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Abstract
We use aquatic plants to analyze the heavy metal pollution of a lake environment; they have a number of advantages over the standard chemical methods of the analysis of metal presence in lakes. The macrophyta Chara tomentosa L., sampled from Lake Ohrid in Macedonian part, has been used as a bio-indicator. It can accumulate metals from water. Bioaccumulation of heavy metals (Cu, Cd, Ni, Fe and Pb) was examined by atomic absorption spectrophotometer in Ohrid lake samples of two different depths. This is a first experience for this specie in Ohrid Lake, and I am interested with these results to monitor, at some other sites. The experimental results clearly shows that Fe and Ni were the metals found in higher concentration followed by Cr and Cu whilst Pb and Cd were found in low levels. Concentration of all studied metals resulted to be higher in plant species collected at 5 m depth compared to that sampled at 10 m depth (a = 0.05) except for Pb and Cd, which contents did not represent significant variation in different depths (a = 0.05). Chara tomentosa can accumulate heavy metal ions from the sediment as well as from the water were they grow.
Key words: Chara tomentosa, bioaccumulation, heav metals, Ohrid Lake.
Introduction
The ability of aquatic plants to accumulate heavy metals is increasingly being used to monitor changes arising from environmental pollution [9]. The mechanism of metals uptake is not entirely selective, meaning that plants, through roots and other organs, take in all the accessible ions from the environment, although all of them are not necessary for plant metabolism [13].
All aquatic macrophytes are in contact with potential pollutants across their whole body. Being similar to all primary producers, macrophytes react to changes in the quality of the environment in which they live (water/sediment), and are good bioindicators of surface water condition. The chemical analysis of aquatic plants leads not only to an understanding of the current situation but also to the evaluation of the tendencies of environmental changes in time and space. In this way, conditions are created for monitoring the quality of the lake ecosystem over a longer period and timely action to prevent the consequences of unfavorable trends can be carried out...