Developing an understanding of dissolved organic matter dynamics in the giant Lake Baikal by ultrahigh resolution mass spectrometry

• Published in: Limnology Vol. 15; no. 2; pp. 127 - 139
• Main Authors: Sugiyama, Yuko, Hatcher, Patrick G, Sleighter, Rachel L, Suzuki, Tomoyo, Wada, Chizuru, Kumagai, Tetsu, Mitamura, Osamu, Katano, Toshiya, Nakano, Shin-ichi, Tanaka, Yuji, Drucker, Valentin V, Fialkov, Vladimir A, Sugiyama, Masahito
• Format: Journal Article
• Language: English
• Published: Tokyo Springer-Verlag 01-04-2014; Springer Japan; Springer Nature B.V
• Subjects: Aromatic compounds; Biomedical and Life Sciences; Dissolved organic carbon; Dissolved organic matter; Ecology; Emissions; Environment; Fourier transforms; Freshwater & Marine Ecology; Geochemistry; Lakes; Life Sciences; Limnology; Mass spectrometry; Photodegradation; principal component analysis; Principal components analysis; Research Paper; River mouth; Water analysis; Water sampling; watersheds; Lake Baikal; Russia, Siberia, Baykal L; Lake Baikal; Dissolved organic matter; Fourier transform ion cyclotron resonance mass spectrometry
• ISSN: 1439-8621; 1439-863X
• DOI: 10.1007/s10201-014-0424-5

To elucidate the molecular characteristics of dissolved organic matter (DOM) in Lake Baikal, 3D excitation-emission matrix spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) were employed. From the linear relationship between the humic-like peak intensities (excitation/emission = 305 nm/430 nm) and dissolved organic carbon (DOC) concentrations in the water samples extending from the Selenga River mouth to offshore (central lake in the south basin), allochthonous DOM appeared to be a main contributor to the DOC concentrations. However, DOM with fewer fluorophores dominated in the South Basin of the lake at stable DOC concentrations of ca. 0.84 mg C l⁻¹. Meanwhile, FT-ICR MS analysis and subsequent principal component analysis across the transect revealed a transition of compounds with high H-deficiency (aromatic) to compounds with low H-deficiency (aliphatic) that dominate pelagic open-lake water. We believe that this molecular change is induced by photo-degradation, which mainly alters aromatic compounds.