古代饱水木材脱水定型机理探讨

从木材干缩的一般理论出发,探讨了古代饱水木材脱水变形的主要影响因素。阐述了古代饱水木材与新鲜木材的区别,提出饱水木材发生形变的主要影响因素同现代木材一样,是由于氢键缔合的结合水挥发,从而引起干缩和开裂。要保持脱水后的定型一方面要加固细胞壁外壁,更重要的从细胞壁内壁进行加固。     

Near infrared spectroscopy as a tool for archaeological wood characterization

Archaeological wood, as most of natural materials, is slowly decomposing on the archaeological site due to various biological factors. Rapid and accurate estimation of the degradation level is extremely important for optimal restoration and conservation. The goal of this research was to verify the effectiveness of Fourier transform near infrared (FT-NIR) spectroscopy for archaeometry. The important advantage of the NIR spectroscopy is its accuracy, simplicity and ability to perform very high number of tests without needs of any destruction to the workpiece. Five oak pieces of the archaeological wood collected from waterlogged sites in Poland have been used. Cellulose and lignin contents, as well as crystallinity and the degree of polymerization were measured with standard reference methods and compared to the contemporary wood. The near infrared spectra represent all the physical/chemical changes of the wood due to waterlogging. This technique was successfully validated in rapid estimation of the cellulose and lignin contents. The method explored in this research might be a novel tool assisting experts in evaluation of the degradation state of archaeological and historical wooden materials.     

Preservation,storage and display of waterlogged wood and wrecks in an aquarium: “Project Aquarius”

A test aquarium containing water and waterlogged historical wooden material was observed during a three-year period at Vänernmuseum, Sweden, to test the feasibility of preserving and exhibiting archaeological wood or shipwrecks in a way accessible to the public. Experiments were also set up in a laboratory environment, to provide information on single factors that could influence the long-term preservation state of wood, and other processes that may occur in the water.     

Out of the Peat: Preliminary Geophysical Prospection and Evaluation of the Mid-Holocene Stationary Wooden Fishing Structures in Haapajärvi,Finland

The huge scientific and interpretive value of wetland archaeological sites has been well demonstrated in several studies. The management of the archaeological resource of wetland landscapes is problematic, however, and there is an urgent need for noninvasive techniques to detect waterlogged organic archaeological remains. Stationary wooden fishing structures associated with fishing sites constitute an important wetland archaeological resource in northern Europe. In Finland, similar wooden constructions have been used for fishing from prehistory to the early modern era. The discovery of sites has been accidental, because the waterlogged organic remains have been considered invisible to conventional geoprospection techniques. Because of this, a small project was launched at Lamminoja, northwest Finland, in order to investigate whether it would be possible to improve our chances to detect fishery sites in demanding wetland habitats. New information was obtained through geophysical prospection, trial excavations, and accelerator mass spectrometry (AMS) dating. Geophysical testing was hampered by several factors, including complex sediments affected by modern drainage. New information was obtained, however, on the composition, age, and spatial distribution of the wooden fishing structures preserved in peat over 5000 years.     

Investigating the processes necessary for satisfactory freeze-drying of waterlogged archaeological wood

Preliminary studies into methods for improving and safeguarding the preservation of waterlogged archaeological wooden artefacts are presented. Mannitol, sorbitol and trehalose have been tested as replacements for polyethylene glycol (PEG) as a treatment prior to freeze-drying of wooden archaeological objects. The highest anti-shrink efficiency achieved in this short experiment was (70 ± 15) % using a 20% weight per volume solution of sorbitol after soaking for one week. The collapse or eutectic temperature of each solution used was determined using a freeze-drying microscope. Importantly, it was noted that the collapse temperature of the solutions was reduced by several degrees after use for treatment of the wood samples for one month. A freeze-drying microscope with a cold light source has been used to observe the real-time freeze-drying behaviour of various treatments inside a thin section of wood, confirming that this novel technique is indeed possible and useful. Lastly, the effects of magnesium phytate as an iron chelator have been studied. It was found that the treatment lowers the collapse temperature of a PEG 600/2000 solution by roughly 3 °C meaning that objects must be freeze-dried at a correspondingly lower temperature. Iron K-edge X-ray absorption near-edge spectroscopy analysis showed that the treatment extracted approximately half of the iron(III) ions present in the timbers.     

