Linking structural and compositional changes in archaeological human bone collagen: an FTIR-ATR approach

Collagen is the main structural and most abundant protein in the human body, and it is routinely extracted and analysed in scientific archaeology. Its degree of preservation is, therefore, crucial and several approaches are used to determine it. Spectroscopic techniques provide a cost-effective, non-destructive method to investigate the molecular structure, especially when combined with multivariate statistics (chemometric approach). In this study, we used FTIR-ATR spectroscopy to characterise collagen extracted from skeletons recovered from necropoleis in NW Spain spanning from the Bronze Age to eighteenth century AD. Principal components analysis was performed on a selection of bands and structural equation models (SEM) were developed to relate the collagen quality indicators to collagen structural change. Four principal components represented: (i) Cp1, transformations of the backbone protein with a residual increase in proteoglycans; (ii) Cp2, protein transformations not accompanied by changes in proteoglycans abundance; (iii) Cp3, variations in aliphatic side chains and (iv) Cp4, absorption of the OH of carbohydrates and amide. Highly explanatory SEM models were obtained for the traditional collagen quality indicators (collagen yield, C, N, C:N), but no relationship was found between quality and δ13C and δ15N ratios. The observed decrease in C and N content and increase in C:N ratios is controlled by the degradation of protein backbone components and the relative preservation of carbon-rich compounds, proteoglycans and, to a lesser extent, aliphatic moieties. Our results suggest that FTIR-ATR is an ideal technique for collagen characterization/pre-screening for palaeodiet, mobility and radiocarbon researchThis research was partially funded by the projects “Galician Paleodiet” (ED481D 2017/014), Consiliencia network (ED 431D2017/08), GPC (ED341B 2018/20) and “Antropoloxía dos restos óseos humanos de Galicia” (Dirección Xeral de Patrimonio Histórico), Xunta de Galicia. OLC is funded by Plan Galego I2C mod.B (ED481D 2017/014) and by Ministerio de Ciencia e Innovación (JIN project PID2019-111683RJ-100)S

Differentiation between pine woods according to species and growing location using FTIR-ATR

Attenuated total reflectance-Fourier transform infrared (FTIR-ATR) spectroscopy was applied to 120 samples of heartwood rings from eight individual pine trees from different locations in Spain. Pinus sylvestris cores were collected at the Artikutza natural park (Ps-ART). Pinus nigra cores were collected in Sierra de Cazorla (Pn-LIN) and in La Sagra Mountain (Pn-LSA). Three discriminant analysis tests were performed using all bands (DFT), lignin bands only (DFL) and polysaccharides bands only (DFP), to explore the ability of FTIR-ATR to separate between species and growing location. The DFL model enabled a good separation between pine species, whereas the DFP model enabled differentiation for both species and growing location. The DFT model enabled virtually perfect separation, based on two functions involving twelve FTIR bands. Discrimination between species was related to bands at 860 and 1655 cm−1, which were more intense in P. sylvestris samples, and bands at 1425 and 1635 cm−1, more intense in P. nigra samples. These vibrations were related to differences in lignin structure and polysaccharide linear chains. Discrimination between growing locations was mainly related to polysaccharide absorptions: at 900, 1085 and 1335 cm−1 more representative of Pn-LIN samples, and at 1105 and 1315 cm−1 mostly associated to Pn-LSA samples. These absorptions are related to β-glycosidic linkages (900 cm−1), cellulose and hemicellulose (C–O bonds, 1085 and 1105 cm−1) and content in amorphous/crystalline cellulose (1315 and 1335 cm−1). These results show that FTIR-ATR in combination with multivariate statistics can be a useful tool for species identification and provenancing for pine wood samples of unknown originS

Potential of pyrolysis-GC–MS molecular fingerprint as a proxy of Modern Age Iberian shipwreck wood preservation

