15:45 〜 16:00
[AHW18-17] Evaluation of the Temporal behavior of Fulvic Acid Iron in Asahi River in Okayama Prefecture, Japan
キーワード：Asahi River, Humic substances, Fulvic acid iron, Total Organic Carbon, SIS
Fulvic acid is a humic substance formed when leaves and other parts of plants from terrestrial environments fall to the ground and are decomposed by microorganisms. Fulvic acid and soil iron combine to generate a complex substance known as fulvic acid iron (FAFe) which is transported to the sea through rivers. Since iron is a micronutrient, FAFe may contribute to the growth of phytoplankton and algae in the sea environment. Apart from metal complexation, fulvic acids also perform many crucial functions such as mineral dissolution, metal transport, leaching, scavenging, sediment formation, and ocean fertilization. However, the behavior of FAFe in the Asahi River which drains into the Seto Inland Sea (SIS) is poorly understood. Therefore, the objective of this study was to assess the behavior of the concentration of FAFe and physicochemical properties of Asahi River in Okayama Prefecture.
Fieldwork carried out involved the measurement of physical parameters (water temperature, pH, EC, ORP, turbidity, DO, TDS, and salinity) and the collection of water samples for laboratory analysis. Climatic data were acquired from the Japan Meteorological Agency. Iron concentration was determined using the ICP-AES (SHIMADZU, ICPE-9820, JAPAN), while TOC concentration was measured using the NPOC method on a Shimadzu Total Organic Carbon Analyzer (TOC-L, SHIMADZU CORP, JAPAN). Graphs and regression analysis were performed using R-package version 4.2.2.
Total suspended solids and a few environmental variables (water temperature, turbidity, and pH) were discovered to positively correlate with FAFe. Results showed low TOC concentration (< 10 mg L-1) as well as low FAFe. However, concentrations of TOC and FAFe were higher in warmer seasons (summer) and lower in colder seasons (winter).
Fieldwork carried out involved the measurement of physical parameters (water temperature, pH, EC, ORP, turbidity, DO, TDS, and salinity) and the collection of water samples for laboratory analysis. Climatic data were acquired from the Japan Meteorological Agency. Iron concentration was determined using the ICP-AES (SHIMADZU, ICPE-9820, JAPAN), while TOC concentration was measured using the NPOC method on a Shimadzu Total Organic Carbon Analyzer (TOC-L, SHIMADZU CORP, JAPAN). Graphs and regression analysis were performed using R-package version 4.2.2.
Total suspended solids and a few environmental variables (water temperature, turbidity, and pH) were discovered to positively correlate with FAFe. Results showed low TOC concentration (< 10 mg L-1) as well as low FAFe. However, concentrations of TOC and FAFe were higher in warmer seasons (summer) and lower in colder seasons (winter).