Modular system for measuring carbon and nitrogen concentrations and isotopes

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In order to conduct pioneering research related to the effects of land use and climate change on different temporal and spatial scales, an IRMS system for measuring carbon (C) and nitrogen (N) in soils, sediments, organic samples and water is required. Thanks to their modular design, new systems in element analysis allow both the measurement of C and N concentrations and the measurement of the respective stable isotopes. (1) C and N concentrations in soils and sediments are indicators for the presence of organic matter. This can provide information on, e.g., soil degradation due to agriculture, eroded topsoil material, if organic material has been washed into lake sediments, or organic residues in a settlement area that can indicate anthropogenic activities. Knowledge of the C content is also the base for further analysis, e.g. biomarker analysis. (2) In geoarchaeology and archaeobotany, the measurement of stable N-isotopes in plant residues indicates the use of organic (green or manure) fertilizer, since locally N-isotope ratios are rather influenced by soil management than by climate. Occurring major research gaps could be closed by the proposed interdisciplinary projects. In paleoecology, the measurement of stable C and N isotopes is important to gain insight into the climate and vegetation history. Examples of applications are the analyses of the proportion of C3 and C4 plants in an ecosystem as a function of aridity, which is relevant for geoarchaeological and ecological studies in savannas and steppes, where isotopic changes in plants are also reflected in soils and grazing animals. The introduction of new crops (e.g. millet) can also be demonstrated in archaeological findings using C isotopy. (3) For the study of soil erosion dynamics, the quantification and qualification of the organic matter that is washed out of the soil and dissolved in the water is important. The input of organic matter into lakes through soil erosion from agricultural land can lead to changes in δ15N and δ13C values of lake sediments, which was also measurable for prehistoric periods. Here, too, are still gaps in our understanding of the underlying processes and the possibility of interpreting the isotope data in sediments. The use of these systems is not a standard application in geoarchaeology. The on-site measurement of the C and N isotope is therefore an important prerequisite for developing methods and working on new research questions, and it would be a unique opportunity to position ourselves internationally as a center for ecological-geoarchaeological research. A unique addition would be the module for measuring the isotopes in soil water.