Even though pyrolysis in combination with gas chromatography and mass spectrometry (Py-GC–MS) is widely used for molecular characterization of wood, its abilities to determine the taxonomy (species), provenance and the nature and intensity of degradation of archaeological woods are hardly explored. We performed principal component analysis (PCA) on Py-GC–MS data of sound woods and shipwreck woods of Pinus sp. and Quercus sp., to identify the impact of diagenesis on pyrolysis fingerprints. It was found that the proportion of most polysaccharide products decreased significantly upon diagenesis with the exception of 3-hydroxy-2-methyl-2-cyclopenten-1-one, which remains relatively well preserved. Furthermore, the guaiacyl lignin products were generally well preserved with the exception of 4-propylguaiacol, the relative contribution of which decreased considerably. New indices are proposed to establish the preservation state of shipwreck wood (shipwreck wood preservation index; SWPI) on the basis of polysaccharides (SWPIPS) and guaiacyl lignin (SWPILG) and syringyl lignin (SWPILS) fingerprints. Stepwise multiple linear regressions analyses applied on FTIR data of the same samples are indicative of the consistency of both techniques and the potential to identify changes in wood chemistry as a result of degradation. Other factors that influence wood composition, such as the differences between soft- and hardwood lignin and sap- and heartwood were also recognizedThis study was developed within the framework of the ForSeaDiscovery project funded by the European Research Council through the Seventh Framework Programme under grant agreement number 607545. We thank the editor and the anonymous reviewer for their time and insightful commentsS

Structural equation modelling of mercury intra-skeletal variability on archaeological human remains

Archaeological burial environments are useful archives to investigate the long-term trends and the behaviour of mercury. In order to understand the relationship between mercury, skeletons and soil, we applied Partial Least Squares - Structural Equation Modelling (PLS-SEM) to a detailed, multisampling (n = 73 bone samples +37 soil samples) design of two archaeological graves dating to the 6th to 7th centuries CE (A Lanzada site, NW Spain). Mercury content was assessed using a DMA-80, and data about bone structure and the grave soil/sediments were obtained using FTIR-ATR spectroscopy. The theoretical model is supported by proxies of bone structure, grave soil/sediments, and location of the bone within the skeleton. The general model explained 61 % of mercury variance. Additionally, Partial Least Square – Prediction Oriented Segmentation (PLS-POS) was also used to check for segmentation in the dataset. POS revealed two group of samples depending on the bone phase (hydroxyapatite or collagen) controlling the Hg content, and the corresponding models explained 86 % and 76 % of Hg variance, respectively. The results suggest that mercury behaviour in the graves is complex, and that mercury concentrations were influenced by i) the ante-mortem status of the bone matrix, related to the weight of each bone phase; ii) post-mortem evolution of bone crystallinity, where bone loses mercury with increasing alteration; and iii) the proximity of the skeletal pieces to mercury target organs, as decomposition and collapse of the thoracic and abdominal soft tissues causes a secondary mercury enrichment in bones from the body trunk during early post-mortem. Skeletons provide a source of mercury to the soil whereas soil/sediments contribute little to skeletal mercury contentPresent research was funded by Estudo de esqueletos humanos e de secuencias edafosedimentarias do xacemento de A Lanzada (2017-CP035) funded by Deputación Provincial de Pontevedra. The study was also supported by the projects “Pollutio” Plan Nacional (PID2019-111683RJ-I00) Spanish Ministerio de Ciencia e Innovacion, “Epidemias del hambre” Beca Leonardo a Investigadores y Creadores Culturales 2020 (2020-PO048) de la Fundación BBVA and “Grupos de Referencia Competitiva” (ED431C 2021/32) by Xunta de Galicia. NAF was funded by Convenio de Colaboración entre a Axencia Galega de Innovación, a Consellería de Cultura, Educación e Universidade, a USC e CSIC para fomentar a actividade Investigadora do persoal investigador finalista nas convocatorias de axudas do ERC no Marco do H2020. OLC is funded by a Ramón y Cajal senior fellowship (RYC2020-030531-I)S

Estacionalidad pluviométrica en Galicia: comportamiento, representatividad espacial y mecanismos asociados

