Evaluation of iron fulvate concentration in the Takahashi River basin

Abstract

The aim of this study is to understand the supply of iron ions from the Takahashi River basin to the Seto Inland Sea, and to clarify its behavior and spatial distribution within the watershed. Specifically, we focus on the iron fulvate that is considered to have a significant impact on the Inland Sea ecosystem. The study period was from September 2021 to February 2022. A total of 10 sites were selected in the mainstream and tributaries of the river, and river water sampling was conducted once a month. As a result, the concentration of dissolved iron in the river samples was low. Although there were differences among sampling sites, the average values ranged from 0.006 to 0.016 mg/L. The values and their fluctuations tended to be higher in the tributaries than in the mainstream. Similarly, the average values of iron fulvate ranged from 0.002 to 0.01 mg/L.