5 - Pollutants/Chemical pollution

Question 1

What is an environmental stressor?

Answer 1

Factors that constrain productivity, reproductive success, and ecological development

Question 2

What is a disturbance?

Answer 2

Episodic, but intense influence that causes severe biological and ecological damage

Question 3

What is pollution?

Answer 3

Exposure to chemicals or energy (or potentially other stressors) at an intensity that exceeds the tolerance of organisms

Question 4

How is pollution different from contamination?

Answer 4

Contamination is when potentially damaging stressors are present in the environment, but intensities are too low to cause damage

All pollutants are contaminants, but contaminants must reach a certain threshold to be considered pollutants

Question 5

Types of pollution (6)

Answer 5

1. Chemical pollution
2. Thermal pollution
3. Biological pollution
4. Noise pollution
5. Light pollution
6. Aesthetic pollution

Question 6

What is chemical pollution?

Answer 6

When one or more substances occur in concentrations high enough to prompt negative physiological responses in organisms, potentially causing toxicity and/or ecological change

Question 7

Examples of chemical pollution

Answer 7

Pesticides, smog, petroleum

Question 8

What is secondary pollution? e.g.

Answer 8

The release of substances that react in the environment, to synthesize chemicals of greater toxicity

E.g. Nitrogen oxides and volatile organic compounds react with sunlight to create tropospheric ozone

Question 9

What is thermal pollution? e.g.

Answer 9

When the release of heat into the environment results in ecological stress, due to variations in species tolerance of temperature extremes
e.g. powerplants, hot springs, urban heat islands

Question 10

What is biological pollution? e.g.

Answer 10

When humans release organisms beyond their natural range:
- non-native (invasive) species
- pathogens

e.g. Lupine (invasive flower. Brought several pathogens. Brought by european settlers in 1800s. Will kill off/outcompete the other flowering plants by taking all available N

Question 11

What is noise pollution

Answer 11

When the level of ambient sound becomes distracting to the normal activities of humans or are detrimental to wildlife

Question 12

What is light pollution

Answer 12

• when artificial light levels are detrimental to wildlife
• often occurs when excess light is bright enough to obscure starts in the night sky

Question 13

What is aesthetic pollution? How is it different

Answer 13

• visual images or environments that are displeasing to many (but not necessarily) all people
• culture-based
• different because it only impacts humans, but we are a part of the environment

Question 14

What is environmental toxicology?

Answer 14

The study of the environmental factors that can influence the exposure of organisms to potentially toxic chemicals
- how toxic chemicals cycle through/react to the environment
- where chemicals may occur
- more organism based

Question 15

What is ecotoxicology

Answer 15

The study of the directly poisonous effects of chemicals, in addition to their indirect ecological effects
- how chemicals alter the species composition
- how chemical accumulation influences ecosystem processes
- impacts of chemicals on the environment and its inhabitants
- more ecosystem based

Question 16

Acute vs chronic toxicity

Answer 16

Acute = short-term exposure to a chemical in a high enough concentration to cause biochemical or anatomical damages, or even death

Chronic = long-term exposure to low or moderate concentrations of a chemical. Over time, chronic exposure may cause biochemical or anatomical damage, or become lethal

Question 17

What is LD50? Measurement

Answer 17

“Lethal dose 50,” the amount of a compound required to kill half of a population of experimental animals

Usually measured in amount of chemical per unit body weight

Question 18

Chemicals with lowest LD50? Highest?

Answer 18

Lowest = botulinum toxin, dioxin, cyanide

Highest = water, vitamin C

Question 19

ED50? TD50?

Answer 19

Effective does 50 (dose producing specific effect in 50% of pop)

Toxic dose 50

Question 20

What are synergistic effects?

Answer 20

Interactive impacts of toxins that are more than, or different from, the simple sum of their constituents effects
Two compounds ‘amplify’ each other together and can be harmful, despite being harmless on their own e.g. vinegar and baking soda explode when mixed

Question 21

Types of toxins

Answer 21

• carcinogens (cancer causing; cigarettes)
• mutagens (DNA mutations; xray radiation)
• teratogens (sedatives)
• allergens (over-active immune response)
• neurotoxins
• endocrine disruptors

Question 22

What is the global distillation effect

Answer 22

“Grasshopper effect”
At low latitudes, evaporation of pollutants exceeds deposition
Pollutants are transported by atmosphere and ocean current
Pollutants enter the polar food web and accumulate in biota

e.g. pesticide contamination in antarctic

Question 23

What are persistent organic pollutants

Answer 23

Organic compounds that are resistant to degradation/decomposition via biological, chemical and photolytic processes

Question 24

POPs include…

Answer 24

Pesticides, industrial chemicals, by-products

Question 25

Bioaccumulation vs biomagnification

Answer 25

Bioaccumulation: build up of a toxin in the tissues of animals. Animal directly consuming or exposed to something that is contaminated Biomagnification: magnification of concentration of toxin as we move up the food chain. Uncontaminated organism consumes contaminated orgnism

Question 26

Quantitative environmental risk assessment? Three factors

Answer 26

Evaluation of the risks associated with some sort of hazard in the environment 1. the likelihood of encountering the hazard 2. the likely intensity of the hazard 3. the biological damage that is likely to result from the predicted exposure

Question 27

Slides 59, 60

Answer 27

Paleolimnological approach

Question 28

Environmental indicators from aquatic systems

Answer 28

- diatoms - chrysophytes - chironomids

Question 29

Environmental indicators from the land for tracking

Answer 29

- pollen - mineral particles - insect remains

Question 30

Environmental indicators from the atmosphere for tracking

Answer 30

- carbon particles from carbon combustion - fly ash from coal combustion - metals and other pollutants from industry

Question 31

Slides 64-68

Answer 31

Lake cores

Question 32

Two ways of determining ecological impacts?

Answer 32

- mesocosm approach - whole ecosystem approach

Question 33

What is the mesocosm approach? Example

Answer 33

Isolate part of the lake with controlled conditions See effects of different pollutants, doses, organisms, invasive species, etc

Question 34

What is the whole ecosystem approach? Example

Answer 34

Study the effects of a factor on the entire ecosystem e.g. Experimental Lakes Area (ELA), Hubbard Brook experimental forest

Question 35

What types of whole-ecosystem experiments were run at ELA?

Answer 35

Acidification impacts, eutrophication, habitat disruption, aquaculture, adding Phosphorous etc

Question 36

Lake 226 ELA experiment

Answer 36

Divided lake into two parts Added nitrogen, carbon to one side Added nitrogen, carbon, and phosphorus to the other side P caused algae bloom. Experiment does not work in the lab bc no wind (adds oxygen to lake surface). Detergents from households contained P that was running off into the lakes.

Question 37

What kinds of experiments were run at Hubbard Brook experimental forest?

Answer 37

Used the forest to examine the effects of clear cutting on nutrients in the river, vertebrates and invertebrates, etc slide 81

Question 38

What was the FACE experiment?

Answer 38

Free-air CO2 enrichment experiment Posts in a circle releasing CO2 towards the middle of the circle. See the effects of increasing atmospheric CO2 (does it increase photosynthesis?)