Lecture & Project Modules

Lectures

Module 1 Isotopes & isotope fractionation: principles & definitions
  Lecturer Dr. Fernando A. Lattanzi, Technische Universität München
  Objectives The stable isotopes of an element (e.g. carbon) are not distributed uniformly in nature. This is related to differences in the behaviour of the isotopes in transport and transformation processes in the environment and in organisms. The goal of this module is to generate the basic understanding of the physical and chemical nature of isotopes and how these control isotope effects (differential distributions of isotopes) in the ‘real world’.
  Contents

Definitions & Terminology: What is an isotope? What is a stable isotope? The definition of isotope abundance: atom% and ‘small delta’. The masses and abundances of the isotopes of the main elements of the biosphere: carbon, oxygen, hydrogen, nitrogen, sulphur.

Isotope effects: Physical and chemical bases of isotope fractionation (discrimination): kinetic isotope effects and equilibrium effects. Isotope effects in open versus closed systems.

     
Module 2 Isotope analysis: instrumentation
  Lecturer Dr. Rudi Schäufele, Technische Universität München
  Objectives Since the 1980’s large progress has been made in methodologies of stable isotope analysis, which opened up new applications in many fields of natural and social science and greatly simplified traditional applications. The module gives an overview of the spectrum of stable isotope analytical techniques, their principles of operation, performance, and fields of application.
  Contents

Stable isotope analysis systems: A short historical overview. Stable isotope ratio mass spectrometers (IRMS). Sample injection systems: dual-inlet versus continuous flow. Laser spectroscopy (tunable diode laser). GC-IRMS systems. On-line versus off-line measurements.

Measurement principles and performance: Ion source and ionisation. Mass-to-charge ratio. Hierarchy of isotope standards. Reference gases. Calibration procedures.

     
Module 3 Sampling, sample preparation for isotope analysis, laboratory standards and quality control
  Lecturer Dr. Rudi Schäufele, Technische Universität München
  Objectives As broad as the fields of applications of stable isotopes are the types of samples. This module explains what and how to sample and how to prepare samples to extract the required information. The second part illustrates how to ensure that the isotope analysis provides results of high quality, the basis for good isotope science.
  Contents

Sampling: Sampling strategies for different applications. Sample size and detection limits. Sample preparation.

Stable isotope analysis: Sample preparation systems for analysis of bio-elements. Precision and accuracy. Standard materials. IT (identical treatment) principle. Data correction.

     
Module 4 Carbon isotopes in photosynthesis 
  Lecturer Prof. Jiri Santrucek, Czech Academy of Science & University of South Bohemia
  Objectives Photosynthesis provides all heterotrophic life with energy rich carbon compounds and is at the very beginning of global food webs. In the process of photosynthesis, the heavier from both carbon stable isotopes, 13C, is discriminated depending on the type of carboxylation, water and CO2 availability. The aim of this module is to promote the basic knowledge on the isotopic fractionation during carbon assimilation, show the contributions of CO2 transport steps and biochemistry of CO2 fixation in 13C discrimination and give examples of applications in plant physiology, breeding and in ecology.
  Contents

13C discrimination: From empirical observations to modelling:Carbon isotopes in atmosphere and plant body. 13C discrimination in C3, C4 and CAM plants. Isotopic effects in diffusion and carboxylation. Models.

Applications: Water use efficiency. Vegetation history. Primary productivity. Physiological performance.

     
Module 5 Oxygen and hydrogen isotopes in leaf water 
  Lecturer Prof. Jiri Santrucek, Czech Academy of Science & University of South Bohemia
  Objectives Water obeys kinetic and equilibrium isotopic fractionation through its global cycle leaving the signature in soil water, the main source of transpiration stream. Here, we will provide the recent knowledge on fractionation of water isotopes during root water uptake, transfer into the leaves, mechanisms of leaf water enrichment in 18O and deuterium (D) and transfer of this enrichment into early assimilates and gasses exchanged with atmosphere with the aim to develop abilities of applications in relevant fields.
  Contents

Isotopic fractionation of water in plant body: From molecules to global scale and soil water. Fractionation in water uptake, redistribution, stem water transport. Isotopic leaf water enrichment: desert river analogy, Peclet effect, environmental isotopic signature. Principle of 18O exchange in chloroplasts, Dole’s effect.

Applications: Tracing of water source, plant water use strategy. Leaf temperature integrator. Evapotranspiration partitioning.

     
Module 6 Isotopes in the hydrological cycle
  Lecturer Prof. Karl Auerswald, Technische Universität München
  Objectives Isotopes in the hydrological cycle (2H, 18O) are used as tracers for water of different origin and to quantify processes like evaporation, transpiration and precipitation. The lecture presents the basic principles underlying these applications.
  Contents

Principles of fractionation of 2H and 18O: Equilibrium fractionation. Temperature effects. Rayleigh fractionation.

Spatial and temporal variation of rain isotope composition: Seasonal effect. Altitudinal effects. Latitudinal effect. Continental effect. Amount effect.

Models of evaporation and transpiration.

     
Module 7 Carbon transformations in soil
  Lecturer Prof. Hana Santruckova, University of South Bohemia
  Objectives The distribution of stable isotopes of carbon in soil organic matter (SOM) follows the distribution of stable carbon isotopes in vegetation, but it can be shifted by several per mil. This shift is caused by isotope effects of the physico-chemical processes in soil and biochemical transformations of organic compounds. The goal of this module is to explain the mechanisms behind the isotopic discrimination connected with carbon transformations in soil and to show a range of isotopic shifts of C compounds in the soil.
  Contents

Soil processes and isotope discrimination connected with them: Importance of soil in terrestrial ecosystem. Main processes of C transformations in soil. Discrimination connected with physicochemical phenomena with biochemical C transformations. Shift in isotopic signal of soil organic matter caused by change of vegetation cover.

