Vern. Lecture 6. Flashcards
What organic pollutants can be phytoremediated?
Petroleum byproducts, PAHs, BTEX…
What is it that actually degrades organic pollutants?
Bacteria associated with plant roots, not plants themselves.
What were planted in the Argonne East site (volatile organic compound) to degrade organic pollutants?
Hybrid willows
Why were poplars used on the trees?
To direct the tree’s roots towards the contaminated plume as their sole source of water.
What four conditions are needed in the phytoremediation of heavy metals?
- Bioavailability of elements generally higher
- at low pH
- in wet conditions
- where organic acids and root exudates function and plants pick up mobilised elements
What are hyperaccumulators? Give an example
Plants with high capacity to tolerate and accumulate huge levels of elements.
The nickel hyperaccumulator, Berkheya coddii native to South Africa
What is the Biological Adsorption Coefficient?
The concentration of element in plant ash divided by the concentration of element in the substrate (e.g. soil)
BAC = Cp/Cs
Name the three mechanisms of ion adsorption in plants
- Diffusion into root tips cells
- Cation exchange
- Folair absorption
Why do some plants accumulate selenium for their own benefit?
Protects against herbivores but can lead to the evolution of selenium tolerant herbivores e,g, diamondback moth
Why can plant element accumulation be dangerous?
Makes elements bioavaliable to livestock and hence humans at levels which may be harmful.
Hyperaccumulators make large amounts of toxic metals bioavaliable. Why can this be useful?
Can be used to scavenge metal from spoil heaps (Phytoextraction) but system is not that effective
How does ion adsorption work by the diffusion into root cells?
Common, requires energy to concentrate ions in cell fluid
Describe cation exchange as a mechanism of ion adsorption
Most important, CO2 from root respiration which generates H+ which exchanges for nutrients bound on clay surfaces
Describe folair absorption as a mechanism of ion adsorption
Dust dissolves in moisture on leaves and nutrients adsorbed
