Temporal changes of (a) rainfall and (b) river-water discharge, as well as absorbance at 254 nm (UV254), which is an indicator of the concentration of dissolved organic matter (DOM); (c) concentrations of dissolved REEs (lanthanum (La), europium (Eu), and erbium (Er)). The concentrations of DOM and REEs increased at the same time and these changes occurred shortly after an increase in discharge during a rainfall event.