Seasonal characterization of CDOM for lakes in semiarid regions of Northeast China using excitation–emission matrix fluorescence and parallel factor analysis (EEM–PARAFAC)

Abstract. The seasonal characteristics of fluorescent components in chromophoric dissolved organic matter (CDOM) for lakes in the semiarid region of Northeast China were examined by excitation–emission matrix (EEM) spectra and parallel factor analysis (PARAFAC). Two humic-like (C1 and C2) and protein-like (C3 and C4) components were identified using PARAFAC. The average fluorescence intensity of the four components differed under seasonal variation from June and August 2013 to February and April 2014. Components 1 and 2 exhibited a strong linear correlation (R² =  0.628). Significantly positive linear relationships between CDOM absorption coefficients a(254) (R² = 0.72, 0.46, p < 0.01), a(280) (R² = 0.77, 0.47, p < 0.01), a(350) (R² = 0.76, 0.78, p < 0.01) and F_max for two humic-like components (C1 and C2) were exhibited, respectively. A significant relationship (R² = 0.930) was found between salinity and dissolved organic carbon (DOC). However, almost no obvious correlation was found between salinity and EEM–PARAFAC-extracted components except for C3 (R² = 0.469). Results from this investigation demonstrate that the EEM–PARAFAC technique can be used to evaluate the seasonal dynamics of CDOM fluorescent components for inland waters in the semiarid regions of Northeast China, and to quantify CDOM components for other waters with similar environmental conditions.