MATERIAL AND ENVIRONMENTAL ISOTOPE GEOCHEMISTRY (Stables Isotopes and Radiocarbon)
Material and Environmental Isotope Geochemistry Project has been developed in both Stable and Radiocarbon isotopes in order to conduct basic and applied research in the scientific field of Isotopic Geochemistry, focusing on material science, environmental evolution and cultural heritage. In more detail:
- The Stable Isotope Laboratory (SIL), of the Institute of Nanoscience and Nanotechnology, National Center for Scientific Research Demokritos, accredited according to EN ISO/IEC 17025:2005 (no 579). In SIL, the isotopic measurements include the stable isotopes of inorganic carbonate materials (δ13C, δ18Ο), organic materials (δ13C, δ15Ν), water (δ18Ο, δ2Η, δ11B), sulfates (δ34S), as well as elemental analysis of C, N and S in geological, biological, composite and natural materials.
- Radiocarbon Laboratory, which is under construction however available in early 2016, is fully equipped with Liquid Scintillation Counting (LSC) and Gas Proportional Counting (GPC) analytical techniques for radiocarbon analysis (14C) as well as the required lines for sample (archaeological and modern materials) preparation. The combined use of radiocarbon and stable isotope systems for highlighting ancient and modern environments is further enhanced by radiogenic isotopes of 87Sr/86Sr, 143Nd/144Nd, 206Pb/207
These analytical techniques support our research work which is centered in tracing analysis for the origin of raw materials (glass, mortar), paleoecological reconstruction (bones, teeth, speleothems, soil drilling) and the authenticity/fingerprint of food industry products (wine, milk, oil, honey). The research is centered in the following scientific areas:
- Provenance determination and weathering of ancient and modern materials
- Paleoenvironmental and paleoclimatic reconstruction
- Depositional conditions of carbonate materials
- Hydrogeochemical processes in open and close system
- Origin of geofluids-pollution, palaeohydrology
- Characterization and investigation of the technology of ancient –historic structural materials (marbles, glass and mortars)
- Damage diagnosis and scientific determination of weathering and decay mechanisms of ancient-historic materials and development of conservation materials.
- Radiocarbon analysis in archaeological and environmental material
- Authenticity and fingerprinting of food and products
History technology of the construction of vitreous materials
Investigation of glass raw material and heat manufacture technology.
The archaeological glasses originate Roman, Byzantine and Ottoman period.
Archaeologists argued that in Greek antiquity glass was not made but the vitreous material was imported from different areas of the East Mediterranean coast. Especially in the Greco-Roman age, glass artefacts in Greece are considered to have been manufactured using raw glass made with sand and natron, and produced in Egyptian and Near East glass-making factories. These factories probably produced only batches of raw glass and not necessarily vessels or other objects. The importation of raw glass complicates more the existing problem regarding the identification of the origin of the basic components of glass and the fusion processes. Thus, it is of utmost importance to distinguish the origin and composition of ‘Roman’ age glasses from glasses imported from other provenances. In this study chemical and isotopic methods, were employed for the identification of the fingerprint of Roman glasses manufactured in Greece, for distinguishing the different raw materials and fluxes used and for defining the production technology.
Glass constitutes a very complex material and through the “glass study” arises until now some unanswered internationally questions, regarding the origin of row material of early glass and need to be addressed in Cultural Heritage studies. Given the importance of glass made objects as an indicator of every-day ancient cultural, social and trading practices it is of great significance to recognize isotopic and compositional trends of different raw materials, production technology, and/or provenance of early glasses.
The investigation has been focused on biological materials (bone, teeth), water systems, sediment deposition and other environments that can provide information for dating, origin as well as evolution and recovery of palaeoenvironment and palaeoecology. The analysis of 13C, 18O and 14C isotopes in materials such as bones, speleothems, carbonate sediments, etc., which varies, depending on climatic changes, can supply also information for palaeoenvironment reconstruction.
a) Bones and Teeth
During the last four decades, the analysis of radiocarbon and stable isotopes in terrestrial teeth and bones has provided valuable information about the palaeoclimatic and palaeoenvironmental conditions on the Quaternary period as well as palaeodiet habits for a variety of species. Oxygen and carbon comprise principal structural materials of skeleton and teeth. These elements mainly originate from the water and food that the animal consumes, and reflect the respective isotopic fingerprints of their original sources. Bones and teeth samples of Ursus ingressus from Loutra Arideas Cave (Greece) were used to determine the diet of this extinct species and to reconstruct the palaeoclimatic conditions. Several possible effects that may affect the isotopic composition of apatite were investigated, including age, sex, tooth type and diagenesis. Moreover the prehistoric (middle Neolithic, ~5500 BC, until the first stages of Early Chalcolithic, ~3500 BC) lakeside settlement of Dispilio (Northern Greece, Kastoria) have been studied based on animal bone and tooth findings. Sample treatment protocols were constructed for a sufficient secondary calcite removal as well as for bioapatite and collagen extraction. The organic phase of bones, as well as of soils, was subjected under radiocarbon dating (14C) in order to set the observed “shifts” in Neolithic frame
b) Land snail research for palaeoenvironmental changes in Greece.
