【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(δ13CDIC)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δ13CDIC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δ13CDIC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δ13CDIC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δ13CDIC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δ13CDIC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δ13CDIC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δ13CDIC值与水化学存在差异.因此,δ13CDIC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.更多还原

【Abstract】 Based on the seasonal characteristics of groundwater hydrochemistry and the carbon isotopes( δ13 C) of dissolved inorganic carbon( DIC) in the Hongjiadu Basin,Guizhou Province,this paper discusses the natural processes and anthropogenic factors affecting the characteristics of δ13 CDICin 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 δ13 CDICvalues 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 δ13 CDICvalues 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 δ13 CDICin 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 δ13 CDICvalues and hydrochemistry. Therefore,δ13 CDICcan reflect the impact of human activities on karst aquifers,which has important ecological significance.更多还原