Analyses plan Module 19  Major base cations to be determined by ICP-AES  Conductivity and temperature  {H + } determined using pH electrode  Al fractionation  Major anions to be determined by IC Use of auto-pipettes Use of auto-pipettes  Total organic carbon UV and Vis absorption UV and Vis absorption

Conductivity   Master student lab V160   Ecoscan Con5 (Eutech instruments) conductivity meter. The instrument is calibrated using 1000 and 1433 µS calibration solutions   The measurements are done for quality control purposes in order to compare measured and calculated conductivity

{H + } determined using pH electrode  Analytical Chemistry lab Ø109  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 The pH-meter is calibrated with pH = 4.00 and 7.01 buffer solutions

Major base cations to be determined by ICP-AES  Ca 2+, Mg 2+, Na +, K + Method will be demonstrated in Module 24Method will be demonstrated in Module 24 Appropriate calibration solutions are prepared by Masha Appropriate calibration solutions are prepared by Masha Conducted by Anne-Marie Skramstad Conducted by Anne-Marie Skramstad

Major anions to be determined by Ion Chromathograph (IC)  Analytical Chemistry lab Ø109  Tot-F, Cl -, NO 3 -, SO 4 2- Principle Principle The sample is injected in a flow of eluentThe 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 materialThe 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 -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 conductometerThe 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 Presented by Hege Lynne et al

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 CO 2 by high temperature and catalysis. The amount of CO 2 produced is measured using av IR detector The organic carbon is combusted to CO 2 by high temperature and catalysis. The amount of CO 2 produced is measured using av IR detector  Presented by Hege Lynne et al. Analytes measured may include: TC, IC, TOC, NPOC, and POC Analytes measured may include: TC, IC, TOC, NPOC, and POC

Al fractionation  Master student lab V160  Method presented as example in Lecture 1 (slide 15)  Download manual from

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 M_MEF_4010/

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

Inorganic complexes  Major cations in natural waters H +, Ca 2+, Mg 2+, Na +, K + H +, Ca 2+, Mg 2+, Na +, K +  Common ligands in natural systems: OH -, HCO 3 -, CO 3 2-, Cl -, SO 4 2-, F - & organic anions OH -, HCO 3 -, CO 3 2-, Cl -, SO 4 2-, F - & organic anions In anoxic environment: HS - & S 2- In anoxic environment: HS - & S 2-  Dominating species in aerobic freshwater at pH 8 are:

Hydrolysis  In aqueous systems, hydrolysis reactions are important Hydrolysis reactions are controlled by {H + } Hydrolysis reactions are controlled by {H + } The higher the pH, the stronger the hydrolysis of metal cationsThe higher the pH, the stronger the hydrolysis of metal cations E.g. AluminiumE.g. Aluminium Al 3+ aq denotes Al(H 2 O) 6 3+Al 3+ aq denotes Al(H 2 O) 6 3+

Concentrations of dissolved Fe 3+ species Two total Fe concentrations, Fe T = M and Fe T = M

Dissolved Organic Matter  Low molecular weight (LMW) < 1000Da (e.g. C 32 H 80 O 33 N 5 P 0.3 ) < 1000Da (e.g. C 32 H 80 O 33 N 5 P 0.3 ) E.g.: E.g.:  High molecular weight > Da > Da Humic substance Humic substance Very complex and coloured substancesVery complex and coloured substances  Enhances weathering The protolyzation of weak organic acids The protolyzation of weak organic acids Complexation of Al and Fe Complexation of Al and Fe Total congruent dissolutionTotal congruent dissolution

Concentrations and activities

Activity  {X}=  X · [X] {X} is the activity to X {X} is the activity to X [X] is the concentration to X [X] is the concentration to X  X is the activity coefficient to X  X is the activity coefficient to X  X are dimensionless  X are dimensionless It is determined by:It is determined by: The diameter (å) of the hydrated X The diameter (å) of the hydrated X Its valence (n X ) Its valence (n X ) The ionic strength (I) The ionic strength (I) n=1 n=2 n=3 n=4   when I  0   1 when I<10 -5 M Anions + cations Not possible to calculate further than I=0.1

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 < 0.1 I < & 0.33 are temperature dependent table values 0.5 & 0.33 are temperature dependent table values Presented values are for 25°CPresented values are for 25°C å X is a table value for the specie in question å X is a table value for the specie in question