摘要
Understanding the responses of fluorescence spectral characteristics of cave drip waters to modern environment and climate changes is key to the reconstructions of environmental and climatic changes using fluorescence spectral characteristics of speleothems. The fluorescence spectral characteristics of dissolved organic carbon (DOC) in four active cave systems were analyzed with a three-dimensional (3D) fluorescence spectral analysis method. We found that the fluorescence types of DOC were mainly of fulvic-like and protein-like fluorescences, both in soil waters and cave drip waters. The intensity of fulvic-like fluorescence was positively correlated with the concentrations of DOC, suggesting that the DOC of cave drip waters was derived from the overlying soil layer of a cave system. Compared with the other cave systems, the variation range of the excitation and emission wavelengths for fulvic-like fluorescence of cave drip waters in Liangfeng cave system that had forest vegetation was smaller and the excitation wavelength was longer, while its fluorescence intensity varied significantly. By contrast, the excitation and emission wavelengths and fluorescence intensity for that in Jiangjun cave system that had a scrub and tussock vegetation showed the most significant variation, while its excitation wavelength was shorter. This implies that the variation of vegetation overlying a cave appears to be a factor affecting the fluorescence spectral characteristics of cave drip waters.
Understanding the responses of fluorescence spectral characteristics of cave drip waters to modern environment and climate changes is key to the reconstructions of environmental and climatic changes using fluorescence spectral characteristics of speleothems. The fluorescence spectral characteristics of dissolved organic carbon （DOC） in four active cave systems were analyzed with a three-dimensional （3D） fluorescence spectral analysis method. We found that the fluorescence types of DOC were mainly of fulvic-like and protein-like fluorescences, both in soil waters and cave drip waters. The intensity of fulvic-like fluorescence was positively correlated with the concentrations of DOC, suggesting that the DOC of cave drip waters was derived from the overlying soil layer of a cave system. Compared with the other cave systems, the variation range of the excitation and emission wavelengths for fulvic-like fluorescence of cave drip waters in Liangfeng cave system that had forest vegetation was smaller and the excitation wavelength was longer, while its fluorescence intensity varied significantly. By contrast, the excitation and emission wavelengths and fluorescence intensity for that in Jiangjun cave system that had a scrub and tussock vegetation showed the most significant variation, while its excitation wavelength was shorter. This implies that the variation of vegetation overlying a cave appears to be a factor affecting the fluorescence spectral characteristics of cave drip waters.
基金
the National Key Basic Research Program (GrantNo. 2006CB403200)
the International Partnership Project
the Knowledge Innovation Project of Chi-nese Academy of Sciences (Grant No. kzcx2-yw-306)
the National Natural Science Foundation of China (Grant No. 90202003)
关键词
中国
贵州
洞穴水
三维荧光光谱
土层类型
植物类型
cave drip water, three-dimensional fluorescence spectral characteristics, fulvic-like fluorescence, vegetation type, soil layer type
