V., Sathyendranath, S., Thomas, R. B., Vogelmann, T. C., Williams, P., and Woodward, I. F.: Primary Productivity of Planet Earth: Biological Determinants and Physical Constraints in Terrestrial and Aquatic Habitats, Glob. Change Biol., 7, 849–882, 2001.

Gilbert, J. A., Steele, J. A., Caporaso, J. G., Steinbrück, L., Reeder, J., Temperton, B., Huse, S., McHardy, A. C., Knight, R., Joint, I., Somerfield, P., Fuhrman, J. A., and Field, D.: Defining seasonal marine microbial community dynamics, ISME J., 6, 298–308, 2012.

Graeve, M. and Janssen, D.: Improved separation and quantification of neutral and polar lipid classes by HPLC-ELSD using a monolithic silica phase: Application to exceptional marine lipids, J. Chromatogr. B., 877, 1815–1819, 2009.

Hansell, D. A.: Dissolved organic matter in the ocean, Oceanography, 22, 202–211, 2009.

Hansell, D. A.: Recalcitrant Dissolved Organic Carbon Fractions, Annu. Rev. Mar. Sci., 5, 421–445, https://doi.org/10.1146/annurev-marine-120710-100757, 2013.

Hansell, D. A. and Carlson, C. A.: Deep-ocean gradients in the concentration of dissolved organic carbon, Nature, 395, 263–266, 1998.

Hansen, P. E.: 13C NMR of Polycyclic Aromatic Compounds. A Review, Org. Magn. Reson., 12, 109–142, 1979.

Hansman, R. L., Griffin, S., Watson, J. T., Druffel, E. R. M., Ingalls, A. E., Pearson, A., Aluwihare, L. I.: The radiocarbon signature of microorganisms in the mesopelagic ocean, P. Natl. Acad. Sci. USA, 106, 6513–6518, 2009.

Hebting, Y., Schaeffer, P., Behrens, A., Adam, P., Schmitt, G., Schneckenburger, P., Bernasconi, S. M., and Albrecht, P.: Biomarker evidence for a major preservation pathway of sedimentary organic carbon, Science, 312, 1627–1631, 2006.

Hedges, J. I.: Global biogeochemical cycles: progress and problems, Org. Geochem., 39, 67–93, 1992.

Hedges, J. I. and Oades, J. M.: Comparative organic geochemistries of soils and marine sediments, Org. Geochem., 27, 319–361, 1997.

Hedges, J. I., Baldock, J. A., Gelinas, Y., Lee, C., Peterson, M., and Wakeham, S. G.: Evidence for non-selective preservation of organic matter in sinking marine particles, Nature, 409, 801–804, 2001.

Hedges, J. I., Baldock, J. A., Gelinas, Y., Lee, C., Peterson, M. L., and Wakeham, S. G.: The biochemical and elemental compositions of marine plankton: A NMR perspective, Mar. Chem., 78, 47–63, 2002.

Hernes, P. J. and Benner, R.: Photochemical and microbial degradation of dissolved lignin phenols: Implications for the fate of terrigenous dissolved organic matter in marine environments, J. Geophys. Res., 108, 3291, https://doi.org/10.1029/2002JC001421, 2003.

Hernes, P. J. and Benner, R.: Terrigenous organic matter sources and reactivity in the North Atlantic Ocean and a comparison to the Arctic and Pacific Oceans, Mar. Chem., 100, 66–79, 2006.

Hertkorn, N. and Kettrup, A.: Molecular level structural analysis of natural organic matter and of humic substances by multinuclear and higher dimensional NMR spectroscopy, in: Use of humic substances to remediate polluted environments: From theory to practice, edited by: Perminova, I., Hatfield, K., and Hertkorn, N., Springer Netherlands, 391–435, 2005.

Hertkorn, N., Benner, R., Frommberger, M., Schmitt-Kopplin, P., Witt, M., Kaiser, K., Kettrup, A., and Hedges, J. I.: Characterization of a major refractory component of marine dissolved organic matter, Geochim. Cosmochim. Ac., 70, 2990–3010, 2006.

Hertkorn, N., Ruecker, C., Meringer, M., Gugisch, R., Frommberger, M., Perdue, E. M., Witt, M., and Schmitt-Kopplin, P.: High-precision frequency measurements: Indispensable tools at the core of the molecular-level analysis of complex systems, Anal. Bioanal. Chem., 389, 1311–1327, 2007.

