LAI Manting, ZHONG Jun*, WANG Wanfa, YI Yuanbi, CHEN Shuai, XU Sheng
(Institute of Surface-Earth Science System, School of Earth Science System, Tianjin University, Tianjin 300072, China)

Abstract: Riverine carbon cycle is one of the most important components and research hotspot in studying the global carbon cycle. However, few studies focused on the riverine carbon cycle in the Tibetan Plateau. Bailong River catchment is located on the northeast edge of Tibetan Plateau, being the ideal areas to study the carbon cycle of catchment on the plateau. In order to study the spatial distribution, sources and controlling factors of dissolved organic carbon (DOC) of Bailong River catchment, the river water samples were systematically collected from the Bailong River catchment and analyzed for the temperature, pH, electrical conductivity (EC), concentration of DOC, UV optical properties and δ13C of DOC. The analytical results show that the concentration of DOC is in the range of 0.4-4.1 mg/L with an average 1.4 mg/L, and δ13CDOC ranges from -27.2‰ to -26.2‰. There is a trend of DOC spatial distribution, being high in the upstream and low in downstream, and the range of DOC concentration in the middle and lower reaches of main stream is similar, while the concentration of DOC in the southern tributary decreases gradually from the upstream to the downstream. The DOC concentration reveals positive correlations with the soil organic carbon concentration and α(254) value. These features together with δ13CDOC values suggested that DOC in Bailong River catchment were mainly derived from the decomposition of terrestrial C3-type organic matter, and were controlled by the altitude (temperature) and land use.

Key word: dissolved organic carbon; terrestrial C3-type organic matter; spatial distribution; Bailong River

EARTH AND ENVIRONMENT Vol.49, No.3, Tot No.341, 2021, Page 227-237