Use of natural abundance of carbon stable isotopes as a tool studying C transformations in soil: Priming effect. Labelling studies. C flux (partitioning) in plant – soil system

     
Module 8 Isotopes in the ecology of animals and man 
  Lecturer Prof. Hans Schnyder, Technische Universität München
  Objectives Since “You are what you eat, isotopically” (DeNiro & Epstein 1978), isotope analysis can reveal feeding/eating habits and migration patterns of individuals and populations, as well as trophic interactions (feeding relationships) in ecosystems/food webs. These factors are among the most important controls of ecosystem structure and functioning. Moreover, food stuffs carry isotope signatures that are characteristic of production methods and geographic origin, making food stuff isotope analysis an important tool in forensics, and in food traceability and authenticity control. The goal of this module is to provide the basic knowledge of (1) how the (multi-elemental) isotopic composition of animals and man is related to diet, (2) the main factors causing variation of diet isotopic composition, and (3) the spectrum of isotope applications in animal and human behavioural and nutritional ecology.
  Contents

Variation of feed/food isotope composition (13C, 15N, 18O): Biological, ecological, edaphic and climatic controls. Traceability of food stuffs by isotope analysis

Isotopic composition of consumer and consumer tissues: Variation in base-line isotopic composition of food chains. Diet-consumer isotopic shifts: constants or variables? Multi-element partitioning of food sources.

Case studies:,Dietary habits of man. The nutritional ecology of East African mammals. Migration patterns and diet changes of elephants as revealed by hair stable isotope analysis.The role of spiders in termitaria – friend or foe?

     
Module 9 The oxygen isotope composition of plant tissues
  Lecturer Dr. Thorsten Grams, Technische Universität München
  Objectives

Stable oxygen isotope analysis of plant biomass components is rapidly becoming an important tool in plant physiological, ecological, paleoclimatic and forensic studies (Barbour 2007 Plant Cell Environ). This module presents current theoretical models of the environmental control of organic oxygen isotope composition, and applications of the oxygen isotope analysis and modelling.

  Contents

Mechanistic / process-based models predicting the oxygen isotope composition of plant organic materials.

Influences of soil water isotope composition. Evaporative enrichment in transpiring leaves. Isotopic exchange between oxygen atoms in organic compounds and water in the tissues in which they are formed (e.g. cellulose in leaf and stem tissue).

     
Module 10 Nitrogen in the plant-soil system 
  Lecturer Prof. Hana Santruckova, University of South Bohemia
  Objectives Nitrogen cycle is the most complex biogeochemical cycle in the terrestrial ecosystem. Almost each process involved in N cycling can be connected with isotopic discrimination and can bring a shift in natural abundance of stable N isotopes. The goal of this module is to explain processes of N transformations in the terrestrial ecosystems and shift in stable isotope distribution during these processes. Additional goal is to explain pool dilution assay for measuring N transformation in the soil.
  Contents

N transformation and shift in natural abundance of  N stable isotopes: Terrestrial N cycle – global pools and fluxes. N discrimination in soil processes – N fixation, nitrification, effect of mycorrhiza, distribution of heavy N isotope in the world terrestrial ecosystems.

N isotopes as a tool for studying N transformation and fluxes: Pool dilution assay. Labelling studies. Use of double labelling approach.

     
Module 11 Compound- and position-specific isotope signals in bio-geochemical studies
  Lecturer Prof. Gerd Gleixner, Max-Planck-Institut für Biogeochemie
  Objectives The distribution of stable isotopes between and within individual compounds stores information of the chemical history of individual compounds. The corresponding information can be used vice versa to reconstruct this history in order to identify the geographical origin of these compounds, the growth conditions of plants or the adulteration of flavors and fragrances. This lecture will provide the necessary basis to perform compound-specific isotope measurements and will give some applications in the field of biogeochemistry
  Contents

Technical background: GC/MS-IRMS systems, liquid extracts, pyrolysis, chromatographic separation, identification of compounds in MS, formation of measuring gas for IRMS measurements of H,C,N and O, comparison of online and offline measurements, LC-IRMS systems, operation of IRMS, ion source, magnetic sector, detectors.

Use of natural 13C labeled C4 vegetation to understand carbon cycling in ecosystems: Compound-specific turnover of soil organic matter, labeling of food sources of microbial populations, mechanisms of carbon cycling in grasslands and the influence of biodiversity.

Use of natural abundance 13C values of plant metabolites to understand the effects of plant diversity on plant performance in grasslands: LC-IRMS to measure primary plant metabolites, effect of stress on plant isotopes, isotopes and plant performance.

Research Projects

Research Projects in isotope applications to agricultural, ecological and environmental issues
Project leaders All teachers depending on the number of groups
Duration 25 working hours per project
Organisation There will be up to 6 project groups. Each group is led by at least one teacher, and includes a maximum of 3 students.
Objectives Each project group works on an original research question. Each group will perform all phases of a real isotope research project: reading and discussing the relevant literature; developing hypotheses and experimental/sampling schemes; collect and prepare samples for isotope analysis; analyse and evaluate the isotope data; interpret the isotope data in the context of the research hypothesis; and present the project results in a short paper and in a Symposium at the EGF General Meeting

The aim of the project is (1) to apply the basic methodological and theoretical knowledge to a real research question, (2) to perform all steps of an isotope project, and (3) to learn – by own experience – the potential of isotope uses/analysis.

Research projects will also have practical teaching contents, including ‘how to write a research paper’, ‘how to prepare and give an oral communication’, literature searching tools and strategies, and journal/paper clubs.