Immobilization of relic anthropogenic dissolved organic matter from alpine rivers in the Himalayan-Tibetan Plateau in winter

TY - JOUR

T1 - Immobilization of relic anthropogenic dissolved organic matter from alpine rivers in the Himalayan-Tibetan Plateau in winter

AU - Chen, Meilian

AU - Li, Chaoliu

AU - Zeng, Chen

AU - Zhang, Fan

AU - Raymond, Peter A.

AU - Hur, Jin

N1 - Publisher Copyright: © 2019 Elsevier Ltd

PY - 2019/9/1

Y1 - 2019/9/1

N2 - The Tibetan Plateau is a critical ecosystem that sensitively responds to ongoing glacier shrinkage and permafrost thaw. Dissolved organic matter (DOM) in Tibetan Alpine rivers plays pivotal roles in the biogeochemical cycling of elements and nutrients at regional and even global scales, impacting water quality, downstream environments, and climate. However, little is known about the characteristics and dynamics of DOM in these watersheds. We investigated five major Himalayan rivers in the southern Tibetan Plateau, utilizing bulk dissolved organic carbon (DOC), optical properties, and molecular formulas. We found extremely low DOC and fluorescent DOM (FDOM) levels in the rivers (average DOC: 0.25–0.87 mg L−1, FDOM: 0.02–0.05 RU) with a highly degraded molecular signature, which was enriched with heteroatomic molecular formulas (S-containing: 58–72%, N-containing: 61–86%) and condensed aromatics (31–39% vs. ∼11% in world major rivers). Further, 81–99% of the condensed aromatics was identified as dissolved black nitrogen (DBN) with multiple nitrogen atoms, typical for grassy biomass combustion. The findings highlighted potentially fast DOM remineralization leading to the release of CO2 and enriched apparently anthropogenic condensed aromatics and heteroatomic formulas in what have been considered pristine Tibetan rivers. These findings should be considered in future biogeochemical models and ecosystem management.

AB - The Tibetan Plateau is a critical ecosystem that sensitively responds to ongoing glacier shrinkage and permafrost thaw. Dissolved organic matter (DOM) in Tibetan Alpine rivers plays pivotal roles in the biogeochemical cycling of elements and nutrients at regional and even global scales, impacting water quality, downstream environments, and climate. However, little is known about the characteristics and dynamics of DOM in these watersheds. We investigated five major Himalayan rivers in the southern Tibetan Plateau, utilizing bulk dissolved organic carbon (DOC), optical properties, and molecular formulas. We found extremely low DOC and fluorescent DOM (FDOM) levels in the rivers (average DOC: 0.25–0.87 mg L−1, FDOM: 0.02–0.05 RU) with a highly degraded molecular signature, which was enriched with heteroatomic molecular formulas (S-containing: 58–72%, N-containing: 61–86%) and condensed aromatics (31–39% vs. ∼11% in world major rivers). Further, 81–99% of the condensed aromatics was identified as dissolved black nitrogen (DBN) with multiple nitrogen atoms, typical for grassy biomass combustion. The findings highlighted potentially fast DOM remineralization leading to the release of CO2 and enriched apparently anthropogenic condensed aromatics and heteroatomic formulas in what have been considered pristine Tibetan rivers. These findings should be considered in future biogeochemical models and ecosystem management.

KW - Alpine rivers

KW - Anthropogenic effects

KW - EEM-PARAFAC

KW - FT-ICR-MS

KW - Himalayan-Tibetan plateau

KW - dissolved organic matter

UR - http://www.scopus.com/inward/record.url?scp=85066036260&partnerID=8YFLogxK

U2 - 10.1016/j.watres.2019.05.052

DO - 10.1016/j.watres.2019.05.052

M3 - 文章

C2 - 31132566

AN - SCOPUS:85066036260

VL - 160

SP - 97

EP - 106

JO - Water Research

JF - Water Research

SN - 0043-1354

ER -