崇明东滩湿地土壤溶解性有机质的光谱特征分析

为了解滨海湿地土壤中溶解性有机质(DOM)的组成、分布及来源特征,采用紫外可见光谱和三维荧光光谱技术,并结合平行因子模型(PARAFAC)对崇明东滩湿地表层土壤DOM进行研究。结果表明:东滩表层土壤DOM吸收系数a(355)的均值为(13.72±9.47) m^-1,呈由高潮滩向低潮滩递减的趋势;光谱斜率S_275-295的均值为(15.22±2.07)μm^-1,反映出湿地南部土壤DOM的分子量较高,受大分子有机质影响较大。PARAFAC解析出的DOM含有2类3个荧光组分,即F_C1类蛋白质、F_C2陆源类腐殖质和F_C3自生源类腐殖质,各组分对总荧光强度的贡献率分别为40.70%、23.04%和36.26%。空间分布上,3组分荧光强度的高值集中于北部互花米草(Spartina alterniflora)和芦苇(Phragmites australis)湿地,且自北向南逐渐递减。荧光指数(FI)、生物源指数(BIX)和腐殖化指数(HIX)显示东滩湿地表层土壤DOM的...

SPECTRAL CHARACTERISTICS OF SOIL DISSOLVED ORGANIC MATTERS IN CHONGMING DONGTAN WETLAND

In order to elucidate the composition, distribution and source characteristics of soil dissolved organic matter (DOM) in coastal wetland, ultraviolet-visible absorption spectrum and excitation-emission matrix spectroscopy combined with parallel factor analysis (PARAFAC) were applied to investigate the DOM in the surface soil of Dongtan in Chongming District, Shanghai. The results indicated that the mean value of DOM absorption coefficient (a(355)) was (13.72±9.47) m-1, which showed a trend of decreasing from high tide beach to low tide beach. The mean value of the spectral slope (S_275-295) was (15.22±2.07) μm-1 and it reflected that the soil DOM had a higher molecular weight in the south of the wetland, which was greatly affected by macromolecular organic matter. Three fluorescence components were identified by PARAFAC, including protein-like component named F_C1, land-sourced humic-like component named F_C2, and authigenic-source humic-like component named F_C3. The contribution rates of F_C1, F_C2 and F_C3 to total fluorescence intensity were 40.70%, 23.04% and 36.26%, respectively. Spatially, the peak values of the intensity of three components were observed in the Spartina alterniflora and Phragmites australis wetland, and gradually decreased from the north to the south. Fluorescence index (FI), biogenic index (BIX) and humification index (HIX) showed that the soil DOM in Dongtan was mainly derived from endogenous sources. The fluorescence components were significantly positively correlated with each other, and each component was closely related to the migration and transformation of carbon and nitrogen. Chromophores and fluorophores of DOM shared a common source.