ASSESSING BENTHIC ANIMAL AND WATER PLANT USE IN ESTIMATING RIVER AL AND CR CONTAMINATION IN THE KINOKAWA RIVER CATCHMENT

Abstract

Benthic animals and water plants species useful for devising an index to indicate the extent of
Al and Cr contamination in the Kinokawa River catchment area were studied. Studies revealed that the Al
concentrations in crane fly larvae (260 to 5,260 mg/kg-dry) and bryophytes (640 to 20,000 mg/kg-dry) around
a closed Cu mine were about 1.5 times higher than those around a non-mine area (530 to 3,100 for crane fly
larvae and 220 to 13,000 mg/kg-dry for bryophytes). Cr concentrations in dragonfly larvae around the
serpentinite (3 to 30 mg/kg-dry) were about 3 times higher than those around the non-serpentinite area (0.6 to
9 mg/kg-dry). Cr concentrations in bryophytes around the serpentinite (3 to 91 mg/kg-dry) were about 1.5 times
higher than those around the non-serpentinite area (2 to 53 mg/kg-dry). Al concentrations in Pottiaceae, a kind
of bryophyte found around a closed Cu mine (890 to 20,000 mg/kg-dry) were about 2.5 times higher than those
around a non-mine area (6,300 to 8,000 mg/kg-dry). Cr concentrations in Pottiaceae found around the
serpentinite area (91 mg/kg-dry) were about 3 times higher than those around the non-serpentinite area (3 to
29 mg/kg-dry). Additionally, crane fly larvae, dragonfly larvae, bryophytes, and Pottiaceae were widely
distributed as they were sampled around both contaminated and non-contaminated areas. Therefore, it was
concluded that useful species for devising an index to indicate contamination included the crane fly larvae for
Al, dragonfly larvae for Cr, and the bryophytes, especially Pottiaceae for Al and Cr.