Bioaccumulation of Nickel and Lead by Bermuda Grass (Cynodon dactylon) and Tall Fescue (Festuca arundinacea) from Two Contaminated Soils

Abstract

Soil and sediments of the estuaries and wetlands in Northwest of Persian Gulf are recently polluted with
different heavy metals because of municipal and industrial wastewaters. Therefore an urgent soil cleaning
up and remediation program is vital in this region. Consequently, this study was initiated to screen two
plant species (Festuca arundinacea and Cynodon dactylon) for hyperaccumulation of nickel (Ni) and lead (Pb)
as one of the candidate methods for cleaning-up soil and sediments of Shadegan wetland. Soil samples (0-
30 cm) were collected from two sites in the wetland. The soil samples were treated with solutions of Ni
and Pb separately which resulted into content of 50 and 100 mg kg-1 of metals in each soil. Thereafter, the
plants were sown in the soils under greenhouse conditions and harvested after 10 weeks. Ni and Pb
contents were measured in root and shoot of plants. Results showed that accumulation of Ni and Pb in tall
fescue roots were significantly (P<0.05) greater than that in Bermuda grass. The amounts of Pb in root and
shoot of plants were increased when soil Pb contents were increased from 50 to 100 mg kg-1 while Ni
contents were only increased in the roots in response to increase in soil Ni content. The comparing of the
shoot-root ratio showed that Pb accumulation in the roots of both plants was higher than that in the
shoots, while for Ni was reverse. Due to difference in backgrounds of soil metal contents and soil
characteristics, accumulation of Ni and Pb by plants were different in two soils