湿地植物芦苇根系分泌物的三维荧光光谱表征分析

针对湿地植物芦苇根系分泌物特性不明确的问题,于北京建筑大学大兴校区人工湖实地采集湿地植物芦苇,在实验室水培后采用三维荧光光谱技术考察了芦苇根系分泌溶解性有机物组成随时间的变化规律。结果表明:芦苇根系可分泌溶解性有机物,使根系周围水体有机碳含量增加;芦苇根系分泌物主要为含芳环结构类色氨酸蛋白物质;随时间延长,三维荧光光谱图出现代表微生物代谢物的荧光峰,推测根系周围出现微生物活动,微生物利用根系分泌物生长繁殖,并将类蛋白物质转化为类腐殖酸物质,产生代谢物,使根际周围溶解性有机物组成发生改变。

Characterization analysis for Phragmites australis root exudates of wetland plant via three-dimensional excitation emission matrix fluorescence spectroscopy

This paper intends to make an exploration of the released capacity of the dissolved organic matter and the characteristic features of the exudates from Phragmites australis roots of the wetland plant by using three-dimensional excitation emission matrix (3D-EEM) fluorescence spectroscopy.As we know,since the characteristic features of the exudates from Phragmites australis roots in the constructed wetland remain ambiguous,it is difficult to explore the nature of the pollutants removal by the rhizosphere microorganisms.To be exact,what is dealt with is Phragmites australis that have been collected from the artificially constructed lake in Beijing University of Civil Engineering and Architecture,Daxing District in Beijing.To solve the problem,we have done an imitative experiment in collecting water samples from the surrounding Phragmites australis roots for 20 days.And,then,we began to measure the dissolved organic carbon (DOC) in the water samples everyday and analyze its variations with time by using a total organic carbon (TOC) analyzer.And,simultaneously,we have analyzed the composition of exudates from Phragmites australis roots by 3D-EEM.The results of our experiment have shown that Phragmites australis roots can release a kind of dissolved organic matter,increasing the content of DOC in surrounding water of root.Through the analysis of 3D-EEM spectra,it has been found that the dominant exudates are composed of tryptophan protein substances with aromatic structures.Furthermore,we have also found that,with the increase of the experiment period,the fluorescent peak associated with the microbial metabolites is observable,which suggests that the microbial activities should be involved with Phragmites australis rhizosphere.In addition,the microorganisms can also help to convert the protein substances into the humic-like substances and produce metabolites,thus,leading to the change of the compositions of the dissolved organic matters in the surrounding water.Thus,it can be concluded that the results of this paper can be expected to bring its contribution to a better understanding of the pollutant removal process caused by the rhizosphere microorganisms,and in turn to provide a useful research reference to the investigation of the purification mechanisms in the artificially constructed wetland areas.