5 - Pollutants/Chemical pollution Flashcards
What is an environmental stressor?
Factors that constrain productivity, reproductive success, and ecological development
What is a disturbance?
Episodic, but intense influence that causes severe biological and ecological damage
What is pollution?
Exposure to chemicals or energy (or potentially other stressors) at an intensity that exceeds the tolerance of organisms
How is pollution different from contamination?
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
Types of pollution (6)
- Chemical pollution
- Thermal pollution
- Biological pollution
- Noise pollution
- Light pollution
- Aesthetic pollution
What is chemical pollution?
When one or more substances occur in concentrations high enough to prompt negative physiological responses in organisms, potentially causing toxicity and/or ecological change
Examples of chemical pollution
Pesticides, smog, petroleum
What is secondary pollution? e.g.
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
What is thermal pollution? e.g.
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
What is biological pollution? e.g.
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
What is noise pollution
When the level of ambient sound becomes distracting to the normal activities of humans or are detrimental to wildlife
What is light pollution
- when artificial light levels are detrimental to wildlife
- often occurs when excess light is bright enough to obscure starts in the night sky
What is aesthetic pollution? How is it different
- 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
What is environmental toxicology?
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
What is ecotoxicology
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
Acute vs chronic toxicity
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
What is LD50? Measurement
“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
Chemicals with lowest LD50? Highest?
Lowest = botulinum toxin, dioxin, cyanide
Highest = water, vitamin C
ED50? TD50?
Effective does 50 (dose producing specific effect in 50% of pop)
Toxic dose 50
What are synergistic effects?
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
Types of toxins
- carcinogens (cancer causing; cigarettes)
- mutagens (DNA mutations; xray radiation)
- teratogens (sedatives)
- allergens (over-active immune response)
- neurotoxins
- endocrine disruptors
What is the global distillation effect
“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
What are persistent organic pollutants
Organic compounds that are resistant to degradation/decomposition via biological, chemical and photolytic processes
POPs include…
Pesticides, industrial chemicals, by-products
Bioaccumulation vs biomagnification
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
Quantitative environmental risk assessment? Three factors
Evaluation of the risks associated with some sort of hazard in the environment
- the likelihood of encountering the hazard
- the likely intensity of the hazard
- the biological damage that is likely to result from the predicted exposure
Slides 59, 60
Paleolimnological approach
Environmental indicators from aquatic systems
- diatoms
- chrysophytes
- chironomids
Environmental indicators from the land for tracking
- pollen
- mineral particles
- insect remains
Environmental indicators from the atmosphere for tracking
- carbon particles from carbon combustion
- fly ash from coal combustion
- metals and other pollutants from industry
Slides 64-68
Lake cores
Two ways of determining ecological impacts?
- mesocosm approach
- whole ecosystem approach
What is the mesocosm approach? Example
Isolate part of the lake with controlled conditions
See effects of different pollutants, doses, organisms, invasive species, etc
What is the whole ecosystem approach? Example
Study the effects of a factor on the entire ecosystem
e.g. Experimental Lakes Area (ELA), Hubbard Brook experimental forest
What types of whole-ecosystem experiments were run at ELA?
Acidification impacts, eutrophication, habitat disruption, aquaculture, adding Phosphorous etc
Lake 226 ELA experiment
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.
What kinds of experiments were run at Hubbard Brook experimental forest?
Used the forest to examine the effects of clear cutting on nutrients in the river, vertebrates and invertebrates, etc
slide 81
What was the FACE experiment?
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?)
