On the Capability of the Epigeous Organs of Phragmites australis to Act as Metal Accumulators in Biomonitoring Studies

Alessandro Bellino,Daniela Baldantoni

doi:10.3390/su13147745

Abstract

With a view of shedding light on the accumulation capability of the epigeous organs of common reed (Phragmites australis), employed worldwide in metal biomonitoring, an accumulation study of Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn was performed, focusing on leaves belonging to different whorls and culms. To this end, in five sampling sites on the littoral zone of the volcanic Lake Averno (Italy), and in one occasion (autumn) before plant senescence, leaves of different ages and culms were collected and analyzed for metal concentrations. In terms of the suitability for biomonitoring, culms demonstrated poor performances in relation to the low metal accumulation and the difficulties in sampling and processing, whereas leaves proved their effectiveness in highlighting whole plant exposure. Since the accumulation degree of Cr, Cu, Fe and Zn is unaffected by leaf age, the pooling of leaves from different whorls is advisable to improve the representativeness of samplings. This strategy becomes mandatory in the case of Ni, the non-monotonic age-dependent variations of which would affect the derivation of contamination gradients otherwise. For Mn, Cd and Pb, the accumulation patterns strictly dependent on age can instead be exploited in selecting the sensitivity of biomonitoring by focusing on the organs where they are preferentially accumulated: old leaves for Mn and young leaves for Cd and Pb.

Highlights

The toxic and hazardous nature of metal contamination in freshwater ecosystems has become a global concern because these inorganic pollutants are persistent in the environment and are biomagnified through the food chains [1]
Metal concentrations measured in non-senescing leaves from different whorls and in culms of P. australis collected in the five sampling sites on the littoral zone of Lake
In spite of the preferential accumulation of metals, Cu and Mn concentrations in both leaves and culms were in the same order of magnitude of those found in the same organs of P. australis growing at the mouth of two rivers, in Southern Italy, flowing in areas affected by urban, agricultural and industrial activities [2,12]

Summary

Introduction

The toxic and hazardous nature of metal contamination in freshwater ecosystems has become a global concern because these inorganic pollutants are persistent in the environment and are biomagnified through the food chains [1]. The leaves of several helophytes effectively serve as good biomonitors of metal concentration gradients in freshwater ecosystems, both in relation to metal absorption (and translocation) from water and sediments [1,2,9,10,11] and atmospheric depositions [3,9] In this context, useful in metal biomonitoring studies are the epigeous organs of Phragmites australis (Cav.) Trin. It is one of the most common macrophytes living in freshwater ecosystems throughout the world, able to withstand extreme environmental conditions, including high concentrations of toxic contaminants [8,13] This rooted and emerged aquatic plant can absorb and accumulate metals through both the root-rhizome system and the leaf–culm system, above all in relation to the expanded area of the epigeous apparatus, able to trap particulate matter, sorb metal ions and accumulate and sequester pollutants [14].

Methods

Results

Conclusion