Cu, Zn and As pollution of river insect, plant and water along the metal mine tailing in Waidani area, Okayama prefecture, Japan
Comparing metal concentration and distribution for river insect larva in metal contaminated and not contaminated areas, dobsonfly was clarified to be an effective indicator for metal contamination. The Waidani area was selected as metal contaminated area. Although the maximum concentration of effluent for Cu, Zn and As was 0.18, 1.5 and 0.07 mg/l, under the Japanese Effluent Standard, the maximum metal load for Cu, Zn and As reached 35, 250 and 9 kg per year, abundant of Japanese diving beetles, were only found and then specialized condition was thought to be made by the effluent. Cu, Zn and As concentrations of dobsonfly and the other river insect larva were measured in the mine areas including the Waidani mine, limestone area and not contaminated area. Dobsonfly, just one specie, Protohermes grandis, was able to cover wide concentration range for Cu (several 10 to several 1000 ppm), Zn (several 100 to several 1000 ppm) and As (0.000 to 400 ppm) and had a wide distribution. Then, its concentration was depended on metal contamination. Although the other insects had wide concentration ranges and wide distributions as well as dobsonfly, they have many kinds of species. Therefore, their concentration did not depend on metal contamination but also species.