ELECTRON SPIN RESONANCE STUDY OF PAPER SAMPLES DATING FROM THE FIFTEENTH TO THE EIGHTEENTH CENTURY

Electron paramagnetic resonance spectroscopy is used to detect paramagnetic impurities in differently degraded antique sheets of unprinted paper. Impurities consist primarily of transition metal ions (Fe³⁺, Mn²⁺, Cu²⁺) present in different environments and symmetries. Organic radicals, common in modern, wood pulp paper, are absent in these antique samples made from rags. Fe³⁺ is the largest impurity (from 300 to 700 ppm). Mn²⁺ is also present but its concentration does not exceed 50ppm. Cu²⁺ has been detected in about one-third of the samples. Coupled with nuclear magnetic resonance data, these results describe degradation as an hydrolytic process leading to a net increase of amorphous cellulose and to a decrease of bound water. Copper and rhombic iron appear to act as efficient degradation catalysts, whereas the presence of octahedral iron is almost irrelevant.     

三种含Cu、As绿色颜料的拉曼光谱研究

分析和确认古代颜料的成分是文物研究中的一项重要工作。为对四个来自不同地区的含Cu、As元素的绿色颜料进行鉴别,应用拉曼光谱仪并辅助以扫描电镜能谱分析仪(SEMEDX)和X射线衍射仪(XRD)进行研究。结果表明其分别为墨绿砷铜矿、氯砷钠铜石以及巴黎绿。对其来源分别进行了讨论,因巴黎绿在国内青铜修复和古建彩画当中的大量应用,过去对于含有Cu、As的绿色颜料通常鉴定为巴黎绿。墨绿砷铜矿和氯砷钠铜石为在文物彩绘中新发现的两种矿物颜料,为绿色颜料的鉴定提供了新的思路。     

Study of interactions between polyethylene glycol and archaeological wood components by C high-resolution solid-state CP-MAS NMR

While use of polyethylene glycols, PEG, polymers for archaeological wood conservation has been well established, there is almost no study of such composite materials with carbon thirteen high-resolution solid-sate NMR. We demonstrate that NMR is an useful analytical tool to characterize rapidly samples of conserved wooden objects. By choosing an appropriate value of the contact time (from 3 to 5 ms) for which the PEG component gives only a small residual NMR signal in the CP-MAS experiment, it is possible to edit selectively the spectra of the wood components. It allows one to visualize the degradation extent of the archaeological wood even when the conservation processes have been already applied. Moreover, by studying the kinetics of CP-MAS experiments, the time constants, T_1ρH and T_CH values for PEG moiety were computed. From these data, it is shown that either in the crude commercial product or in incorporated in archaeological woods, two components are present and they are the signatures of crystalline (or ordered) and amorphous (or disordered) molecular domains. Moreover, it was shown in the archaeological woods that almost 30% of PEG was in close molecular interactions with lignins. This study is the first evidence that the PEG in conserved wood can interact at a molecular level with wood components. It also demonstrates that the PEG diffuses inside the residual cell walls of archaeological wood. This data are important for scientists in charge of process development for the conservation of wooden artifacts.     

Roman blue-green bottle glass: chemical–optical analysis and high temperature viscosity modelling

Chemical analysis, optical absorption spectroscopy and mathematical modelling of high temperature viscosity have been carried out on five 1st–2nd century AD Roman blue-green bottle glass fragments from Coppergate, York. Modelled viscosities indicate remarkable consistency within the sample set studied and support the suggestion that temperatures of ∼1000–1150 °C were required to remelt these glasses and to provide suitable viscosities for forming articles. Iron redox ratios (Fe²⁺/ΣFe), analysed SO₃ contents and the absence of characteristic Fe³⁺–S²⁻ amber absorption bands suggest that melting conditions for all studied glasses were mildly, rather than strongly, reducing (estimated pO₂ ≈ 10⁻¹–10⁻⁶ bar). These furnace conditions are consistent with the effects of combustion gases and carbonaceous matter contained in the raw materials.     

