1. Analyses plan Module 19 Conductivity
{H+} determined using pH electrode
Major base cations to be determined by ICP-AES
Major anions to be determined by IC
Total organic carbon
Al fractionation

2. Conductivity Master student lab V150
Ecoscan Con5 (Eutech instruments) conductivity meter.
The instrument is calibrated using and 1433 µS calibration solutions
The measurements are done for quality control purposes in order to compare measured and calculated conductivity

3. {H+} determined using pH electrode
Master student lab V160
Thermo Orion model 720 pH-meter with a Blueline 11-pH electrode.
The pH-meter is calibrated with pH = 4.00 and 7.01 buffer solutions
Presented by Xie

4. Major base cations to be determined by ICP-AES
Ca2+, Mg2+, Na+, K+
Method will be demonstrated in Module 24
Appropriate calibration solutions are prepared by Xie
Conducted by Anne-Marie Skramstad

5. Major anions to be determined by Ion Chromathograph (IC)
Analytical Chemistry lab Ø109
Tot-F, Cl-, NO3-, SO42-
Principle
The sample is injected in a flow of eluent
The analyte ions are separated by different degree of binding to the active sites on the ion exchange material
Ions with opposite charge of the analyte is exchanged with H+ or OH-
The activity of the analyte is and accompanied H+ or OH- in the eluent stream is measured by means of a conductometer
Presented by Hege Lynne et al

6. Total organic carbon Analytical chemistry lab Ø 104
High temperature (680C) catalytic combustion analysis on a Shimadzu TOC-5000A instrument
Principle:
The organic carbon is combusted to CO2 by high temperature and catalysis. The amount of CO2 produced is measured using av IR detector
Presented by Hege Lynne et al.
Analytes measured may include: TC, IC, TOC, NPOC, and POC

7. Al fractionation Download manual from Master student lab V160
Method presented as example in Lecture 1 (slide 15)
Presented by Xie)
Download manual from

8. QC of data
After the analysis the data must be compiled and quality controlled by ion balance and agreement between measured and calculated conductivity
For this purpose you may use the Data compilation and QC worksheet available at

9. Species in natural freshwater Central equilibriums in natural water samples
KJM MEF 4010
Module 19

10. Inorganic complexes Major cations in natural waters
H+, Ca2+, Mg2+, Na+, K+
Common ligands in natural systems:
OH-, HCO3-, CO32-, Cl-, SO42-, F- & organic anions
In anoxic environment: HS- & S2-
Dominating species in aerobic freshwater at pH 8 are:
The table shows the % of the aqueous ligand relative to the sum of the M species
Free hydroxyl only at pH > 8 though cations of weak bases hydrolyse
Bicarbonate and carbonate only at pH>5
Significant amounts of F only where there is high conc. of Al

11. Hydrolysis In aqueous systems, hydrolysis reactions are important
Hydrolysis reactions are controlled by {H+}
The higher the pH, the stronger the hydrolysis of metal cations
E.g. Aluminium
Al3+aq denotes Al(H2O)63+
This is especially the case for amphoteric species
The hydrolysis is actually a removal of a proton as the more electronegative oxygen and central atom has taken the electron cloud.

12. Concentrations of dissolved Fe3+ species Two total Fe concentrations, FeT = 10-4M and FeT = 10-2M

13. Dissolved Organic Matter
Low molecular weight (LMW)
< 1000Da (e.g. C32H80O33N5P0.3)
E.g.:
High molecular weight
> Da
Humic substance
Very complex and coloured substances
Enhances weathering
The protolyzation of weak organic acids
Complexation of Al and Fe
Total congruent dissolution
Commonly 2-6 mg C/L
Secondary synthesis products of the decomposition of organic matter
No clear distinctions (boarders). Poorly defined
The colour is due to conjugated double bounds
Since the humic substances have multiple functional groups that may be used to complexbind metal ions . Such polydentate chelates are very stable (See Soil chemistry, slide 31).
Enhances the mobility of heavy (transition) metals (Cd, Ni, Co, Zn) and lipophilic micro pollutants
The amount of colour increaeses in many parts of Northern Europe and North America

14. Concentrations and activities

15. Not possible to calculate further than I=0.1
Activity
{X}=X · [X]
{X} is the activity to X
[X] is the concentration to X
X is the activity coefficient to X
X are dimensionless
It is determined by:
The diameter (å) of the hydrated X
Its valence (nX)
The ionic strength (I)
Not possible to calculate further than I=0.1
n=1
n=2
”I” is expressed in mol/L
Apply the square root of charge to simplify the DH equation and since the  is proportional to the square root of n
On the blackboard:
c Molar of the salt give rise to an I equals;
AgCl: ½(c·1²+c·1²) = ½ · 2c
Ba(IO3)2 : ½(c·2²+2c·1²)= ½ · 6c
BaSO4: ½(c·2²+c·2²) = ½ · 8c
Al(NO3)3: ½(c·3²+3c·1²)= ½ ·12c
I can be roughly estimated based on the amount of solved material (TDS): I=2.5•10-5 •TDS (mg/L)
or charge: I=1.7•10-5 • SpC (S/cm)
n=3
n=4
  when I  0   1 when I<10-5M
Anions + cations

16. Debye Huckel (DH) equation
For ionic strengths (I) < 0.1M the X can be calculated by means of e.g. the Debye Huckel equation:
I < 0.1
I < 0.005
0.5 & 0.33 are temperature dependent table values
Presented values are for 25°C
åX is a table value for the specie in question
Notice the denomination of the å in nm or Ångstrøm in both factors
An alternative equation for the extended DH is the Günterberg equation
In this equation the expression 3.3å is replaced by 1 (i.e. å is given the Value of 0.3)
A other equation is the Davis equation