Changes in the Dissolved Organic Matter Characteristics Released from Sediment According to Precipitation in the Namhan River with Weirs: A Laboratory Experiment

Abstract

In this study, changes in the properties of dissolved organic matter (DOM) released from sediments into water layers were investigated. To analyze the spatial and temporal variation in dissolved organic carbon (DOC), sediment and bottom water samples were collected upstream of the Gangcheon, Yeoju, and Ipo weirs of the Namhan River during the rainy and non-rainy seasons. The initial DOC was correlated with precipitation (R2 = 0.295, p = 0.034) and residence time (R2 = 0.275, p = 0.040). The change in the bottom water DOC concentration resulted from the DOC released from the sediments, which may cause water quality issues in the bottom water. The fluorescence analysis revealed that the DOM contained higher levels of hydrophilic and low-molecular-weight (LMW) organic matter in the non-rainy season and higher levels of hydrophobic and high-molecular-weight (HMW) organic matter in the rainy season. Since the Namhan River is the main resource of drinking water for the Seoul metropolitan area, our results can help to optimize the drinking water treatment process by reflecting the DOM characteristics that vary with the seasons. Furthermore, the statistical analysis confirmed that the nutrient content of pore-water and sediment can be used to estimate the DOM release rate from the sediment to the water layer. The results of this study provide a better understanding of DOM movement in aquatic ecosystems and the influences of rainfall on the water quality of the surface waterbody.

Seasonal and Spatial Variations in the Optical Characteristics of Dissolved Organic Matter in the Huma River Basin, China

“…The specific UV absorbance at 254 nm (SUVA 254 ) was defined as the UV absorbance coefficient (m −1 ) at 254 nm divided by the DOC concentration (mg/L) [23]. Oh and Choi [24] found that SUVA 254 was high when high-molecular-weight natural organic matter flowed into rivers through rainfall and runoff. The spectral slopes for the wavelength intervals of 275-295 nm (S 275-295 ) and 350-400 nm (S 350-400 ) were obtained using linear regression of the natural log-transformed absorption spectra [25].…”

Spectroscopic properties of dissolved organic matter during the wet season in the Huma River Basin, China

“…The speci c UV absorbance at 254 nm (SUVA 254 ) was de ned as the UV absorbance coe cient (m − 1 ) at 254 nm divided by the DOC concentration (mg/L) (Weishaar et al, 2003). Oh and Choi (2022) found that SUVA 254 was high when high-molecular-weight natural organic matter owed into rivers through rainfall and runoff. The spectral slopes for the wavelength intervals of 275-295 nm (S 275 − 295 ) and 350-400 nm (S 350 − 400 ) were obtained using linear regression of the natural log-transformed absorption spectra (Helms et al, 2008).…”