Optical Properties of Chromophoric Dissolved Organic Matter in the Yinma River Watershed and Drinking Water Resource of Northeast China

Abstract

Spectral characteristics of optically active constituents (OACs) in waters are key parameters of biooptical modeling. Comparative analyses about the differences of optical characteristics and composition between riverine and reservoir waters in the second Songhuajiang River tributaries were conducted, and the infl uencing factors impacting on chromophoric dissolved organic matter (CDOM) and organic carbon (DOC) were examined based on the absorption properties. Dissolved organic carbon (DOC) and total suspended matter (TSM) were signifi cantly higher in the riverine waters, and chlorophyll-a (Chl-a) was opposite. The relationship between the CDOM absorption coeffi cient at specifi c wavelength and DOC concentration both in the riverine and reservoir waters exhibited a positive correlation (r = 0.90, p< 0.01). The close relationship between Chl-a concentration and CDOM absorption confi rmed a small amount of phytoplankton absorption to total absorption in the individual samplings. Analysis of absorption ratio (E 250:365 ), specifi c UV absorbance (SUVA 254 ), and spectral slope ratio (S r ) indicated that CDOM in riverine waters had lower aromaricity, molecular weight, and vascular plant contributions than in reservoir waters. Furthermore, non-algal particles played an important role in the total non-water absorption for riverine waters, and CDOM was dominant in the reservoir waters. This indicated that the Yinma River watershed was strongly infl uenced by the artifi cial discharge. As a parameter of the bio-optical model, the spectral characteristics of CDOM could help to adjust derived algorithms based on remote sensing and to estimate the dissolved organic carbon fl ux.