Bioaccumulation and translocation of heavy metals by Ceratophyllum demersum from the Skadar Lake, Montenegro

Lacustrine systems are very complex water systems in terms of the transport of and interaction with heavy metals. Primarily due to its high variability and current chemical parameters, the tissue of macrophytes is a more plausible bio-indicator of the load level of metals within lake ecosystems than are water or sediment analyses. The macrophyte, Ceratophyllum demersum, sampled from the Skadar Lake in Montenegro was used as a bio-indicator. Sediments, water and plants were examined for their contents of ten metals in four different periods of 2011. The concentrations of the metals followed the trend: sediment > leaf C. demerswn > stem C. demersum > water. There were differences in the sequences of the metal content in the plant compared to the sequences of their bioaccumulation ability. These differences suggest a different capacity of macrophytes for different metals. The accumulation of Mn was several times higher than the accumulation of the other analyzed metals. The highest ratio of leaf/stem concentrations was recorded for Mn (2.19) and the lowest was for Pb (1.04). The highest contents of Cd, Co, Cr, Pb, V and Sr were found in the tissues of C. demersum at the beginning of the growing season, whereas Ni, Zn, Cu and Mn were found at the end of the vegetative phase.