Using δ13C to reveal the importance of different water transport pathways in two nested karst basins, Southwest China

JOURNAL OF HYDROLOGY

卷:571

Article

Hao, Zhuo^1,2  Gao, Yang^1,2  Ma, Mingzhen^1,2  Green, Sophie M.³  Wang, Jing^1,2  Song, Xianwei^1,2  Dungait, Jennifer A. J.³  Johnes, Penny J.⁴  Xiong, Bailian⁵  Quine, Timothy A.³  Sun, Xiaomin^1,2  Wen, Xuefa^1,2  He, Nianpeng^1,2 

[1] Chinese Acad Sci, Inst Geog Sci & Nat Resources Res, Key Lab Ecosyst Network Observat & Modeling, Beijing 100101, Peoples R China

[2] Univ Chinese Acad Sci, Coll Resources & Environm, Beijing 100190, Peoples R China

[3] Univ Exeter, CLES, Geog, Amory Bldg,Rennes Dr, Exeter EX4 4RJ, Devon, England

[4] Univ Bristol, Sch Geog Sci, Univ Rd, Bristol BS8 1SS, Avon, England

[5] Zunyi Normal Coll, Coll Resources & Environm, Zunyi, Guizhou, Peoples R China

关键词: Carbon cycle;    Source partition;    Hydrological pathway;    Catchment;   

DOI  :  10.1016/j.jhydrol.2019.01.070

来源: Elsevier

【 摘 要 】

This study used carbon (C) isotope sourcing to determine transport processes of dissolved inorganic carbon (DIC) from the land surface to river catchments in Southwest China. Both nested karst watersheds investigated (Chenqi and Houzhai) are representative of typical karst landform environments (e.g., primary forest, secondary forest, and farmland). We measured DIC concentrations and the delta C-13 values of rainfall, river water, groundwater, soil, and plants. To do so, we used IsoSource (a Visual Basic program) to determine source partitioning over time (seasonal) and across the two nested watersheds. In 2017, the mean DIC concentration was 0.06 +/- 0.03 mmol L-1 and the rainfall delta C-13(DIC) value was -14.4 parts per thousand +/- 1.9 parts per thousand. We found similar DIC concentrations in the surface and groundwater of both watersheds, ranging from 0.20 to 0.71 mmol L-1 (seasonal) and from - 3.7 parts per thousand to - 9.4 parts per thousand (delta C-13(DIC)) in the Chenqi catchment and from 0.33 to 0.60 mmol L-1 (seasonal) and from -10.3 parts per thousand to - 6 parts per thousand (delta C-13(DIC)) in the Houzhai watershed. The average delta C-13 values of soil and local plants were - 24.6 +/- 1.4 parts per thousand and - 28.9 +/- 1.2 parts per thousand in the Chenqi catchment and -25.8 +/- 0.9 parts per thousand and - 27.2 +/- 1.8 parts per thousand in Houzhai watershed, respectively. In addition, carbonate bedrock and groundwater were the main sources of surface water in the Chenqi and Houzhai nested watersheds, both being greater than 30%. Source percentages were similar to 20% from atmospheric deposition and similar to 10% from soil. Furthermore, HCO3- was the predominant form of DIC (pH values > 8), and the contribution rates of dissolved carbonate minerals (HCO3-) were approximately 10.4% and 19.6% in the Chenqi catchment and the Houzhai watershed, respectively.

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