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phytoremediation- wiki notes

introduction

  • phytoremediation- using plants to take care of contamination

  • to “contain, remove, or render harmless“ contaminants

  • Cost-effective, BUT- not been shown to have significant change

  • uses plant’s ability to “concentrate elements and compounds” and “detoxify various compounds“

    • comes from hyperaccumulators which bioaccumulate chemicals

background

  • phytoremediation can be used on polluted soil or water

  • used for soils with:

    • cadmium

    • lead

    • aluminium

    • arsenic

    • antimony

  • such metals cause oxidative stress, break down cell membrane, cause many other negative effects etc.

  • SUCCESSFUL:

    • abandoned mines- polychlorinated biphenyl dumpings- contaminated soil, water, and air

    • metal, peticides, solvents, explosives, crude oil

    • toxic waste mitigated: mustard plants, alpine pennycress, hemp, pigweed

Limitations

  • limited by how extensive plant root systems are

  • even with phytoremediation- groundwater can still be contaminated

  • plants may, of course, die

  • some metals are stuck to soil- plant can’t extract

Processes

  • phytoextraction

    • takes contaminants- better for the plant- makes for a healthier plant- becomes a part of the plant

    • hyperaccumulators

    • can also be done with plants that have a low amt of pollutant capacity- but grow very fast- still remove a lot of pollutants

    • must be done with many different harvest cycles to ensure a fully clean area

    • Hyperaccumulators are metallophytes- plants that can withstand lots of heavy metals

    • list of toxins and plants that can accumulate

      • arsenic- sunflower, chinese brake fern

      • cadmium- willow ( additionally- willow was good at cadmium, zinc, copper, and can transport large amt, large biomass production, can also be used for BIO ENERGY in biomass power plants

      • cadmium and zinc- alpine pennycress, can accumulate a large amt, copper slows growth

      • chromium- tomatoes (some promise)

      • lead- indian mustard, ragweed, hemp dogbane, poplar

      • sodium chloride (for fields flooded with seawater)- barley, sugar beets

      • caesium-137, strontium-90,, sunflowers after chernobyl

      • mercury, selenium, PCBs- TRANSGENIC PLANTS- WITH GENES FOR BACTERIAL ENZYMES

phytostabilization

  • “reduces mobility of substances in environment- less leakage or leaching

  • fortifies “long-term stabilization”

  • binds pollutants to soil-less available for organism uptake

  • isolates toxins near roots but not in tissues- pollutants less available- reduces exposure

  • plants can secrete subtance- triggers chem reaction, makes metal less toxic

  • example:

    • vegetative cap- mine tailings

  • can increase or decrease radio source mobility- specific grass used makes the difference

phytodegradation

  • plants degrade organic pollutants in soil or in plant

  • using enzymes secreted from roots, take in the polutants and transpire them

    • best with herbicides, trichloroethylene, methyl tert-butyl ether

  • Chemical modification of environmental substances due to plant metabolism

    • inactivation, degradation, or immobillization

  • orgtanic. pollutants- Cannas plant’s metabolism detoxifiys them

  • plant roots+microorganisms - metabolize

  • cant break down into basic molecules(water, co2 etc)

  • structural change - not full breakdown

phytodegradation- metabolism

  • Phase 1

    • uptake in xenobiotics

    • increase polarity of xenobiotics- by adding hydtoxyl groups

    • enzymes used: peroxidases, phenoloxidases, esterases, nitroreductases

  • phase 2

    • biomolecules (glucose, amino acids), added to polarized xenobiotics- makes even more polar

  • (increasing polarity- decreaseds toxicity)

  • phase 3

    • xenobiotics create a structure “sequestered” - polymerize like a lignin

      • stored within the plant

      • can be toxic to animals that eat them

xenobiotic= foreign substance

phytostimulation

  • making soil microbes better to degrade xenobiotics

    • uses roots mainly

  • happens in rhizosphere- soil layer that surrounds roots

  • plants release carbs and acids that create microbe activity- biodegrades- microoranisms can digest toxins

