Seasonal variations and factors controlling the stable isotopic composition of dissolved inorganic carbon in the Karst Xiangxi River Basin of the Three Gorges Reservoir, China

被引：0

作者：

Shi, Tingting ^{[1
,2
]}

Zhang, Wei ^{[2
]}

Wu, Xia ^{[1
]}

Jin, Xiaowen ^{[3
]}

Chen, Zhihua ^{[1
,3
]}

机构：

[1] Karst Dynamics Laboratory, MLR and GZAR, (Institute of Karst Geology, CAGS), Guilin, China

[2] Three Gorges Research Center for geo-hazard, Ministry of Education, China University of Geosciences, 388 Luomo Road, Wuhan, China

[3] School of Environmental Studies, China University of Geosciences, 388 Luomo Road, Wuhan, China

来源：

International Journal of Earth Sciences and Engineering | 2014年 / 7卷 / 06期

关键词：

Carbon dioxide - Dissolution - Hydrogeology - Rivers - Watersheds - Carbonation - Drought - Carbonates - Groundwater - Isotopes - Biogeochemistry - Carbon - Organic compounds - Biological materials - Lithology;

D O I：

暂无

中图分类号：

学科分类号：

摘要：

The stable isotopic composition (δ13CDIC) of dissolved inorganic carbon (DIC) was investigated as a potential tracer to distinguish the DIC source and to determine the contribution of atmospheric (soil) CO2 and carbonate rocks to DIC at the Xiangxi River Basin of the Three Gorges Reservoir in Hubei Province, China. Surface water and groundwater samples were collected at six time points from upstream to downstream of three sub-basins. The δ13CDIC of surface water samples from the Xiangxi River Basin is between -8.67‰ and -4.79‰ (-7.35‰ in average) during the rainy season as well as -9.04‰ and -5.11‰ (-8.00‰ in average) during the dry season. The δ13CDIC of the underground streams in the Xianglong and Xiangshui Caves are -10.57‰ and -10.84‰ during the rainy season as well as -11.79‰ and -8.65‰ during the dry season, respectively. The main factor controlling the DIC content was the water cycle condition. Soil can also significantly affect DIC content. The spatial differences of DIC concentration were caused by the basin lithology and hydrogeological conditions. The seasonal variation in the δ13CDIC values was clearly affected by the decomposition of organic matter and the biogeochemical processes involved. During different seasons, the DIC concentration and δ13CDIC demonstrated a negative relationship, which was controlled by plankton photosynthesis. The spatial distribution of δ13CDIC was related to watershed characteristics and river hydrodynamic conditions. In the Nanyang River Basin, the geological characteristics of the regional carbonate rocks were the most significant factors. In the Gufu and Gaolan River Basins, the soil CO2 mainly influenced the δ13CDIC. The inorganic carbon from plant root respiration and soil organic matter oxidation in the recharge area of the two underground streams was higher during summer. During winter, only the recharge area of the Xianglong Cave was affected by the dissolved CO2 gas in the soil carbonate system, which continued to react and exhibit strong microbial activity. The relationship of the δ13CDIC values and the distance to the estuary clearly had opposite trends for the Gaolan and Nanyang River Basins, which could be attributed to their different characteristics. © 2014 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.

引用

页码：2135 / 2143