ch.2b Flashcards
What categories are contaminants generally divided into
Organic and inorganic
What are some general characteristics of metals
-shiny
-malleable
-Ductile
Conductive
What are some general characteristics of metalloids
- semiconductors
- some metallic properties
What are some general characteristics of heavy metals
- metals that are denser then iron
- term now applies to metallic elements of concern regardless of density
What are trace elements
Those present in low concentrations (less than ppm)
True or false: 3. Many important contaminants have both natural and anthropogenic sources.
True
Where do metal gradients develop
- Near cities/other developed areas
- mining operations
- near human activity
Can metals and metalloids be artificially produced
No
What should you consider before classifying something as a contaminant
The background levels in that area as in some places the normal levels can be much high then recommended levels
When is a higher then recommended metal concentration considered a pollutant
If all 3 are met
- Concentrations higher then background levels
- least partially caused by humans
- Has a deleterious effect
Why is it difficult to prove polltuion
- it mixes with things in the env (one contam can look like many)
- Env interactions ( is Al toxic or the low pH)
What is the transport of contaminants influenced by
How they partition between phases (Gas/Aq or Aq/Sed or Dissolved liquid/Solid)
Can you assume Thermodynamic Equilibrium on a board scale
NO
Can you assume that the local distribution of a compound is approximately at steady state
Yes
Do you assume partitioning is fast or slow
Fast
Can you assume that X (in pase A) is in equilibrium with X (in phase B)
Yes
What is Kow
Octanol/water coefficient
What is Kp
Partition Coefficient
What is Kd
Distribution Coefficient
What is the equation for Kd
(Conc of X in phase solid)/(conc of X in phase liquid)
What is adsorption
implies association with surface only – difficult to distinguish surface and subsurface
How adsorption for a compound usually determined
Empirically estimated with laboratory experiments
What can Henry’s law help you predict
Portioning between aqueous and gas phase
What is the Equation for henry’s LAw
H=P/C
H: Henry’s law coefficient
P: Vapour pressure
C Water solubility
What does a low Henry’s Law coef mean
Compound tends to stay in the aqueous phase
What does a high Henry’s law Coef mean
Likely will travel atmospherically if discharged aqueously
How are contaminants usually degraded? What are some other ways
- oxidative
- Hydrolysis
Other ways:
- Enzymes
- abiotic (UV, heat)
- photolysis
True or false: Biological degredation can proceed to mineralization
True
True or False: Mineralization often occurs abiotically
False
What is photolysis
chemical bonds broken when they destabilize due to absorbed light (usually UV-vis)
True or false: Rings and double bonds are the most vulnerable to photolysis
True
What is direct photolysis
The compound absorbs light and breaks on its own
What is indirect photolysis
Other compound absorbed light and becomes reactive with compound of interest
What is the results of hydrolysis
Hydroxy and molecular splitting
Does hydrolysis occur abiotically at a significant rate
No
What are the major classes of contaminants
- Organic compounds
- Inorganic Gases
- Metals and Metalloids
- Nutrients
- Organometals
What class of contaminants compounds used as poisons and by-products/ products of industrial processes
-Organic compounds
Give 5 examples of Organic compounds
- CFC’s
- Dioxins
- PAH
- PCB
- Herbicides
Give 3 examples of inorganic gases
- CO2
- NOx
- SO2
Give 5 examples of metals and metalloids
- Al (mine drainage)
- As (mining)
- Cd (electroplating)
- Cr (Catalysts)
- Pb (Gasoline)
- Hg (Amalgams)
Give 2 examples of things that would fall into the nutrient class of contaminants
- Nitrogen species
2. Phosphate species
Give 4 examples of things that would fall into the organometal class of contaminants
- Tin (TBT (causes shell abnormalities), TMT (neurotoxin), TET(neurotoxin))
- Used as antifouling paints - Tetra alkyl lead (anti knock)
- Methyl mercury
- Radionuclides (weapons products)
