Lecture 3 Flashcards
(22 cards)
what is the octanol-water partitioning coefficient?
- measure of hydrophobicity
- used in the regulation of chemicals; Log Kow > 5 deemed bioaccumulative
- Kow = Concentration octanol/concentration water
what does a high Kow mean?
higher molecules in octanol = more likely to partition into tissue/plants/sediment
what are the 3 types of pollutants?
1) organic pollutants: carbon based, industrial chemicals, pesticides
eg. PCBs, DDT, current use pesticides (Alachor)
2) inorganic pollutants: elements, salts
eg. mercury, arsenic, cadmium, lead, chromium
3) biological pollutants: bacteria, parasites, biotoxins
which of the ‘dirty dozen’ are considered industrial chemicals, legacy pesticides, and by-products?
industrial chemicals: PCBs, hexachlorobenzene
legacy pesticides: aldrin, chlorane, DDT, dieldrin, endrin, heptachlor, hexachlorobenzene, mirex, toxaphene
by-products: hexachlorobenzene, PCDD/PCDF
what are persistent organic pollutants (POPs)?
- organic substances that are persistent, bioaccumulative, and toxic
- prone to long range transport via atmospheric transport and deposition
- likely to cause significant adverse human health or environmental effects near to and distant from their sources
why are harbour seals good to use to determine contaminant concentrations?
they have small home ranges, which makes them a more suitable species than one that migrates
what are PCBs?
- polychlorinated biphenyls
- industrial chemical
- organic chemical consisting of carbon, hydrogen, and chlorine
- 209 different compounds of analytes (congeners)
- the number and location of chlorine atoms determine many of PCBs physical and chemical properties
- used in electrical transformers, capacitors, heat exchange fluids, additives in paint
- listed under Annex A (prohibits new production) and Annex C (must reduce unintentional release)
how are PCBs remediated or disposed of?
- regulating the chemical
- environmental degradation
- waste management
- contaminated site cleanup
- incineration temp above 1000 degrees
- can accumulate into biosolids which can be removed and disposed of
how are marine mammals impacted by PCBs?
PCBs are the dominant contaminant class still present in most marine mammal populations worldwide. It impacts species that are high in trophic levels and long-living
what are organochlorine pesticides?
- legacy pesticides
- widely used in agriculture and for general pest control
- 9 of the 12 ‘dirty dozen’ were OCPs
what is DDT?
- anthropogenic organic chemical
- commercial grade DDT contains DDE and DDD, which are metabolites of DDT and have similar properties
- first used during WWII to combat malaria and typhus
- used as an agricultural and household pesticide
- listed under Annex B (restrict production and use)
what is chlordane?
- anthropogenic organic chemical
- used as a termite treatment
- listed under Annex A (prohibits production and use)
what is heptachlor?
- organic chemical
- once in your body, heptachlor changes to heptachlor epoxide
- largely used for termite control, also used against soil insects, cotton insects, grasshoppers, crop pests, and to combat malaria
what is endrin?
- anthropogenic organic chemical
- primarily used as an agricultural insecticide
- listed under Annex A
- it is rapidly metabolized by animals and does not accumulate in the fat to the same extant as other compounds with similar structures
what is dieldrin/aldrin?
- anthropogenic organic chemical
- aldrin is not toxic to insects; it is oxidized in the insect to form dieldrin which is the active compound
- developed as a DDT alternative
- used primarily to control termites and textile pests
- listed under Annex A
- highly toxic to fish and other aquatic animals such as frogs
what is hexachlorobenzene?
- organic chemical
- fungicide primarily used as a seed treatment, especially on wheat to control fungal diseases
- when people ate HCB treated grain, they developed skin lesions, colic, and debilitation. several thousand people also developed a metabolic disorder that disturbs hemoglobin metabolism and caused skin lesions
- listed under Annex A and Annex C
what is mirex?
- organic chemicals
- used as a stomach insecticide (has to be ingested by the organism to poison it). formulated into baits to control fire ants and harvester ants
what is toxaphene?
- organic chemical
- mixture of over 670 different chemicals and is produced by reacting chlorine gas with camphene
- used as an insecticide primarily for cotton, cereal grains, fruits, nuts, and vegetables. has also been used to control ticks and mites in livestock
what are the modes of pollutant entry to aquatic environments?
- wastewater discharged from manufacturing and formulation plants
- direct use as a pesticide
- drift from spraying (non target)
- soil runoff
- strongly adsorbed into sediments
what are dioxins/furans?
- organic chemical
- produced unintentionally as by-products of industrial processes
- TCDD and TCDF are two of the most toxic dioxins/furans
- family of 210 compounds
- formed at low levels during any hydrocarbon combustion where chlorine is present
- sources: incineration, combustion, volcanic eruptions
- exposure can result in acute skin condition known as chloroache
- listed under Annex C
what are the chemical properties of POPs?
- stable and persistent
- resistant to chemical, photolytic, microbial, metabolic, and thermal degradation
- low water solubility
- high lipid solubility
what are the known toxic effects of POPs?
- endocrine disruption = altered growth and development, reduced reproduction
- altered energy metabolism
- immunotoxicity = increased susceptibility to disease or parasites
- carcinogenicity
