The use of aquatic bryophytes to monitor heavy metals pollution of freshwaters as illustrated by case studies

Summary

General concepts on aquatic bryophytes as monitors of heavy metals pollution are illustrated by case studies of a wide range of pollutants: As, Cd, Cu, Fe, Pb, Zn and Cr. Since bryophytes are attached, it is possible to pinpoint the single source of Cu amidst 13 metal coating factories often located less than 300 m apart. In a river undergoing effluents from a tannery, concentrations of metals in Platyhypnidium are slightly higher than in Fontinalis; the two species still yield similar profiles along the river. The third studied river sets up new record values of metals in aquatic bryophytes: 277g Zn · kg⁻¹, 98g Fe kg⁻¹, 15g Cr kg⁻¹, 3.7g Cu · kg⁻¹, 2.9g Pb · kg⁻¹ and 187 mg As · kg⁻¹. The record values of Fe, Cr and As were obtained in bryophytes transplanted for just three days in the most polluted site.