Abstract:
Dissolved organic matter (DOM) is a labile and reactive fraction of soil organic matter. The molecular characterization of DOM is helpful to clarify its ecological and environmental effects, especially its pivotal role in soil fertility and carbon cycling in the context of global environmental change. This paper aims to summarize the common analytical methods of DOM, the basic principles and applications of Ultraviolet-Visible Spectroscopy, Fourier Transform Infrared Spectroscopy, Nuclear Magnetic Resonance Spectroscopy, Fourier Transform Ion Cyclotron Resonance Mass Spectrometry and Three-dimensional Excitation-Emission Matrix Fluorescence Spectroscopy (3D-EEM). The important influencing factors, common fluorescence indices and data processing methods of Three-dimensional Excitation-Emission Matrix Fluorescence Spectroscopy in the application of soil DOM component analysis were emphatically reviewed. Among these techniques, 3D-EEM has the merits of easy operation, simple configuration, high throughput as well as low cost and has been widely applied for the source identification by fluorescence index, humification index and biological source index. Moreover, the chemical components of DOM and their responses to land use patterns, farming systems and global change factors can be analyzed by parallel factor analysis. However, the 3D-EEM also has the limitations of being susceptible to environmental impact and difficulty in spectrum analysis. Future research needs to quantitatively analyze the influence of environmental factors on the fluorescence characteristics of DOM, to strengthen the combination with other analytical techniques and methods of more accurately and comprehensively determining the DOM components, and further to understand its ecological and environmental effects.