Phytoremediation of Heavy Metals - COSMOS

Phytoremediation ofHeavy MetalsBrian HuynhCOSMOS 2009Cluster 1: Biotechnology

Key Terms• Phytoremediation: The use of green plants toremove, contain or render pollutants harmless• Hyperaccumulator: Plants that canaccumulate high concentrations of certainsubstances, such as heavy metals, in theirtissues• Surfactant: Wetting agents that lower thesurface tension of a liquid, allowing easierspreading, and lower the interfacial tensionbetween two liquids.

Need for Bioremediation• Human pollution• Lead (Pb)• Mining• Sewage Sludge Treatment• Battery Disposal• Combustion of Leaded Gasoline• Heavy metals• Radionuclides• Polycyclic Aromatic Hydrocarbons (PAH)

Why Phytoremediation?• Cost effective versus current conventionalmethods• In Situ bioremediation: Chemicals are added to thecontaminated soil to stabilize the contaminants• Ex Situ bioremediation: Soil is removed from thecontaminated area and treated off-site• Long term applicability• Aesthetic advantages• Phytomining

The Plant Requirements• Ability to accumulate the intended metalin aboveground parts• High Biomass• Fast Growth• Tolerance to high levels of metalconcentrations• Easily Grown• Fully Harvestable

Surfactants• Surface Active Agents• Two Portions• Hydrophobic portion (long hydrocarbon chain) that haslittle affinity for the aqueous solution• Hydrophilic polar head group that has affinity for the bulkmedium

Micelles and Lead• Micelles: Ball of hydrophobictails facing inward andhydrophobic heads facingoutwards• The Problem• Lead readily forms soil precipitate (Carbonates,hydroxides, and phosphates)• Lead has low aqueous solubility• The Solution• Micelles can encapsulate Pb 2+ ions increasingbioavailability

Researchable Question• How do surfactants, such as SodiumLauryl Sulfate (SLS), affect the absorptionand uptake of heavy metals such as lead(Pb 2+ ), in Brassica juncea, Indianmustard?Sodium Lauryl Sulfate (C 12 H 25 SO 4 Na)

Materials• Brassica Juncea seeds• Lead-contaminated soil• Several pots• SLS (Sodium Lauryl Sulfate)• Hoagland’s Solution• Photosynthetically active radiation (PAR)

Growing Plants Controllably• Brassica juncea seeds willbe placed in soil with Pb 2+homogenously distributed• Several pots with fourplants each• One Control Pot withoutsurfactant• Several Treated Pots withdifferent concentrations ofsurfactantBrassica Juncea plant

Growing Plants Controllably Cont.• 60 Days• 22 ± 2 °C• 500 μmols m−2 s−1 of photosyntheticallyactive radiation (PAR) at the plant top with a12:12 h photoperiod• Watered twice a week during the first monthand then every 2 days, alternating distilledwater and a modified diluted (1:5) Hoaglandsolution for sufficient mineral nutrition

Tracking Data• Biomass• Height• Dry Weight• Amount of Pb 2+ (mg kg-1)• AAS: Atomic Absorption Spectroscopy

AAS: How It Works

AAS: How It Works• Atoms and Ions must be vaporized in a graphitefurnace• The amount of light absorbed by the gas-phaseatoms can be analyzed to determine theconcentration of the atoms

Predicted Results• I predict that the surfactants will increaseabsorption of Pb in Brassica juncea• The surfactants will form micelles about thePb 2+ ions therefore increasing bioavailabilityand solubility allowing the B. juncea plants toincrease uptake and accumulation of thePb 2+ ions.

Potential Problems• Pb bioavailability may cause toxic effects to B.juncea resulting in a decrease in plant biomass• Pb may complex with plant nutrients limitingtranslocation from roots to shoots• Increased bioavailability of Pb results in anincreased chance for contamination withgroundwater

Bibliography• Eapen, Susan, and S. F. D’Souza. “Prospects of genetic engineering ofplants for phytoremediation of toxic metals .” Biotechnology Advances23.2 (2005): 97-114.• Gregorio, Simona Di, Meri Barbafieri, Silvia Lampis, Eliana Tassi, AnnaMaria Sanangelantoni, and Giovanni Vallini. "Combined application ofTriton X-100 and Sinorhizobium sp. Pb002 inoculum for the improvementof lead phytoextraction by Brassica juncea in EDTA amended soil"Chemosphere 63.2 (2006): 293-99.• Jadia, Chhotu D., and M. H. Fulekar. “Phytoremediation of heavy metals:Recent techniques.” African Journal of Biotechnology 8.6 (2009): 921-928.• Marchiol, Luca, et al. “Reclamation of polluted soil: PhytoremediationPotential of crop-related Brassica species.” Water Air and Soil Pollution158.1 (2004): 345-356.• Prasad, Majeti Narasimha Vara, and Helena Maria de Oliveiras Freitas.“Metal hyperaccumulation in plants - Biodiversity prospecting forphytoremediation technology .” Electronic Journal of Biotechnology 6.3(2003): 285-321.

Bibliography cont.• "Surfactant-Enhanced Phytoremediation of Soils Contaminated withHydrophobic Organic Contaminants: Potential and Assessment."Pedosphere 17.4 (2007): 409-18.• http://amadeus.biosci.arizona.edu/~jdhall/Protocols/PlantNutrientSolution.doc• La Fleur, Terry. "Rheology of Rodlike Micelles of Surfactants." PrincetonUniversity, Summer 2003. Web. 28 July 2009..• Fiegl, Joseph L., Bryan P. McDonnell, Jill A. Kostel, Mary E. Finster, andKimberly Gray. "Phytoremediation of Lead in Urban, Residential Soils."Northwestern University - Civil and Environmental Engineering. Web. 28July 2009..• Tissue, Brian M. "Atomic-Absorption Spectroscopy." ElectrochemistryLaboratory, Chemistry, KAIST. 1996. Web. 28 July 2009..

Picture Bibliography• http://www.plantcare.com/oldSite/httpdocs/images/namedImages/Brassica_Juncea.jpg• http://arabidopsis.info/students/dom/phyto1.jpg• http://upload.wikimedia.org/wikipedia/commons/8/85/Atomic_absorption_spectroscopy.jpg• http://i134.photobucket.com/albums/q101/inwales/Thesis/surfactant.jpg• http://www.made-in-china.com/image/2f0j00LCKEHRJsYUupM/Atomic-Absorption-Spectrophotometer-AAS7003-AAS7003M-.jpg• http://elchem.kaist.ac.kr/vt/chem-ed/spec/atomic/graphics/aa-expt.gif• http://www.uic.edu/classes/bios/bios100/lecturesf04am/micelle.jpg• http://upload.wikimedia.org/wikipedia/commons/a/ae/SDS-2D-skeletal.png