Heavy metal monitoring in contaminated river systems using Mayfly larvae

Abstract

Insect larvae of the orders ephemeroptera (mayflies), plecoptera (stoneflies) and tricoptera (caddisflies) were investigated with respect to possible use as biomonitors of heavy metal pollution in rivers affected by current or previous mining activity. Samples from two rivers in central Norway were collected 3 times during the summer of 1985 and analyzed for Cu, Zn. and Cd. Of the three orders, mayflies was the only showing promise for further work. Repeated sampling of mayflies in one of the rivers in 1993 showed the same levels of Zn and Cd as before, whereas the copper level was reduced by a factor of 3. This may be explained by measures taken by the mining company upstream the sampling sites, reducing considerably the downstream transport of particles. Apparently Cu in this river is associated with particles to a much greater extent than Zn and Cd.