Seasonal changes of iron in rivers and relation to structural features of humic acids in their sediments of the northwest of Hokkaido,Japan

摘要

Seasonal changes of iron concentrations in seven rivers of the northwest of Hokkaido,Japan have been monitored together with nitrogen and phosphate concentrations.Stable isotope ratios of carbon(δ~(13)C)and nitrogen(δ~(15))in these seven rivers and structural features of humic acids(HAs)derived from representative river sediments were also investigated.The results suggested that the river environments including iron concentrations,δ~(15)N values,and structural features of HAs were influenced primarily by land use in the river basins.