Elizabeth Pilon-Smits BZ572 - Phytoremediation Elizabeth Pilon-Smits Biology Department E413 ANAZO 491-4991 epsmits@lamar.colostate.edu

Let’s hear from you Please write on piece of paper: Degree, major/department, reg./auditing? What is your career goal? How does phytoremediation fit in? Any particular aspects of phytoremediation you are most interested in?

BZ572 – Course Info Text: No book, only papers from course website webct Text: No book, only papers from course website Topics: Intro to phytoremediation Phyto of inorganics*) Phyto of organics*) 1 Lab expt, 1 trip to a lab, 1 field trip (if interest), 5 guest lectures, in-class exercises, job info *) mechanisms of uptake, translocation, detoxification, effects of soil, microbes on remediation, approaches to enhance phyto efficiency, including genetic engineering

Grading: Conventional, no curving Exams: 50% of total grade - 1 midterm + 1 final exam (not comprehensive) essay questions Term paper & presentation: 30% of grade write web page/proposal/review + present In-class participation: 20% of grade lab report, in-class group assignments, literature discussions

Introduction to Phytoremediation History Status Uses Advantages Limitations Phytoremediation strategies

History of phytoremediation for centuries: wetlands used for waste treatment in Europe last century: metal hyperaccumulator plants discovered - used as indicators for mining 1970s: - clean water act, clean air act 1980s: - superfund act (1986 - 8.5 billion $) - idea to use hyperaccumulator plants for metal cleanup (Chaney)

History of phytoremediation (cont.) 1994: phytoremediation term coined (Ilya Raskin) massive interest from gov. & industry - DOE phytorem. workshop - first phytorem. company (Phytotech) 1995: first phytorem. conference phytoremediation takes off

History of phytoremediation (cont.) (Raskin) 1994: Term phytoremediation first used 1995: First phyto conference Columbia MO 2000: EPA phyto conference 2000: 1st phyto faculty positions 2000: 1st phyto course (this one) 2001, 2003: 1st, 2nd phyto call for proposals (NSF/EPA/DOE) 2000, 2001: 1st, 2nd professors in phyto (U Mich, U S-Carolina)

Status of phytoremediation U.S. phytoremediation market (Glass, 1999, 2004 pers. comm.) 1999 $ 30 - 49 million / yr 2004 $ 100-150 million / yr World phytoremediation market 1999 $ 34 - 58 million Total remediation market US: $ 6-8 billion/yr World: $ 25-50 billion/yr

Status of phytoremediation (cont.) 9 purely phytorem. companies 7 constructed wetland companies > 40 consulting/engin. companies that also do phytoremediation ~200 field projects - funded mostly by EPA, DOD, DOE - some commercial/joint projects

Uses of phytoremediation Remediation of different media: air soils, sediments groundwater wastewater streams - industrial - agricultural - municipal, sewage

Uses of phytoremediation (cont.) Remediation of different pollutants: organics: - PCBs - PAHs - TCE TNT MTBE - pesticides - petroleum hydrocarbons Etc. inorganics: - metals (Pb, Cd, Zn, Cr, Hg) - metalloids (Se, As) - “nutrients” (K, P, N, S) - radionuclides (Cs, U)

Uses of phytoremediation (cont.) Remediation using different systems: farming polluted soil irrigation with polluted groundwater letting trees tap into groundwater letting plants filter water streams constructed wetlands, hydroponics

different systems: Hydraulic barrier

different systems: Vegetative cap

different systems: Constructed wetlands

different systems: hydroponics with polluted wastewater

Acting as filters for heavy metals There is important research being done by CSU personnel under the direction of Dr. Duane Johnson and Dr. Leanne Pilon-Smits to find the species of plants that will be the most effective in filtering out the zinc, magnesium, cadmium, and lead in the effluent. Plants such as mustard, canola, barley (in the background), and quinoa are being tested for their effectiveness. Transgenic mustards, that have genes which limit absorption of heavy metals by plants, may allow for greater up-take (beyond toxic levels) of heavy metals. Roots of mustard Extend into effluent Acting as filters for heavy metals

Uses of phytoremediation (cont.) Remediation using different plants Properties of a good phytoremediator: high tolerance to the pollutants high biomass production, fast growth large, deep root system good accumulator/degrader of pollutant able to compete with other species economic value

Popular plants for phytoremediation Uses of phytoremediation (cont.) Popular plants for phytoremediation trees various organics metals gum tree poplar yellow poplar willow

Brassicaceae: grasses For inorganics Thlaspi Alyssum Brassica juncea Uses of phytoremediation (cont.) Popular plants for phytoremediation (cont.): Brassicaceae: grasses For inorganics Thlaspi Alyssum Brassica juncea

various grasses for organics hemp for inorganics kenaf bamboo Uses of phytoremediation (cont.) Popular plants for phytoremediation (cont.): various grasses for organics hemp buffalo grass red fescue for inorganics kenaf bamboo

aquatic plants halophytes for inorganics for organics Uses of phytoremediation (cont.) Popular plants for phytoremediation salicornia aquatic plants cattail parrot feather halophytes for inorganics for organics reed poplar, willow spartina