  • effective in hydrocarbons, PCB, PAH

  • can use aquatic plants- atrazine, hornwort

Phytovolatilization- turns into vapor

  • removing substances from soil and water- release into air

  • can be phytodegradation that resulted in less harmgul substances

  • xenobiotics takes up and transpirated, gets evaporated in atmosphere

    • volatilization happens at stem and leaves

    • indirect volatilization- volatilized at roots

    • Se and Hg--- good phytovolatilization from soil qith poplar trees (high transpiration rate)

rhizofiltration

  • water filtered through roots to remove xenobiotics

  • substances remain in roots

  • used to cleangroundwater- planting directly in site- or removedd and treated in a diff location

biological hydraulic containment

  • when plants draw water from soil into roots and out of plant

  • decreases downward mov ement of contaminants into water

phytodesalination

  • halophytes (plants that can withstand salty soil)

    • used to remove salt from soil and improve quality for other plants

GENETICS!!!!!!

  • breeding and GENETIC ENGINEERING are “powerful tools“ for phytoremediation

  • genes can come from a microorganism or from another plant thats better suited for cleanup

  • EG::: genes for nitroreductase from bacteria- put into tobacco- faster TNT removal- better resistance to TNT

  • new discovery- mechanism in plants that lets them grow even when soil is toxic.

    • natural biodegradable compounds, eg. exogenous polyamines, lets plants withstand 500x higher amt of pollutants

hyperaccumulators and biotic interactions

  • hyperaccumulator- concentrate toxins greater than or equal to set amount (amount varies by pollutant)

    • eg. >100mg/kg for nickel, >10,000mg/kg for zinc

  • ability to accumulate- hypertolerance (just thru evolution and adaptations)

phytoscreening

  • biosensors of subsurface contamination- toxins can be dealt with quickly

  • extract part of plant to see if contaminated

Hyperaccumulators:

  • can grow in high conc of metals

  • can absorb metal through roots

  • can store high amts of metal in tissues

  • ability to hyperaccumulate due to different GENE EXPRESSION AND REGULATION of genes found in said species and related ones

physiological basis

  • in normal plants- more metal in roots than shoots

  • in HAs (hyperaccumulator) plants- more metal in leaves--- metals are brought to shoots to protect roots from toxins

  • lack of knowledge on tolerance::::::::::

    • tolerance and accumulation are separate and moderated by genetics and physiological things

  • species spec characgterists

    • alpine pennycress accumulates more zinc but when there is a low supply

  • active accumulation

    • low concentration

  • passive accumulation

    • very high concentration

genetic basis

  • HA (hyperaccumulator) geenes foiund in 450+ species

  • ability to hyperaccumulate if::::envifronmental expostre and expressiioin of ZIP gene framily

    • envtion exposure- only plants that are exposed to such metals have the opportunity to absorb such metal

    • but comes down to genes

    • can b inheritied

  • ZIP family- encodes Cd, Mn, Fe, and Zn transporters, supplying ZN to metalloproteins

  • ZTP and ZNT families- zinc transproters

  • zinc transporters cant discrinimtate agaisnt speciici metal ions- can accumulate a wide variety of metals

    • hyperaccumulation happens with an overexpressed Zn transport system- plants cant differentiate between different kinds of metals

metal transporters

  • another important trait: good translocation of metal to shoot.