Seasonality of rainfall in Galicia (NW Spain) is studied by means of a simple index propossed by Walsh & Lawler (1983). Average values of the index for the 180 meteorological stations studied, indicate that rainfall has distribution patterns ranging from moderate to strong seasonality. Inner areas of the Atlantic Galician Rias, some sectors with cape effect and the valleys of eastern and southeastern rivers are the ones with the gratest degree of seasonality. Nevertheless, a detailed analysis of rainfall series for each meteorological station, reveals that almost all the region has experienced years with rainfall going from weak seasonality to moderate concentration, being strong and extreme concentration unfrequent. Using the frequence of each degree of, seasonality a cluster analysis was performed and corroborated by a discriminant analysis, defining five principal groups. These groups are mapped. Finally, relations betwen seasonality variations and mean anual, winter, spring, summer and fall precipitacions are described. References are also rnade to climatic mechanism implied.En este trabajo se aborda el estudio de la estacionalidad pluviométrica en Galicia por medio de un índice sencillo, IE, propuesto por Wakh y Lawler (1983). En función de los valores medios que toma el índice puede decirse que la lluvia en Galicia presenta patrones de distribución con estacionalidad moderada a fuerte. Siendo las áreas interiores de las rías atlánticas, ciertos sectores con efecto quilla y los valles de los ríos orientales y surorientales, aquellos donde se manifiesta el mayor grado de estacionalidad. Sin embargo, el análisis de las series de precipitación para cada estación, revela que en la mayor parte del territorio ha habido años con niveles que van desde la estacionalidad débil a la concentración moderada. En base a la frecuencia de años en cada clase del IE, se han agrupado las estaciones mediante un análisis de asociación, comprobando la validez de los grupos definidos por medio de una nálisis discriminante. Eso nos ha permitido la cartografía de los distintos sectores geográficos de estacionalidad pluviométrica. Finalmente, se describen las relaciones entre las variaciones de la estacionalidad y los valores medios de precipitación anual, de invierno, verano, primavera y otoño. Haciendo referencia a los mecanismos climáticos que pueden estar implicados

Settlement, landscape and land-use change at a Pictish Elite Centre : Assessing the palaeoecological record for economic continuity and social change at Rhynie in N.E. Scotland

Open Access via the Jisc Sage Agreement Acknowledgements: Special acknowledgements go to Audrey Innes for her laboratory support, to Edouard Masson-Maclean who helped with the extraction of the core and who got slightly wetter than intended, and to the Leverhulme Trust who have funded this project: Grant number RG13876-10.Peer reviewedPublisher PD

Approaching mercury distribution in burial environment using PLS‑R modelling

Present research was funded by Estudo de esqueletos humanos e de secuencias edafosedimentarias do xacemento de A Lanzada (2017-CP035) funded by Deputación Provincial de Pontevedra. It was supported by the project Fomentar a actividade investigadora do persoal investigador finalista nas convocatorias de axudas da ERC do H2020 by GAIN (2021-CP052). We thank Deputación de Pontevedra, Museum of Pontevedra and the Dirección Xeral de Patrimonio da Xunta de Galicia for providing access to the archaeological soil samples. Special thanks go to the director or archaeological campaign Rafael Rodríguez Martinez for his support in all studies related to A Lanzada. Thanks to the Ecoloxicoloxía e Ecofisioloxía Vexetal research group and Jesús Aboal as well as to RIAIDT for providing access to equipment facilities. This project is funded by Grupos de Referencia Competitiva (ED431C 2021/32) by Xunta de Galicia. Authors would like to thank the use of RIAIDT-USC analytical facilities. OLC is funded by JIN project (PID2019-111683RJ-I00) Spanish Ministerio de Ciencia e Innovacion and Beca Leonardo a Investigadores y Creadores Culturales 2020 (2020-PO048) de la Fundación BBVA. NAF and ZGL are funded by the project Fomentar a actividade investigadora do persoal investigador finalista nas convocatorias de axudas da ERC do H2020 by GAIN (2021-CP052).Mercury environmental cycle and toxicology have been widely researched. Given the long history of mercury pollution, researching mercury trends in the past can help to understand its behaviour in the present. Archaeological skeletons have been found to be useful sources of information regarding mercury loads in the past. In our study we applied a soil multi-sampling approach in two burials dated to the 5th to 6th centuries AD. PLRS modelling was used to elucidate the factors controlling mercury distribution. The model explains 72% of mercury variance and suggests that mercury accumulation in the burial soils is the result of complex interactions. The decomposition of the bodies not only was the primary source of mercury to the soil but also responsible for the pedogenetic transformation of the sediments and the formation of soil components with the ability to retain mercury. The amount of soft tissues and bone mass also resulted in differences between burials, indicating that the skeletons were a primary/secondary source of mercury to the soil (i.e. temporary sink). Within burial variability seems to depend on the proximity of the soil to the thoracic area, where the main mercury target organs were located. We also conclude that, in coarse textured soils, as the ones studied in this investigation, the finer fraction (i.e. silt + clay) should be analysed, as it is the most reactive and the one with the higher potential to provide information on metal cycling and incipient soil processes. Finally, our study stresses the need to characterise the burial soil environment in order to fully understand the role of the interactions between soil and skeleton in mercury cycling in burial contexts.Deputación Provincial de PontevedraERC do H2020Estudo de esqueletos humanos e de secuencias edafosedimentarias do xacemento de A Lanzada 2017-CP035JIN PID2019-111683RJ-I00Ministerio de Ciencia e Innovacion 2020-PO048Fundación BBVAAxencia Galega de Innovación 2021-CP052, ED431C 2021/32Xunta de Galici

