Abstract:To investigate the spectral absorption characteristics, spatial distribution and source of colored dissolved organic matter (CDOM), 53 surface water samples were collected from Xin'anjiang Reservoir in July, 2013. The spatial distribution of CDOM absorption coefficient at 350nm [a(350)], carbon-specific CDOM absorption coefficient [a*(350)], the spectral slope (S), as well as the relationships between CDOM and water quality parameters were studied. Using hierarchical cluster analysis, we divided a(350) into three districts (A, B, and C districts). a(350) decreased from north western area (A district) to the central reservoir and the north eastern area (B district), and to the south western area and the south eastern area (C district). The distribution pattern of a (350) was similar to the distribution of a*(350) but different from that of S. Significantly positive linear correlations between a (350) and chlorophyll a concentration, phytoplankton absorption coefficient and suspended solids indicated a critical contribution of phytoplankton metabolism and degradation products of CDOM.