The concentrations of Cd, Cu, Pb, and Zn in sediments, water, and different plant organs of six aquatic vascular plant species,
Ceratophyllum demersum L.
Echinochloa pyramidalis (Lam.) Hitchc. & Chase;
Eichhornia crassipes (Mart.) Solms-Laub;
Myriophyllum spicatum L.;
Phragmites australis (Cav.) Trin. ex Steud; and
Typha domingensis (Pers.) Poir. ex Steud, growing naturally in the Nile system (Sohag Governorate), were investigated. The aim was to define
which species and which plant organs exhibit the greatest accumulation and evaluate whether these species could be usefully
employed in biomonitoring and phytoremediation programs. The recorded metals in water samples were above the standard levels
of both US Environmental Protection Agency and Egyptian Environmental Affairs Agency except for Pb. The concentrations of
heavy metals in water, sediments, and plants possess the same trend: Zn > Cu > Pb > Cd which reflects the biomonitoring potentialities
of the investigated plant species. Generally, the variation of heavy element concentrations in water and sediments in relation
to site and season, as assessed by two-way repeated measured ANOVA, was significant (
p < 0.05). However, insignificant variations were observed in the concentrations of Pb and Cd in sediments in relation to season
and of Cu and Zn in relation to site. Results also showed that the selectivity of the heavy elements for the investigated
plants varied significantly (
p < 0.05) with species variation. The accumulation capability of the investigated species could be arranged according to this
pattern:
C. demersum >
E. crassipes >
M. spicatum >
E. pyramidalis >
T. domingensis >
P. australis. On the basis of the element concentrations, roots of all the studied species contain higher concentrations of Cu and Zn
than shoots while leaves usually acquire the highest concentrations of Pb. Cd concentrations among different plant organs
are comparable except in
M. spicatum where the highest Cd concentrations were recorded in the leaves. Our results also demonstrated that all the studied species
can accumulate more than 1,450-fold the concentration of the investigated heavy elements in water rendering them of interest
for use in phytoremediation studies of polluted waters. Given the absence of systematic water quality monitoring, heavy elements
in plants, rather than sediments, provide a cost-effective means for assessing heavy element accumulation in aquatic systems
during plant organ lifespan.
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