Identification and Choice of a Biological Indicator for the Study of the Contamination of a River Environment by Heavy Metals

Biological indicators are efficient tools for establishing pollution levels in a given environment (Phillips, 1980). In this study the organisms used are endowed with the ability to accumulate heavy metals in the river ecosystem, where a biological indicator may be preferable to direct analysis of water samples as a means of monitoring pollution (Popham and D'Auria, 1981). Further, biological indicators provide estimates of the average level of pollution over a given period of time, and can discriminate a given pollutant present in water on the basis of its biological availability. The selection of a suitable organism, however, should fulfil other requirements, thus it must be sedentary, abundant in various environments and longeval. In the Po river a bivalve mollusc (Unio elongatulus) and some macrophytes (Potamogeton crispus, Lagarosiphon major, Miriophyllum verticillatum, Phragmitescornrnunis), known for their bio-accumulative properties (Ravera, 1966, 1973) have been identified as possible biological indicators of heavy metals (Pb, Cd, Cu, Zn, Ni, Co, Cr, Mn, Fe).