The combination of 14C ages, along with biostratigraphic and archaeological remains has been used to establish the cave’s chronology and the phases of human occupation from the late Pleistocene (Upper Palaeolithic) to the early Holocene (Mesolithic). This research deals with stable isotopic data (oxygen and carbon )and radiocarbon (14C) from late Pleistocene-Holocene (~13 to ~10,5 cal ka BP) shells of the gastropod helicid land snail Helix figulina, from Franchthi Cave (Greece). It aims to explore palaeoclimatic and palaeoenvironmental implications of isotope palaeoecology of archaeological shells at the time of human occupation of the cave. Radiocarbon analysis (14C), carried out mainly on charcoal. Modern shells of Helix figulina and other gastropod helicid species from around the cave (Eobania vermiculata and Cornu aspersum), were also analysed to compare with isotopic signatures of archaeological shells. Carbon isotope composition of modern shells (δ13Cs) depicts the consumption of C3 vegetation; no evidence for species-specific feeding behaviour and the contribution of other sources of carbon was observed. Shell oxygen isotopic values (δ18Os) are consistent with other Mediterranean snail shells from coastal areas. Combining empirical linear regression and an evaporative model (FBM), the δ18Os suggest that modern snails in the study area are active during periods of higher relative humidity (RH) and lower δ18Op, probably at night. Late glacial and early Holocene δ18Os show lower values compared to modern ones. Early Holocene δ18Os values likely track enhanced moisture and isotopic changes in the precipitation source (Mediterranean). By contrast lower late glacial δ18O could reflect lower temperatures and δ18Op, compared to present day. The results provide an innovative contribution to the discussion of the palaeoclimatic implications of shell δ18O. Interplaying variables, such as atmospheric and hydrological regime, may contribute to a different extent to δ18Os. Shell carbon isotopes indicate the presence of C3 vegetation as main source of carbon to late glacial and early Holocene snails. Estimated late glacial and early Holocene plant δ13C values approach that of some modern Mediterranean woody shrub species adapted to drought
C) Speleothems and soils
Secondary cave carbonates such as stalagmites have been used as great recorders of continental palaeo–environments. Assuming that speleothem calcite is deposited at or close to oxygen isotope equilibrium with cave dripwater the δ18O of the precipitated calcite reflects both the δ18O of the dripwater and the temperature at which calcite deposition occurs. Therefore speleothems from Kastoria caves were sampled and subjected under stable and radiogenic isotope analysis in order to confirm or not the conclusions for palaeoenvironmental conditions that were resulted from bone material regarding prehistoric settlement of Dispilio. At the same approach a soil drilling was performed in Dispilio prehistoric settlement were the palaeo-cost of Kastoria Lake was studied. Finally radiocarbon (14C) analysis of cores from the vicinity of Nea Nikomidiea has made it possible to unravel c. 10.000 years of sediment accumulation and associated palaeoenvironmental changes.
Mortar samples from historic masonries dated from Hellenistic to Ottoman period were examined using stable isotope analysis. The study focuses on the analysis of stable isotopes of oxygen and carbon (13C and 18O), to determine the origin of calcite and to diagnose the state of preservation of historic mortars.
Samples of mortars were collected from historic constructions and wall-paintings dating from Hellenistic to Ottoman period. The main aims of this research programme are to investigate the technological transition of historic mortars from Hellenistic to Ottoman period and to examine the potential sources of material degradation. To achieve the aims of the project the samples will be analysed using traditional techniques of instrumental analysis such as X-ray diffraction and scanning electron microscopy with X-ray microanalysis. Parallel to this, stable isotope analysis (13C and 18O) will be performed in order to obtain further knowledge on the technology, provenance and degradation of historic mortars. The signs of material decay are expected to be reported in isotopic values and therefore determine the sources of mortar’s degradation. Moreover it has been developed a calibration model based on stable isotope of carbon (13C) and radiocarbon (14C) analysis for dating culture heritage material of mortars. The experience of response of ancient and historic mortars under radiocarbon and stable isotopes interpretation, resulted in development of construction materials for restoration projects in order to assess the degradation of historical buildings due to environmental impact (air pollution, acid rain, salinity, microbiological process).
Modern Environment – Pollution (3H, 14C , 13C, 18O)
The use of stable isotopes (13C, 18O34S, 18O (SO4), 18O (CO2), 2H, 18O, 11B, 87Sr/86Sr) and radiocarbon (14C) allows the study of aquatic environment (the source of dissolved carbonate, source of water, source of data, mixing), the deep geothermal fluids (water source, source of elements, water-rock interaction, geothermometria) of geological materials (origin of carbonate rocks, travertine, etc.), of the atmosphere (the source of infection through the study of CO2 and CO and control of human intervention in the surrounding cities or industrial zones).
Over the past years the importance of the determination of isotope contents, stable ((18O, 2H, 13C) and radiocarbon (14C), for the verification of the origin and authenticity of food and food additives has grown significantly. Applying isotope methods to food analysis can provide information about the geographic origin of food, authenticity of food and food additives (undeclared additives and/or verification of purity), as well as compliance with legal regulations and treaty agreements.The isotopic composition of plants reflects the environmental regime in which they grow giving the possibility of isotopically labelled natural products. For example the differect photosynthetic pathway (C3, C4 or CAM) is one of the rules that control the δ13C values in natural sugars. Furthermore radiocarbon (14C) values in alcohol discriminate fraud events. The information resulting from the development of isotopic techniques in natural products concern:
- The determination of the geographical origin of products
- The labelling of products (traceability-authentication)
- The development of new improved products following the legal provisions
- Stable Isotope Laboratory
- Radiocarbon Laboratory