Lecture 12 - DA

Question 1

Define soil.

Answer 1

Unconsolidated material on Earths surface.

Question 2

What is soil composed of?

Answer 2

Mineral grains and decomposing organic matter.

Question 3

What is the problem with applying thresholds to soils?

Answer 3

Difficult, as soils differ in their contents so much.

Question 4

Does the air within different soil pores differ significantly?

Answer 4

No.

Question 5

What must soil ecotoxicology tests be?

Answer 5

Ecologically relevant and applicable to a range of soils, or you cant generalise.

Question 6

What are 3 exposure routes in soil? Which one is difficult to distinguish from the rest?

Answer 6

Ingestion
Dermal
Inhalation
Inhalation is difficult to distinguish from the rest.

Question 7

Is there a standardised method for testing soil?

Answer 7

No.

Question 8

What are 3 advantages and 2 disadvantages of microbial soil tests?

Answer 8

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.

Question 9

What are nematodes important for?

Answer 9

Nutrient recycling via decomposition.

Question 10

What does the presence of a lot of nematodes in soil suggest?

Answer 10

That it is good soil.

Question 11

Where do nematodes live in soil?

Answer 11

Within water in pores.

Question 12

What is the problem with using compost worms in a standardised test? Wh not use earthworms?

Answer 12

Live in compost, so have little ecological relevance.

Earthworms are harder to keep, and compost worms are cheaper.

Question 13

Is there a single test species for using plants in ecotoxicology tests?

Answer 13

No, a variety used.

Question 14

Name 3 endpoints for plants used in soil tests.

Answer 14

Biomass production
Germination
Root elongation

Question 15

Which plant is typically used for soil tests and why?

Answer 15

Arabidopsis as genome is mapped and has controllable genes.

Question 16

Is it relevant to use food plants like lettuce in soil tests? Explain.

Answer 16

Yes, because they are our food.

Question 17

Are trees used in soil testing? Explain why.

Answer 17

No, as they have hard seeds that need to be broken, and take long to mature.

Question 18

Can food plants be related to the field?

Answer 18

Its hard, as they dont really exist outside of human use.

Question 19

Is total metal a good indicator of risk? Explain.

Answer 19

No, bioavailable metal is much better.

Question 20

What percentage of metal is typically not bioavailable?

What about the remaining percentage?

Answer 20

Up to 90% not bioavailable.
9% are potentially available, takes a long time.
1% is available immediately.

Question 21

What is the most bioavailable fraction of soil?

Answer 21

Pore water.

Question 22

What is the predominant charge of soil?

Answer 22

Negative.

Question 23

Define occlusion in ecotoxicological terms.

Answer 23

Physically covered, and unavailable.

May be potentially available.

Question 24

Name elemental interactions that results in decreased bioavailability using phosphate and arsenic as an example.

Answer 24

Phosphates naturally taken up. Arsenic taken up due to similarity.
More phosphate means less arsenic bioavailability.

Question 25

Define bioaccessibility.

Answer 25

Defines what crosses the biological membrane.

Question 26

What is the NEPM?

Answer 26

National objectives for protecting the environment.

Question 27

Define the source pathway receptor model.

Answer 27

Involves a source - like soil
A pathway - absorption/leaching
A receptor - a water system, an organism
All three must be present to be bioavailable.

Question 28

Define investigation level.

Answer 28

Concentrations of a contaminant above which further investigation is required.

Question 29

Name the formula for ecology based investigation levels (EIL). What value of EC is it based on, and why?

Answer 29

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.

Question 30

When doing a soil test, how many taxa and species must be represented?

Answer 30

3 taxa and 5 species.