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SIU CE 210 - Phytoremediation

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PhytoremediationDr. Samuel MaCE 210What am I going to talk about?  Introduction to phytoremediation Phytoremediation of organic compounds Phytoremediation of heavy metals Current ResearchPopularity of Phytoremediation050100150200250300350400199319941995199619971998199920002001200220032004200520062007YearNumber of peer-reviewed publicationsPhytoremediation markets Summary of the Size of Potential U.S. Markets for Phytoremediation Market sector Annual U.S. potential market Metals from soils$1.2-1.4 billion Metals from groundwater$1.2-1.4 billion Organics from soils$2.3-2.6 billion Organics from groundwater$2.3-2.6 billion Radionuclides (all media)$1.5-2.0 billion Industrial wastewater$7.0-10.0 billion Municipal wastewater$18-28 billion Landfill leachate control$0.6-1.2 billion Agricultural runoff$0.4-0.5 billion Stormwater management$0.2-1.0 billion Treatment of drinking water$0.6-1.0 billionTotal$35.3-51.7 billionPhytoremediationPhytoremediation is the technology to use plants to degrade, extract, contain and immobilize environmental contaminants in various environmental media. Phytoremediation is both an in-situ and ex-situ remediation technology.In-situ: contaminant reduction and transport mitigation, not for source control, many cases phytoremediation is a polishing technologyEx-situ: wastewater irrigation and solid waste remediationPlants: terrestrial, wetland and aquatic.Environmental media: air, water, soil, sedimentsContaminants: organics, inorganics, metals, radionuclideContaminantsOrganics:Chlorinated solvents PCE, TCE, DCEPCBs,PAHsDioxins1,4-dixoneExplosives: TNT, RDXOxygenates: MTBEPesticides;Emerging contaminants:Heavy metalsZincLeadChromiumCopperAluminumMercuryArsenicCobaltNickelOther inorganicsRadionuclidePerchlorateN, P by constructed wetlandsPhytoremediation plantsTrees:Hybrid poplarsWillowsPteris vittata (fern)Pine treesSweetgumEastern CottonwoodGrasses:Thlaspi caerulescens (Alpine pennycress)Amaranthus retroflexus (pigweed)Typha (cattail)Phragmites (reed)Myriophyllum aquaticum (Parret feather) Helianthus annuus (sunflower)Medicago sativa (alfalfa)Brassica juncea (Indian mustard)http://www.phytopet.usask.ca/indPlant.phpPlantsPlant SelectionIndigenous plant species are preferred over foreign plants.(1) Plant root type and depth:Taproot systemFibrous roots system(2) Plant biomass:Large plant biomass is preferred. (3) Plant toleranceRemoval mechanisms Enhanced rhizosphere degradation Phytoextraction Phytodegradation Phytovolatization Phytostabilization Hydraulic controlApproaches to enhance phytoremediation Genetically engineered plants EndophytesNature biotechnology, 2006, 24, 161-163.The root of a popular tree colonized by endophytic bacteria containing a green fluorescent protein to mark their presence. Equipped with metabolic pathways that enable them to degrade environmental pollutants, these microbes can increase the plants effectiveness in phytoremediation.Advantages and DisadvantagesAdvantages•Low capital cost•Low maintenance cost•Aesthetically pleasing•Minimal soil disturbance•Wide public acceptanceDisadvantages•Time consuming•Only applicable for sites with low to moderate contamination in shallow area•Uptake and storage of contaminants in plant tissues pose risks to wildlife•Regulation difficultiesPhytoremediation of organicsMechanisms:•Enhanced rhizosphere degradation•Uptake and phytovolitilization•Phytodegradation or PhytotransformationRhizosphere: the area of soil that surrounds the roots of a plant and is altered by the plant's root growth, nutrients, respiration, etc. Raina Maier et al., 2000, environmental microbiologyEnhanced Rhizosphere Degradation ItemsTyphaRoots SedimentEubacteria2.16 ×109+1.66 ×108#2.35 ×108+6.62 ×106Dehalococcoides2.82 ×107+1.10 ×1064.58 ×105+2.34 ×105Dhc/Eubacteria1.30 0.190204060801000 25 50 75 100 125Time (days)Percentage (%)ControlTyphaPhragmitesThe key is to find the right combination of soil, plant and bacteriaPhytoremediation of Organics (cont.)Uptake and transport:00.20.40.60.81-1 0 1 2 3 4 5nitrobenzenem-xyleneRDXTCBphenolatrazineTCEPCPanilinetoluenebenzene ethylbenzeneTSCF, experimentalTSCF, literatureTranspiration StreamConcentration FactorLog KowApoplastic pathway vs.Symplastic pathwayPhytoremediation of organicsUptake and Transport:Phytoremediation of OrganicsPhytovolatilization01234560 5 10 15 20 25 30Height (cm)TCE diffusion (mg)Tree #1Tree #2Tree #3Phytoremediation of Organics0100020003000-10 0 10 20 30 40 50Height (ft)TCE concentration (ug/l)PhytovolatilizationPhytoremediation of OrganicsPhytodegradation or PhytotransformationGreen-liver theory: Organic compound in environmentUptake and transportOrganic compounds in root tissuesTransformation reactionsMetabolites in plant tissueConjugationConjugate, bound and solubleSequestrationCompartmentalized; conjugated compound, vacuole or cell wallAn example: Metabolism of TNTPhytoremediation of Heavy MetalsMechanisms:PhytostabilizationPhytoextractionPhytostabilizationdepends on the root ability to limit contaminant mobility and bioavailability in the soil. Phytostabilization can occur through sorption, precipitation, complexation and metal valence reduction.Phytoremediation of Heavy MetalsPhytoextraction orPhytoaccumulationIndicatorexcluderHyperaccumulatorHyperaccumulators are plants which can absorb high levels of contaminants either in their roots, shoots and leaves. Cadmium or other rare metals, 0.01% dry weight;Lead, nickel, copper, zinc and manganese, 1% dry weight.ConcentrationsconcentrationsTypes of phytoaccumulationNatural phytoextractionThlaspi caerulescens (Alpine pennycress)Pteris vittata (fern) Chelate assisted phytoaccumulation (HS, EDTA…)Genetic engineering to improve phytoextraction (e.g. increase the mass of biomass)My Research ProjectsCompetitive Uptake and Phytomonitoring of Organic Contaminant MixturesXingmao (Samuel) MaChen WangMichael P. WalshPhytomonitoring in phytoremediationVroblesky et al., ES&T, 1999R2 = 0.975703691215180 10 20 30 40 50 60bulk solution (ppm)Aqueous concentration (ppm)Larson et al., ES& T 2008 Gopalachrishina et al., GM&R, 2007Goals and ObjectivesWhen multiple contaminants are present, how do they affect phytomonitoring? Is there competitive uptake between co-contaminants? If there is, how significant is the competitive uptake? What are the implications to phytomonitoring? Can plants maintain the signature of


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SIU CE 210 - Phytoremediation

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