This quality has been used successfully in forensic science for the geochemical fingerprinting of narcotics, to study the ethnic background of an individual living in a society, to track the migration pattern of communities, to pinpoint location of death and to trace food adulteration, especially in the wine industry. The cells of humans, plants, and other animals reflect the isotopic signature of the food and water from their habitats, including the strontium signature of 87Sr/ 86Sr. The concept of “we are what we eat” is very true when it comes to the isotopic signature of living organisms. This method gives a maximum time resolution of 1 million years.Ĩ7 Sr/ 86 Sr ranges of geological substrates (open boxes) and wines (filled boxes) from the vineyards on the same substrate in different regions of Italy. This method works best for time periods with long-term unidirectional shifts in the 87Sr/ 86Sr ratio, such as the Tertiary, but technically can work over the past 600 million years. 2012).īy measuring the 87Sr/ 86Sr ratio in the sample and placing it on the standard seawater Sr-curve the age of the sample (marine minerals) can be determined. This seawater Sr curve has been developed over the past 850 million years using foraminiferal calcite, belemnite guards, ammonite aragonite, atoll carbonates, and marine cement (McArthur et al. This 87Sr/ 86Sr ratio of the ocean varies through time, creating a predictable seawater curve that can be used for dating calibration. Precipitation of marine biogenic carbonates and phosphates involves uptake of strontium from seawater with the 87Sr/ 86Sr ratio identical to that of the oceanic value at the time of incorporation. Red area denotes the 95-percent confidence interval. Strontium isotopic ratio ( 87 Sr/ 86 Sr) of seawater during geological time based on analyses of bulk sediment, unaltered brachiopods, belemnites, conodonts and foraminifera samples from various locations around the world. Read more about Sr-Nd Isotopes for Weathering Studies. Using the Sr isotopic ratio along with the Sr concentration in the water is a powerful method to trace groundwater mixing and contamination, as well as saltwater intrusion.įor example, strontium concentration and isotopic values can be used to trace the source and contamination level within groundwater profiles, as demonstrated by Nigro et al.
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Since the 87 Sr/ 86 Sr ratio is not impacted by weathering, it holds the signature of the surrounding rock formations and therefore the type of rocks weathered can also be analysed.įurthermore, the 87Sr/ 86Sr ratio of groundwater reflects the isotopic signature of the source water plus the rock formations along its flow path. Physical processes such as weathering do not cause fractionation in strontium isotopes. Saltwater intrusion in the Biscayne aquifer as indicated by strontium isotopic ratio ( 87 Sr/ 86 Sr) of water samples collected in Miami-Dade County during 2009. Tracing the diet of herbivores and omnivores through isotopic analysis to learn more. The use of isotopic analysis on bones: dating, environmental analysis & migration Furthermore, 87Sr/ 86Sr of hair and nails, which are constantly being replenished, can provide evidence of the location later in life prior to death. For example, the analysis of 87Sr/ 86Sr in human teeth can provide information on the location of birth as we are born with both permanent and temporary teeth. Measuring the 87Sr/ 86Sr ratio in human and animal bone and hair is a powerful tool for tracking mobility and migration. Ca).Īs humans and animals move from one habitat to another, they may be exposed to different sources of water and food (plant and animal). Thus, humans, plants, and other animals inherit the Sr isotopic signature of their habitat as Sr is incorporated in their cells along with other elements (i.e. The geology and in turn soils have a specific 87Sr/ 86Sr signature tied to their origin. Adapted from Lugli et al., 2019.Įach region in the world presents a specific 87 Sr/ 86 Sr ratio based on the surrounding geology and water sources. Strontium isotopic ratio (87Sr/86Sr) of human deciduous teeth showing human mobility in southern Italy during the Gravettian and Epigravettian periods (32157-19097 yr cal BP), across the Last Glacial Maximum.
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