PHYTOREMEDIATION

1. PHYTOREMEDIATION • NEW & UNIQUE • EXPLOITS NATURAL PROPENSITIESOF CERTAIN PLANTS TO REMOVE CONTAMINANTS FROM SOIL/WATER • CAN REMOVE ORGANICS & METALS • NEED A MANAGEMENT GUIDE

2. PHYTOREMEDIATION (cont) • PLANTS CAN METABOLIZE CONTAMINANTS IN SHOOTS OR • RELEASE CHEMICALS THAT CAN REACT WITH THE CONTAMINANT & DIMINISH THE HAZARD.OR • INDIRECT EFFECTS – INTERACTIONS BETWEEN ROOTS, MICROBES & SUBSTRATES ENHANCE MICROBE ACTIVITY WHICH CAN DEGRADE CONTAMINANTS (RHIZOREMEDIATION) • DIRECT & INDIRECT PROCESS CAN OCCUR CONCURRENTLY.

3. MANAGER SHOULD KNOW WHETHER • UPTAKE & METABOLISM OF CONTAMINANT WILL RESULT IN COMPLETE REMOVAL & DETOX. OR • A TRANSFORMATION PRODUCT HAS ACCUMULATED IN THE PLANT (CAN BE HAZARDOUS).OR • WHETHER PLANT-MICROBE INTERACTION IN ROOTS HAS DEGRADED CONTAMINANT IN THE MATRIX.

4. NATURE OF CONTAMINANT WILL: • DETERMINE PARTITIONING INTO WATER PHASE (SOLUBILITY) OR LIPID PHASE IN A MATRIX (FAT SOLUBILITY).  • LIPOPHILICITY OF A CONTAMINANT CONTROLS ITS AVAILABILITY & TRANSLOCATION IN A PLANT. • MEASURED AS OCTANOL-WATER PARTITION COEF. (KOW). • KOW – RATIO: CONTAMINANT CONC. IN ORGANIC SOLVENT TO ITS CONC. IN WATER. • LOW KOW = HIGH WATER SOLUBLE COMPOUND • HIGH KOW = HIGH FAT-SOLUBLE COMPOUND

5. GENERAL RULE: • UPTAKE OF ORGANICS BY PLANT ROOTS INCREASES WITH INCREASING KOW. • FOR TRANSLOCATION – AN OPTIMUM KOW EXISTS. • COMPOUNDS WITH LOW KOW < 10 ARE NOT READILY UPTAKEN BY ROOTS. CAN FLOW AWAY. • IF LOW KOW ENTERS PLANT, ANY TRANSLOCATION IS LIMITED BY LIPID COMPONENTS OF PLANT TISSUES. • HIGH FAT-SOLUBLE COMPOUNDS, KOW >103, HAVE LIMITED DELIVERY TO ROOTS DUE TO LOW WATER SOLUBILITIES & HIGH PARTITIONING TO LIPID PHASES IN THE MATRIX. • COMPOUNDS MOST READILY TAKEN UP AND TRANSLOCATED INTO PLANTS HAVE KOW BETWEEN 10 - 103.

6. IMPORTANT FOR MANAGER: • AN OPTIMUM KOW EXISTS FOR TRANSLOCATION OF ORGANICS. • MANY CHEMICALS & PESTICIDES FALL IN THE RANGE FOR UPTAKE & TRANSLOCATION (KOW 10-103). • PCB’S, HYDROCARBONS, DIOXINS HAVE KOW’s 104-1010. • MOST SUCCESSFUL WHEN FOCUS IS ON STIMULATION OF RHIZOSPHERE BIODEGRADATION INSTEAD OF PROMOTING PLANT UPTAKE & METABOLISM.

7. PLANT ENZYMES • CAN CAUSE TRANSFORMATIONS WITHIN THE PLANT. • ENZYMES CAN TRANSFORM CONTAMINANTS OUTSIDE THE PLANT (EXPLANTA). • CAN TRANSFORM MUNITION WASTE (TNT) & ORGANIC DEGREASERS (TCE).

