Li Li, Pu Jun-Bing, Li Jian-Hong, Zhang Tao
Key Laboratory of Karst Dynamics, Ministry of Land and Resources & Guangxi, Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin 541004, China.
School of Geographical Sciences, Southwest University, Chongqing 400715, China.
Huan Jing Ke Xue. 2017 Feb 8;38(2):527-534. doi: 10.13227/j.hjkx.201607171.
Stable carbon isotope of dissolved inorganic carbon (δC), which is mainly constituted by HCO in karst water, is widely used to trace the different sources and influential factors of dissolved inorganic carbon (DIC). In order to understand the distribution of DIC and δC in subtropical karst area, this paper researched the water chemistry and δC in a karst surface stream in detail, which is fed by Guancun subterranean stream in Liuzhou City, Guangxi Province, in the southwest of China. The results showed that the contents of DIC in subterranean stream outlet (G1 site) ranged from 4.60 to 4.90 mmol·L with an average of 4.73 mmol·L in dry season, and from 2.80 to 4.70 mmol·L with an average of 4.23 mmol·L in rainy season. The contents of DIC in 1.35 km downstream site (G2 site) ranged from 4.30 to 4.90 mmol·L with an average of 4.56 mmol·L in dry season, and from 3.00 to 4.70 mmol·L with an average of 4.20 mmol·L in rainy season. The δC of subterranean stream outlet (G1 site) varied from -12.8‰ to -11.53‰ with an average of -12.22‰ in dry season, and from -13.12‰ to -11.01‰ with an average of -12.28‰ in rainy season. The δC of stream downstream site (G2 site) ranged from -11.71‰ to -9.55‰ with an average of -10.73‰ in dry season, and ranged from -12.18‰ to -9.85‰ with an average of -11.10‰ in rainy season. The contents of DIC of G1 site were higher than those of G2 site. The DIC contents in dry season in both G1 and G2 site were higher than those in rainy season. The values of δCof G1 and G2 site in dry season were more positive than those in rainy season. The δCvalue of G1 site was more negative than that of G2 site. The main sources of DIC in underground river and surface stream were soil COand carbonate dissolution. However, the differences of DIC and δCbetween G1 and G2 site showed that COdegassing and photosynthesis of aquatic plants had significant influence on water DIC and δC value. This study is helpful to understand the dynamic change and distribution of DIC and δC in karst surface stream.
溶解无机碳（δC）的稳定碳同位素主要由岩溶水中的HCO构成，被广泛用于追踪溶解无机碳（DIC）的不同来源和影响因素。为了解亚热带岩溶地区DIC和δC的分布情况，本文详细研究了中国西南部广西壮族自治区柳州市官村地下河补给的一条岩溶地表溪流的水化学和δC。结果表明，地下河出口（G1点）的DIC含量在旱季为4.60至4.90 mmol·L，平均为4.73 mmol·L，雨季为2.80至4.70 mmol·L，平均为4.23 mmol·L。下游1.35 km处（G2点）的DIC含量在旱季为4.30至4.90 mmol·L，平均为4.56 mmol·L，雨季为3.00至4.70 mmol·L，平均为4.20 mmol·L。地下河出口（G1点）的δC在旱季为-12.8‰至-11.53‰，平均为-12.22‰，雨季为-13.12‰至-11.01‰，平均为-12.28‰。溪流下游点（G2点）的δC在旱季为-11.71‰至-9.55‰，平均为-10.73‰，雨季为-12.18‰至-9.85‰，平均为-11.10‰。G1点的DIC含量高于G2点。G1和G2点旱季的DIC含量均高于雨季。G1和G2点旱季的δC值比雨季更偏正。G1点的δC值比G2点更负。地下河和地表溪流中DIC的主要来源是土壤CO和碳酸盐溶解。然而，G1和G2点之间DIC和δC的差异表明，CO脱气和水生植物的光合作用对水体DIC和δC值有显著影响。本研究有助于了解岩溶地表溪流中DIC和δC的动态变化及分布。
