Analyses of three native aquatic plant species to assess spatial gradients of lake trace element contamination

A bioaccumulation study was performed on Lake Averno, a volcanic lake close to Naples (southern Italy), to ascertain the degree of trace element contamination. Good information to assess spatial gradients of Cd, Cr, Cu, Fe, Ni, Pb, V and Zn contamination was provided by analysing Phragmites communis roots, Najas marina shoots, Potamogeton pectinatus leaves and surface sediments of Lake Averno collected from July 1999 to July 2000 at three sites in the littoral zone. The highest concentrations of the trace elements were measured in sediments and plants from the site where a nearby sewage outfall channel reaches the lake, the lowest at the site below woodland. Significant correlations were found between sediment and plant element concentrations. For almost all the elements, values 2-4-fold higher were found for the site affected by the sewage effluent. Among the plant species, Ph. communis is the most useful species in biomonitoring studies due to its ability to accumulate trace elements in the roots and its collectability throughout the year. Given the absence of systematic water quality monitoring, trace elements in plants, rather than sediments, provide a cost-effective means for assessing trace element accumulation in aquatic systems during plant organ lifespan.