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United States Department of Agriculture

Agricultural Research Service

Research Project: OPTIMIZING FORAGE-BASED COW-CALF OPERATIONS TO IMPROVE SUSTAINABILITY OF BEEF CATTLE AGRICULTURE AND WATER QUALITY PROTECTION AND MANAGEMENT Title: Phytoextraction of lead-contaminanted soil using Vetiver grass (Vetiveria Zizanioides L.), Cogongrass (Imperata cylindrica L.) and Caraboagrass (Paspalum conjugatum L.)

Authors
item Paz-Alberto, Annie - LUZON STATE UNIVERSITY
item Sigua, Gilbert
item Bellrose, G. - LUZON STATE UNIVERSITY
item Prudente, J. - LOUSIANA STATE UNIVERSITY

Submitted to: Environmental Science and Pollution Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 21, 2007
Publication Date: August 1, 2007
Citation: Paz-Alberto, A.M., Sigua, G.C., Bellrose, G.B., Prudente, J.A. 2007. Phytoextraction of lead-contaminated soil using Vetiver grass (Vetiveria zizaniodes L.), Cogongrass (Imperata cylindrica L.) and Carabaograss (Paspalum conjugatum L.). Environmental Science and Pollution Research. 14(7):505-509.

Interpretive Summary: Various techniques are used for cleaning up Pb-contaminated soils. Recently, heavy metal phytoextraction has emerged as a promising, cost-effective alternative to the conventional engineering-based remediation. Phytoremediation is an alternative method that uses plants to clean up a contaminated area. However, the plant species being used must grow well in toxic levels of heavy metal conditions and can produce high biomass. The success of phytoremediation is greatly dependent upon the choice of plant species to be used. Plant species must adapt to the extreme conditions and must be relatively tolerant to high concentration of metals in soil. The use of the plants (grasses in this study) in phytoremediation may be cost effective and could be environmentally friendly, but the practical phytoremediation tool for the control and remediation of Pb contamination in soil using tropical grasses is not well understood. The objectives of study were: (1) to determine the survival rate and vegetative characteristics of three grass species grown in soils with different Pb levels; and (2) to determine and compare the ability of the three grass species as potential phytoremediators in terms of Pb accumulation by plants’ roots and shoots organ. The three test plants: vetivergrass (Vetiveria zizanioides L.); cogongrass (Imperata cylindrica L.); and carabaograss (Paspalum conjugatum L.) were grown in individual plastic bags containing soils with 75 mg/kg (37.5 kg/ha) and 150 mg/kg (75 kg/ha) of Pb, respectively. On the vegetative characteristics of the test plants, vetivergrass registered the highest whole plant dry matter weight (33.85–39.39 Mg/ha). Carabaograss had the lowest herbage mass production of 4.12 Mg/ha and 5.72 Mg/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. Levels of Pb among the three grasses (shoots + roots) did not vary significantly with the amount of Pb added (75 and 150 mg/kg) to the soil. Vetivergrass yielded the highest biomass; it has also the greatest amount of Pb absorbed (roots + shoots). This can be attributed to the highly extensive root system of vetivergrass with the presence of enormous amount of root hairs. 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. The important implication of our findings is that vetivergrass can be used for phytoextraction on sites contaminated with high levels of heavy metals particularly Pb.

Technical Abstract: The global problem concerning contamination of the environment as a consequence 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. Phytoremediation is an alternative 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, cogongrass and carabaograss grown in soils with different Pb levels; and (2) to determine and compare the ability of the three grass species as potential phytoremediators in terms of Pb accumulation by plants. The three test plants: vetivergrass (Vetiveria zizanioides L.); cogongrass (Imperata cylindrica L.); and carabaograss (Paspalum conjugatum L.) were grown in individual plastic bags containing soils with 75 mg/kg (37.5 kg/ha) and 150 mg/ kg (75 kg/ha) of Pb, respectively. On the vegetative characteristics of the test plants, vetivergrass registered the highest whole plant dry matter weight (33.85–39.39 Mg/ha). Carabaograss had the lowest herbage mass production of 4.12 Mg/ha and 5.72 Mg/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. Levels of Pb among the three grasses (shoots + roots) did not vary significantly with the amount of Pb added (75 and 150 mg/kg) to the soil. 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. The important implication of our findings is that vetivergrass can be used for phytoextraction on sites contaminated with high levels of heavy metals particularly Pb.

Last Modified: 4/18/2014
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