  • usually tolerated by plants that are native to metalliferous soils

  • ways plants can tolerate

    • exclusion:

      • resist metal (bad)

      • absorbtion and sequestratioin (good for remediaton)- pass metal thru shoot and accumulate it

        • hyperaccumulators need this ^ and the ability to absorb 100x more metal than others

metallophyte

  • plant that can tolerate high amounts of heavy metals

  • Obligate metallophytes- can only survive with these metals

  • facultative metallophytes- can tolerate them, but arent bound to them

phytoremediation- wiki notes

introduction

  • phytoremediation- using plants to take care of contamination

  • to “contain, remove, or render harmless“ contaminants

  • Cost-effective, BUT- not been shown to have significant change

  • uses plant’s ability to “concentrate elements and compounds” and “detoxify various compounds“

    • comes from hyperaccumulators which bioaccumulate chemicals

background

  • phytoremediation can be used on polluted soil or water

  • used for soils with:

    • cadmium

    • lead

    • aluminium

    • arsenic

    • antimony

  • such metals cause oxidative stress, break down cell membrane, cause many other negative effects etc.

  • SUCCESSFUL:

    • abandoned mines- polychlorinated biphenyl dumpings- contaminated soil, water, and air

    • metal, peticides, solvents, explosives, crude oil

    • toxic waste mitigated: mustard plants, alpine pennycress, hemp, pigweed

Limitations

  • limited by how extensive plant root systems are

  • even with phytoremediation- groundwater can still be contaminated

  • plants may, of course, die

  • some metals are stuck to soil- plant can’t extract

Processes

  • phytoextraction

    • takes contaminants- better for the plant- makes for a healthier plant- becomes a part of the plant

    • hyperaccumulators

    • can also be done with plants that have a low amt of pollutant capacity- but grow very fast- still remove a lot of pollutants

    • must be done with many different harvest cycles to ensure a fully clean area

    • Hyperaccumulators are metallophytes- plants that can withstand lots of heavy metals

    • list of toxins and plants that can accumulate

      • arsenic- sunflower, chinese brake fern

      • cadmium- willow ( additionally- willow was good at cadmium, zinc, copper, and can transport large amt, large biomass production, can also be used for BIO ENERGY in biomass power plants

      • cadmium and zinc- alpine pennycress, can accumulate a large amt, copper slows growth

      • chromium- tomatoes (some promise)

      • lead- indian mustard, ragweed, hemp dogbane, poplar

      • sodium chloride (for fields flooded with seawater)- barley, sugar beets

      • caesium-137, strontium-90,, sunflowers after chernobyl

      • mercury, selenium, PCBs- TRANSGENIC PLANTS- WITH GENES FOR BACTERIAL ENZYMES

phytostabilization

  • “reduces mobility of substances in environment- less leakage or leaching

  • fortifies “long-term stabilization”

  • binds pollutants to soil-less available for organism uptake

  • isolates toxins near roots but not in tissues- pollutants less available- reduces exposure

  • plants can secrete subtance- triggers chem reaction, makes metal less toxic

  • example:

    • vegetative cap- mine tailings

  • can increase or decrease radio source mobility- specific grass used makes the difference

phytodegradation

  • plants degrade organic pollutants in soil or in plant

  • using enzymes secreted from roots, take in the polutants and transpire them

    • best with herbicides, trichloroethylene, methyl tert-butyl ether

  • Chemical modification of environmental substances due to plant metabolism

    • inactivation, degradation, or immobillization

  • orgtanic. pollutants- Cannas plant’s metabolism detoxifiys them

  • plant roots+microorganisms - metabolize

  • cant break down into basic molecules(water, co2 etc)

  • structural change - not full breakdown

phytodegradation- metabolism

  • Phase 1

    • uptake in xenobiotics

    • increase polarity of xenobiotics- by adding hydtoxyl groups

    • enzymes used: peroxidases, phenoloxidases, esterases, nitroreductases

  • phase 2

    • biomolecules (glucose, amino acids), added to polarized xenobiotics- makes even more polar

  • (increasing polarity- decreaseds toxicity)

  • phase 3

    • xenobiotics create a structure “sequestered” - polymerize like a lignin

      • stored within the plant

      • can be toxic to animals that eat them

xenobiotic= foreign substance

phytostimulation

  • making soil microbes better to degrade xenobiotics

    • uses roots mainly

  • happens in rhizosphere- soil layer that surrounds roots

  • plants release carbs and acids that create microbe activity- biodegrades- microoranisms can digest toxins

