Application Of Spectroscopy In The Characterization And Source Analysis Of Organic Matter In Sediments

The purpose of this study is to us spectroscopy to characterize the organic matter in the lake sediments,and to compare the applicability of different spectral techniques by combining multiple statistical methods to analyze the composition and source of the organic matter in the sediments,so as to provide references for pollution source tracing and pollution control.According to the lake water dynamics of Wuliangsuhai Lake and regional distribution,sediment samples were collected at different positions and depths from north to south,and the basic chemical indicators of sediments,three-dimensional fluorescence spectra(3DEEMs),UV-visible absorption spectra(UV-Vis),and Fourier transform infrared spectra(FTIR)of solid and liquid organic matter were measured,combined with statistical analysis methods such as spectral index,parallel factor analysis(PARAFAC),classification and regression tree(CART),two-dimensional correlation spectroscopy(2D-COS).The following conclusions are drawn:(1)Through basic indicators and coupling analysis,the nutrient contents of the sediments in Wuliangsuhai Lake are relatively high.The C and N contents are higher in the northern part of the lake,whereas the P content is higher in the south area.Severe eutrophication is found in the heart of the lake.C and N show strong homology,but weak homology with P.(2)Through the 3DEEMs analysis of the solid and liquid organic matter,the sediments are both terrestrial and biological,and are mainly composed of protein-like substances,microbial metabolites,fulvic acid and humic-like substances.There are large spatial differences in the content and relative content of each component.Fluorescent materials with high excitation wavelength are gradually converted to low excitation wavelength as the sediment depth increases.(3)Through UV-Vis analysis,the sediment has a high degree of humification,a large degree of molecular condensation.Lignin sulfonic acid content is higher in the north while lignin content is high in the south.The surface sediment has a high degree of aromatization,and the aromatic hydrocarbon structure contains more polar functional groups.(4)According to FTIR analysis,there is little spatial difference in the types of functional groups contained in the lake sediments.The composition of the functional groups at the southern end of the lake is relatively complex and contains more chlorine elements.Combining analysis results of chemical indicators,spectral characteristics,and statistical analysis,Wuliangsuhai Basin pollution should be controlled from both internal and external sources.Lake sediment treatment should be divided into north and south areas,namely,in-situ ecological restoration and sediment dredging projects.After a comparative analysis of the three types of spectral techniques in terms of information amount,accuracy,and operability,it can be considered that the 3DEEMs and UV-Vis are more practical techniques for sediment organic matter characterization.