Advantages & Limitations of Phytoremediation

Mechanical/chemical treatment Phytoremediation In situ Solar energy Fossil fuels for energy Ex situ Mechanical/chemical treatment Soil washing Excavation + reburial Chemical cleanup of soil/water Combustion

Advantages of phytoremediation Phytoremediation vs. Mechanical/chemical treatment Advantages of phytoremediation ~10 - 100x Cheaper Excavation & reburial: up to $1 million/acre Revegetation: ~$20,000/acre

Mechanical/chemical treatment Phytoremediation vs. Mechanical/chemical treatment Advantages of phytoremediation (cont.) Less intrusive Can be more permanent solution Better public acceptance

Limitations of phytoremediation Phytoremediation vs. Mechanical/chemical treatment (cont.) Limitations of phytoremediation Can be slower Limited by rate of biological processes Accumulation in plant tissue: slow e.g. metals: average 15 yrs to clean up site - Filter action by plants: fast (days) - Metabolic breakdown (organics): fairly fast (< 1yr)

Mechanical/chemical treatment (cont.) Phytoremediation vs. Mechanical/chemical treatment (cont.) Limitations of phytoremediation (cont.) Limited root depth Trees > prairie grasses > forbs, other grasses Max depth ~5 m Can be increased up to 20m with “deep planting”

Mechanical/chemical treatment (cont.) Phytoremediation vs. Mechanical/chemical treatment (cont.) Limitations of phytoremediation (cont.) Plant tolerance to pollutant/conditions - Bigger problem with metals than organics - Can be alleviated using amendments, or treating hot spots by other method Bioavailability of contaminant - Bioavailability can be enhanced by amendments

So, when choose phytoremediation? Sufficient time available Pollution shallow enough Pollutant concentrations not phytotoxic $$ limited Note: Phyto may be used in conjunction with other remediation methods For very large quantities of mildly contaminated substrate: phytoremediation only cost-effective option

Phytoremediation processes

Phytoremediation processes phytostabilization

pollutant immobilized in soil Phytostabilization: pollutant immobilized in soil - Metals - Non-bioavailable organics Plants reduce leaching, erosion, runoff  pollutant stays in place 2. Plants + microbes may transform pollutant to less bioavailable form (e.g. metal precipitation on roots)

Phytoremediation processes phytostimulation

Phytostimulation: plant roots stimulate degradation of pollutant by rhizosphere microbes Organics e.g. PCBs, PAHs bacteria, fungi

Phytoremediation processes phytodegradation

plants degrade pollutant, with/without uptake, translocation Phytodegradation: plants degrade pollutant, with/without uptake, translocation Via enzymes, e.g. oxygenases nitroreductase in tissues or in root exudate Certain organics e.g. TCE, TNT, atrazine

Phytoremediation processes phytoextraction accumulation

Phytoextraction: pollutant accumulated in harvestable plant tissues mainly inorganics: metals metalloids radionuclides Plant biomass may be used (e.g. to mine metals, or non-food industrial use) or disposed after minimizing volume (incineration, composting)

Phytoremediation processes phytovolatilization

Phytovolatilization: pollutant released in volatile form into the air some metal(loid)s: Se, As, Hg some volatile organics: TCE, MTBE

Phytoremediation applications may involve multiple processes at once accumulation volatilization stabilization degradation

Rhizofiltration water

Rhizofiltration: pollutant removed from water by plant roots in hydroponic system for inorganics Plant roots & shoots harvestable (may be used to mine metals) or disposed after minimizing volume metals metalloids radionuclides

Hydroponics for metal remediation: 75% of metals removed from mine drainage Rhizofiltration Involves: phytoextraction phytostabilization

Constructed wetland for Se remediation: 75% of Se removed from ag drainage water Involves: phytoextraction phytovolatilization phytostabilization (rhizofiltration) (phytostimulation)

Natural attenuation: polluted site left alone but monitored Vegetative cap: polluted site revegetated, then left alone, monitored with/without adding clean topsoil

Hydraulic barrier Water flow redirected Pollutants intercepted H2O

Phytoremediation project (1996-) (Phytokinetics inc.) Oregon site Soil polluted with PAHs Planted with grass (Lolium perenne) Results: bare soil: some PAH removal vegetated soil: increased PAH removal (~4x) Process? Phytostimulation/phytodegradation

Phytoremediation project (1995-1998) (Phytotech inc.) New Jersey site Soil polluted with lead (Pb) Planted with Indian mustard (Brassica juncea) Results (after 3 growing seasons): bare soil: 6% reduction in Pb vegetated soil: 29% reduction in Pb Process? Phytoextraction

Phytoremediation project (1997) (COE) Mississippi site Groundwater polluted with TNT pumped through constructed wetland Results: 95% reduction in TNT endogenous plant enzymes found to degrade TNT Process? Phytodegradation

Print from Course Website EPA: Citizen’s guide to Phytoremediation Some light reading: Print from Course Website EPA: Citizen’s guide to Phytoremediation EPA: Citizen’s guide to Natural Attenuation Pilon-Smits, 2005 Phytoremediation (review) Ann Rev Plant Biology