Phytoremediation: Using Green Plants To Clean Up Contaminated Soil, Groundwater, And Wastewater

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ABSTRACT Phytoremediation, an emerging cleanup technology for contaminated soils, groundwater, and wastewater that is both low-tech and low-cost, is defined as the engineered use of green plants (including grasses, forbs, and woody species) to remove, contain, or render harmless such environmental contaminants as heavy metals, trace elements, organic compounds, and radioactive compounds in soil or water. A greenhouse experiment on zinc uptake in hybrid poplar (Populus sp.) was initiated in 1995. These experiments are being conducted to confirm and extend field data from Applied Natural Sciences, Inc. (our CRADA partner), indicating high levels of zinc (4,200 g/g [ppm]) in leaves of hybrid poplar growing as a cleanup system at a site with zinc contamination in the root zone of some of the trees. Analyses of soil water from lysimeter pots that had received several doses of zinc indicated that the zinc was totally sequestered by the plants in about 4 hours during a single pass through the root sys...

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    ABSTRACT: Range finding test is a first step of phytotoxicity test that aims to determine the concentration of lead which can be uptaken by a plant species. In this study, range finding test was carried out to Scirpus grossus, to obtain the minimum concentration of Lead (Pb) which will give effect on the plant growth. The obtained concentration will be used as a based concentration in conducting the next phytotoxicity study. The study was conducted in a batch system for an observation period of 7 weeks and sampling was done weekly. Three plants of Scirpus grossus were planted in each container of a volume 5 L using sand medium and spiked water. The spiked water contained soluble Pb 2+ ions in different concentration of 50, 100, 200, 350, 500, 650 and 800 mg/L. The results showed that the concentrations of 350 and 500 mg/L had withered 33.33% and 66.67% of the plants respectively, whilst 100% of the plants were withered in 650 and 800 mg/L containers. The wet and dry weight of plant was also measured to determine the plant biomass. The dry weight (y) was correlated to the wet weight (x) through a regression line y=0.261x-1.4636 with R 2 =0.885.
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    ABSTRACT: Typha latifolia L. from aquatic plants is widely found throughout Kehli Stream (Elazig, Turkey). This study examined the uptake of some metals by T. latifolia and the transfer from roots to other plant parts. The accumulation of Mn in T. latifolia L. can be suggested as a tolerance strategy due to its transfer factor higher than 1.0. The enrichment coefficients in the leaves of T. latifolia L. were higher than 1.0 for Zn and Mn and often lower than 1.0 for other metals. Similarly, the enrichment coefficients of all metals, except for Cr, in roots of T. latifolia L. were higher than 1.0. This study demonstrated that T. latifolia L. could be considered as either a bio-indicator or a bio-accumulator for sediments and water polluted by metals.
    Ecological Engineering. 01/2008;
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    ABSTRACT: Poplar (Populus), the model system in tree research, is a fast-growing and high biomass plant which is promising for energy, paper and pulp production, and for growth in soils contaminated with metals. Contamination of soils and water with heavy metals has become a widespread problem; environmental pollution by excess zinc (Zn), one of the more important contaminants, occurs frequently and yet the responses of Populus to high Zn concentrations are still not clearly understood.We investigated the effects of Zn on the functional and structural parameters in the Populus × euramericana clone I-214 by Zn localization in frozen-hydrated leaves and roots by cryo-scanning electron microscopy (cryo-SEM)/energy-dispersive X-ray microanalysis (EDXMA). The experiment was conducted on cuttings grown in nutrient solutions with an increasing Zn concentration gradient (0.001–10 mM).Biomass partitioning and Zn uptake were affected by the metal treatments, showing organ- and tissue-dependent responses. In particular, Zn accumulated in old leaves and moved from shoot to root as the Zn concentration in the growth medium increased. At the highest treatment concentration (10 mM), Zn was preferentially localized in photosynthetic tissues of shoots, and in epidermis and cortex tissues of roots. Gas exchange and chlorophyll measurements showed impairments in leaf biochemistry rather than in stomatal function. Modifications in foliage area, stomatal density and leaf layer thickness were investigated to reduce and/or compensate the negative effects of excess Zn on CO2 assimilation.To counteract Zn toxicity, clone I-214 adopted different defense/tolerance mechanisms involving complex structural, physiological and biochemical processes, attributed to both Zn excluders and accumulators. This study demonstrates the advantages of combining cryo-SEM/EDXMA, gas exchange and chemical analyses for studying metal localization and structural as well as physiological responses in plants.
    Environmental and Experimental Botany. 01/2009;

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