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Ecology of Aquatic Environments > Heavy Metal Pollution > Flashcards

Heavy Metal Pollution Flashcards

1
Q

Are trace metals a source of pollution?

A

Yes, they are the main source of metal toxicity in the environment

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2
Q

What are trace metals defined as?

A

Occurring at 1000 parts per million or less in the earth’s crust

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3
Q

Are all metals toxic and persistant?

A

All metals are persistent but not all are bio-accumulative or toxic

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4
Q

What are the three groups of metals that are of biological concern?

A

-Light metals (< 5 gcm-3)
-Transitional metals
-Metalloids (Heavy metals >gcm-3)

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5
Q

What are some examples of light metals?

A

Sodium, potassium, calcium
-Normally transported as mobile cat ions in aqueous solutions

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6
Q

What are some examples of transitional metals?

A

Iron, copper, cobalt
-Essential at low concentrations but may be toxic at high concentrations

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7
Q

What are some examples of heavy metals?

A

Mercury, lead, arsenic,
-Not required for metabolic activity and toxic at low concentrations

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8
Q

What does PBT stand for?

A

Persistent, Bio-accumulative and toxic

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9
Q

What nutrient metals are not PBT?

A

Iron (Fe), Manganese (Mn), Vanadium (V)

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10
Q

What are five nutrient metals that are persistent, bio-accumulative and toxic?

A

Copper (Cu), Nickel (Ni), Zinc (Zn), Selenium (Se), Chromium (Cr)

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11
Q

What are five non-nutrient metals that are PBT?

A

Antimony (Sb), Arsenic (Ar), Cadmium (Cd), Mercury (Hg) Lead (Pb)

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12
Q

What is the most toxic heavy metal?

A

Mercury (Hg)

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13
Q

List natural sources of heavy metal pollution

A

-Normal geological formations (ore formations)
-Weathering of rock and leaching
-Degassing (Hg and Volcanoes)
-Forest Fires
-Food and drinking water

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14
Q

What is degassing?

A

Is the removal of dissolved gases from liquids, especially water or aqueous solutions

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15
Q

What are some anthropogenic sources of heavy metals?

A

-Burning fossil fuels
-Mining, smelting and processing metal ores
-Discharging industrial, agri. domestic waste and effluent
-Application of pesticides fungicides and fertilisers
-Paints, dyes, leather, rubber, textiles etc.
-Oil spills

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16
Q

What heavy metal is present in haemocyanin (molluscs and crustaceans respiratory pigment)

A

Copper (Cu)

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17
Q

What heavy metal is present in haemoglobin? (vertebrates and invertebrates )

A

Iron (Fe)

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18
Q

What heavy metal is in respiratory pigments of tunicates?

A

Contains V (Vanadium)

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19
Q

How do organisms obtain essential heavy metals?

A

-Uptake is by passive diffusion
-Active transport systems
-Food and water
-At higher doses than those needed for nutrition, metals can be toxic

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20
Q

Why are metals permanent additions to the environment?

A

Metals are not subject to bacterial degradation

21
Q

How can heavy metals impact the environment?

A

-Impact the physiology and/or behaviour of an organism
-Reduce growth, reproduction and survival
-Can indirectly effect organisms by reducing their prey

22
Q

What are organo-metal complexes?

A

-When heavy metals bind with organic substances

23
Q

Describe organo-metal complexes?

A

-They bind hydric soils (eg. Al, Fe with phosphate)
-Can reduce their toxicity
-Many organo-metal complexes are extremely toxic to aquatic organisms

24
Q

Do heavy metals move up the food chain?

A

Yes, the effects of heavy metals can become severe as they pass through the food chain
(Bioaccumulation and Biomagnification)

25
Q

How do heavy metals enter aquatic ecosystems?

A

-Atmosphere dust and acid rain
-Run off from land and sediment
-Direct discharge

26
Q

What occurs in severely effected areas by heavy metals, when organisms are absent and scarce?

A

-Large inter-specific variation in responses to heavy metals
-Toxicity also depends on environmental conditions
-Sensitivity within a taxonomic group differs between fresh and salt water

27
Q

What are the normal concentrations of heavy metals in freshwater?

A

-Naturally low metal concentrations
-Higher concentrations cause adverse effects to aquatic organisms

28
Q

What are the normal concentrations of heavy metals in marine waters?

A

-Naturally higher concentrations than in freshwater

29
Q

What is the estimated input of Hg (Mercury) into the sea?

A

6000-7500 tons which 50-75% is a result of human activity

30
Q

What organisms are very sensitive to organo-mercurical fungicides?

A

Phytoplankton, just 0.001 ppm reduces photosynthetic efficiency

31
Q

Why are plants suspectable to Hg?

A

Algae and plants have the ability to absorb and concentrate Hg from surrounding environment with high concentrations killing the plants

32
Q

Do animals accumulate Hg?

A

Yes, usually through their food

33
Q

What happens to Hg in the marine environment?

A

Most forms of Hg are converted methly mercury

34
Q

Where does fish eating seabirds accumulate Hg?

A

In their feathers (biomagnification) and feathers are lost when the birds moult

35
Q

What happens to long-lived fish in regards to Hg?

A

Fish like tuna and swordfish accumulate Hg 3000 times higher levels than that of their surrounding waters and are dangerous for human consumption (bioaccumulation)

36
Q

What does an increase of 20 degrees temperature cause in relation to toxicity?

A

Can produce a 100 fold increase in toxicity of Cd, Cu, Pb, Hg, Ni and Zn

37
Q

What is the estimated total inputs of Cd to oceans?

A

8000 t yr-3 from human activites

38
Q

What does Cd exposure do to blue mussels (Mytilus edulis)

A

Inhibited DNA repair, causing genetic damage

39
Q

Does Cd absorb into tissues?

A

Plants and animals readily absorb Cd and accumulate concentrations in their tissues

40
Q

What does Copper (Cu) and Zinc (Zn) do to corals?

A

Can impair reproduction in corals via reduced fertilisation success

41
Q

What are the effects of Lead (Pb) in the environment?

A

-High concentrations accumulate in organisms, sometimes not causing harm like impets, seaweeds, mussels
-Effects reproduction in birds
-Decreased egg production, hatchability and increased hatchelling mortality
-Young, growing birds more sensitive

42
Q

What are the effects of arsenic in the environment?

A

-Accumulates along the food chain, crabs and lobsters worst affected
-Algae, crustaceans and fish bioaccumulate As

43
Q

What organisms are most sensitive to heavy metal pollution?

A

Crustaceans

44
Q

What organisms are not as sensitive to heavy metal pollution?

A

Annelids

45
Q

What are some options to remove heavy metal pollution from environment?

A

-Removed from sediments by dredging
-Sediments can be capped with sand and fine particles that absorb heavy metals
-Wetland creation (Phragmite australis and Lemna minor are tolerant to heavy metals and absorb them)
-Dead plant matter binds to heavy metals and remove them from environment

46
Q

How does heavy metals contaminate Irish waters?

A

Cadmium and mercury released to the atmosphere by fossil fuels and end up in water bodies from atmospheric deposition

47
Q

What is another source contaminating Irish waters?

A

-Historic mining activates
-Emissions from waste-water treatment plants are sources of cadmium, lead and mercury

48
Q

In 2021, how many surface water bodies failed to achieve good chemical status?

A

173 (50%) out of 349 failed (EPA 2021)

49
Q

What was 87 (26.4%) of the failures due to? (EPA 2021 report)

A

Due to substances containing metals,
-Cadmium
-Lead
-Mercury

Ecology of Aquatic Environments (14 decks)

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