Sr/ 86 Sr reference maps (isoscapes) are a key tool for investigating past human and animal migrations. However, there is little understanding of which biosphere samples are best proxies for local bioavailable Sr when dealing with movements of past populations. In this study, biological and geological samples (ground vegetation, tree leaves, rock leachates, water, soil extracts, as well as modern and archeological animal teeth and snail shells) were collected in the vicinity of two early medieval cemeteries ("Thuringians", 5-6th century AD) in central Germany, in order to characterize 87 Sr/ 86 Sr of the local biosphere. Animal tooth enamel is not appropriate in this specific context to provide a reliable 87 Sr/ 86 Sr baseline for investigating past human migration. Archeological faunal teeth data (pig, sheep/goat, and cattle) indicates a different feeding area compared to that of the human population and modern deer teeth 87 Sr/ 86 Sr such as freshwater bivalve shells and tree cores were examined in order to track potential historic anthropogenic contamination of the water and the vegetation. The data obtained from the archeological bivalve shells show that the modern rivers yield 87 Sr/ 86 Sr ratios which are similar to those of the past. However, the tree cores registered decreasing 87 Sr/ 86 Sr values over time towards present day likely mirroring anthropogenic activities such as forest liming, coal mining and/or soil acidification. The comparison of 87 Sr/ 86 Sr of the Thuringian skeletons excavated in the same area also shows that the vegetation samples are very likely anthropogenically influenced to some extent, affecting especially 87 Sr/ 86 Sr of the shallow rooted plants.

Future climate change will have significant effects on ecosystems worldwide and on polar regions in particular. Hence, palaeo-environmental studies focussing on the last warmer-than-today phase (i.e. the early Holocene) in higher latitudes are of particular importance to understand climate development and its potential impact in polar systems. Molluscan bivalve shells constitute suitable bio-archives for high-resolution palaeo-environmental reconstructions. Here, we present a first reconstruction of early Holocene seasonal water temperature cycle in an Arctic fjord based on stable oxygen isotope (δ 18 O shell ) profiles in shells of Arctica islandica (Bivalvia) from raised beach deposits in Dicksonfjorden, Svalbard, dated at 9954-9782 cal. yr BP. Reconstructed maximum and minimum bottom water temperatures for the assumed shell growth period between April and August of 15.2°C and 2.8°C imply a seasonality of about 12.4°C for the early Holocene. In comparison to modern temperatures, this indicates that average temperature declined by 6°C and seasonality narrowed by 50%. This first palaeo-environmental description of a fjord setting during the Holocene Climate Optimum at Spitsbergen exceeds most previous global estimates (+1-3°C) but confirms studies indicating an amplified effect (+4-6°C) at high northern latitudes.

Biological hard parts and skeletons of aquatic organisms often archive information of past environmental conditions. Deciphering such information forms an essential contribution to our understanding of past climate conditions and thus our ability to mitigate the climatic, ecological, and social impacts of a rapidly changing environment. Several established techniques enable the visualization and reliable use of the information stored in anatomical features of such biogenic archives, i.e., its growth patterns. Here, we test whether confocal Raman microscopy (CRM) is a suitable method to reliably identify growth patterns in the commonly used archive Arctica islandica and the extinct species Pygocardia rustica (both Bivalvia). A modern A. islandica specimen from Norway has been investigated to verify the general feasibility of CRM, resulting in highly correlated standardized growth indices (r > 0.96; p < 0.0001) between CRM-derived measurements and measurements derived from the established methods of fluorescence microscopy and Mutvei's solution staining. This demonstrates the general suitability of CRM as a method for growth pattern evaluation and cross-dating applications. Moreover, CRM may be of particular interest for paleoenvironmental reconstructions, as it yielded superior results in the analysis of fossil shell specimens (A. islandica and P. rustica) compared to both Mutvei staining and fluorescence microscopy. CRM is a reliable and valuable tool to visualize internal growth patterns in both modern and fossil calcium carbonate shells that notably also facilitates the assessment of possible diagenetic alteration prior to geochemical analysis without geochemically compromising the sample. We strongly recommend the CRM approach for the visualization of growth patterns in fossil biogenic archives, where conventional methods fail to produce useful results.

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Amiantis purpurata is a common warm-temperate water bivalve species distributed from southern Brazil to northern Patagonia, Argentina, which has a rich and well preserved fossil record in the San Matias Gulf (SMG) dating back to the late Quaternary. This study aims to establish A. purpurata shells as a new palaeoarchive of past marine conditions in South America. We compared the stable oxygen and carbon profiles (8 18 O,heu; 8 13 C S hcii) of eleven specimens of A. purpurata from different geological times (modem, Late Holocene and interglacial Late Pleistocene), and additionally present in situ oxygen isotope values of seawater within SMG (S ,8 O watcr ). Using both sets of information, we calculated and reconstructed palaeowater temperatures for the Late Holocene and compared them to modem water temperatures. Our findings indicate that A. purpurata records past environ mental parameters such as water temperatures on a seasonal scale and can therefore be considered a suitable candidate for future palaeoenvironmental reconstructions in Northern Patagonia. This study is the first step towards further stable isotope analyses on fossil A. purpurata shells, which will show whether and if so, to what extent, important global climate events such as the Neoglacial (Early Holocene), the Hypsithermal (Middle Holocene) and the Little Ice Age (Late Holocene) occurred in South America.