  • effective in hydrocarbons, PCB, PAH

  • can use aquatic plants- atrazine, hornwort

Phytovolatilization- turns into vapor

  • removing substances from soil and water- release into air

  • can be phytodegradation that resulted in less harmgul substances

  • xenobiotics takes up and transpirated, gets evaporated in atmosphere

    • volatilization happens at stem and leaves

    • indirect volatilization- volatilized at roots

    • Se and Hg--- good phytovolatilization from soil qith poplar trees (high transpiration rate)

rhizofiltration

  • water filtered through roots to remove xenobiotics

  • substances remain in roots

  • used to cleangroundwater- planting directly in site- or removedd and treated in a diff location

biological hydraulic containment

  • when plants draw water from soil into roots and out of plant

  • decreases downward mov ement of contaminants into water

phytodesalination

  • halophytes (plants that can withstand salty soil)

    • used to remove salt from soil and improve quality for other plants

GENETICS!!!!!!

  • breeding and GENETIC ENGINEERING are “powerful tools“ for phytoremediation

  • genes can come from a microorganism or from another plant thats better suited for cleanup

  • EG::: genes for nitroreductase from bacteria- put into tobacco- faster TNT removal- better resistance to TNT

  • new discovery- mechanism in plants that lets them grow even when soil is toxic.

    • natural biodegradable compounds, eg. exogenous polyamines, lets plants withstand 500x higher amt of pollutants

hyperaccumulators and biotic interactions

  • hyperaccumulator- concentrate toxins greater than or equal to set amount (amount varies by pollutant)

    • eg. >100mg/kg for nickel, >10,000mg/kg for zinc

  • ability to accumulate- hypertolerance (just thru evolution and adaptations)

phytoscreening

  • biosensors of subsurface contamination- toxins can be dealt with quickly

  • extract part of plant to see if contaminated

Hyperaccumulators:

  • can grow in high conc of metals

  • can absorb metal through roots

  • can store high amts of metal in tissues

  • ability to hyperaccumulate due to different GENE EXPRESSION AND REGULATION of genes found in said species and related ones

physiological basis

  • in normal plants- more metal in roots than shoots

  • in HAs (hyperaccumulator) plants- more metal in leaves--- metals are brought to shoots to protect roots from toxins

  • lack of knowledge on tolerance::::::::::

    • tolerance and accumulation are separate and moderated by genetics and physiological things

  • species spec characgterists

    • alpine pennycress accumulates more zinc but when there is a low supply

  • active accumulation

    • low concentration

  • passive accumulation

    • very high concentration

genetic basis

  • HA (hyperaccumulator) geenes foiund in 450+ species

  • ability to hyperaccumulate if::::envifronmental expostre and expressiioin of ZIP gene framily

    • envtion exposure- only plants that are exposed to such metals have the opportunity to absorb such metal

    • but comes down to genes

    • can b inheritied

  • ZIP family- encodes Cd, Mn, Fe, and Zn transporters, supplying ZN to metalloproteins

  • ZTP and ZNT families- zinc transproters

  • zinc transporters cant discrinimtate agaisnt speciici metal ions- can accumulate a wide variety of metals

    • hyperaccumulation happens with an overexpressed Zn transport system- plants cant differentiate between different kinds of metals

metal transporters

  • another important trait: good translocation of metal to shoot.

  • usually tolerated by plants that are native to metalliferous soils

  • ways plants can tolerate

    • exclusion:

      • resist metal (bad)

      • absorbtion and sequestratioin (good for remediaton)- pass metal thru shoot and accumulate it

        • hyperaccumulators need this ^ and the ability to absorb 100x more metal than others

metallophyte

  • plant that can tolerate high amounts of heavy metals

  • Obligate metallophytes- can only survive with these metals

  • facultative metallophytes- can tolerate them, but arent bound to them

robot