日本語フィールド
著者：Hiroki Kodama*, Nobuko Fukazawa, Daigo Ito, Tohru Miyajima題名：Characterizations of Chikugo river fulvic acids about structural property and complexation ability to Fe3＋発表情報：International humic substances societyキーワード：概要：In natural water systems, organic matter, humic substances (HSs) in particular, play important roles in mobilization and transport of trace metals through complexation. Because of the importance of iron from land to coastal area as a limiting trace-nutrient for primary production, the quantity and quality of HSs in natural water sysems have drawn special attention. Iron is essential to photosynthetic organisms, and photosynthetic available only dissolved iron. Though, iron precipitate as iron hydroxide in natural water condition, many photosynthetic organisms live in coastal areas. It is believed that dissolved ferric ion is stabilized by complexation in the sea area, and fulvic acid is the most possible candidate of complexing agent. In this work, HSs in non-colored river water have been collected and purified, and their structural characteristics and metal complexation characteristics have been investigated. Chikugo River, a representative fresh water environment, is located in Kyushu island Japan. HSs in the river water from upper stream to near river mouth were collected by an automatic concentration system, which includes a large column of 900 cm2 cross section filled with 5kg DAX-8 resin. The HSs samples were analyzed as follows; elemental analysis (C, H, N, S), functional group analysis (carboxyl, calbonyl, phenolic, and alcoholic hydroxyl groups)by use of 13C-NMR and 1H NMR spectroscopic measurements, molecular size analysis by using HPSEC system. Metal complexation ability of FA were estimated with acid-base equilibrium analysis by using acid-base auto titration system. However, the yield was in the season and sampling region, no distinct difference in structural characteristic has been found in FA samples. This may imply that the concentration of FA in Chikugo river may be determined by use of the FA samples as standard materials. From structural study, FA molecules have obviously carboxyl and phenolic groups. Distribution of acid-base equilibrium constants in fulvic acids were estimated and it was revealed that fulvic cids have large percentage of low pKa components (pKa =2.58). O-salicylic acid which have large complexation constant to Fe3+(logKFe =17.44) is considered as strong binding site to Fe3+ ion.抄録：英語フィールド
Author：Hiroki Kodama*, Nobuko Fukazawa, Daigo Ito, Tohru MiyajimaTitle：Characterizations of Chikugo river fulvic acids about structural property and complexation ability to Fe3＋Announcement information:International humic substances societyAn abstract：In natural water systems, organic matter, humic substances (HSs) in particular, play important roles in mobilization and transport of trace metals through complexation. Because of the importance of iron from land to coastal area as a limiting trace-nutrient for primary production, the quantity and quality of HSs in natural water sysems have drawn special attention. Iron is essential to photosynthetic organisms, and photosynthetic available only dissolved iron. Though, iron precipitate as iron hydroxide in natural water condition, many photosynthetic organisms live in coastal areas. It is believed that dissolved ferric ion is stabilized by complexation in the sea area, and fulvic acid is the most possible candidate of complexing agent. In this work, HSs in non-colored river water have been collected and purified, and their structural characteristics and metal complexation characteristics have been investigated. Chikugo River, a representative fresh water environment, is located in Kyushu island Japan. HSs in the river water from upper stream to near river mouth were collected by an automatic concentration system, which includes a large column of 900 cm2 cross section filled with 5kg DAX-8 resin. The HSs samples were analyzed as follows; elemental analysis (C, H, N, S), functional group analysis (carboxyl, calbonyl, phenolic, and alcoholic hydroxyl groups)by use of 13C-NMR and 1H NMR spectroscopic measurements, molecular size analysis by using HPSEC system. Metal complexation ability of FA were estimated with acid-base equilibrium analysis by using acid-base auto titration system. However, the yield was in the season and sampling region, no distinct difference in structural characteristic has been found in FA samples. This may imply that the concentration of FA in Chikugo river may be determined by use of the FA samples as standard materials. From structural study, FA molecules have obviously carboxyl and phenolic groups. Distribution of acid-base equilibrium constants in fulvic acids were estimated and it was revealed that fulvic cids have large percentage of low pKa components (pKa =2.58). O-salicylic acid which have large complexation constant to Fe3+(logKFe =17.44) is considered as strong binding site to Fe3+ ion.