Towards a better understanding of the past: Investigating the sea spray effect in modern coastal environments

Stable isotope analyses of archaeological finds from coastal environments have been shown to be influenced by sea spray. Sea spray consists of aerosols derived from seawater that may contain various ions, potentially resulting in a marine-like isotope signature in terrestrial organisms. This so-called sea spray effect can hamper or even falsify the reconstruction of the diet or provenance, for example when investigating archaeological human skeletal remains. The magnitude of the sea spray effect and the underlying mechanisms are still unknown. In order to quantify the present-day local sea spray effect on several isotope systems (δ¹³C, δ¹⁸O, δ³⁴S, ⁸⁷Sr/⁸⁶Sr) at different sites close to the North and Baltic Sea, modern environmental samples are investigated. This will help us to understand the effect of sea spray on biochemical pathways in plants and the isotope signature of organisms feeding on them. Preliminary results show seasonal and regional variations in the local sea spray effect in plants. This suggests that a varying sea spray effect should also be expected in prehistoric samples from different archaeological sites. Investigating modern environmental samples of known origin will provide a better understanding of the local sea spray effect and enable the correction of the isotope fingerprints of (local) archaeological remains (e.g., animals, humans) against the regional sea spray effect. This will result in a more correct diet or provenance reconstruction and, thus, a better understanding of the past.