Hertkorn, N., Frommberger, M., Witt, M., Koch, B. P., Schmitt-Kopplin, P., and Perdue, E. M.: Natural organic matter and the event horizon of mass spectrometry, Anal. Chem., 80, 8908–8919, 2008.

Hockaday, W. C., Grannas, A. M., Kim, S., and Hatcher, P. G.: Direct molecular evidence for the degradation and mobility of black carbon in soils from ultrahigh-resolution mass spectral analysis of dissolved organic matter from a fire-impacted forest soil, Org. Geochem., 37, 501–510, 2006.

Hopkinson, C. S. and Vallino, J. J.: Efficient export of carbon to the deep ocean through dissolved organic matter, Nature, 433, 142–145, 2005.

Jiao, N., Herndl, G. J., Hansell, D. A., Benner, R., Kattner, G., Wilhelm, S. W., Kirchman, D. L., Weinbauer, M. G., Luo, T. W., Chen, F., and Azam, F.: Microbial production of recalcitrant dissolved organic matter: Long-term carbon storage in the global ocean, Nat. Rev. Microbiol., 8, 593–599, 2010.

Jimenez, J. L., Canagaratna, M. R., Donahue, N. M., Prevot, A. S. H., Zhang, Q., Kroll, J. H., DeCarlo, P. F., Allan, J. D., Coe, H., Ng, N. L., Aiken, A. C., Docherty, K. S., Ulbrich, I. M., Grieshop, A. P., Robinson, A. L., Duplissy, J., Smith, J. D., Wilson, K. R., Lanz, V. A., Hueglin, C., Sun, Y. L., Tian, J., Laaksonen, A., Raatikainen, T., Rautiainen, J., Vaattovaara, P., Ehn, M., Kulmala, M., Tomlinson, J. M., Collins, D. R., Cubison, M. J., Dunlea, E. J., Huffman, J. A., Onasch, T. B., Alfarra, M. R., Williams, P. I., Bower, K., Kondo, Y., Schneider, J., Drewnick, F., Borrmann, S., Weimer, S., Demerjian, K., Salcedo, D., Cottrell, L., Griffin, R., Takami, A., Miyoshi, T., Hatakeyama, S., Shimono, A., Sun, J. Y., Zhang, Y. M., Dzepina, K., Kimmel, J. R., Sueper, D., Jayne, J. T., Herndon, S. C., Trimborn, A. M., Williams, L. R., Wood, E. C., Middlebrook, A. M., Kolb, C. E., Baltensperger, U., and Worsnop, D. R.: Evolution of organic aerosols in the atmosphere, Science, 326, 1525–1529, 2009.

Kaiser, E., Simpson, A. J., Dria, K. J., Sulzberger, B., and Hatcher, P. G.: Solid-state and multidimensional solution-state NMR of solid phase extracted and ultrafiltered riverine dissolved organic matter, Environ. Sci. Technol., 37, 2929–2935, 2003.

Kaiser, K. and Benner, R.: Organic matter transformations in the upper mesopelagic zone of the North Pacific: Chemical composition and linkages to microbial community structure, J. Geophys. Res., 117, C01023, https://doi.org/10.1029/2011JC007141, 2012.

Kelleher, B. P. and Simpson, A. J.: Humic substances in soils: Are they really chemically distinct?, Environ. Sci. Technol., 40, 4605–4611, 2006.

Kleckner, I. R. and Foster, M. P.: An introduction to NMR-based approaches for measuring protein dynamics, BBA-Proteins Proteom., 1814, 942–968, 2011.

Knicker, H.: "Black nitrogen" – an important fraction in determining the recalcitrance of charcoal, Org. Geochem., 41, 947–950, 2010.

Koch, B. P. and Dittmar, T.: From mass to structure: An aromaticity index for high-resolution mass data of natural organic matter, Rapid. Commun. Mass. Sp., 20, 926–932, 2006.

Koch, B. P. and Kattner, G.: Sources and rapid biogeochemical transformation of dissolved organic matter in the Atlantic surface ocean, Biogeosciences, 9, 2597–2602, https://doi.org/10.5194/bg-9-2597-2012, 2012.

