中文关键词土地利用碳同位素溶解无机碳(DIC)水化学地下水岩溶区洪家渡盆地 英文关键词land usecarbon isotopedissolved inorganic carbon(DIC)hydrochemistrygroundwaterkarst areaHongjiadu Basin

作者	单位	E-mail
任坤	中国地质科学院岩溶地质研究所, 桂林 541004 自然资源部广西岩溶动力学重点实验室, 桂林 541004	rkhblhk@163.com
潘晓东	中国地质科学院岩溶地质研究所, 桂林 541004
曾洁	中国地质科学院岩溶地质研究所, 桂林 541004
焦友军	中国地质科学院岩溶地质研究所, 桂林 541004
彭聪	中国地质科学院岩溶地质研究所, 桂林 541004
梁嘉鹏	中国地质科学院岩溶地质研究所, 桂林 541004

中文摘要 通过分析贵州洪家渡盆地地下水水化学和溶解无机碳（dissolved inorganic carbon，DIC）同位素（δ¹³C_DIC）季节变化特征，探讨岩溶区不同土地利用类型下影响地下水δ¹³C_DIC特征的自然过程和人为因素.结果表明：洪家渡盆地地下水中DIC主要来源于碳酸盐岩风化和土壤CO₂.地下水δ¹³C_DIC值冬季为-14.8‰~-4.1‰，平均值-10.1‰；夏季为-14.5‰~-6.3‰，平均值-10.2‰.含煤地层中硫化物氧化和酸雨带来的H₂SO₄参与碳酸盐岩风化使地下水δ¹³C_DIC值整体偏正.由于土壤CO₂效应，人类活动干扰程度小的林地地下水δ¹³C_DIC值夏季<冬季.夏季农业活动施用的大量肥料产生的HNO₃参与了碳酸盐岩风化，使耕地地下水δ¹³C_DIC值夏季>冬季.居住区人为输入的有机质降解对地下水DIC贡献较大，冬夏季δ¹³C_DIC平均值分别-11.9‰和-11.6‰，季节差异较小.不同季节、不同土地利用类型下，人类活动方式不同导致地下水δ¹³C_DIC值与水化学存在差异.因此，δ¹³C_DIC可以反映人类活动对岩溶含水层的影响，具有良好的生态指示意义. 英文摘要 Based on the seasonal characteristics of groundwater hydrochemistry and the carbon isotopes (δ¹³C) of dissolved inorganic carbon (DIC) in the Hongjiadu Basin, Guizhou Province, this paper discusses the natural processes and anthropogenic factors affecting the characteristics of δ¹³C_DIC in karst groundwaters under different land use types. The results show that the main sources of DIC in groundwater are carbonate weathering and soil CO₂. In winter, the δ¹³C_DIC values for groundwater ranged from -14.8‰ to -4.1‰ with an average of -10.1‰ and, in summer, ranged from -14.5‰ to -6.3‰ with an average of -10.2‰. Sulfuric acid from sulfide oxidation in coal-bearing strata and acid rain is involved in carbonate weathering, resulting in the enrichment of groundwater with heavy carbon isotopes. Due to the soil CO₂ effect, the δ¹³C_DIC values of woodland groundwater experiencing less disturbance from human activities are lower in summer than in winter. The degradation of organic matter input from residential areas is a significant contributor of DIC to groundwater. The average values of δ¹³C_DIC in winter and summer were -11.9‰ and -11.6‰, respectively, and the seasonal difference was relatively small in residential areas. During different seasons and for different types of land use, human activities could lead to differences in groundwater δ¹³C_DIC values and hydrochemistry. Therefore, δ¹³C_DIC can reflect the impact of human activities on karst aquifers, which has important ecological significance.

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