LAUSR

In this study, we investigated the chemical composition of dissolved solids in the Ca River basin, North-Central Vietnam. Water samples were collected from August 2017 to July 2018 at three hydrological stations located in the main stream of the Ca River. Carbonate weathering was found as the dominant process controlling the water chemistry in that area. The average concentrations of dissolved solids generally decreased from upstream to downstream, resulting in low concentrations of the major ions in the downstream basin. Variations in the concentrations of major chemical ions and suspended solids at discharge were also investigated. Major chemical weathering products were found to behave chemostatically with increasing discharges upstream. However, dilution behaviors of solutes were shown in both midstream and downstream. Primary evidence shows that water storage in reservoirs impacts a variety of suspended solids and dissolved solids in the Ca River.