Atmospheric deterioration of Qin brick in an environmental chamber at Emperor Qin's Terracotta Museum, China

Potential mechanisms for the changing appearance of Qin terracotta was evaluated on simulated bricks with, SO₂, NH₃, O₃, and a NH₃/O₃ mixture for total dosages of 2.2–5.4 ppm-years. Changes in the surface composition and appearance were evaluated with scanning electron microscopy/energy dispersive X-ray analysis (SEM–EDX) and X-ray photoelectron spectroscopy (XPS). No observable changes with O₃ exposure were found. Sulfate as sulfur and ammonium as nitrogen increased by 1.2 at% and 0.8 at% of the surface deposit as determined by XPS. O₃ did not have a detectable effect by itself, but when combined with NH₃, NO₃ as nitrogen increased by 1.5 at%, indicating a strong oxidation of NH₃ to nitric acid. The combination of outdoor O₃ infiltration with indoor NH₃, presumably from the visitors, appears to have a greater potential for damage than either pollutant by itself. SEM–EDX mapping of the surface showed sulfur associated with calcium and magnesium compounds after SO₂ exposure, but not before. More detailed microscopic examination showed this primarily in the form of gypsum, especially near cracks and pits in the surface. Both of these mechanisms are probably among the causes of changes in terracotta appearances since they were unearthed in 1974.     

Mössbauer Spectroscopic and Chromaticity Analysis on the Colourative Mechanism of Ancient Goryeo Celadon from GangJin and Buan

In ancient Goryeo celadon excavated from the kiln sites in the GangJin and Buan areas, the effect of the chemical composition and ionic state of Fe on the colour was evaluated by Mössbauer spectroscopy and chromaticity analysis. According to chromaticity analysis, the L* value (brightness) of the glaze was shown to be affected more by TiO₂ and MnO than by Fe₂O₃, and the body was affected more by Fe₂O₃ than by TiO₂. The a* value was found to be affected by Fe₂O₃ and TiO₂ in the glaze, whereas there was hardly any change in the body according to the composition. As for the b* value, changes due to the composition were shown to be smaller than those for the L* and a* values. According to the Mössbauer spectroscopy results, as the quantities of TiO₂ and Fe₂O₃ are increased, Fe²⁺/Fe³⁺ decreases; while the changes in Fe²⁺/Fe³⁺ with MnO and P₂O₅ are negligible. As the quantity of Fe²⁺/Fe³⁺ increases, the a* and b* values decrease, which results in the change of colour from red–yellow to blue–green. The characteristic green colour can be attributed to increased L* (brightness) and decreased a* and b* values (blue–green shift) due to the reduced Fe ion, which is mainly determined by the TiO₂ and Fe₂O₃ contents.     

安徽铜陵师姑墩遗址出土原始瓷的初步分析研究

通过对铜陵师姑墩遗址出土的29件原始瓷进行的检测分析表明,师姑墩原始瓷胎为高硅低铝型,部分器物胎体的Fe_2O_3和TiO_2含量较高;釉属高温钙釉,釉中Mn和P含量相对较高,其可能由草木灰引入,部分器物釉中含较高的Fe_2O_3,致使釉色较深。这一结果为皖南地区先秦时期原始瓷手工业发展研究提供了新的科学依据。     

Analysis of the spatial distribution of geochemical signatures for the identification of prehistoric settlement patterns in ADE and TMA sites in the lower Amazon Basin

