Week 10 Flashcards
Bioaccumulation
Progressive increase in the amount of a substance in an organism that occurs because the rate of intake exceeds the
organism’s ability to remove the substance from the body.
Greatest environmental impact has resulted from
- wide-spread use of coal and oil as fuel
- development of motor vehicle
- use of certain classes of new chemicals
DDT
- Persistence of contaminants
- Environment is a closed system
- High toxicity of contaminants
effected ability to fly due to redistribution of organochlorine chemicals to breast tissue. Weakened egg shells
Compartments of the environment (biosphere)
Air
Water
Soil
Biota
Type of media effects movement and degradation of chemical
Biomass
amount of biota, which includes all organisms,
e.g. bacteria, plants and animals
Large numbers of species form interdependent communities
that exhibit:
* Highly variable capabilities of degrading chemicals
* Complex toxicological responses under chemical stress
physicochemical properties
- volatility facilitates distribution into the atmosphere
- water solubility facilitates distribution into water
- lipid solubility facilitates distribution into the biomass
Bioconcentration:
Process leading to a higher concentration of a substance in an organism than in environmental media to which it is exposed.
Biomagnification:
Process leading to a higher concentration of a substance in an organism than in its food
Cumulative pollution
Chemicals with long half-lives are more likely to go above the critical pollution level
ecosystem may never recover, even after the contamination has ceased
point sources
well defined eg. factories or sewage treatment plants
non-point sources
diffuse eg. effluent run offs from agriculture
Endocrine disrupting compounds
Natural and synthetic estrogens are the most potent estrogen receptor agonists.
Adverse effects in aquatic wildlife caused by low levels.
Biomarkers
Biological responses reflecting exposure and/or effect
(toxicity)
* Measurable effects include: Skeletal abnormalities;
Histopathological lesions; DNA changes; Enzyme alterations;
Endocrine effects; Immune dysfunction; Behavioural changes
Bioindicators
Indicator species used as indicators of ecotoxicological effects
Challenging Issues for Environmental Protection
- Excessive human activity impacting on the environment
- Excessive energy usage
- Excessive release of combustion products
