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Water Res. 2014 Jun 15;57:280-94. doi: 10.1016/j.watres.2014.02.051. Epub 2014 Mar 20.

Molecular and structural characterization of dissolved organic matter during and post cyanobacterial bloom in Taihu by combination of NMR spectroscopy and FTICR mass spectrometry.

Author information

1
State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 3663 North Zhongshan Road, 200062 Shanghai, China.
2
Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Institute of Ecological Chemistry, Ingolstaedter Landstrasse 1, D-85764 Neuherberg, Germany.
3
Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Institute of Ecological Chemistry, Ingolstaedter Landstrasse 1, D-85764 Neuherberg, Germany. Electronic address: hertkorn@helmholtz-muenchen.de.

Abstract

Seasonal molecular changes in dissolved organic matter (DOM) isolated from Tai Lake (Taihu) both during (June) and following (November) an algal bloom event in 2007 were characterized by nuclear magnetic resonance spectroscopy (NMR) and Fourier transform ion cyclotron resonance (FTICR) mass spectrometry. Considerable biosignatures were present in summer DOM, yet with a near absence of algal extract compounds. Extensive molecular alteration resulting from multistep and massively parallel biotic and subordinated abiotic transformations of algal biomass to DOM included loss and synthesis of carbohydrates, fundamental changes of aromatic compounds and progressive formation of carboxyl-rich alicyclic compounds (CRAM). The DOM transformation from summer to fall resulted in smaller molecules, increased abundance of CHNO continuous molecular series and overall molecular diversity. Analysis of MS-derived compositional networks placed summer DOM in-between the algal extract and fall DOM. Metabolic pathway annotation by means of high-resolution mass analysis provided a wide range of pathways associated with secondary metabolites in DOM and more basic ones like carbohydrate metabolism characteristic of algal extract compounds. Overall, the time-dependent molecular signature of Taihu DOM was likely dominated by microbial metabolism rather than abiotic chemical transformations. Results from this study indicate that high-resolution organic structural spectroscopy resolves meaningful structural detail out of complex environmental mixtures and has the potential to contribute significantly to future functional biodiversity studies.

KEYWORDS:

Algal bloom; DOM; Mass spectrometry; NMR; Network; Taihu

PMID:
24727497
DOI:
10.1016/j.watres.2014.02.051
[Indexed for MEDLINE]

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