Reconstructing the impact of human activities in a NW Iberian Roman mining landscape for the last 2500 years

This article was made available through the Brunel Open Access Publishing Fund.Little is known about the impact of human activities during Roman times on NW Iberian mining landscapes beyond the geomorphological transformations brought about by the use of hydraulic power for gold extraction. We present the high-resolution pollen record of La Molina mire, located in an area intensely used for gold mining (Asturias, NW Spain), combined with other proxy data from the same peat core to identify different human activities, evaluate the strategies followed for the management of the resources and describe the landscape response to human disturbances. We reconstructed the timing and synchronicity of landscape changes of varying intensity and form occurred before, during and after Roman times. An open landscape was prevalent during the local Late Iron Age, a period of relatively environmental stability. During the Early Roman Empire more significant vegetation shifts took place, reflected by changes in both forest (Corylus and Quercus) and heathland cover, as mining/metallurgy peaked and grazing and cultivation increased. In the Late Roman Empire, the influence of mining/metallurgy on landscape change started to disappear. This decoupling was further consolidated in the Germanic period (i.e., Visigothic and Sueve domination of the region), with a sharp decrease in mining/metallurgy but continued grazing. Although human impact was intense in some periods, mostly during the Early Roman Empire, forest regeneration occurred afterwards: clearances were local and short-lived. However, the Roman mining landscape turned into an agrarian one at the onset of the Middle Ages, characterized by a profound deforestation at a regional level due to a myriad of human activities that resulted in an irreversible openness of the landscape. © 2014 The Authors

Post-disturbance vegetation dynamics during the Late Pleistocene and the Holocene: An example from NW Iberia

This is the post-print version of the final paper published in Global and Planetary Change. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2012 Elsevier B.V.There is a wealth of studies dealing with the reconstruction of past environmental changes and their effects on vegetation composition in NW Iberia, but none of them have focused specifically on the post-disturbance dynamics (i.e. the type of response) of the vegetation at different space and time scales. To fill this gap, we analysed the record of pollen and non-pollen palynomorphs (NPP) of a 235-cm thick colluvial sequence spanning the last ~ 13,900 years. The aims were to detect the changes in vegetation, identify the responsible drivers and determine the type of responses to disturbance. To extract this information we applied multivariate statistical techniques (constrained cluster analysis and principal components analysis on transposed matrices, PCAtr) to the local (hydro-hygrophytes and NPP) and regional (land pollen) datasets separately. In both cases the cluster analysis resulted in eight local and regional assemblage zones, while five (local types) and four (regional types) principal components were obtained by PCAtr to explain 94.1% and 96.6% of the total variance, respectively. The main drivers identified were climate change, grazing pressure, fire events and cultivation. The vegetation showed gradual, threshold and elastic responses to these drivers, at different space (local vs. regional) and time scales, revealing a complex ecological history. Regional responses to perturbations were sometimes delayed with respect to the local response. The results also showed an ecosystem resilience, such as the persistence of open Betula-dominated vegetation community for ~ 1700 years after the onset of the Holocene, and elastic responses, such as the oak woodland to the 8200 cal yr BP dry/cold event. Our results support the notion that palaeoecological research is a valuable tool to investigate ecosystem history, their responses to perturbations and their ability to buffer them. This knowledge is critical for modelling the impact of future environmental change and to help to manage the landscape more sustainably.The Spanish Governmen