Alicia Van Ham Meert

Dendrochronology (tree-ring analysis) allows us to precisely date and identify the origin of timber from historic contexts. However, reference datasets to determine the origin can include timber of non-local origin. Therefore, we have applied Sr isotopic on timbers from three buildings in Jutland, Denmark, mostly dating from the late 16 th and early 17 th centuries CE to improve and refine the provenance identification. The dendrochronology suggested that some timbers analysed were imported from the Swedish side of Øresund/Kattegat while others were local, and others again might be from south Norway. By adding the Sr isotopic analysis, a far more detailed interpretation of the origin of these timbers can be presented for non-Danish timbers. In this paper we suggest that Danish ports in the provinces of Halland and Skåne played a major role in the timber trade between the Danish and Swedish parts of the Danish kingdom. For Danish timbers dendroprovenancing proved better than Sr isotopic analysis. Furthermore, a small number of Sr isotopic analyses were performed to contribute to the base-line along the Gö ta-river in Southern-Sweden.

Strontium isotope ratios (87 Sr/ 86 Sr) are commonly used in archeological and forensic studies to assess if humans and fauna are local to the place they were found or not. This approach is largely unexplored for wooden artifacts recovered in archeological contexts, as wood-in the rare instances it does survive-is often poorly preserved. One of the most common ways wood is preserved is through the anoxic conditions found in waterlogged contexts. A more unusual form of preservation is through submergence in natural pitch. These depositional media contribute their own strontium values to the in vivo 87 Sr/ 86 Sr wood values, which needs to be removed prior to analysis. Here we test several pre-treatment methods to remove potential strontium contamination from wood samples that were artificially immersed in seawater and pitch from Trinidad's Pitch Lake. Water rinses and acid-leaching tests were carried out with hydrochloric acid and acetic acid to remove exogenous strontium from experimentally waterlogged wood. These tests removed large amounts of strontium from the samples and did not enable the recovery of the endogenous 87 Sr/ 86 Sr signal. For samples artificially immersed in pitch, the pre-treatments tested were based on radiocarbon dating procedures and carried out with and without the aqueous-based acid-base-acid (ABA) step. The use of organic solvents alone (methanol and toluene) removed exogenous strontium originating from the pitch. However, the ABA step eliminates large amounts of in vivo strontium from the samples. These tests show that 87 Sr/ 86 Sr values of wood are altered by the presence of pitch and water. With adequate pre-treatment using exclusively organic solvents, it may be possible to remove this contamination for samples immersed in pitch. However, the aqueous-based ABA pre-treatment should be avoided. The removal of contamination from waterlogged samples was unsuccessful with the current pre-treatment protocols and more research is needed. More importantly, and unexpectedly, 87 Sr/ 86 Sr values may Frontiers in Ecology and Evolution | www.frontiersin.org 1 January 2021 | Volume 8 | Article 589154

Sr isotopes represent a potential means to trace the provenance of archaeological timber. Such tracing allows us to examine the transport, by past people, of wooden objects and of wood and timber as a raw material. However, issues exist with the mobility of Sr and addition of exogenous Sr during waterlogging. This paper presents a systematic assessment of cleaning methods to remove exogeneous Sr from waterlogged wood. Neither a large number of Milli-Q washes, a combination of MQ and Hydrofluoric acid (HF) or alpha-cellulose extraction were able to retrieve the original signature. It was also shown that ashing leads to higher uncertainties due to the smaller amount of Sr available for analysis, this method will only be really useful when large samples are available, is not recommended for small archaeological samples. Our studies also highlight that the distribution of Sr in waterlogged wood is highly heterogeneous.

