Investigation of Heavy Metals Accumulation in Plants Growing in Contaminated Soils (Case Study: Qazvin Province, Iran)

Abstract

Environmental pollution with heavy metals is a global disaster that is related to<br />human activities. This study was conducted to determine the extent of heavy metals<br />accumulation by plant species in Lia industrial city (Qazvin, Iran) and to investigate the<br />remediative capacity of native plant species grown in the contaminated soils. Soil and<br />industrial wastewater sampling was done radially along transects with 300 m intervals<br />from exit point of wastewater at three sites. In each sampling point, along 100 m transects<br />within 5×2 m plots, the plant samples and soil samples were collected in depth of 0-20 cm<br />and 20-40 cm from rhizosphere zone. Concentration of copper, zinc and chromium in root<br />and shoot of 11 plant species, soil and wastewater were analyzed in three sits for<br />mentioned metals. Bio Concentration factors and translocation factor were determined to<br />ensure phytoremediation availability. Results showed that the concentrations of metals in<br />the soil and wastewater greatly exceeded the threshold limit values. The contents of metals<br />in soils ranged in the order of Cr>Zn>Cu and in wastewater were in the order of<br />Zn>Cr>Cu, respectively. Results showed that Scirpus maritimus L. and Phragmites<br />australis (Cav.) Trin. ex Steudel presented the highest accumulation of Zn, Cu and Cr in<br />their root tissues which were suitable for phytostabilization (with a high BCF couple with<br />low TF). The lowest extractable Zn (7.24 and 3.29 mgkg-1 for shoot and root respectively,<br />BCF=0.07) and extractable Cu (2.56 and 2.80 mgkg-1 for shoot and root respectively,<br />BCF=0.14) were related to Hordeum glaucum L. Moreover, the relatively lowest values of<br />Cr were measured for Taraxacum officinale L. Results indicated that the species, which<br />had low metal bioaccumulation in their roots and high TF, could play important roles for<br />removal of heavy metals through phytoextraction.