Env Chemistry Test 3
Terms
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- Bow Model: half-life for a simple, static system
- t1/2 = 1.58 x 10-8 (Koc Cw/P) days Koc-soil org. carbon to water S- aq. solubility P- vapor pressure
- Leaching Capacity
- R = 1/ Kd(1-phi^2/3)ds R- leaching capacity Kd- soil/water conc. Ds- density of solids Phi- pore water fraction of the soil
- Mobility Index
- MI = log(SV/Koc) S- water solubility V- vapor pressure Koc- soil org. C to water
- Estimating Koc from Kow
- Koc = 0.66 Kow ^(1.03)
- Fugacity
- Tendency of a chemical to escape from a compartment of phase through a boundary layer. Measured in Pa (pascals) for gas
- Fugacity and Z
- Conc. = Zf M(mass) = Conc. Volume
- Capacity Factor Z from PV= nRT
- Z-air = 1/ RT (R = constant, T = K) Z-water = 1/H (H-Henry's constant)
- Zair
- 1/RT
- Zwater
- 1/H 1/(vap press, aq. solubility)
- Zsoil
- Ksorb(soil)/H
- Zsediment
- Ksorb/H
- Zbiota
- Kb/H
- Kb
- [Biota]/ [Water] flipid/Kow
- Ksorb
- [solid]/ [water] 0.41foc Kow
- Kow
- [octanol]/[water]
- Henry's Law
- H = partial pressure of air/ conc. in water H = Pa/ moles cubic meters H units- Pa m^3 mole^-1
- As pH increases, Cation Exchange Capacity (CEC)(Increases/Decreases)
- Increases
- Measurement of CEC in Lab
- Saturate with NH4+, Wash with Na+, measure NH4+ released
- Rule of Thumb for Cation Exchange Capacity
- 1/2 X% clay + 2X% organic carbon = mEq/100g
- Soil Horizons
- O- organic layer A- topsoil E- leaching zone B- subsoil C- soil parent material R- bedrock
- Freundlich equation
- Cs = Kd Cw^n Cs- organic compound in solid phase (mg/kg) Cw- dissolved organic compound (mg/L) Kd- Cs/Cw^n n- empirically determined
- Charge of Organic Residues in soil
- Positive at low pH, Negative at high pH
- Gas Constant- R Standard Temp
- R- 0.0821 L*atm/mol K K- 298
- f for a system
- f = Mtotal/ SUM ZiVi
- Mi =
- Mi = f ZiVi
- Ci =
- Ci = Mi/Vi