Spatial distribution of heavy metals in soils and plants in Zinc Town, northwest Iran|
Delavar, M.A. & Safari, Y.
Identification of heavy metals spatial variability
in soil and plants may provide useful information on how
to manage the polluted sites. The main objective of this
study was to determine the spatial distribution of selected
heavy metals in soils and natural plants of Zanjan city,
northwest Iran. A total of 184 composite topsoil samples
(0–10 cm) and 98 natural plant samples were systematically
taken from an area of about 4000 ha located around
an industrial complex, covering rangeland and agricultural
and industrial land uses. All samples were analyzed for
their total concentration of Zn, Pb and Cd. The results
showed that the average concentrations of Zn, Pb and Cd in
the soil samples were up to 294.2, 152.8 and 5.6 mg kg-1,
respectively, whereas in the plant samples, these values
decreased to 131.4, 113.2 and 2.5 mg kg-1, respectively.
These contents are much higher than the normal range in
soil and plant communities, leading to classify the studied
area as a polluted site. Variography analyses revealed a
similar spatial structure for the studied heavy metals in the
soil and plant samples. Based on interpolated maps, the
highest concentrations of the selected heavy metals in the
soil and plant samples were found in the vicinity of
industrial complex. These findings clearly highlight the
role of industrial activities in simplifying the entrance of
dangerous trace elements to the human food chain.
Application of ordinary kriging technique to predict the
heavy metals spatial variability in the plant community
resulted in logical estimations with acceptable error values.
Heavy metals; Industrial activities; Ordinary kriging; Spatial variability