Koch, B. P., Witt, M. R., Engbrodt, R., Dittmar, T., and Kattner, G.: Molecular formulae of marine and terrigenous dissolved organic matter detected by electrospray ionization fourier transform ion cyclotron resonance mass spectrometry, Geochim. Cosmochim. Ac., 69, 3299–3308, 2005.

Kok, M. D, Schouten, S., and Sinninghe Damsté, J. S.: Formation of insoluble, nonhydrolyzable, sulfur-rich macromolecules via incorporation of inorganic sulphur species into algal carbohydrates, Geochim. Cosmochim. Ac., 15, 2689–2699, 2000.

Koprivnjak, J. F., Pfromm, P. H., Ingall, E., Vetter, T. A., Schmitt-Kopplin, P., Hertkorn, N., Frommberger, M., Knicker, H., and Perdue, E. M.: Chemical and spectroscopic characterization of marine dissolved organic matter isolated using coupled reverse osmosis-electrodialysis, Geochim. Cosmochim. Ac., 73, 4215–4231, 2009.

Korzhnev, D. M., Salvatella, X., Vendruscolo, M., Di Nardo, A. A., Davidson, A. R., Dobson, C. M., and Kay, L. E.: Low-populated folding intermediates of Fyn SH3 characterized by relaxation dispersion NMR, Nature, 430, 586–590, 2004.

Kovalevskii, D. V., Permin, A. B., Perminova, I. V., and Petrosyan, V. S.: Recovery of conditions for quantitative measuring the NMR spectra of humic acids, Vestn. Mosk. U. Khim., 41, 39–42, 2000.

Kroll, J. H., Donahue, N. M., Jimenez, J. L., Kessler, S. H., Canagaratna, M. R., Wilson, K. R., Altieri, K. E., Mazzoleni, L. R., Wozniak, A. S., Bluhm, H., Mysak, E. R., Smith, J. D., Kolb, C. E., and Worsnop, D. R.: Carbon oxidation state as a metric for describing the chemistry of atmospheric organic aerosol, Nat. Chem., 3, 133–139, 2011.

Kujawinski, E. B.: Electrospray ionization fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS): Characterization of complex environmental mixtures, Environ. Forensics, 3, 207–216, 2002.

Kujawinski, E. B.: The Impact of Microbial Metabolism on Marine Dissolved Organic Matter, Annu. Rev. Mar. Sci., 3, 567–599, 2011.

Kujawinski, E. B., Longnecker, K., Blough, N. V., Del Vecchio, R., Finlay, L., Kitner, J. B., and Giovannoni, S. J.: Identification of possible source markers in marine dissolved organic matter using ultrahigh resolution mass spectrometry, Geochim. Cosmochim. Ac., 73, 4384–4399, 2009.

Lam, B., Baer, A., Alaee, M., Lefebvre, B., Moser, A., Williams, A., and Simpson, A. J.: Major structural components in freshwater dissolved organic matter, Environ. Sci. Technol., 41, 8240–8247, 2007.

Leenheer, J. A., Nanny, M. A., and McIntyre, C.: Terpenoids as major precursors of dissolved organic matter in landfill leachates, surface water, and groundwater, Environ. Sci. Technol., 37, 2323–2331, 2003.

Lipp, J. S. and Hinrichs, K. U.: Structural diversity and fate of intact polar lipids in marine sediments, Geochim. Cosmochim. Ac., 73, 6816–6833, 2009.

Mahieu, N., Powlson, D. S., and Randall, E. W.: Statistical analysis of published carbon-13 CPMAS NMR spectra of soil organic matter, Soil Sci. Soc. Am. J., 63, 307–319, 1999.

Maie, N., Parish, K. J., Watanabe, A., Knicker, H., Benner, R., Abe, T., Kaiser, K., and Jaffe, R.: Chemical characteristics of dissolved organic nitrogen in an oligotrophic subtropical coastal ecosystem, Geochim. Cosmochim. Ac., 70, 4491–4506, 2006.

Mao, J. D., Kong, X. Q., Schmidt-Rohr, K., Pignatello, J. J., and Perdue, E. M.: Advanced Solid-State NMR Characterization of Marine Dissolved Organic Matter Isolated Using the Coupled Reverse Osmosis/Electrodialysis Method, Environ. Sci. Technol., 46, 5806–5814, 2012.

