Riverine dissolved organic carbon and its optical properties in a permafrost region of the Upper Heihe River basin in the Northern Tibetan Plateau

Tanguang Gao; Shichang Kang; Rensheng Chen; Taigang Zhang; Tingjun Zhang; Chuntan Han; Lekhendra Tripathee; Mika Sillanpää; Yulan Zhang

doi:10.1016/j.scitotenv.2019.05.478

Riverine dissolved organic carbon and its optical properties in a permafrost region of the Upper Heihe River basin in the Northern Tibetan Plateau

Sci Total Environ. 2019 Oct 10:686:370-381. doi: 10.1016/j.scitotenv.2019.05.478. Epub 2019 Jun 3.

Authors

Tanguang Gao¹, Shichang Kang², Rensheng Chen³, Taigang Zhang¹, Tingjun Zhang¹, Chuntan Han³, Lekhendra Tripathee³, Mika Sillanpää⁴, Yulan Zhang⁵

Affiliations

¹ Key Laboratory of Western China's Environmental System (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, China.
² State key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China.
³ State key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China.
⁴ Laboratory of Green Chemistry, Lappeenranta University of Technology, Mikkeli 50130, Finland.
⁵ State key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China. Electronic address: yulan.zhang@lzb.ac.cn.

PMID: 31181523
DOI: 10.1016/j.scitotenv.2019.05.478

Abstract

Riverine dissolved organic carbon (DOC) and its optical properties were investigated in two sub-river basins (Yeniugou and Hulugou river) of the Upper Heihe river basin in the northern Tibetan Plateau. The results showed that DOC concentrations ranged from 0.25 to 12.2 and 0.18-1.04 mg L^-1 for Yeniugou and Hulugou river basin with an average of 0.82 and 0.33 mg L^-1, respectively. Export of DOC from the studied river (YNG: ~0.86 Gg C yr^-1) was lesser compared with other large river in the Tibetan Plateau and Arctic regions because of the small drainage area and lower DOC concentrations. There exhibited significant seasonality for DOC in Yeniugou river basin with higher values observed during late spring and summer; however, no such distinct trend was observed for DOC in the studied rivers of Hulugou river basin. In contrast, total dissolved nitrogen showed a slightly lower value during the summer season. A strong relationship was determined between DOC concentrations and spectral UV absorbance at 254 nm (SUVA₂₅₄), absorption coefficients and spectral slope for both sub-river basins, attributing that the riverine DOM in the northern Tibetan Plateau has a remarkably high content of aromatic compounds in late spring and summer. Considering the less snow cover percentage, this study highlights the potential impacts of permafrost thaw on the riverine DOC and its characteristics in the permafrost region under climate change.

Keywords: Absorbance; DOC; Permafrost; River water; Spectral slope; Tibetan Plateau.