EVALUATION OF METAL CONTAMINATION FOR RIVER USING BRYOPHYTE IN THE KINOKAWA RIVER CATCHMENT

Abstract

Metal concentration of river water is not always useful for evaluating metal contamination in a catchment because metal concentration of river water is neither always high nor uniform. Therefore, we studied the evaluation of river metal contamination using the metal concentration of bryophyte. Metal concentrations of bryophyte sampled in both the lower stream of the closed Cu mine (120 to 26,000, 25 to 2,400 and 50 to 190 mg/kg-dry for Cu, Co and Ni) and the serpentinite (24 to 59 and 58 to 650 mg/kg-dry for Co and Ni) were higher than background metal concentrations of bryophyte (2 to 96, 2 to 20 and 2 to 43 mg/kg-dry for Cu, Co and Ni). Therefore, it was thought that metal concentrations of bryophyte sampled in the lower stream of the closed Cu mine (Cu, Co and Ni) and the serpentinite (Co and Ni) were affected by the closed Cu mine and the serpentinte, respectively. A kind of hyper accumulator bryophyte similar Scopelophila cataractae was often found around the closed Cu mine and was found around the serpentinite. Its metal concentration was high (1,100 to 26,000, 33 to 2,400 and 81 to 650 mg/kg-dry for Cu, Co and Ni). Metal concentrations of another hyper accumulator bryophyte similar Scopelophila cataractae had high and a wide range of metal concentrations (2 to 5,900, 2 to 150 and 2 to 590 mg/kg-dry for Cu, Co and Ni). Therefore, those of hyper accumulator bryophyte were thought to be useful for a Cu, Co and Ni contamination indicator.