Martin, G. E., Hilton, B. D., Moskau, D., Freytag, N., Kessler, K., and Colson, K.: Long-range 1H-15N heteronuclear shift correlation across wide F1 spectral windows, Magn. Reson. Chem., 48, 935–937, 2010.

Masiello, C. A.: New directions in black carbon organic geochemistry, Mar. Chem., 92, 201–213, 2004.

Masiello, C. A. and Druffel, E. R. M.: Black carbon in deep-sea sediments, Science, 280, 1911–1913, 1998.

McCaul, M. V., Sutton, D., Simpson, A. J., Spence, A., McNally, D. J., Moran, B. W., Goel, A., O'Connor, B., Hart, K., and Kelleher, B. P.: Composition of dissolved organic matter within a lacustrine environment, Environ. Chem., 8, 146–154, 2011.

McCollom, T. M. and Seewald, J. S.: Abiotic synthesis of organic compounds in deep-sea hydrothermal environments, Chem. Rev., 107, 382–401, 2007.

McKee, G. A. and Hatcher, P. G.: Alkyl amides in two organic-rich anoxic sediments: A possible new abiotic route for N sequestration, Geochim. Cosmochim. Ac., 74, 6436–6450, 2010.

Mopper, K., Stubbins, A., Ritchie, J. D., Bialk, H. M., and Hatcher, P. G.: Advanced instrumental approaches for characterization of marine dissolved organic matter: Extraction techniques, mass spectrometry, and nuclear magnetic resonance spectroscopy, Chem. Rev., 107, 419–442, 2007.

Moskau, D.: Application of real time digital filters in NMR spectroscopy, Concept. Magnetic Res., 15, 164–176, 2002.

Nagata, T., Tamburini, C., Arístegui, J., Baltar, F., Bochdansky, A. B., Fonda-Umani, S., Kukuda, H., Gogou, A., Hansell, D. A., Hansman, R. L., Herndl, G. J., Panagiotopoulos, C., Reinthaler, T., Sohrin, R., Verdugo, P., Yamada, N., Yamashita, Y., Yokokawa, T., and Bartlett, D. H.: Emerging concepts on microbial processes in the bathypelagic ocean – ecology, biogeochemistry, and genomics, Deep-Sea Res. Pt. II, 57, 1519–1536, 2010.

Ohno, T., He, Z. Q., Sleighter, R. L., Honeycutt, C. W., and Hatcher, P. G.: Ultrahigh resolution mass spectrometry and indicator species analysis to identify marker components of soil- and plant biomass-derived organic matter fractions, Environ. Sci. Technol., 44, 8594–8600, 2010.

Opsahl, S. and Benner, R..: Distribution and cycling of terrigenous dissolved organic matter in the ocean, Nature, 386, 480–482, 1997.

Opsahl, S. and Benner, R..: Photochemical reactivity of dissolved lignin in river and ocean waters, Limnol. Oceanogr., 43, 1297–1304, 1998.

Panagiotopoulos, C., Repeta, D. J., and Johnson, C. G.: Characterization of methyl sugars, 3-deoxysugars and methyl deoxysugars in marine high molecular weight dissolved organic matter, Org. Geochem., 38, 884–896, 2007.

Paytan, A., Mackey, K. R. M., Chen, Y., Lima, I. D., Doney, S. C., Mahowald, N., Labiosa, R., and Post, A. F.: Toxicity of atmospheric aerosols on marine phytoplankton, P. Natl. Acad. Sci. USA, 106, 4601–4605, 2009.

Perdue, E. M., Hertkorn, N., and Kettrup, A.: Substitution patterns in aromatic rings by increment analysis. Model development and application to natural organic matter, Anal. Chem., 79, 1010–1021, 2007.

Pohl, C., Croot, P. L., Hennings, U., Daberkow, T., Budeus, G., and v. d. Loeff, M. R.: Synoptic transects on the distribution of trace elements (Hg, Pb, Cd, Cu, Ni, Zn, Co, Mn, Fe, and Al) in surface waters of the Northern- and Southern East Atlantic, J. Mar. Syst., 84, 28–41, 2011.

Pos, W. H., Riemer, D. D., and Zika, R. G.: Carbonyl sulfide (OCS) and carbon monoxide (CO) in natural waters: Evidence of a coupled production pathway, Mar. Chem., 62, 89–101, 1998.

