The Water Analysis exercises (TuCaN 3214) are part of Special Modul SM9 “Hydrogeological Methods” of the MSc TropHEE and scheduled for the 1nd semester but had to be adjourned to the 2nd semester due to capacity bottlenecks in the lab. This course prepares for the HydrogeologicalField Course (TuCaN 3417) scheduled for the 2nd semester.
The Water Analysis course contains lectures and a practical part with surface water sampling, measuring water temperature, EC, pH, oxygen concentration and alkalinity in the field as well ion concentrations in the lab with AAS, IC and Photometry. A salt concentration experiment (EC = f(salt concentration)) with 2 different salts and an introduction to chromatography was also part of the exercises.
Monday we walked along the stream Darmbach with a water sampling case with multimeter, several electrical probes, plastic bottles, titrator, .... At six stations we took water samples: 2 plastic bottles per station/location - one for anion-analysis and one for cationanalysis (with 1 cubic cm of acid HCl to stabilize the sample against degradation/precipitation before being analyzed in the lab) and measured water parameters like water temperature, EC, pH and oxygen concentration. Alkalinity (HCO3+, CO32+) was measured by titration with 1.6 normal sulfuric acid (H2SO4) until the related indicator changes color (at pH 4.3).
One week later we got an introduction to chromatography and conducted an experiment dissolving increasing amounts of 2 salts and measuring the electric conductivity EC of the two solutions.
On friday we analyzed our water samples from Darmbach with lab equipment like AAS, IC and Photometry.
Table of Contents
1 Introduction
2 Field work at Darmbach (May 11)
2.1 Multimeter measurements
2.2 Titration for alkalinity
2.3 Results from field measurements
3 Chromatography & salt experiment (May 18)
3.1 Chromatography
3.2 Salt experiment
4 Lab analysis with AAS, IC and Photometry (May 22)
4.1 Atomic absorption spectroscopy - AAS
4.2 Ion Chromatography - IC
4.3 Photometry
5 Synopsis of measurements
5.1 Schoeller diagram & ion balance
5.2 Stiff diagrams
5.3 Piper diagram
5.4 Discussion of Darmbach water properties
6 References
Research Objectives and Key Topics
This report documents the methodological approach and analytical results of water quality examinations conducted on the Darmbach stream. The primary objective is to characterize the hydrogeological and chemical properties of the water through field sampling and standardized laboratory techniques, subsequently visualizing the data using various geochemical classification diagrams.
- Field sampling and in-situ parameter monitoring (pH, EC, oxygen)
- Laboratory analysis using Atomic Absorption Spectroscopy (AAS) and Ion Chromatography (IC)
- Data processing and scripting using Gnuplot and Python for hydrochemical visualization
- Comparative analysis of water chemistry via Schoeller, Stiff, and Piper diagrams
- Discussion of ion concentrations and potential anthropogenic influences on the Darmbach stream
Excerpt from the Report
3.1 Chromatography
With Chromatography chemical mixtures are separated by injection system, chromatographic column and a solvent (liquid or gas) that transports the components of the mixture with different speeds through the column, so that they leave the column at different times: different substance is converted into different time of leaving the column.
The transport speed of every compound depends on physico-chemical properties like (de-)sorption to the filling material (stationary phase) in the column and the solubility of the compound into the solvent (mobile phase, GC=Gas Chromatograph, HPLC = High Performance / Pressure Liquid phase Chromatograph). High adsorption slows a substance. High solubility makes a substance faster. The retention time = time a substance is retained by adsorption – desorption processes is an identifying property of a substance.
The original sample (e.g. soil) is often not adequate for injection into a chromatograph. First the interesting substances must be extracted, filtered, enhanced in concentration, ... An Accelerated Solvent Extractor (Soxlet) – ASE – that treats dry soil with hot solvents (acetone) was shown to us. After distillation small amounts of samples appropriate for injection (e.g. with a 1 µL syringe) into the chromatograph are provided. Other extraction methods are e.g. Solid-Phase Extraction – SPE – where the sample is given to a solid-phase agent that only binds one component that we want to to analyze and let all other components being washed away. An other solvent = eluant extracts than the component we want analyze from the solid phase.
Summary of Chapters
1 Introduction: Overview of the course objectives within the MSc TropHEE program, focusing on hydrogeological methods and field training.
2 Field work at Darmbach (May 11): Description of the field sampling campaign, covering measurement protocols for in-situ parameters and alkalinity titration.
3 Chromatography & salt experiment (May 18): Explanation of the principles of chromatography and the results of a controlled experiment observing how salt concentration affects electrical conductivity.
4 Lab analysis with AAS, IC and Photometry (May 22): Detailed account of laboratory procedures using spectroscopy and chromatography to measure ion concentrations in stream water samples.
5 Synopsis of measurements: Synthesis of all collected data through advanced hydrogeochemical visualization techniques including Schoeller, Stiff, and Piper diagrams, concluded by a discussion of water properties.
6 References: Compilation of literature and technical resources used for the analysis.
Keywords
Darmbach, Hydrogeology, Water Analysis, Chromatography, Atomic Absorption Spectroscopy, AAS, Ion Chromatography, IC, Photometry, Schoeller Diagram, Stiff Diagram, Piper Diagram, Electrical Conductivity, Alkalinity, Hydrochemical Characterization
Frequently Asked Questions
What is the primary focus of this report?
The report details the analysis of water samples from the Darmbach stream, focusing on chemical characterization through field and laboratory techniques.
Which laboratory methods are utilized for water analysis?
The analysis employs Atomic Absorption Spectroscopy (AAS) for metal detection, Ion Chromatography (IC) for anions and cations, and Photometry for specific ion quantification.
What is the main goal of the practical exercises?
The goal is to enable students to apply standard hydrogeological and laboratory techniques to analyze water samples and interpret the resulting chemical data.
How is the data visualized in the report?
Data is visualized using Schoeller, Stiff, and Piper diagrams, which are generated via computational tools like Gnuplot and Python.
What does the "Salt experiment" chapter cover?
This chapter investigates the relationship between salt concentration and electrical conductivity, providing a theoretical and empirical foundation for interpreting EC measurements.
Which scientific software is used for data processing?
The report utilizes Gnuplot for plotting conductivity data and Python for generating complex hydrogeochemical diagrams like the Stiff and Piper plots.
Why are the Darmbach samples diluted during IC analysis?
Dilution is required to ensure that ion concentrations remain within the calibration range of the Ion Chromatography equipment for precise measurement.
What does the discussion of water properties conclude regarding the stream?
The analysis identifies the Darmbach water as Ca-carbonate type and suggests that variations in sodium and chloride concentrations may be linked to runoff from road salt.
- Quote paper
- Dipl.-Ing., MSc, Rainer Stickdorn (Author), 2015, Water Analysis in field and lab (chromatography, AAS, IC, photometry), Munich, GRIN Verlag, https://www.hausarbeiten.de/document/433465