The Archeological Dark Earth (ADE) and Terra Mulata (TMA) anthrosols found at Juruti, on the lower Amazon River, extend over a wide area located within the local ferralsol domain. The ADE soils are dark in color and contain large quantities of fragmented ceramics, while the TMA soils are also relatively dark, but lack ceramics. Multi-element chemical analyses of soil samples of ADE and TMA from the A2 horizon (depths of 10–20 cm) indicated that the ADE soils are characterized by higher concentrations of P₂O₅, CaO, K₂O, MgO, Cu, Mn, and Zn, while the TMAs have median levels of these compounds, and the ferralsols have much lower concentrations. These chemical elements make up the geochemical signature of these anthrosols, whereas Al₂O₃, Fe₂O₃, TiO₂, Cr, Sr, La, Li, Ni, Pb, V, Y, and Zr characterize the geochemical signature of the ferralsols, which was identified partially in the ADEs and TMAs. The isoline maps of these two geochemical associations permitted the delimitation of the different areas and the identification of the ADEs as sites of long-term human occupancy, and the TMA as an area of temporary occupation associated with agricultural activities. Seven villages were delimited within the study area, and were separated by corridors of ferralsols. These settlements were established on the riverbank, with the more temporary cultivated areas behind them, running almost parallel to the river. The identification of functional patterns based on geochemical associations, the abundance of ceramic material, and concentrations of organic matter, indicated that an area of more than 350 ha was occupied.     

Stable carbon and oxygen isotopic compositions of wood ash: an experimental study with archaeological implications

Wood ash, composed mainly of the mineral calcite, is an important component in many archaeological sites. Identification of wood ash in the archaeological record is often difficult due to mixing of ash with other calcitic components of geogenic origin and/or due to diagenetic changes. A recent empirical study using the stable isotope compositions of carbon (δ¹³C) and oxygen (δ¹⁸O) in wood ash enabled the identification of mixtures of wood ash with geogenic calcite and to follow diagenetic changes due to partial dissolution and re-precipitation of ash in two prehistoric cave sites in Israel. Little however is known about the processes responsible for the isotopic compositions of wood ash in relation to formation at various temperatures and the influence on isotopic composition of ash from a variety of plant species. Here we present an experimental study of wood ash formed by burning three C3 tree species and one C4 desert bush at different temperatures. The results indicate that there are significant differences in the isotopic compositions of carbon and oxygen between wood ash that forms by combustion at a relatively low temperature (500 °C) and at a higher temperature (900 °C). In addition, we show that the isotopic composition of carbon and oxygen in high temperature wood ash approaches equilibrium over a period of several months and that the carbon isotopic composition of low temperature wood ash may reflect the photosynthetic pathway of the burnt woody species. Lastly, we show that the isotopic compositions obtained from wood ash prepared at different temperatures do not reflect a temperature dependent fractionation process, but a mixing line between calcite that formed by low temperature combustion and calcite formed by high temperature combustion which later underwent re-carbonation with atmospheric CO₂. In addition, we suggest that exchange processes may possibly occur during combustion between decomposing calcium-oxalate and atmospheric O₂, CO₂ and CO. The archaeological implications of this study are discussed in relation to identification of wood ash in the archaeological record, identification of fuel sources and burning temperatures, and diagenetic changes expected in karstic cave environments. The method presented here can be applied at any archaeological site.     

An archaeometric study of Hellenistic glass vessels: evidence for multiple sources

In the present study, 53 glass fragments from core-formed vessels and 3 glass beads are investigated using SEM/EDX, EPMA and LA-ICP-MS. All samples were excavated in the Latin settlement of Satricum in central west Italy and apart from two, were found in the so-called fourth–third c. BC Hellenistic Votive deposit, also known as Votive Deposit III, discovered in front of the sanctuary of Mater Matuta on top of the acropolis. The analytical results indicate that the glass from Satricum is a typical soda-lime-silica type with natron used as a flux. Its chemical compositions display a relatively low compositional variation. Small differences in the concentrations of major and minor oxides (SiO₂, Al₂O₃, CaO and Fe₂O₃) and in trace elements (Sr, Zr and Nd) between individual samples suggest the use of different types of raw materials, especially sand. In turn, this suggests that the glass derived from more than one glass making centre. The combined investigation of colourants (Co, Cu and Mn) reinforces and confirms the idea that glass from Satricum was made using different manufacturing traditions during the Hellenistic period.     

