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为探究氮沉降对亚热带杉木人工幼林土壤溶液可溶性有机物质(DOM)浓度及光谱学特征的影响,采用负压法,对0~15和15~30 cm土层土壤溶液DOM进行了2年的动态监测及光谱学特征研究.结果表明:氮沉降显著减少了各土层土壤溶液可溶性有机碳(DOC)浓度,增加了芳香化指数(AI)及腐殖化指数(HIX),但对可溶性有机氮(DON)无显著影响.土壤溶液DOM浓度存在明显的季节变动,夏秋季显著高于春冬季.傅里叶红外光谱结果表明,森林土壤溶液DOM在6个区域的相似位置存在吸收峰,其中1145~1149 cm~(-1)的吸收峰最强.三维荧光光谱表明,DOM主要以类蛋白质物质(Ex/Em=230 nm/300 nm)和微生物降解产物(Ex/Em=275 nm/300 nm)为主,施氮使0~15 cm土层类蛋白质物质减少.氮沉降可能主要是通过降低土壤pH、抑制土壤碳矿化和刺激植物生长等途径显著抑制土壤溶液DOC浓度,而表层被抑制的DOC成分以类蛋白质物质和羧酸盐物质为主.氮沉降短期可能有利于土壤肥力的储存,但随着氮沉降量的积累,土壤中营养物质将难以得到有效利用.
In order to explore the effect of nitrogen deposition on DOM concentration and spectral characteristics of soil in subtropical Chinese fir young plantations, the DOM of 0-15 and 15-30 cm soil layers was subjected to two years of dynamic The results showed that nitrogen deposition significantly reduced the concentrations of soil dissolved organic carbon (DOC) in soil layers and increased the aromatics index (AI) and humicidal index (HIX), but the contents of soluble organic nitrogen (DON). There was a significant seasonal variation in DOM concentration in soil solution, which was significantly higher than that in spring and winter in summer and autumn. The results of Fourier transform infrared spectroscopy showed that there were absorption peaks in similar positions of DOM in forest soil solution, 1145 The absorption peak at 1149 cm -1 was the strongest, and the three-dimensional fluorescence spectra showed that the DOM mainly consisted of protein-like substances (Ex / Em = 230 nm / 300 nm) and microbial degradation products ), And nitrogen application reduced soil protein content in 0 ~ 15 cm soil layer. Nitrogen deposition may be mainly inhibited soil DOC concentration by reducing soil pH, inhibiting soil carbon mineralization and stimulating plant growth, while the surface layer was inhibited DOC components to protein-like substances and carboxyl Salt-based substance. N deposition may be beneficial for short-term storage of soil fertility, but with the accumulation of nitrogen deposition amount of soil nutrients will not be effectively utilized.