Dataset Information

Signatures of Molecular Unification and Progressive Oxidation Unfold in Dissolved Organic Matter of the Ob-Irtysh River System along Its Path to the Arctic Ocean.

ABSTRACT: The Ob-Irtysh River system is the seventh-longest one in the world. Unlike the other Great Siberian rivers, it is only slightly impacted by the continuous permafrost in its low flow. Instead, it drains the Great Vasyugan mire, which is the world largest swamp, and receives huge load of the Irtysh waters which drain the populated lowlands of the East Siberian Plain. The central challenge of this paper is to understand the processes responsible for molecular transformations of natural organic matter (NOM) in the Ob-Irtysh river system along the South-North transect. For solving this task, the NOM was isolated from the water samples collected along the 3,000?km transect using solid-phase extraction. The NOM samples were further analyzed using high resolution mass spectrometry and optical spectroscopy. The obtained results have shown a distinct trend both in molecular composition and diversity of the NOM along the South-North transect: the largest diversity was observed in the Southern "swamp-wetland" stations. The samples were dominated with humic and lignin-like components, and enriched with aminosugars. After the Irtysh confluence, the molecular nature of NOM has changed drastically: it became much more oxidized and enriched with heterocyclic N-containing compounds. These molecular features are very different from the aliphatics-rich permafrost NOM. They witnesses much more conservative nature of the NOM discharged into the Arctic by the Ob-Irtysh river system. In general, drastic reduction in molecular diversity was observed in the northern stations located in the lower Ob flow.

SUBMITTER: Perminova IV

PROVIDER: S-EPMC6925193 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature

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Signatures of Molecular Unification and Progressive Oxidation Unfold in Dissolved Organic Matter of the Ob-Irtysh River System along Its Path to the Arctic Ocean.

Perminova I V IV Shirshin E A EA Zherebker A A Pipko I I II Pugach S P SP Dudarev O V OV Nikolaev E N EN Grigoryev A S AS Shakhova N N Semiletov I P IP

Scientific reports 20191220 1

The Ob-Irtysh River system is the seventh-longest one in the world. Unlike the other Great Siberian rivers, it is only slightly impacted by the continuous permafrost in its low flow. Instead, it drains the Great Vasyugan mire, which is the world largest swamp, and receives huge load of the Irtysh waters which drain the populated lowlands of the East Siberian Plain. The central challenge of this paper is to understand the processes responsible for molecular transformations of natural organic matt ...[more]

PMID: 31862928

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Project description:As consequences of global warming sea-ice shrinking, permafrost thawing and changes in fresh water and terrestrial material export have already been reported in the Arctic environment. These processes impact light penetration and primary production. To reach a better understanding of the current status and to provide accurate forecasts Arctic biogeochemical and physical parameters need to be extensively monitored. In this sense, bio-optical properties are useful to be measured due to the applicability of optical instrumentation to autonomous platforms, including satellites. This study characterizes the non-water absorbers and their coupling to hydrographic conditions in the poorly sampled surface waters of the central and eastern Arctic Ocean. Over the entire sampled area colored dissolved organic matter (CDOM) dominates the light absorption in surface waters. The distribution of CDOM, phytoplankton and non-algal particles absorption reproduces the hydrographic variability in this region of the Arctic Ocean which suggests a subdivision into five major bio-optical provinces: Laptev Sea Shelf, Laptev Sea, Central Arctic/Transpolar Drift, Beaufort Gyre and Eurasian/Nansen Basin. Evaluating ocean color algorithms commonly applied in the Arctic Ocean shows that global and regionally tuned empirical algorithms provide poor chlorophyll-a (Chl-a) estimates. The semi-analytical algorithms Generalized Inherent Optical Property model (GIOP) and Garver-Siegel-Maritorena (GSM), on the other hand, provide robust estimates of Chl-a and absorption of colored matter. Applying GSM with modifications proposed for the western Arctic Ocean produced reliable information on the absorption by colored matter, and specifically by CDOM. These findings highlight that only semi-analytical ocean color algorithms are able to identify with low uncertainty the distribution of the different optical water constituents in these high CDOM absorbing waters. In addition, a clustering of the Arctic Ocean into bio-optical provinces will help to develop and then select province-specific ocean color algorithms.

Dataset Information

Signatures of Molecular Unification and Progressive Oxidation Unfold in Dissolved Organic Matter of the Ob-Irtysh River System along Its Path to the Arctic Ocean.

Publications

Signatures of Molecular Unification and Progressive Oxidation Unfold in Dissolved Organic Matter of the Ob-Irtysh River System along Its Path to the Arctic Ocean.

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