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Ecotoxicology > Lecture 7 - DA > Flashcards

Lecture 7 - DA Flashcards

1
Q

Define radiation.

A

Energy that can be transferred from one body to another through vacuum.

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2
Q

What are the two types of radiation? Give 3 examples for both.

A

Non-ionising - low energy photon: infrared, visible, UV, radiowaves
Ionising - high energy: alpha, beta, gamma

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3
Q

What happens when beta and gamma rays penetrate matter?

A

They dissipate their energy through collisions, and the absorbing ions become ionised, breaking molecular bonds.

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4
Q

Define the two sources of ionising radiation.

A

Natural - produced in nuclei within naturally occurring unstable atoms as they decay.
Artificial - unstable nuclei created by bombarding them with high energy particles, and which will later decay.

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5
Q

Define isotope.

A

Atoms of an element with the same proton number, but atomic mass.

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6
Q

Which is worse, external or internal irradiation, and why?

A

Internal, as external can be blocked or removed, while internal cannot. Also makes alpha radiation dangerous.

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7
Q

What are the two molecular impacts of radiation?

A

Ionisation - may cause unstable fragments - free radicals.
Excitation - elevates electrons to a higher state, causing potential dissociation or transfer of energy when it returns to the lower state.

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8
Q

Define the two forms of biological damage.

A

Direct - radiation strikes a molecule, causing damage.

Indirect - radiation strikes a molecule, causing it to release free radicals, which then cause damage.

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9
Q

Define a free radical.

A

Free uncombined atom, molecule, or atomic group, carrying an unpaired electron.

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10
Q

Which is worse, neutral free radicals, or charged free radicals?

A

Charged free radicals.

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11
Q

Define somatic damage and genetic damage.

A

Somatic - damage to enzymes, membranes, organelles, and in DNA leading to cancer.
Genetic damage - damage to DNA and chromosomes in reproductive tissue, leading to birth defects.

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12
Q

Most radiation damage occurs as mutations and cancers, rather than damage to proteins. Explain why.

A

A high dose is required for direct damage, so mostly causes mutations leading to cancer, which requires a low dose.

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13
Q

Name the three syndromes that collectively cause acute radiation syndrome, and describe the response for each. List them in order of the dose needed to be induced.

A

Haemopoietic syndrome - recovery or death
Gastrointestinal syndrome - death
Neurovascular (CNS) syndrome - death

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14
Q

What is the true cause of death in gastrointestinal syndrome? What is the underlying cause of this outcome?

A

Infection rather than gastrointestinal dysfunction. The higher chance of infection is due to the loss of the lymphocyte population from haemopoietic syndrome.

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15
Q

What are the two possible explanations of neurovascular (CNS) syndrome?

A

Leakage of blood vessels into the brain (ie a haemorrhage) causing pressure
Changes in neuronal permeability, leading to loss of action potential

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16
Q

What are the three pathologies of gastrointestinal syndrome and what does it lead to (4)?

A

Death of GIT mucosa
Increased shedding of mucosal cells
Decreased replacement of mucosal cells
Leads to a denuded GIT, starvation, water loss, and electrolyte loss.

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17
Q

Define alpha radiation.

A

Identical to a helium nuclei - 2 protons, 2 neutrons.

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18
Q

Define beta radiation.

A

Energetic electron ejected from an atom following the conversion of a neutron to a proton.

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19
Q

Define gamma radiation.

A

EM radiation ejected from a nucleus.

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20
Q

Describe what materials are needed to block alpha, beta, and gamma radiation.

A

Alpha - stopped by paper
Beta - goes through paper, stopped by 3mm Al foil
Gamma - goes through paper, Al foil, stopped by slab of lead

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21
Q

Define decay rate.

A

Number of nuclei decaying per unit time.

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22
Q

Define half-life.

A

Time taken for half the radioactive atoms to decay.

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23
Q

Describe the following formula:

At = Ao/2n

A

At=activity after time
Ao = activity at time 0
n = number of half lives

24
Q

How can isotopes be differentiated? What else does this feature reveal?

A

Each isotope has a characteristic half-life. Also explains why some are more dangerous than others.

25
Q

What can radioactive isotopes with long half-lives be likened to in terms of toxicology?

A

Persistent toxicants.

