Fluorescence Spectroscopic Properties of Dissolved Fulvic Acids from Salined Flavo-aquic Soils around Wuliangsuhai in Hetao Irrigation District, China

摘要

This study was conducted to discuss fluorescence spectroscopic properties of dissolved fulvic acids (FA) isolated from salined flavo-aquic soils around Wuliangsuhai Lake in Hetao Irrigation District, and to evaluate humification degree of FA and soil salinization processes. Composite soil samples of different depths (0-20, 20-40, 40-60, and 60-80 cm) were collected from four different halophyte communities along a saline-impact gradient around Wuliangsuhai Lake, namely, Comm. (Community) Salicornia europaea (CSE), Comm. Suaeda glauca (CSG), Comm. Kalidium foliatum (CKF), and Comm. Sophora alopecuroides (CSA). Ten humification indices (HIX) (A(4)/A(1), A(465), I-383/I-330, I-460/I-355, I-460/I-380, S355-460, S380-460, AF(3)/AF(1), AF(3)/AF(2), and r), deduced from fluorescence spectra of FA, were used to assessing humification degree. Aromatic C structure of FA was the most complex in the CSA soils, and humificaiton degree was the highest too, followed by CKF, CSG, and CSA. There were significant relationships among the 10 HIX (P < 0.01), and A(465), S355-460, and S380-460 can more indistinctly differentiate humification degree than the other seven HIX. The 10 HIX exhibited good correlations with exchangeable sodium percentage (ESP), and humification degree rose with the decreasing ESP. The HIX not only indicate humification degree, but character soil salinization processes. Therefore HIX may be used as a surrogate for ESP, and may be indicative of soil salinization processes. This study can provide a theoretical basis for the prevention of desertification and saline soil remediation.