Articles | Volume 13, issue 5
Research article
17 Mar 2016
Research article |  | 17 Mar 2016

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

Ying Zhao, Kaishan Song, Zhidan Wen, Lin Li, Shuying Zang, Tiantian Shao, Sijia Li, and Jia Du

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 Fmax 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.

Short summary
Our results of this study show that two humic-like C peaks and two protein-like B and T peaks were identified from CDOM using PARAFAC for investigated lakes. The average fluorescence intensity of the components differed seasonally. Components 1 and 2 exhibited strong linear correlation (R2 = 0.63). Significantly positive linear relationships, between aCDOM and Fmax, and between DOC and salinity (R2 = 0.93), were revealed.
Final-revised paper