Marine sediments represent a major carbon reservoir on Earth.Dissolved organic matter(DOM)in pore waters accumulates products and intermediates of carbon cycling in sediments.The application of excitation-emission mat...Marine sediments represent a major carbon reservoir on Earth.Dissolved organic matter(DOM)in pore waters accumulates products and intermediates of carbon cycling in sediments.The application of excitation-emission matrix spectroscopy(EEMs)in the analysis of subseafloor DOM samples is largely unexplored due to the redox-sensitive matrix of anoxic pore water.Therefore,this study aims to investigate the interference caused by the matrix on EEMs and propose a guideline to prepare pore water samples from anoxic marine sediments.The parameters determined by fluorescence spectra include 3D-index derived from EEMs after parallel factor analysis(PARAFAC),fluorescence index(FI)(contribution of terrigenous DOM),biological index(BIX)and humification index(HIX)derived from 2D emission spectra.First,we investigated the impacts of extensively-presented ions as typical electron acceptors,which are utilized by anaerobic microbes and stratified in marine sediments:Fe(II),Fe(III),Mn(II)and sulfide in anoxic pore water resulted in biases of fluorescent signals.We proposed threshold concentrations of these ions when the interference on EEMs occurred.Effective removal of sulfide from sulfide-rich samples could be achieved by flushing with N_(2)for 2 min.Second,the tests based on DOM standard were further verified using pristine samples from marine sediments.There was a significant change in the fluorescence spectra of DOM in anoxic sediments from the Rhône Delta.This study demonstrated that the change was caused by oxidation of the matrix rather than the intrinsic alteration of DOM.It was confirmed by extracted DOM via both EEMs analysis and Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR-MS).Slight oxidation of sulfur-containing compounds(e.g.,sulfhydryl)and polyphenol-like compounds occurred.Finally,a sample preparation sequence is proposed for pore water from anoxic sediments.This method enables measurement with small volumes of the sample(e.g.,50µL in this study)and ensures reliable data without the interference of the redox-sensitive matrix.This study provides access to the rapid analysis of DOM composition in marine sediments and can potentially open a window into examining the carbon cycling of the marine deep biosphere.展开更多
The autofluorescence spectroscopy of biologi- cal tissues is a powerful tool for non-invasive detection of tissue pathologies and evaluation of any biochemical and morphological changes arising during the lesions＇ gr...The autofluorescence spectroscopy of biologi- cal tissues is a powerful tool for non-invasive detection of tissue pathologies and evaluation of any biochemical and morphological changes arising during the lesions＇ growth. To obtain a full picture of the whole set of endogenous fluorophores appearing in the gastrointestinal （GI） tumors investigated, the technique of excitation-emission matrix （EEM） development was applied in a broad spectral region, covering the ultraviolet and visible spectral ranges. We could thus address a set of diagnostically-important chromophores and their alterations during tumor develop- ment, namely, collagen, elastin, nicotinamide adenine dinucleotide （NADH）, flavins, porphyrins, while hemo- globin＇s absorption influence on the spectra obtained could be evaluated as well. Comparisons are presented between EEM data of normal mucosae, benign polyps and malignant carcinoma, and the origins are determined of the fluorescence signals forming these matrices.展开更多
The main objective of the study was to investigate the characteristics of dissolved organic matter （DOM） in leachate with different landfill ages through the chemical, spectroscopic, and elemental analysis. Humic ac...The main objective of the study was to investigate the characteristics of dissolved organic matter （DOM） in leachate with different landfill ages through the chemical, spectroscopic, and elemental analysis. Humic acid （HA）, fulvic acid （FA）, and hydrophilic （HyI） fractions were isolated and purified by the XAD-8 resin combined with the cation exchange resin method. The analytical results of fluorescence excitation-emission matrix spectroscopy （EEMs） revealed that the fluorescence peaks were protein-like fluorescence for young landfill leachate, while the fluorescence peaks for medium and old landfill leachate were humic-like and fulvic-like fluorescence, respectively. Elemental analysis showed that carbon, hydrogen, and nitrogen content decreased with landfill age, while the oxygen content increased. Moreover, the nitrogen content in these isolated fractions followed： HA 〉 HyI 〉 FA. The results of elemental analysis, FT-IR, and fluorescence EEMs also confirmed that aromatic carbons and portions of aliphatic functional groups were more abundant in leachate samples with increasing landfill age.展开更多
基金The European Union’s Seventh Framework Programme—Ideas Specific Programme under contract No.247153(Advanced Grant DARCLIFEPrincipal Investigator,K.-U.)+2 种基金the Fund of the Deutsche Forschungsgemeinschaft through the Research Center/Excellence Cluster MARUM—Center for Marine Environmental Sciences,Project GB2the Fund of China Scholarship Councilthe Fund of Bremen International Graduate School for Marine Sciences.