8. ENHANCED MICROBIAL ACTIVITY IN PLANT RHIZOPHERES • CAN SPEED UP ANY TRANSFORMATIONS. • NEED SUITABLE PHYSIOCHEMICAL ENVIRONMENTS. • PLANTS ROOT EXUDATES, I.E. CARBOHYDATES & AMINO ACIDS. ENHANCES GROWTH / BIOACTIVITY OF MICROBIAL COMMUNITIES IN SOIL & PROMOTES DEGRADATION. • BIOFILMS ON ROOT SURFACES (PLANT MUCILAGE) PROMOTES DEVELOPMENT OF MICROBES. MICROBIAL RESPIRATORY ACTIVITY CAN REDUCE O2 CONC. & CREATEREDUCED ENVIRONMENTS. CAN TRANSFORM HIGHLY CHLORINATED COMPOUNDS.

9. METALS REMEDIATION POTENTIAL • SOILS CONTAMINATED BY METALS: • MINING • MANUFACTURING • URBAN ACTIVITIES • CAN DISRUPT ECOSYSTEMS • CAUSE HEALTH PROBLEMS • INJURE PLANTS • CAUSE ANIMAL FATALITIES • LEAD PROBLEM – CHILDREN

10. METALS REMEDIATION POTENTIAL (cont) • EXAMINED TECHNOLOGIES • EXCAVATION • ELECTROCHEMICAL • ENCAPSULATING • PHYSICAL • METALS ARE NOT BIODEGRADABLE. • MICROBIAL PROCESSES OFFER PROMISE. • A MICROBIAL PROCESS INVOLVES OXIDATION-REDUCTION REACTIONS • TRANSFORMS METAL SPECIES FROM SOLUBLE, MOBILE AND MORE TOXIC INTO INSOLUBLE, LESS MOBILE & LESS TOXIC FORM. • THEN SEPARATED BY CHEMICAL/PHYSICAL PROCESS. • EX. REDUCTION OF HAZARDOUS, SOLUBLE Cr6+ to INSOLUBLE, LESS MOBILE & LESS TOXIC Cr3+, AND CHEMICAL PRECIP. AS Cr (OH)3.

11. HYPERACCUMULATORS: • CERTAIN PLANTS CAN REMOVE METALS FROM MATRICES BY UPTAKE, TRANSLOCATION, & ACCUMULATION IN SHOOTS. • A HYPERACCUMULATOR CAN YIELD GREATER THAN OR EQUAL TO 0.1 % Cr, Ni, Co OR GREATER THAN 1.0% Zn or Mn IN ABOVE GROUND SHOOTS ON A DRY WEIGHT BASIS. • ECONOMIC VALUE - CAN LEAD TO PHYTOMINING/PHYTOEXTRACTION • SOME PLANTS CAN ACCUMULATE UP TO 1% OF BIOMASS FOR Zn, Ni, Co, Mn, Ar.

12. HYPERACCUMULATORS: (cont) • TREES OFFER ADVANTAGE OF HIGH BIOMASS PRODUCTION. • TREES GENERALLY SLOW GROWING & POTENTIAL FOR LEAF DISPERSION. • GRASSES & CROPS HAVE HIGH GROWTH RATES & SOME HAVE HIGH METAL ACCUMULATION. • WITH LOW BIOMASS PRODUCTION, GRASSES TAKE LONGER TO ACCUMULATE METALS. • CROPS ( HIGH BIOMASS) CAN CREATE A HAZARD TO THE FOOD CHAIN.

13. HYPERACCUMULATORS: (cont) • MOST STUDIED PLANTS ARE: • FAMILY BRASSICACSAE: • GENERA – BRASSICA & THYLASPI • B. JUNCEA- LEAD, CADMIUM, ZINC • T. CAERULESCENS (ALPINE PENNYCRESS) – ZINC, CADMIUM FAVORED WITH LOWERING THE pH. • LOW GROWTH RATE AND LOW YIELD ARE LIMITING FACTORS. • BIOTECHNOLOGY CAN HELP.

