泾渭河交汇区域平水期水体和表层沉积物溶解性有机质的光谱性质

摘要

As the representative component for eco-environmental researchers,dissolved organic matter (DOM)is playing a sig-nificant role for the indication effect on environmental quality and efficiency assessment on remediation approaches.Nowadays,it lacks related investigation on DOM derived from rivers and sediments,and the advanced discussion is in urgent need because of the dynamic variations of experimental target,such as spatial-temporal condition,hydrological condition,environmental condi-tion and research dimension.The spectral approaches,including elemental analysis,ultraviolet spectra (UV),Fourier transform infrared spectroscopy (FT-IR),Raman spectra (Raman),three dimensional excitation emission matrix fluorescence spectroscopy (3D-EEMs)and nuclear magnetic resonance (NMR)were used to reveal the characteristics of DOM derived from water and sedi-ment samples in the intersection zone of Jing River and Wei River (Gaoling District,Xi’an City,Shaanxi Province).The results showed:the ratios of H/C and N/C for DOM in sediment are higher than that of DOM in water,suggesting the saturation de-gree in DOM from sediment are higher with more content of nitrogen.The UV absorbance of DOM decreases with the increasing of wave length,and obvious absorption region (240~310 nm)appears in DOM from sediment.The functional groups of —OH, C—C and C—O could be found in DOM from FTIR spectra,and the characteristics might be more complicated in sediment for various peak shapes and intensities.The Raman spectra of DOM in water are similar to that of the sediment.The fluorescence peaks of DOM in water are regarded as visible tryptophane-like and UV fulvic-like components,mainly from terrestrial source;while fluorescence peaks of DOM in sediment belong to UV fulvic-like fluorescence without protein-like fluorescence peaks being detected.The principal carbon chains are similar in DOM samples from water and sediment,and the aliphatic characteristics are more obvious for the latter,which contains more carbohydrate-binding hydrogen than aromatic-binding hydrogen andγ-H.It proves that DOM in water mainly comes from terrestrial source,and DOM in sediment is more complicated and fresher.The achievements are significant to reveal the microscopic characteristics and environmental behavior of DOM in representative sys-tems.%溶解性有机质是环境生态学者关注的典型对象,其对环境质量的指示作用以及修复策略的效果评价具有重要参考价值。现阶段,对于河流和沉积物DOM的研究略显不足,尤其考虑到目标组分的动态差异(时空、水文、环境、尺度等),相关方面的精细化研究便显得尤为必要。以泾渭河交汇区域(陕西西安高陵段)水体和表层沉积物为研究对象,通过光谱联用技术(元素分析、UV、FTIR、Raman、3D-EEMs 和 NMR)深度揭示其微观特征。研究表明：沉积物DOM的 H/C和 N/C比都高于水体DOM,说明沉积物DOM碳氢饱和度更高,同时含有更多含氮组分。DOM紫外吸光度随吸收波长的增加逐渐下降；水体 DOM吸收平台极弱,但沉积物DOM发现较明显的吸收平台(240~310 nm)。DOM含有—OH, C—C,C—O 等基团,沉积物DOM官能团性质略为复杂,具体体现在峰形和峰强的局部差异上。水体和沉积物DOM的Raman图谱相似,基本无法给予有效的区别信息。水体DOM荧光峰归属为可见光区类色氨酸和紫外区类富里酸,以陆源有机质为主；沉积物DOM荧光峰均属于紫外区类富里酸荧光峰,没有发现类蛋白组分特征峰。水体和沉积物DOM具有类似的C骨架,但沉积物DOM的脂族特性更明显。1 H NMR 结果表明碳水化合物 H 含量较高,而芳香族 H、γ-H 等含量较低。总体认为水体 DOM的陆源性更加明显,沉积物 DOM组分更为复杂和“年轻”。相关结果有助于深度明晰典型环境体系DOM的微观性质和环境行为。