ORIGIN OF IRON IN RIVER AND POND WATER AROUND SUMISYONISHI DISTRICT, MANNO TOWN, KAGAWA PREFECTURE

Abstract

Fe concentrations in the brook and pond water around the Sumisyonisi district in Kagawa prefecture were extremely high and some of the brook water reached over 50 mg/L. Fe concentrations of soil and plants were also analyzed to determine the Fe origin. Fe concentrations of brook and pond water were high along the upper stream and decreased down the stream. In particular, Fe concentrations of the upper stream water at the marsh surrounded by the forest were high. Reductive and low pH condition caused by decomposition of organic compounds such leaves was thought to increase Fe solubility. Fe concentrationsoftreeleavesaroundtheforestw (as) ere very low although Fe concentrations of leaves of water plant were high. As Fe in soil and weathered rock were easily soluble in reduction and low pH condition, the origin of Fe in water was thought to be soil and weathered rock.