14. REMOVAL BY PLANT ROOTS • RHIZOFILTRATION -   • REMOVES METALS FROM SURFACE & GROUNDWATER BY: • ABSORPTION • CONCENTRATION • PRECIPTATION • TERRESTRIAL PLANTS ARE BEST: • LONG, FIBROUS ROOTS • LARGE SURFACE AREA • EX. CONSTRUCTED WETLANDS SHALLOW LAGOONSGW/WASTE WATER PUMPING

15. PHYTOSTABILIZATION: • INTERIM CONTAINMENT STRATEGY • FOR SITES WITH LOW METAL LEVELSBELOW RISK THRESHOLDS. • LARGE SCALE REMOVAL ACTION NOT FEASIBLE. • PLANTS WITH HIGH TOLERANCE FORMETALS IN SOIL & LOW ACCUMULATION. • VIGOROUSLY GROWING & EXERT HYDRAULIC CONTROL OVER TRANSPORT OF METALS.

16. MATRIX CONTROLS: • PLANT ESTABLISHMENT, PROLIFERATION, & PERFORMANCE. • PH, OXIDATION-REDUCTION. • COMPOSITION & DISTRIBUTION OF REACTIVE SURFACES. • PRESENCE OF MULTIPLE & MIXED CONTAMINATION • INTERACTION WITH CLIMATE FACTORS

17. CLIMATE – TEMPERATURE • TEMPERATE REGIONS - LIMITED TO WARMER PARTS OF YEAR. • SHORT- TIME AVAILABLE. • OK WHEN NO IMMEDIATE THREAT EXISTS. • WARMING TECHNOLOGIES EXIST/QUESTIONABLE ECONOMIES.

18. SOIL MATRIX: • MADE UP OF SOIL PHASES • PHYSIOCHEMICAL PROPERTIES OF pH & REDOX. • CAN INFLUENCE MOBILITY . • CAN REGULATE CONTAMINANT EXPOSURE & SUSCEPTIBILITIES TO BIOLOGICAL TRANSFORMATION /REMOVAL PROCESSES. • CONTROL PROCESSES THAT ELIMINATE/REDUCE EFFECTS OF CONTAMINANTS IN ENVIRONMENT. • IMPACT ORGANICS & METALS DIFFERENTLY.

19. COLLOIDAL NATURE EFFECTSREACTIVITY OF SOIL PHASES (INORGANIC & ORGANIC) • SOIL COLLOIDS ARE: • EXTREMELY SMALL SIZE • LARGE SURFACE AREA • NEGATIVELY CHARGED SURFACEAREA – INFLUENCE ATTRACTIONOR REPULSION BETWEEN SOIL & CONTAMINANT.

20. ORGANIC PHASE IN SOIL: • HIGH ORGANIC CONTENT IN SOIL • CAN RESULT IN MODERATE TO HIGH LIPOPHILOC ORGANIC TOXICS BEING TRAPPED IN ORGANIC MATTER. • UNAVAILABLE FOR PLANT UPTAKE. • CAN ENHANCE DEGRADATION IN RHIZOPHERES BY STIMULATING MICROBIAL GROWTH & BIOACTIVITY • METALS CAN BOND WITH ORGANICS & REDUCE AVAILABILTY FOR PLANT UPTAKE. • METAL BONDING WITH ORGANICS CAN ASSIST IN SITE STABILIZATION.

21. ORGANIC PHASE IN SOIL: (cont) • EX. LEAD STABILIZATION • AVAILABILITY OF METALS IN CLAYS WITH HIGH COLLOIDAL SOLIDS WILL BE REDUCED COMPARED WITH SAND SOILS. • BECAUSE: • POSITIVE CHARGED CATIONS OF CONTAMINANTS ATTRACTED TO NEGATIVE CHARGED MINERAL SURFACES. • CHELATING AGENTS ARE BEING RESEARCHED TO IMPROVE METAL AVAILABILITY.

22. MATRIX (SOIL) pH • EXERTS GREATER IMPACT ON METALS. • PLANTS ABSORB METALS IN IONIC FORM. • METAL CONCENTRATION INCREASES WITH DECREASING pH. (INCREASES HYDROGEN IONS ACTIVITY). • MAY BE TOXIC TO PLANTS. • RESEARCH IS ON ACIDIFIERS. • EX. SULFUR.