This paper presents a new non-destructive sampling method for the lead isotope analysis of lead objects using acidified cotton swabs. The results are indistinguishable within error margin from conventional sampling methods. This method was applied to a series of Sasanian lead coins from the Royal Museums of Art and History as well as a private collection. Elemental analysis was performed using micro-X-ray fluorescence. Isotopic analysis was performed using multi collector-inductively coupled plasma-mass spectrometry. Lead isotope analysis showed that at least four distinct sources of lead were used over time by the Sasanians to produce coins. Elemental analysis revealed three compositional groups distinct from the isotope groups, showing that a change in composition did not necessarily follow a change in raw materials supply. The uniformity of isotope compositions within particular periods, and of chemical composition across different mints, may point to a central control of both raw material supply and composition of Sasanian lead coins.

This paper presents the chemical and isotopic analyses of glass from the first century CE excavated in Dibba (United Arab Emirates). The elemental composition was determined using inductively coupled plasma-optical emission spectrometry (ICP-OES) and micro-X-ray fluorescence (μXRF), as well as the isotopic composition using laser ablation-multi collector-ICP-mass spectrometry (LA-MC-ICP-MS) for Sr and solution MC-ICP-MS for Nd. This study revealed the unique elemental and isotopic composition of this material, matching the local geology and providing a strong argument for a previously unknown production site, possibly local, for this material. Two glass hues are observed in the assemblage (green and amber); both have the same chemical composition. The colour difference is due to differences in the oxidation state of the chromophores whether or not purposefully is unclear. The production of blown glass vessels shows a technology, not yet evidenced before, for this period in this region.

A batch of green- and amber-coloured glass chunks and unguentaria dating from the first century CE was found in 2007 at Dibba al Hisn, a site on the Arabian Sea coast of the United Arab Emirates (UAE). Its elemental and isotopic composition revealed the glass to be of a previously unknown plant ash glass type, different from known contemporary Roman, Mesopotamian, and Indian glass. The
Sr isotopic composition of the glass corresponds to locally available plants, pointing to the possible existence of a first-century CE local glass production centre.
To explore this possibility, sands from around the UAE were analysed to establish their suitability for glass making and correspondence with the Dibba finds. This paper presents the results of the elemental analysis of fourteen sands. The analysis, performed using inductively coupled plasma optical emission spectroscopy (ICP-OES), revealed all sands to be rich in lime and alumina. X-ray diffraction revealed the presence of calcite and other carbonate minerals, as well as antigorite and quartz. Comparison of the sand compositions to average first-century CE
non-Roman glass found at Dibba showed them to be unsuitable as raw material for producing the glass of Dibba. The evidence thus identifies this glass batch as imported, contrary to what was suggested before. This paper also reviews the occurrence of thick-walled unguentaria in the region.

The extraction and study of organic residues from ceramics has been a subject of interest for the last 50 years in archeology and archeological science. Lipids are among the best-preserved organic substances in archeological contexts and can provide information about the diets of ancient populations as well as past environments. Here, we present a method which demonstrates significantly improved extraction of lipids from archeological pots by replacing liquid organic solvents with supercritical fluids. Optimization of the procedure using response surface methodology (RSM) approach showed that, on our system, optimal conditions for supercritical extraction of lipids from synthetic fired clay ceramics could be achieved using carbon dioxide with 16 vol % of cosolvent EtOH−H 2 O (95:5 v/ v) in 90 min at a flow rate of 2.3 mL/min, for a pressure of 30 MPa and a temperature of 50 °C. For all reference and archeological samples included in this study, lipid yields obtained by supercritical fluid extraction under these optimal conditions were systematically higher than by conventional solvent extraction. This study also highlighted a variability of the ratio of unsaturated versus saturated fatty acids depending on the extraction method. This can have important implications in the identification of the residue(s). The increased extraction efficiency provided by supercritical fluids, as well as their minimally destructive nature, enable new and refined approaches to residue analysis and dating of archeological ceramics. A rchaeological investigations of lives and lifestyles of human populations in the past are based, almost exclusively, on studies of material remains such as stone tools, ceramic vessels, glass or metal artifacts, textiles, and other organic substances (i.e., bone, wood, charcoal, seeds). Archaeologists have always relied on scientific methods to enrich their interpretations of these remains, and over the last few decades, techniques to characterize organic substances at a molecular level have improved dramatically. This trend is seen clearly in the ever-expanding application of analytical techniques based on the use of chromatography and mass spectrometry (e.g., high-performance liquid chromatography (HPLC) and gas chromatography/ mass spectrometry (GC/MS)). 1 Although these techniques have many applications in archeological science, the most common relates to the question of ancient diet and the analysis of ancient food residues preserved within the fabric of ceramic containers. 2−4 To exploit this valuable source of information, scientists conventionally pulverize fragments of pottery and apply a combination of liquid organic solvents such as chloroform or dichloromethane and methanol. Other approaches using chemical reagents (e.g. acidified methanol) have also been explored. 5 The extracted residue is then characterized by GC/MS or GC-C-IRMS. 4 This is a time-consuming process which requires toxic solvents and is also destructive as the sherd needs to be crushed to increase the surface interface between ceramic and solvent. Over the last few decades, the field of analytical chemistry has seen substantial transformations such as with the development and application of new instrumentation using supercritical fluids (SFs) for extraction and chromatographic separation (SFE and SFC, respectively). In the field of archeological science, the use of supercritical fluids has not yet been fully

