Submitted to: Florida Scientist
Publication Type: Abstract Only
Publication Acceptance Date: January 9, 2008
Publication Date: March 6, 2008
Citation: Sigua, G.C., Paz-Alberto, A.M. 2008. Phytoremediation Potential of Lead-Contaminated Soil Using Tropical Grasses [abstract]. Florida Scientist. 71(1): 1-6.
The global problem concerning contamination of the environment because of human activities is increasing. Most of the environmental contaminants are chemical by-products and heavy metals such as lead (Pb). Lead released into the environment makes its way into the air, soil and water. Lead contributes to a variety of health effects such as decline in mental, cognitive and physical health of the individual. An alternative way of reducing Pb concentration from the soil is through phytoremediation, a method that uses plants to clean up a contaminated area. The objectives of this study were: (1) to determine the survival rate and vegetative characteristics of three grass species such as vetivergrass (Vetiveria zizanioides L.), cogongrass (Imperata cylindrica L.), and carabaograss (Paspalum conjugatum L.) grown in soils with different Pb levels (75 and 150 mg/kg); and (2) to determine and compare the ability of the three grass species as potential phytoremediators in terms of Pb accumulation by plants. The Pb contents of the test plants and the soil were analyzed before and after experimental treatments using an atomic absorption spectrophotometer. This study was laid-out following a 3 x 2 factorial experiment in a completely randomized design. On the vegetative characteristics of the test plants, vetivergrass registered the highest whole plant dry matter weight (33,853 - 39,386 kg/ha). Carabaograss had the lowest herbage mass production of 4,120 kg/ha and 5,720 kg/ha from soils added with 75 and 150 mg Pb/kg, respectively. Vetivergrass also had the highest percent plant survival, which meant it best tolerated the Pb contamination in soils. Vetivergrass registered the highest rate of Pb absorption (10.16 ± 2.81 mg/kg). This was followed by cogongrass (2.34 ± 0.52 mg/kg) and carabaograss with mean Pb level of 0.49 ± 0.56 mg/kg. This can be attributed to the highly extensive root system of vetivergrass with the presence of enormous amount of root hairs. Extensive root system denotes more contact to nutrients in soils, therefore more likelihood of nutrient absorption and Pb uptake. The present study indicated that vetivergrass possessed many beneficial characteristics to uptake Pb from contaminated soil. It was the most tolerant and could grow in soil contaminated with high Pb concentration. Cogongrass and carabaograss are also potential phytoremediators since they can absorb small amount of Pb in soils although cogongrass is more tolerant to Pb-contaminated soil compared with carabaograss.