23. OXIDATION-REDUCTION • MANY ELEMENTS ARE MORE MOBILE DEPENDING ON OXIDATION STATE. • EX. CHROMIUM – Cr6 IS HIGHLY OXIDIZED FORM & IS MORE TOXIC, MORE SOLUBLE & MOBILE THAN Cr3+ (REDUCED FORM). • PHYTOREMEDIATION MAY FAVOR PRESENCE OF Cr6. • OTHER REMOVAL SCHEME MAY BE TO REDUCE Cr6 TO Cr3 AND PRECIPITATE AS INSOLUBLE, IMMOBILE HYDROXIDE, Cr(OH)3. • THE CHOICE IS THE MANAGER’S.

24. DEEP ROOTED PLANTS • EARLY ASSUMPTION THAT PHYTOREMEDIATION DEPTH WAS LIMITED TO 15-30 CM. • RESEARCHERS ARE DEVELOPING DEEP ROOTED PLANT SYSTEMS. • EX. • HYBRID POPLAR TREES. • GROUNDWATER CONTAINING ATRAZINE AND TNT.

25. METALS ARE DIFFICULT DUE TO: • LOW SOLUBILITY • ATTRACTION TO SOIL SURFACES • TEND TO REMAIN IN ROOT ZONES

26. PRESENCE OF OTHER TOXICS • EASILY OVERLOOKED VARIABLETHAT CAN IMPEDE REMEDIATION • MOST CONTAMINATED SITES CONTAIN MIXTURES OF COMPOUNDS(ORGANICS & INORGANICS). • AN EXAUSTIVE CHARCTERIZATION MAY BE REQUIRED FOR DECISION.

27. MANAGEMENT AIDS • REQUIREMENTS: • POTENTIAL SUCCESS OF TECHNOLOGY • STAKEHOLDER CONCERNS • CAREFUL PLANNING (TEAM OF EXPERT) • SCHEDULING • BUDGETING • IMPLEMENTATION • MONITORING • CONTROLLING

28. MANAGEMENT AIDS (cont) • PRODUCES EXPECTED RESULTS. • PLANNING: • SITE CONDITIONS • LEGAL REQUIREMENTS • OBJECTIVES & TARGETS • IMPLEMENTATION: • RESPONSIBILITIES/AWARNESS • COMMUNICATION • DOCUMENTATION OF PROCESS • MONITORING:  • MEETING OBJECTIVES & TARGETS • ANY CORRECTIVE ACTION

29. TEAM OF EXPERTS • TECHNICAL EXPERTISE REQUIRED • MICROBIAL BIOLOGY • SOIL SCIENCE/GEOLOGY • HYDROLOGY • PLANT PHYSIOLOGY • PROJECT MANAGEMENT

30. RECOVERY OF CONTAMINANTS • HARVEST CONTAMINATED PLANTS • LOW GRADE ORE (PHYTOMINING) • RECYCLED • UNDISTURBED ENVIRONMENT

31. ESTIMATED FINANCIAL RECOVERIES: • HYPERACCUMULATOR PRODUCE 10-20 TONS BIOMASS/HECTARE/YR WITH VOLUME 10O KG/HECTER/YR (FOR NICKEL, WOULD RECOVER $550/HECTARE AT MARKET VALUE OF $2.50/LB.) • $960/HECTARE WITH ALFALFA PRODUCTION OF 500 KG OF Zn/HECTARE AT $1.92/KG.

32. ESTIMATED COMPARISON COSTS

33. CONCLUSIONS • PHYTOREMEDIATION : • PERMANENT IN-SITU OPTION • PHYTOMINING CAN BE PROFITABLE • MANY PLANTS HAVE ABILITY TO CONCENTRATE CONTAMINANTS IN SHOOTS & LEAVES • DEPENDENT ON CLIMATE, MATRIX, pH, REDOX POTENTIAL, KOW, ORGANIC MATTER. • PLANNING, SCHEDULE, BUDGET, CONTROLS, MONITORING SYSTEM, PROJECT MANAGER, TEAM OF EXPERTS, TOP SUPPORT SUPPORT. • RECYCLING CAN DEFRAY COSTS.