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NRSC 333 > 4. Metals > Flashcards

4. Metals Flashcards

1
Q

What are POPs?

A

Persistent Organic Pollutants

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2
Q

Where do POPs circulate and accumulate?

A
  • Circulate globally, move through the atmosphere
  • Accumulate in cold climates
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3
Q

What is the dirty dozen?

A

12 POPs:
- Aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, mirex, toxaphene, hexachlorobenze,
- PCBs, PCDDs (dioxins), PCDFs (furans)

  • pesticides
  • can occur naturally
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4
Q

What are examples of POPs (4)

A
  • the dirty dozen
  • PAHs
  • flame retardants
  • TBT (tributylin)
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5
Q

What are PBTs?

A

PBTs are chemicals that are persistent, bioaccumulative and toxic

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6
Q

What is “persistent” related to in terms of risk = exposure x hazard?

A

exposure

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7
Q

What is “toxic” related to in terms of risk = exposure x hazard?

A

hazard

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8
Q

What is most concerning?

A chemical that is very hazardous but not persistent
or
A chemical that is persistent but not hazardous?

A

A chemical that is persistent but not hazardous

A chemical that isn’t persistent but is hazardous becomes concerning when the contaminant is everywhere, for example, flame retardant → you are exposed constantly even though it is not persistent

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9
Q

Characteristics of metals (8)

A
  • High electrical conductivity
  • Luster (shine)
  • Generally cations (positive)
  • Naturally occurring (they are elements)
    ○ Become contaminants when measured levels > background levels
  • Not created or destroyed
  • Human activities alter availability, speciation, and distribution
  • Essential nutrients AND toxicants (U-shaped dose response)
    ○ You need a little bit, but too much becomes bad for you
  • Complex chemistries → difficult to study
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10
Q

What is AEF?

A

Anthropogenic Enrichment Factor
→ The percentage that humans are responsible to having released into the environment VS what was already there
→ If humans hadn’t released any, the AEF would be 0%

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11
Q

What are PVALs?

A

Protective values for aquatic life
→ numeric levels that are considered acceptable for metals in a body of water

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12
Q

What is ISQGs

A

Interim sediment quality guidelines (a PVAL)

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13
Q

What are PELs?

A

Probable effect levels (a PVAL)

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14
Q

What are the general mechanisms of toxicity of metals? (3)

A
  • Promote formation of oxyradicals
  • Competition for divalent cation binding sites
  • Binding of sulfhydryl
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15
Q

What are oxyradicals?

A

Reactive oxygen molecules that can cause damage to DNA.
(they can potentially lead to cancerous cells)

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16
Q

What does it mean “Competition for divalent cation binding sites”?

A

Metals often have a +2 charge and will compete with other metals with that same charge:
* e.g. calcium, iron-dependent systems
- Mercury could come in and take the place of calcium
- Metals can come in and displace iron, causes issues (e.g. hemoglobin)

17
Q

What does it mean for metals to bind to sulfyhydryl

A

○ Sulfur containing group (also called ‘thiol’)
○ 2 sulfur containing amino acids (methionine and cysteine)
i.e. metals can bind to proteins (amino acids are what make up proteins)

18
Q

What are organometallic compounds?

A

Organic compouds with a metal element

19
Q

Characteristics of organometallic compounds (2ish)

A
  • Can be manufactured or formed naturally
  • Behave differently than the pure element
    ○ Propensity to biomagnify
    ○ May exhibit different toxicities
20
Q

What are non essential metals (3)

A
  • cadmium
  • lead
  • mercury
21
Q

Example of an essential metal

A

Iron (Fe)
* it is in hemoglobin
* hemoglobin = iron containing oxygen transport metalloprotein in red blood cells

22
Q

3 forms of mercury

A
  • Elemental mercury - Hg(0)
  • Inorganic mercury - Hg(II)
  • Organic mercury - e.g. HgCH3 (methylmercury)
23
Q

Characteristics of elemental mercury (3)

A
  • Liquid at room temperature (e.g. in old thermometers)
  • Released as a vapor when coal or other fossil fuels are burned
  • Human exposure: inhalation
24
Q

Characteristics of inorganic mercury (3)

A
  • Formed when elemental mercury combines to other elements (e.g. HgCl2, Hg(OH)2, HgO)
  • Can be manmade or occur naturally in environment
  • Human exposure: workplace
25
Q

Characteristics of organic mercury (3)

A
  • Formed when elemental mercury combines with carbon (e.g. methylmercury)
  • Biomagnifies
  • Human exposure: diet, through placenta
26
Q

Which form of mercury is the most concerning?

A

Methylmercury, because it biomagnifies

27
Q

What is mercury (effect-wise)

A

A potent neurotoxicant

28
Q

What species can mercury be found in?

A

Fish

29
Q

Characteristics of Lead (Pb) (3 points)

A
  • Complex chemistry: Pb2+, Pb4+, up to 4 Pb-C bonds
    ○ All have different fates (how they move around in the environment) toxicities
  • Legacy sources (banned in the 1970s)
    ○ Antiknock gas, paint pigment
  • Current source
    ○ Lead shot/sinkers
    § Impact on waterfowl
    ○ Storage batteries
30
Q

Consequences of led poisonning (2)

A
  • low IQ
  • motor deficits
31
Q

Examples of anions (2)

A

Nitrates and phosphates

32
Q

Consequence of nitrates and phophates

A

Eutrophication → algal blooms → hypoxia

33
Q

Characteristics of nitrates and phosphates

A

Less toxic (hazard) but released in large quantities (exposure) and can be persistent (exposure)

NRSC 333 (23 decks)

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