Repeta, D. J., Quan, T. M., Aluwihare, L. I., and Accardi, A. M.: Chemical characterization of high molecular weight dissolved organic matter in fresh and marine waters, Geochim. Cosmochim. Ac, 66, 955–962, 2002.

Rezende, C. E., Pfeiffer, W. C., Martinelli, L. A., Tsamakis, E., Hedges, J. I., and Keil, R. G.: Lignin phenols used to infer organic matter sources to Sepetiba Bay – RJ, Brasil, Estuar. Coast. Shelf. Sci., 87, 479–486, 2010.

Ritchie, J. D. and Perdue, E. M.: Analytical constraints on acidic functional groups in humic substances, Org. Geochem., 39, 783–799, 2008.

Schmidt, F., Elvert, M., Koch, B. P., Witt, M., and Hinrichs, K.-U.: Molecular characterization of dissolved organic matter in pore water of continental shelf sediments, Geochim. Cosmochim. Ac., 73, 3337–3358, 2009.

Schmidt, F., Koch, B. P., Elvert, M., Schmidt, G., Witt, M., and Hinrichs, K. U.: Diagenetic transformation of dissolved organic nitrogen compounds under contrasting sedimentary redox conditions in the black sea, Environ. Sci. Technol., 45, 5223–5229, 2011.

Schmitt-Kopplin, P., Hertkorn, N., Schulten, H. R., and Kettrup, A.: Structural changes in a dissolved soil humic acid during photochemical degradation processes under O2 and N2 atmosphere, Environ. Sci. Technol., 32, 2531–2541, 1998.

Schmitt-Kopplin, P., Gabelica, Z., Gougeon, R. D., Fekete, A., Kanawati, B., Harir, M., Gebefuegi, I., Eckel, G., and Hertkorn, N.: High molecular diversity of extraterrestrial organic matter in murchison meteorite revealed 40 years after its fall, P. Natl. Acad. Sci. USA, 107, 2763–2768, 2010a.

Schmitt-Kopplin, P., Gelencser, A., Dabek-Zlotorzynska, E., Kiss, G., Hertkorn, N., Harir, M., Hong, Y., and Gebefuegi, I.: Analysis of the unresolved organic fraction in atmospheric aerosols with ultrahigh-resolution mass spectrometry and nuclear magnetic resonance spectroscopy: Organosulfates as photochemical smog constituents, Anal. Chem., 82, 8017–8026, 2010b.

Simpson, A. J. and Brown, S. A.: Purge NMR: Effective and easy solvent suppression, J. Magn. Reson., 175, 340–346, 2005.

Simpson, A. J., Kingery, W. L., Hayes, M. H. B., Spraul, M., Humpfer, E., Dvortsak, P., Kerssebaum, R., Godejohann, M., and Hofmann, M.: Molecular structures and associations of humic substances in the terrestrial environment, Naturwissenschaften, 89, 84–88, 2002.

Simpson, A. J., McNally, D. J., and Simpson, M. J.: NMR spectroscopy in environmental research: From molecular interactions to global processes, Prog. Nucl. Mag. Res. Sp., 58, 97–175, 2011.

Smernik, R. J. and Oades, J. M.: Paramagnetic effects on solid state 13C nuclear magnetic resonance spectra of soil organic matter, J. Environ. Qual., 31, 414–420, 2002.

Sohrin, Y., Urushihara, S., Nakatsuka, S., Kono, T., Higo, E., Minami, T., Norisuye, K., and Umetani, S.: Multielemental determination of Geotraces Key trace metals in seawater by ICPMS after preconcentration using an ethylenediaminetriacetic acid chelating resin, Anal. Chem., 80, 6267–6273, 2008.

Stenson, A. C.: Reversed-Phase Chromatography Fractionation Tailored to Mass Spectral Characterization of Humic Substances, Environ. Sci. Technol., 42, 2060–2065, 2008.

Stenson, A. C., Marshall, A. G., and Cooper, W. T.: Exact masses and chemical formulas of individual Suwannee River fulvic acids from ultrahigh resolution electrospray ionization Fourier Transform ion cyclotron resonance mass spectra, Anal. Chem., 75, 1275–1284, 2003.