26
Q

Name the isotopes that are used as tracers for the following elements:
H, C, Zn

A

H - tritium
C - C14
Zn - Zn65

27
Q

What is the unit of radiation, and what does it represent?

A

Bq - becquerel

One transformation per second

28
Q

What is equivalent dose?

A

Dose taking into account the type of ionising radiation, and the effect it has on living tissue.

29
Q

How is equivalent dose calculated?

A

Equals absorbed dose by weighting factor.

30
Q

What is the SI unit for equivalent dose?

A

Sv - sievert

31
Q

What are dose rates referring to the whole body measured in?

What about rates referring to parts of the anatomy?

A

Whole body - measured in equivalent dose with reference to time
Partial - measured in absorbed dose with reference to time.

32
Q

Is alpha radiation more dangerous than gamma radiation?

A

Yes, but only if alpha radiation is swallowed.

33
Q

What are the sources of exposure to radiation in %?

A 
Internal - 12% (food, water)
Terrestrial - 14%
Medical - 12%
Cosmic - 10%
Rason - 50%
34
Q

What are naturally occurring isotopes called?

A

Cosmogenic.

35
Q

Can a gieger counter distinguish between the types or energy levels of a given radiation?

A

No.

36
Q

Whats worse, terrestrial pollution, or aquatic and why?

A

Aquatic, because it can be carried across the world through currents.

37
Q

Name 8 types of water pollution. Give an example for each.

A 
Organic - sewage
Nutrient - phosphate/nitrate
Atmospheric - chlorine
Thermal - heat
Metal - mercury
Pesticide - self-explanatory
Radioactive - isotopes
Oil - spill/dispersant
38
Q

Define biological oxygen demand (BOD).

A

Measure of pollution potential of waste water with a source of organic carbon to determine oxygen usage.

39
Q

Name 3 effects pollution can have on the water column. What happens to the microbiota?

A

Lowers available oxygen
Increases turbidity
Decreases light availability
Organic waste settles to the bottom, where bacteria multiply

40
Q

Do cleanwater fauna tolerate low oxygen well?

A

No.

41
Q

Define indicator species.

A

Species that by their presence indicate condition of the habitat. Also called sentinel organisms.

42
Q 
what are the indicator species for the following:
Sewage bacteria (2), polluted rivers, recovery zones, a region of nutrient increase, anoxic conditions.
A

Polluted rivers - algae
Recovery zone - diatom
Nutrient increase - filamentous greens, cyanobacteria
Anoxic conditions - tubificid worms

43
Q

Whe presence of which two organisms indicated recovery?

A

Isopods, and amphipods

44
Q

What 3 species are most sensitive to organic pollution?

A

Mayflies, stoneflies, and caddisfish.

45
Q

What dominated polluted waters?

A

Protoxoa.

46
Q

Define eutrophication, and its two types.

A

Enrichment of waters by inorganic plant nutrients like nitrates and phosphates.
Natural - occurs with ageing of the water body.
Artificial - fertiliser runoff.

47
Q

What consequence can atmospheric pollution on water?

A

Acidification of natural waters, like acid rain.

48
Q

Name a source of thermal pollution. What effect does it have on species richness? Do algae tolerate it well?

A

Released from power plants.
Species richness decreases.
Algal productivity increases, leading to blooms.

49
Q

Are accidental oil spills a high contributor to the overall oil pollution?

A

No, tanker operations spill more oil than accidents.

50
Q

Why are oil spills dangerous?

A

Because of the polycyclic aromatic hydrocarbons, and because they float and form an oil slick.

51
Q

What is a consequence of the oil from spills eventually becoming emulsified and dispersed?

A

The more they dissolve, the more they become bioavailable.

52
Q

What are two physical ways an oil spill can be cleaned?

A

Booms and skimmers.

53
Q

What are 3 non-physical ways an oil spill can be cleaned?

A

Burning the oil
Adding dispersants
Bioremediation.
Seeding with oil degrading bacteria.

54
Q

Define bioremediation.

A

Spraying with nutrients to encourage microfauna, which will break the oil down.

55
Q

Are chemical dispersants of oil a good way to clean spills?

A

Some dispersants were found to be more toxic than the oil.

Ecotoxicology (22 decks)

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