A simple guideline to apply excitation-emission matrix spectroscopy(EEMs)for the characterization of dissolved organic matter(DOM)in anoxic marine sediments  

作　　者：Shuchai Gan Verena BHeuer Frauke Schmidt Lars Wörmer Kai-Uwe Hinrichs 

机构地区：[1]MARUM—Center for Marine Environmental Sciences,University of Bremen,Bremen,D-28359,Germany

出　　处：《Acta Oceanologica Sinica》2023年第1期109-119,共11页海洋学报（英文版）

基　　金：The European Union’s Seventh Framework Programme—Ideas Specific Programme under contract No.247153(Advanced Grant DARCLIFE;Principal Investigator,K.-U.);the Fund of the Deutsche Forschungsgemeinschaft through the Research Center/Excellence Cluster MARUM—Center for Marine Environmental Sciences,Project GB2;the Fund of China Scholarship Council;the Fund of Bremen International Graduate School for Marine Sciences.

摘　　要：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 interferen

关 键 词：marine subsurface sediment EEMs PARAFAC FT-ICR-MS anaerobic pore water 

分 类 号：P736.41[天文地球—海洋地质]