Data used to generate the charts in the research paper "Reservoir artificial flood discharge is a critical driver for the compositional and functional shifts of dissolved organic matter in river mouth"

While dam-based water-sediment regulation modifies the natural transport rhythm of riverine materials, the effects of artificial flooding on river mouth dissolved organic matter (DOM) dynamics remain poorly constrained. The Water-Sediment Regulation Scheme in the Yellow River provides a unique snapshot. Optical spectroscopy, stable carbon isotopes, and ultrahigh-resolution mass spectrometry revealed distinct organic matter signatures between the water release phase (WRP) and sediment flushing phase (SFP). Here we show that during WRP, rapid discharge of upper-layer water from Xiaolangdi Reservoir increased the proportion of bio-labile DOM components in the Yellow River mouth. Conversely, during SFP, resuspension and then release of bottom sediments from the reservoir enhanced aromatic DOM components and photo-lability while reducing bio-labile compounds. Although the relative abundance and composition of particulate organic matter remained unchanged during WRP, it increased significantly during SFP. These findings demonstrate that reservoir operations reconfigure river-ocean carbon flows, emphasizing the need to integrate dam management strategies into global carbon cycling models.