Stubbins, A., Niggemann, J., and Dittmar, T.: Photo-lability of deep ocean dissolved black carbon, Biogeosciences, 9, 1661–1670, https://doi.org/10.5194/bg-9-1661-2012, 2012.

Takeda, A., Tsukada, H., Takaku, Y., and Hisamatsu, S.: Fractionation of metal complexes with dissolved organic matter in a rhizosphere soil solution of a humus-rich andosol using size exclusion chromatography with inductively coupled plasma-mass spectrometry, Soil. Sci. Plant. Nutr., 55, 349–357, 2009.

Taylor, B. B., Torrecilla, E., Bernhardt, A., Taylor, M. H., Peeken, I., Röttgers, R., Piera, J., and Bracher, A.: Bio-optical provinces in the eastern Atlantic Ocean and their biogeographical relevance, Biogeosciences, 8, 3609–3629, https://doi.org/10.5194/bg-8-3609-2011, 2011.

Tomczak, M. and Godfrey, J. S.: Regional Oceanography: An Introduction, 2nd Edn., Daya Publishing House, Delhi, 390 pp., 2003.

Tominaga, K., Sakamoto, Y., Fujimaki, Y., Takekawa, M., and Ohshima, S.: Structural analysis of hepta-, nona-, and undeca-cyclic aromatic hydrocarbons by NMR spectroscopy, Polycycl. Aromat. Comp., 30, 274–286, 2010.

Turano, P., Lalli, D., Felli, I. C., Theil, E. C., and Bertini, I.: NMR reveals pathway for ferric mineral precursors to the central cavity of ferritin, P. Natl. Acad. Sci. USA, 107, 545–550, 2010.

Tziotis, D., Hertkorn, N., and Schmitt-Kopplin, P.: Kendrick-analogous network visualisation of ion cyclotron resonance Fourier transform mass spectra: improved options for the assignment of elemental compositions and the classification of organic molecular complexity, Eur. J. Mass Spectrom., 17, 415–421, 2011.

Vraspir, J. M. and Butler, A.: Chemistry of marine ligands and siderophores, Annu. Rev. Mar. Sci., 1, 43–63, 2009.

Walker, B. D., Beaupre, S. R., Guilderson, T. P., Druffel, E. R. M., and McCarthy, M. D.: Large-volume ultrafiltration for the study of radiocarbon signatures and size vs. age relationships in marine dissolved organic matter, Geochim. Cosmochim. Ac., 75, 5187–5202, 2011.

Williamson, D. S., Cremonesi, P., Cavalieri, E., Nagel, D. L., Markin, R. S., and Cohen, S. M.: Assignment of 1H NMR Spectra of Polycyclic Aromatic Hydrocarbons by Multiple Quantum Filtration, J. Org. Chem., 51, 5210–5213, 1986.

Witter, A. E., Hutchins, D. A., Butler, A., and Luther, G. W.: Determination of conditional stability constants and kinetic constants for strong model Fe-binding ligands in seawater, Mar. Chem., 69, 1–17, 2000.

Woods, G. C., Simpson, M. J., Koerner, P. J., Napoli, A., and Simpson, A. J.: HILIC-NMR: Toward the identification of individual molecular components in dissolved organic matter, Environ. Sci. Technol., 45, 3880–3886, 2011.

Woods, G. C., Simpson, M. J., and Simpson, A. J.: Oxidized sterols as a significant component of dissolved organic matter: Evidence from 2D HPLC in combination with 2D and 3D NMR spectroscopy, Water Res., 46, 3398–3408, 2012.

Xia, Y. L., Moran, S., Nikonowicz, E. P., and Gao, X. L.: Z-restored spin-echo 13C 1d spectrum of straight baseline free of hump, dip and roll, Magn. Reson. Chem., 46, 432–435, 2008.

Zepp, R. G., Erickson, D. J., Paul, N. D., and Sulzberger, B.: Effects of solar UV radiation and climate change on biogeochemical cycling: Interactions and feedbacks, Photoch. Photobio. Sci., 10, 261–279, 2011.

Ziolkowski, L. A. and Druffel, E. R. M.: Aged black carbon identified in marine dissolved organic carbon, Geophys. Res. Lett., 37, L16601, https://doi.org/10.1029/2010GL043963, 2010.