Lecture 12 - DA Flashcards
Define soil.
Unconsolidated material on Earths surface.
What is soil composed of?
Mineral grains and decomposing organic matter.
What is the problem with applying thresholds to soils?
Difficult, as soils differ in their contents so much.
Does the air within different soil pores differ significantly?
No.
What must soil ecotoxicology tests be?
Ecologically relevant and applicable to a range of soils, or you cant generalise.
What are 3 exposure routes in soil? Which one is difficult to distinguish from the rest?
Ingestion
Dermal
Inhalation
Inhalation is difficult to distinguish from the rest.
Is there a standardised method for testing soil?
No.
What are 3 advantages and 2 disadvantages of microbial soil tests?
Advantages Soil Measures ecosystem functioning Can be rapid Disadvantages May miss impacts on sole species if other species increase activity to compensate. May take a long time.
What are nematodes important for?
Nutrient recycling via decomposition.
What does the presence of a lot of nematodes in soil suggest?
That it is good soil.
Where do nematodes live in soil?
Within water in pores.
What is the problem with using compost worms in a standardised test? Wh not use earthworms?
Live in compost, so have little ecological relevance.
Earthworms are harder to keep, and compost worms are cheaper.
Is there a single test species for using plants in ecotoxicology tests?
No, a variety used.
Name 3 endpoints for plants used in soil tests.
Biomass production
Germination
Root elongation
Which plant is typically used for soil tests and why?
Arabidopsis as genome is mapped and has controllable genes.
Is it relevant to use food plants like lettuce in soil tests? Explain.
Yes, because they are our food.
Are trees used in soil testing? Explain why.
No, as they have hard seeds that need to be broken, and take long to mature.
Can food plants be related to the field?
Its hard, as they dont really exist outside of human use.
Is total metal a good indicator of risk? Explain.
No, bioavailable metal is much better.
What percentage of metal is typically not bioavailable?
What about the remaining percentage?
Up to 90% not bioavailable.
9% are potentially available, takes a long time.
1% is available immediately.
What is the most bioavailable fraction of soil?
Pore water.
What is the predominant charge of soil?
Negative.
Define occlusion in ecotoxicological terms.
Physically covered, and unavailable.
May be potentially available.
Name elemental interactions that results in decreased bioavailability using phosphate and arsenic as an example.
Phosphates naturally taken up. Arsenic taken up due to similarity.
More phosphate means less arsenic bioavailability.
Define bioaccessibility.
Defines what crosses the biological membrane.
What is the NEPM?
National objectives for protecting the environment.
Define the source pathway receptor model.
Involves a source - like soil
A pathway - absorption/leaching
A receptor - a water system, an organism
All three must be present to be bioavailable.
Define investigation level.
Concentrations of a contaminant above which further investigation is required.
Name the formula for ecology based investigation levels (EIL). What value of EC is it based on, and why?
EIL = ABC + ACL
ABC - ambient background concentration
ACL - added contaminant level.
ACL is based on EC30, EC10 isnt considered statistically significant, and EC50 isnt considered protective enough.
When doing a soil test, how many taxa and species must be represented?
3 taxa and 5 species.
