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Bioremediation > L6 - Phytoremediation of metals > Flashcards

L6 - Phytoremediation of metals Flashcards

1
Q

What inorganic pollutants can be phytoremediated?

A

Nitrate, phosphate, Cr, Cu, Fe, Mn, Zn, Mo

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2
Q

Why does phytoremediation work?

A

Plants have evolved to deal with toxic compounds and metals and the plasticity of these systems allows them to tackle recently produced synthetic compounds

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3
Q

What is the cost of environmental remediation each year in the world?

A

$25-30 billion

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4
Q

What is phytoextraction?

A

use of plants to remove metals by absorption from soil and conc in shoot tissues

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5
Q

what is Phytodegradation?

A

Absorption and conversion of contaminants by metabolism in root or shoot

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6
Q

What is phytostimulation?

A

Root stimulation of microbial degradation of contaminants

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7
Q

What are the environments of phytoremediation?

A 
Low maintenance
Minimally disruptive
Cheap
Aesthetically pleasing
Compatible with restoration ecology
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8
Q

Disadvantages of phytoremediation?

A 
Limited by root depth
Slow
Limited by climate and soil
Limited by bioavail of pollutants
Limited by toxicity of pollutants
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9
Q

What is constructed wetland?

A

Waste water comes in, cleaned by plants and then is drained to other rivers

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10
Q

How do plants take in organic pollutants and why?

A

Diffuse across membrane because they are man made and so are xenobiotic so plants have no specific transporters

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11
Q

What happens if the organics are too hydrophilic or too hydrophobic?

A

Hydrophilic ( Kow 3) get stuck in membrane

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12
Q

How are inorganics taken up?

A

Membrane transporter proteins

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13
Q

What state are most inorganics in in soil and why?

A

Most oxidised form because most soils are oxidising

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14
Q

What inorganics are similar to nutrients and so are taken up by transporters?

A

Arsenate looks like phosphate

Selenate looks like sulphate

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15
Q

What happens to toxic pollutants after they’re taken up?

A
  • Sequestered to vacuole or cell wall

- Pollutants bound to chelators or conjugates

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16
Q

What are toxic inorganics commonly bound to after uptake?

A

Glutathione or phytochelatins

17
Q

What is phytovolatilisation?

A

Release of pollutants from plant as a gas

18
Q

What can be phytovolatilised?

A

Inorganic Se

19
Q

Why is phytovolatilisation attractive?

A

No need to harvest the plant

20
Q

What kind of pollutants can be degraded by plants?

A

Organic pollutants

21
Q

What is involved in degradation of pollutants?

A

Plant enzymes act to catabolise them to CO2 or partially degrades to compartmentalise

22
Q

What enzymes are involved in degradation?

A

Dehalogenases, monooxygenases, dioxygenases, peroxidases, nitrilases, phosphatases, ntiroreductases

23
Q

What are the most common heavy metals at hazardous waste sites?

A 
Cadmium
Chromium
Copper
Lead
Mercury (most toxic)
Nickel
Zinc
24
Q

How much mercury does WHO say are released each year?

A

10000 tons

25
Q

How does phytoremediation help with heavy metals?

A

Metals precipitate within root zone

26
Q

What is phytoextraction?

A

Use of metal-accumulating plants to remove metals or metalloids from soil by concentrating them into the harvestable parts

27
Q

What are the key processes in metal hyperaccumulation?

A

Metal acquisition - uptake
Chelation - ligands chelate in root to minimise toxicity
Translocation - transport to shoot in xylem
Shoot Accumulation - chelation in cytoplasm, transport to vacuole

28
Q

What is the 1st approach to phytoextraction?

A

Metal-hyperaccumulator plants - low biomass but high conc

29
Q

What is the 2nd approach to phytoextraction?

A

Selected cultivars of crops like Brassica juncea - high biomass, enhanced metal uptake

30
Q

What is the 3rd approach to phytoextraction?

A

Fast growing, high biomass woody crops like Salix and Populud selection lines

31
Q

How can you optimise the candidate plant for phytoextraction?

A

Select line with highest potential yield

Improve metal uptake by conventional breeding or GM

32
Q

How can you optimise the agronomy for phytoextraction?

A

Sowing density, timing, harvest
Fertiliser
Irrigation, weed and pest control

33
Q

How can you optimise the rhizosphere for phytoextraction?

A

Apply amendments to increase bioavail

Innoculate bacteria

34
Q

What is phytomining?

A

Growing crops on soil with metal conc too low for conventional exploitation to then burn and smelt

35
Q

What is induced hyperaccumulation and why is it done?

A

Making gold soluble and making plants take it up using natural chemicals

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