Evaluation of Quantitative XRF Analysis Applied to Determine Cobalt Sources in Chinese Blue‐and‐White Porcelain

A method using the ratios between MnO, Fe₂O₃ and CoO to differentiate the cobalt sources for Chinese blue‐and‐white porcelain was developed in Oxford in the 1950s using X‐ray fluorescence (XRF) analysis directly on the glaze. In this paper, six blue‐and‐white porcelain sherds from the Luomaqiao kiln were analysed by XRF on the glaze and by scanning electron microscopy with energy‐dispersive spectrometry (SEM‐EDS) in cross‐section. The ratios between MnO, Fe₂O₃ and CoO calculated by quantitative XRF and EDS analyses are different. The analysis depths for MnO, Fe₂O₃ and CoO are < 60 μm by XRF analysis. However, the average glaze thickness of samples is > 400 μm, and the MnO, Fe₂O₃ and CoO mainly remain in the lower layer of the glaze, which is beyond the analysis depths of XRF analysis. The limitations of major and minor quantitative analyses for differentiating cobalt sources are discussed.     

临水窑与介休窑白底彩绘工艺的对比研究

白底黑花装饰风格的瓷器,始终是陶瓷、科技界和陶瓷爱好者关注的热点。临水窑(磁州窑)与介休窑白底黑花风格的瓷器之间有着密切的联系,但是对于两窑产品的科技分析甚少,至于两者的对比研究更是无从谈起。因此,本工作利用岩相分析、SEM-EDS等方法分析了临水窑(磁州窑)、介休窑样品的瓷胎、化妆土及瓷釉的化学成分和显微结构。比较分析显示,两窑样品的瓷胎均为低硅高铝配方,且介休窑瓷胎中的Al2O3含量更高;两窑瓷胎粗糙,Fe2O3、TiO2含量较高,致使其呈浅黄色。瓷胎表面均施有化妆土,所不同的是,介休窑的瓷胎表面施有两层化妆土,其靠近釉的一层化妆土(h2),Fe2O3、TiO2含量极低,靠近胎的一层化妆土(h1),Fe2O3、TiO2含量较高;临水窑样品的瓷胎表面仅施一层化妆土,其Fe2O3、TiO2含量较低,但高于介休窑近釉层化妆土中的相应含量。介休窑瓷釉为典型的高钙釉,而临水窑则为典型的碱钙釉和钙碱釉。不难认识到,介休窑似在临水窑白底黑花及化妆土工艺的基础上,因地制宜,勇于创新,形成了成本低廉、技术先进的两层化妆土工艺,在当地原料较为粗糙的条件下,生产出质量较好的白底釉下彩绘瓷器。     

Degradation of Archaeological Wood Under Freezing and Thawing Conditions—Effects of Permafrost and Climate Change

The degradation of archaeological wood at freezing and thawing temperatures is studied at the site of Qajaa in West Greenland through a combination of environmental monitoring, measurement of oxygen consumption and microscopy of wood samples. Permanently frozen wood is still very well preserved after 2–4000 years, while wood samples that thaw every summer show attack by soft rot and an average density loss of 0.1 g cm^–3 (corresponding to 25% of the dry mass) over the past 27 years. Future increases in temperature may increase the decay rate significantly (Q₁₀ = 4.2 at 0–10°C) but the effects on site depend on local hydrology.     

Differentiating between anthropogenic calcite in plaster,ash and natural calcite using infrared spectroscopy: implications in archaeology

Infrared spectroscopy provides information not only on the type of calcium carbonate polymorph, but also on the extent of atomic order. In calcite, three major infrared absorption peaks are identified: ν₃, ν₂, and ν₄. It was shown that the ratio between ν₂ and ν₄ bands reflects the order of the calcite crystal structure. In this paper we analyse this ratio in geologically formed calcites, archaeological plasters, modern plasters and experimentally prepared plasters. For the geological calcite, the values of the ν₂/ν₄ ratio are around 3, whereas for the experimentally prepared plasters, the values are around 6.5. The ν₂/ν₄ ratio for archaeological plasters varies from 3 to 6. This shows that a high ratio is indicative of disorder in the crystal, and implies that the calcite was formed from calcium oxide at high temperatures. It also implies that this disorder can be preserved for at least 14,000 years. The ν₂/ν₄ ratio of calcite from archaeological sites can thus be used to differentiate between anthropogenic calcite, such as in plaster, mortar and wood ash, from geogenic calcite, such as in limestone. The ratio may also be used to identify plaster or ash that still retains its original crystals and therefore carbon-14 content.     

