西安城市河岸带土壤溶解性有机质荧光特性

Fluorescence spectral characteristics of soil dissolved organic matter in riparian zones of the Xi'an

以浐河西安段为研究区域,基于野外调查及三维荧光技术进行光谱分析,探究了城市河岸带土壤溶解性有机质结构特征及其来源。结果表明:综合荧光指数(FI)、生物源指数(BIX)均显示西安浐河土壤DOM具有较强的生物来源属性;经光谱分析,土壤DOM三维荧光光谱中出现了A、C和D等荧光峰,分别代表类富里酸、类腐殖酸和可溶性微生物代谢产物,且以腐殖质类物质为主(占55. 8-66. 7%),且荧光强度随土层深度增加呈下降趋势。相关分析表明,土壤SOC、p H、AP、NO-3-N等性质影响其DOM荧光特性;FI和BIX可综合表征DOM来源与结构组成。由因子特征分类分析表明,外源有机物的输入对表层20cm土壤DOM来源及其性质有主要影响,植被类型及根系作用对其亦有一定影响。

In order to elucidate the structure characteristics of soil dissolved organic matter(DOM)and analyze the sources in riparian zones of the Xi’an Chanhe River,taking Chanhe river in Xi’an as experimental zone,based on the field investigation,the soil samples were collected,and the spectral analysis was made by three-dimensional fluorescent technology.The results showed that the two optical indices,FI and BIX,provided conclusive evidences that DOM originated from microbial metabolite and the humic fractions of DOM were freshly produced.Three fluorescence peaks including A,C and D were found in the three-dimensional fluorescence spectrum,indicating phenol-like,humicacid-like-substances and soluble microbial byproduct-like,respectively.The proportion of humus substance in each fluorescence fraction was 55.8-66.7%.There were some differences in fluorescence peak and fluorescence intensity of different sampling points.The correlation analysis showed that the soil properties of SOC,p H,AP,NO3^--N affected the fluorescence properties of DOM.FI and BIX could express the structure characteristics.The analysis of factor characteristic classification showed that exogenous organic matter input,such as effluent discharge,had a great influence on the organic carbon content and character of the surface soil in 0-20 cm.In addition,vegetation type and root function also had certain influence.