This paper presents the chemical and isotopic analyses of glass from the first century CE excavated in Dibba (United Arab Emirates). The elemental composition was determined using inductively coupled plasma-optical emission spectrometry (ICP-OES) and micro-X-ray fluorescence (μXRF), as well as the isotopic composition using laser ablation-multi collector-ICP-mass spectrometry (LA-MC-ICP-MS) for Sr and solution MC-ICP-MS for Nd. This study revealed the unique elemental and isotopic composition of this material, matching the local geology and providing a strong argument for a previously unknown production site, possibly local, for this material. Two glass hues are observed in the assemblage (green and amber); both have the same chemical composition. The colour difference is due to differences in the oxidation state of the chromophores whether or not purposefully is unclear. The production of blown glass vessels shows a technology, not yet evidenced before, for this period in this region.

Strontium isotope ratios (87 Sr/ 86 Sr) are commonly used in archeological and forensic studies to assess if humans and fauna are local to the place they were found or not. This approach is largely unexplored for wooden artifacts recovered in archeological contexts, as wood-in the rare instances it does survive-is often poorly preserved. One of the most common ways wood is preserved is through the anoxic conditions found in waterlogged contexts. A more unusual form of preservation is through submergence in natural pitch. These depositional media contribute their own strontium values to the in vivo 87 Sr/ 86 Sr wood values, which needs to be removed prior to analysis. Here we test several pre-treatment methods to remove potential strontium contamination from wood samples that were artificially immersed in seawater and pitch from Trinidad's Pitch Lake. Water rinses and acid-leaching tests were carried out with hydrochloric acid and acetic acid to remove exogenous strontium from experimentally waterlogged wood. These tests removed large amounts of strontium from the samples and did not enable the recovery of the endogenous 87 Sr/ 86 Sr signal. For samples artificially immersed in pitch, the pre-treatments tested were based on radiocarbon dating procedures and carried out with and without the aqueous-based acid-base-acid (ABA) step. The use of organic solvents alone (methanol and toluene) removed exogenous strontium originating from the pitch. However, the ABA step eliminates large amounts of in vivo strontium from the samples. These tests show that 87 Sr/ 86 Sr values of wood are altered by the presence of pitch and water. With adequate pre-treatment using exclusively organic solvents, it may be possible to remove this contamination for samples immersed in pitch. However, the aqueous-based ABA pre-treatment should be avoided. The removal of contamination from waterlogged samples was unsuccessful with the current pre-treatment protocols and more research is needed. More importantly, and unexpectedly, 87 Sr/ 86 Sr values may Frontiers in Ecology and Evolution | www.frontiersin.org 1 January 2021 | Volume 8 | Article 589154