SO2与水分综合影响下的云冈石窟砂岩劣化研究

气体污染物SO₂是造成云冈石窟文物本体劣化的重要因素之一。为厘清SO₂与水分耦合作用下的云冈砂岩劣化规律，开展不同SO₂浓度、相对湿度以及降水条件下的室内模拟风化试验，测定试样质量、表面特征和化学成分变化。结果表明：SO₂易与砂岩中的碳酸盐矿物(如方解石)和长石发生化学反应，产物包括CaSO₄·2H₂O、MgSO₄·7H₂O和高岭石等，且随着相对湿度增加，反应程度增大，造成试样的质量、色差值、可溶盐含量上升及硅铝比下降；液态水的参与能显著加快SO₂与砂岩的相互作用过程，不但增加了各项指标的变化幅度，还加大了SO₂入侵深度。研究成果可为砂岩质文物的科学认知和预防性保护提供参考。     

Bleached mudstone,iron concretions,and calcite veins: a natural analogue for the effects of reducing CO2‐bearing fluids on migration and mineralization of iron,sealing properties,and composition of mudstone cap rocks

This study investigates the Wangfu Depression of the Songliao Basin, China, as a natural analogue site for Fe migration (bleaching) and mineralization (formation of iron concretions) caused by reducing CO₂‐bearing fluids that leak along fractures after carbon capture, utilization, and storage. We also examined the origin of fracture‐filling calcite veins, the properties of self‐sealing fluids, the influence of fluids on the compositions of mudstone and established a bleaching model for the study area. Our results show that iron concretions are the oxidative products of precursor minerals (pyrite and siderite) during uplift and are linked to H₂S and CO₂ present in early stage fluids. The precipitation of calcite veins is the result of CO₂ degassing and is related to CO₂, CH₄, and minor heavy hydrocarbons in the main bleaching fluids. In our model, fluids preferentially enter high‐permeability fracture systems and result in the bleaching of surrounding rocks and precipitation of calcite veins. The infilling of calcite veins significantly decreases the permeability of fractures and forces the fluids to slowly enter and bleach the mudstone rocks. The Fe²⁺ released during bleaching migrates to elsewhere with the solutions or is reprecipitated in the calcite veins and iron concretions. The formation of calcite veins reduces the fracture space and effectively prevents fluid flow. The fluids have an insignificant effect on minerals within the mudstone. In terms of the chemistry of the mudstone, only the contents of Fe₂O₃, U, and Mo change significantly, with the content of U increasing in the mudstone and the contents of Fe₂O₃ and Mo decreasing during bleaching.     

Hydrogeochemical modelling of CO2 equilibria and mass transfer induced by organic–inorganic interactions in siliciclastic petroleum reservoirs

