Mobility of Heavy Metals in Plants and Soil: A Case Study From A Mining Region in Canada

Abstract

Understanding the dynamic of metals in soil and plantsis essential for ecosystem management and risks assessment of environmental pollution and sustainability.The main objective of the present study is to determine the mobility of Ni, Cu, Fe, Mg and Zn in soil and their translocation in D. cespitosa plants in a mining region in Northern Ontario.The total amount of Cu, Ni, Fe, Mg and Zn were significantly higher in the top horizon (LFH) compared to the adjacent layer Ae. The vertical distribution of metals in soil varied with the type of metals. The results of this study indicated that only a small portion of total metal was bioavailable to plants. The enrichment factor values for the targeted elements were far above the value of contamination resulting in high availability and distribution of metals in soil. The average bioconcentration/bioaccumulation factors (metal concentration ratio of plant roots to soil) was high and varied from 3.1 to 40 for Cu, 24.5 to 91.6 for Fe, 18.2 to 398.6 for Mg, 10.3 to 75.5 for Ni and 24.9 to 73 for Zn. The translocation factor values were very low for the five metals. They ranged from 0.05 to 0.46 for Cu, 0.03 to 0.1 for Fe, 0.28 to 1.48 for Mg, 0.15 to 0.38 for Ni and 0.68 to 1.16 for Zn. Based on existing classification, Deschampsia. cespitosa is an excluder as it has high levels of metals in the roots but with a shoot/root ratio less than 1. This plant has a high potential for phytoextraction of metals from Northern Ontario soils.