phytoremediation

phytoremediation - Phytoremediation 220,000 Polluted sites...

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Phytoremediation 220,000 Polluted sites in US Not practical to dig them all up and move them Conventional Cleanup costs $100 to $1000/ton 4500 tons/acre = > $450,000/acre Several metals are important pollutants of soil and water Lead, Cadmium, Arsenic, Chromium Mercury, Copper Zinc, Uranium, Plutonium, Chromium Microbial degradation of such metals is limited
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Excavation of wastes often is hugely destructive of the environment
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Where are you going to put it after you dig it up?
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Concentrates pollutant in harvestable part of plant Degradation of organics possible Both organics and some metals can be dispersed Reduce bioavailability of pollutant in environment Phytoremediation ex planta Stimulation of soil microbes Air Filtration Direct absorption of gasses 2 Phytodegradation
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Phytoextraction Most plants are limited in amount of metal they can absorb - < 0.01% of dry wt Therefore not useful in metal extraction Plants with high uptake potential for metal are often low biomass plants Induction of absorption by chelators such as EDTA possible even in low accumulation plants - chelate-assisted extraction Time Chelate Biomass Metal Accumulation Harvest No Chelate
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Metal-chelate is taken up by plant in high quantities - 1-2% of dry wt. Even high biomass/low accumulation plants can be induced to extract metals Movement of metals into plant via xylem: Accumulation and transport of metals via xylem avoids accumulation in roots – facilitates harvest of metals Accumulation of metals may be toxic to plant - triggered shortly before harvest of plants High accumulation may allow metal recovery by burning etc. Downside: Chelates can alter abundance and availability of other beneficial metals
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phytoremediation - Phytoremediation 220,000 Polluted sites...

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