Different feldspar types control complex hydrogeochemical processes in hydrocarbon‐bearing siliciclastic reservoirs, which have undergone different degrees of degradation. To test such processes generically, carbon dioxide equilibria and mass transfers induced by organic–inorganic interactions have been modelled for different hydrogeochemical scenarios. The approach is based on and compared with data from the Norwegian continental shelf ( Smith & Ehrenberg 1989 ) and assumes local thermodynamic equilibrium among solids and fluids. Equilibrating mineral assemblages (different feldspar types, quartz, kaolinite, calcite) are based on the primary reservoir composition. Equilibration and coupled mass transfer were triggered by the addition and reaction of different amounts of CO₂, CH₄ and H₂ (plus acetic acid) at temperatures between 50 and 95°C (323 and 368 K). These components occur in oil fields as products of anaerobic bacterial degradation, hydrolytic disproportionation of hydrocarbons and/or thermal maturation of kerogen. We apply two different computer codes and two different thermodynamic data bases to calculate the results. Reaction of 0.32–0.6 mol CO₂, 0.16–0.3 mol CH₄ and 0.8–1.5 mol H₂ with K‐feldspar, quartz, kaolinite and calcite in 1 l of pore water results in modelled values of 0.3–2.3 mol% CO₂ in a multicomponent gas phase that resembles measured data (0.2–1.5 mol%). Similar CO₂ contents result from acetic acid addition (CO₂, CH₄, H₂ + 0.016 mol CH₃COOH). Equilibration with albite or anorthite reduces the release of CO₂ into the multicomponent gas phase dramatically, by 1 or 4 orders of magnitude compared with the equilibration with K‐feldspar. Minor differences in the modelled CO₂ content (0.1–0.2 mol%) result from calculations with different computer codes if the same thermodynamic data base is applied. Relevant differences (up to 1.9 mol% CO₂) result from calculations using different thermodynamic data bases.     

深圳铁仔山古墓群出土铜器腐蚀情况研究

受深圳地区海洋气候及土壤环境影响,铁仔山古墓群出土铜器锈蚀情况严重。为了给后续的保护修复处理提供科学依据,需研究出土铜器锈蚀情况。为此,通过硝酸银定性分析、X射线荧光能谱分析、拉曼光谱分析等手段,对其表面锈蚀物进行综合分析。结果表明,该批铜器矿化严重,其锈蚀成分以孔雀石为主。其中一件铜器表面锈蚀物中含有氯磷钠铜矿,这在潮湿地区土壤环境出土的铜器中较为少见。此外,在另一件铜器表面锈蚀物中还发现疑似纳米SnO2成分。实验结果可对该批铜器的保护修复处理提供有力的理论依据和数据支持,并为深圳地区出土的其他青铜类文物的保护提供参考。     

PIGMENT IDENTIFICATION IN GREEK POTTERY BY RAMAN MICROSPECTROSCOPY*

Raman microspectroscopy (RMS) is now established as a key technique for the identification of pigments of archaeological pottery that permits the in situ study of art objects by a non‐destructive procedure. The information obtained represents a great aid to restoration and conservation techniques. In this work, the chemical nature of the red, black and white pigments of five samples of Greek pottery from the end of the fifth century and the first half of the fourth century bc , exhumed from the Iberian necropolis of Cabezo Lucero (Guardamar del Segura, Alicante, Spain), has been identified. The black and the red pigments are found to be magnetite (Fe₃O₄) and hematite (α‐Fe₂O₃), respectively. The white pigment is found, for the first time, to be composed of alumina (α‐Al₂O₃ and γ‐Al₂O₃) probably yielded by the thermal decomposition of Greek bauxite.     

典型硫酸盐环境中砖质文物的脱盐与加固材料

中国保存有众多砖质文物建筑,目前这些文物多处于户外环境中,面临严重盐害导致的掏蚀损毁问题。因而,研究兼具脱盐功能的加固材料成为砖质文物等保护的一种创新思路,加固材料的研制和工艺技术的开发是其重点和难点,具有重大的社会需求和急迫性。为此,本工作从可溶性盐的破坏机制出发,研究出一种双组分无机加固材料,加固方法是Ba(OH)_2甲醇溶液与H_2C_2O_4、H_3PO_4乙醇溶液交替滴加,并模拟可溶性盐(NaCl、KCl、Na_2SO_4)分布的典型环境,进行加固、除盐,借助X射线衍射仪(XRD)、X射线荧光光谱仪(XRF)和无线阻尼抗钻仪等现代科学仪器,追踪盐的流出与转化过程。结果表明,本材料不仅能够加固模拟样品,同时能对最具破坏性的盐Na_2SO_4实现不可逆转化,生成重晶石的主要成分BaSO_4,加固与脱盐一次完成,是一种具有实际应用潜力的新材料。