文摘Marine sediments represent a major carbon reservoir on Earth.Dissolved organic matter(DOM)in pore waters accumulates products and intermediates of carbon cycling in sediments.The application of excitation-emission matrix spectroscopy(EEMs)in the analysis of subseafloor DOM samples is largely unexplored due to the redox-sensitive matrix of anoxic pore water.Therefore,this study aims to investigate the interference caused by the matrix on EEMs and propose a guideline to prepare pore water samples from anoxic marine sediments.The parameters determined by fluorescence spectra include 3D-index derived from EEMs after parallel factor analysis(PARAFAC),fluorescence index(FI)(contribution of terrigenous DOM),biological index(BIX)and humification index(HIX)derived from 2D emission spectra.First,we investigated the impacts of extensively-presented ions as typical electron acceptors,which are utilized by anaerobic microbes and stratified in marine sediments:Fe(II),Fe(III),Mn(II)and sulfide in anoxic pore water resulted in biases of fluorescent signals.We proposed threshold concentrations of these ions when the interference on EEMs occurred.Effective removal of sulfide from sulfide-rich samples could be achieved by flushing with N_(2)for 2 min.Second,the tests based on DOM standard were further verified using pristine samples from marine sediments.There was a significant change in the fluorescence spectra of DOM in anoxic sediments from the Rhône Delta.This study demonstrated that the change was caused by oxidation of the matrix rather than the intrinsic alteration of DOM.It was confirmed by extracted DOM via both EEMs analysis and Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR-MS).Slight oxidation of sulfur-containing compounds(e.g.,sulfhydryl)and polyphenol-like compounds occurred.Finally,a sample preparation sequence is proposed for pore water from anoxic sediments.This method enables measurement with small volumes of the sample(e.g.,50µL in this study)and ensures reliable data without the interference of the redox-sensitive matrix.This study provides access to the rapid analysis of DOM composition in marine sediments and can potentially open a window into examining the carbon cycling of the marine deep biosphere.
文摘The autofluorescence spectroscopy of biologi- cal tissues is a powerful tool for non-invasive detection of tissue pathologies and evaluation of any biochemical and morphological changes arising during the lesions＇ growth. To obtain a full picture of the whole set of endogenous fluorophores appearing in the gastrointestinal （GI） tumors investigated, the technique of excitation-emission matrix （EEM） development was applied in a broad spectral region, covering the ultraviolet and visible spectral ranges. We could thus address a set of diagnostically-important chromophores and their alterations during tumor develop- ment, namely, collagen, elastin, nicotinamide adenine dinucleotide （NADH）, flavins, porphyrins, while hemo- globin＇s absorption influence on the spectra obtained could be evaluated as well. Comparisons are presented between EEM data of normal mucosae, benign polyps and malignant carcinoma, and the origins are determined of the fluorescence signals forming these matrices.
文摘The main objective of the study was to investigate the characteristics of dissolved organic matter （DOM） in leachate with different landfill ages through the chemical, spectroscopic, and elemental analysis. Humic acid （HA）, fulvic acid （FA）, and hydrophilic （HyI） fractions were isolated and purified by the XAD-8 resin combined with the cation exchange resin method. The analytical results of fluorescence excitation-emission matrix spectroscopy （EEMs） revealed that the fluorescence peaks were protein-like fluorescence for young landfill leachate, while the fluorescence peaks for medium and old landfill leachate were humic-like and fulvic-like fluorescence, respectively. Elemental analysis showed that carbon, hydrogen, and nitrogen content decreased with landfill age, while the oxygen content increased. Moreover, the nitrogen content in these isolated fractions followed： HA 〉 HyI 〉 FA. The results of elemental analysis, FT-IR, and fluorescence EEMs also confirmed that aromatic carbons and portions of aliphatic functional groups were more abundant in leachate samples with increasing landfill age.
