A greenhouse experiment was carried out on a sandy clay soil cultivated with rose geranium (Pelargonium graveolens) which is a hyper-accumulator plant. The experiment was in a randomized complete block design (factorial ) with two factors : (1) Zeolite application at seven levels: Z0 (no zeolite addition),nZ1 (nano zeolite 0.5 g kg-1 soil), nZ2 (nano zeolite 1.0 g kg-1 soil), nZ3 (nano zeolite 1.5 g kg-1 soil), Z1 (ordinary zeolite 0.5 g kg-1 soil), Z2 (ordinary zeolite 1.0 g kg-1 soil), and Z3 (ordinary zeolite 1.5 g kg-1 soil) and (2) Pb pollution at two levels Pb1 (500 mg Pb kg-1 soil) and Pb2 (1000 mg Pb kg-1 soil). Pb uptake (by shoots, roots, plant) and residual Pb in soil significantly decreased due to zeolite application. The average decrease was in the following descending order: nZ3> nZ2> nZ1> Z3> Z2> Z1. Highest decrease in soil residual Pb was attributed to nZ3 (75.7%) which also had the lowest Pb uptake by shoots (76.9%), roots (70.6%), and plant (75.5%). Nano zeolite treatments were more effective than ordinary ones in decreasing residual Pb in soil (ranging from 63.39 to 75.7%); and Pb uptake by shoots(ranging from 65.2 to 76.9%), by roots (ranging from 57.8 to 70.55% ) and by plant (ranging from 63.5 to 75.5%); and increasing fresh and dry weight of shoots (ranging from 5.4 to 13.2%) and roots( ranging from 7.5 to 11.7%). The most effective treatment for plant weight (fresh and dry) was nZ1. Pb pollution significantly increased Pb uptake (by shoots, roots, and plant). Zeolite increased Pb immobilization at end of experiment with 46.0 to 83.9% immobilized in soils polluted with the low Pb rate; and with 38.7 to 80.1% in soils polluted with the high Pb rate (comparing with initial Pb applied to soil). |
