海拔梯度上川西高山土壤溶解性有机质(DOM)光谱特征

采用三维激发发射矩阵荧光光谱、平行因子分析（EEM-PARAFAC）和荧光区域积分方法（FRI），研究川西高原3200~4000m高寒土壤DOM特征及其在海拔梯度上变化规律.结果表明，高寒土壤DOC含量为0.47~0.81g/kg，随着海拔梯度的升高而呈增加趋势，表层土中含量多高于亚表层土；土壤中DOM组分均呈5个组分，即芳香蛋白类物质I（酪氨酸类，Peak I）、芳香蛋白类物质II（BOD₅，Peak II）、富里酸类（Peak III）、微生物代谢产物（色氨酸类，Peak IV）和腐殖酸类（大分子腐殖酸，Peak V）；高山土壤DOM中以富里酸类有机质和腐殖酸类有机质组分为主，FRI值均随着海拔的升高而降低..川西高山土壤DOM荧光特征参数（荧光指数FI、自生源指数BIX、腐殖化指数HIX、新鲜度指数β：α）表明，土壤DOM的稳定性随着海拔升高而降低，生物有效性随着海拔升高而升高.因此，气候变暖可能将导致高海拔土壤DOM分解加剧而含量降低，但稳定性升高.

Spectroscopic characteristics of soil dissolved organic matter (DOM) along the altitudinal gradient of alpine in western Sichuan

By the use of three-dimensional excitation emission matrix fluorescence coupled with parallel factor analysis (EEM-PARAFAC) and fluorescence regional integration (FRI) analysis, DOM characteristics of the alpine soil and its changing tendency along an altitudinal gradient from 3200 to 4000m in the western Sichuan province were studied. The results showed that, the DOC concentrations for the alpine soil ranged from 0.47 to 0.81g/kg, showing an increasing trend with the altitude elevation in the same soil layer, and mostly higher DOCs in the topsoil layer than the subsoil. There were always five DOM components in the tested soils, namely, aromatic protein substance I (tyrosine, Peak I), aromatic protein substance II (BOD₅, Peak II), fulvic acid-like (Peak III), soluble microbial byproduct-like (tryptophan, Peak IV) and humic acid-like (Peak V). The fulvic acid-like and humic acid-like species are two major DOM components for the alpine soil. FRI values decreased with the altitude increase. Values of fluorescence characteristic parameters (fluorescence index FI, spontaneous source index BIX, humification index HIX, freshness index β:α) have indicated that, the stability of soil DOM decreases with altitude elevation, while the bioavailability increases with elevation. Therefore, climate warming may lead to increased DOM decomposition and decreased contents in high altitude soils but with an increased stability.