1. Aquatic Chemistry 367 Civil and Environmental Engineering
Meeting time: MWF 11:00-11:50am
Meeting room: Abbott Auditorium in Pancoe Pavillion
Instructor: Jean-Francois Gaillard
Grader: Amy Dahl
11/8/2018

2. Species in water Soluble Species Soluble Species Suspended Particles
Small Complexes
Small Complexes
Particles
Particles • •
Colloidal, aggregates
Colloidal, aggregates
e.g.,
e.g.,
Inorganic
Inorganic • •
Oxides (Al, Fe, Mn, Si)
Oxides (Al, Fe, Mn, Si)
Metal Complex
Metal Complex • •
Adsorption: surface
Adsorption: surface
Me(CO
Me(CO ) ) y y - -
complexation
complexation 3 3 n n
Hydrated
Ion Me n+ (H 2 O) n • • Co Co - -
entrainment
entrainment
Hydrated
Hydrated
Ion
Ion Me Me n+ n+ (H (H O) O) 2 2 n n
Living Organisms
Living Organisms • •
Intra/extra
Intra/extra - -
cellular
cellular
Complexes with
Complexes with • •
Oligoelements
Oligoelements
Macromolecules
Macromolecules • •
Toxicity
Toxicity
e.g., Fulvic Acid
e.g., Fulvic Acid • •
Defense Mechanisms
Defense Mechanisms
Sediments
Sediments!
11/8/2018
e.g.,
amorphous or crystalline solids (precipitates and mineral formation)
e.g.,
amorphous or crystalline solids

3. Species in water Dissolved ions: Particulate
Major Cations (Ca2+, Na+, Mg2+, K+, Fe2+ or Fe3+)
Trace elements (Zn2+, Cr3+, Cu2+, Cd2+)
Anions (HCO3-, F-, Cl-, NO3-, SO42-)
Non-charged (SiO)
Organic molecules (humic substances)
Particulate
Organic matter
Clays
Oxides
11/8/2018

4. Chemical Reactions Acid-base chemistry Coordination chemistry
H2CO3  H+ + HCO3-
Coordination chemistry
Hg2+ + Cl-  HgCl+
Precipitation and dissolution
ZnS(s)  Zn2+ + S2-
Redox reactions
4Fe2+ + O2 +4H+  4Fe3+ + 2H2O
11/8/2018

5. Thermodynamic explanation
Assumes equilibrium of a reaction is reached
Simplifies solving mathematical expressions of chemical systems
Use an equilibrium constant, K, to describe ratio of products to reactants:
aA + bB  cC +dD
K = [C]c[D]d/[A]a[B]b
11/8/2018

6. Chemical Accounting - Concentration
Mass concentration
Mass of substance/volume of solution
mg/L or mg/L
Mass of substance/mass of solution
mg/kg = ppm or mg/kg = ppb
When 1ml = 1g (density = 1):
1 mg/L = 1 ppm and 1 mg/L = 1 ppb
11/8/2018

7. Chemical Accounting - Concentration
Molar concentration (M) –
MOST IMPORTANT!!!
Molarity = moles of solute per volume solution in liters
Molality = moles of solute per mass of solvent in kg
11/8/2018

8. Chemical Accounting - Concentration
Normal concentration (N)
1N = 1 equivalent per liter
Based on ion charge
Ca2+ + CO32-  CaCO3(s)
2 equivalents per mol Ca2+
Based on Acid-base reaction
H3PO4  3H+ + PO43-
3 equivalents per mol H3PO4
Based on Redox reaction
4Fe2+ + O2 +4H+  4Fe3+ + 2H2O
4 equivalents per mol O2
11/8/2018

9. Chemical Accounting
Calculating concentrations of all species in a system based on:
Mass conservation of all chemical elements
Reactions occurring in system
Now we will have an EXAMPLE!
11/8/2018

10. Rules for tableau method
Components must be independent: no component should be expressible as a function of other components
Reactions much also be independent: no reaction may be obtained as a linear combination of others
Number of components equals number of species minus the number of chemical reactions:
NC = NS – NR
H2O and H+ should always be chosen as components
Electroneutrality Condition
All positive charges must equal negative charges
11/8/2018