Quantification, modeling, and mapping of the sea spray effect in recent and archaeological environmental samples, animals, and humans from the Baltic and North Sea coast

• Applicant: Dr. Andrea Göhring
• Subject Area: Prehistory and World Archaeology
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 525800434

>The so-called sea spray effect is caused by ocean water spray in coastal regions, whereby marine aerosols are transported to terrestrial environments. This causes a falsification of the isotope signal in coastal plants and animals, what in turn leads to erroneous diet and provenance reconstructions or radiocarbon dating. The aim of this project is the quantification, modeling, and mapping of the sea spray effect in recent and archaeological environmental samples (plants, soil), animals, and humans of the Baltic and North Sea coast by analyses of stable isotopic systems (delta13C, delta15N, delta18O, delta26Mg, delta34S, 87Sr/86Sr) of several compounds (e.g. collagen, apatite, sulfate, α-cellulose), radiocarbon analyses, and (trace) element/ion analytics by means of KDD-based methods (= Knowledge Discovery in Databases). This serves to predict the sea spray impact and a correction of the isotopic fingerprints of archaeological samples. Knowledge of the magnitude of the local sea spray effect on the isotope fingerprint of archaeological samples is of fundamental importance for the interpretation of these data. In order to correctly interpret the isotopic signature (including 14C) of archaeological samples, in the course of phase I of the project the sea spray mechanism and the sea spray effect in the isotope signature of recent plants and mammals have to be understood. In phase II the obtained knowledge will be applied on archaeological finds. The investigation of the impact of an artificially generated sea spray effect in the greenhouse (TP 2) and the influence of the effect on recent sheep wool (TP 3) shall allow the quantification of the magnitude of the regionally expected sea spray effect in each isotopic system. Furthermore, element analyses allow the investigation of the sea spray mechanism in plants (TP 2) and mammals (sheep model; TP 3) with known in- and output. Based on these quantifications, expectation values for the modern (local) sea spray effect are determined and cluster models are trained (TP 7), which are validated using recent environmental samples (TP 1). Changes in the magnitude of the sea spray effect, which might result from climatic changes, can be detected using archaeobotanical samples (TP 4). Finally, isotopic maps for the investigated regions are established based on the generated multi-dimensional isotopic fingerprints (TP 7), what allows the classification of archaeological individuals and thus the validation of the magnitude of the former sea spray effect or, e.g., the detection of non-local individuals (TP 5). In this context it is examined if delta26Mg analyses are a valid tool for diet and provenance reconstruction of archaeological humans as well as for answering paleo-ecological issues. This would be especially relevant regarding a potential replacement of collagen-based isotope systems in the case of poor collagen preservation (TP 6).

• DFG Programme: Independent Junior Research Groups