PEG稳定河姆渡遗址出土香樟的干燥特性研究

研究饱水古木材的干燥特性可以对古木材的定型保护提供重要的参考,因此本研究以河姆渡遗址出土的香樟木材为试样,在加热的条件下,用不同质量百分比浓度的聚乙二醇(PEG 2000)为定形加固剂,研究了降解饱水香樟在自然条件下的干燥特性。结果表明降解饱水香樟的自然干燥过程可以分为干燥初期试样质量的快速下降和干燥后期试样质量平稳变化两个阶段。干燥初期试样质量下降比与干燥时间符合m/m0=-kt+c的干燥方程且线性良好。随着PEG处理浓度的升高,两个阶段之间逐渐出现一个过渡过程,PEG处理浓度越高,过渡过程越明显。达到干燥终点时,香樟试样的尺寸稳定性随着PEG浓度的升高而显著增强,当浓度达到70%时,纵向、径向和弦向的收缩率下降明显,但弦向的收缩率仍相对较大。随着PEG处理浓度的增加,自然干燥后的香樟试样表观色泽逐渐加深。因此,PEG 2000浓度以不超过40%为宜。     

Evaluation of the rate of wood degradation at the Iron Age archaeological site of Biskupin,Poland

A study was made of the degradation of archaeological Scots pine (Pinus sylvestris L.) at the Iron Age archaeological site of Biskupin, Poland. Wood degradation was evaluated after 10 years of deposition of samples in different burial conditions (mineral soil, peat and water) and at different depths (25, 50 and 100 cm) at the location of the original archaeological wood from the Lusatian culture settlement. Changes in the wood samples were assessed on the basis of selected physical (maximum water content, basic density and porosity) and chemical (chemical composition, structure of cellulose and lignin) properties. The observed degradative changes were different for samples deposited in different locations of the archaeological site and at different depths. They relate mainly to carbohydrates—both cellulose and hemicelluloses—although the structure of lignin also underwent changes. The experiment using wood that had been degraded to a similar degree to the Biskupin wood enabled identification of the actual danger of degradation of the latter. It was found that the remains of the wooden structure of the Biskupin settlement are degrading, despite the favourable physicochemical conditions prevailing at the site, and it is necessary to take measures to prevent its further decomposition.     

天然树脂加固淹埋木质文物

为了对剑川海门口遗址出土的古思茅松进行实验性加固保护,对古思茅松进行草酸脱色、甲醇溶剂脱水,然后使用松香和虫胶的甲醇溶液作为加固剂进行渗透、干燥等加固工序。加固后的样品表面色泽浅淡,保持了木材原有的色泽、纹理和质感。基本密度达到0.437g/cm3,已接近现代木材的基本密度。顺纹抗压强度较加固前增加了24.58%。绝干状态时测得的各向全干收缩率分别为:纵向2.22%、径向3.54%、弦向7.73%,均在正常木材干缩变化范围之内。扫描电子显微镜(SEM)研究表明:天然树脂附着在细胞壁表面,对细胞壁起到了足够的支撑作用,加固后的木材细胞壁切面平整、致密、轮廓清晰,胞壁间界面结合好,细胞腔较光滑。研究表明,本加固方法能有效降低木质文物的吸湿性、提高其各项物理力学性质。当木质文物需做其它处理时只需用甲醇或乙醇将松香和虫胶溶出即可,加固过程可逆,这解决了木质文物将来的再处理问题。     

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.     

How an integrated diagnostic approach can help in a correct evaluation of the state of preservation of waterlogged archaeological wooden artefacts

Artefacts made of wood coming from archaeological excavations provide insights into human cultural behaviour of the past. They show how man utilised natural resources and how the development of woodworking techniques and artistic endeavour were developed. Within archaeological contexts, waterlogged anaerobic conditions generally preserve the appearance of artefacts, although wood is subject to severe decay processes. The said conditions can transform the original material into a new one, thus demonstrating specific differences from those of the “fresh” wood of the same species. In order to assess these new properties correctly, an integrated diagnostic approach is needed, one which includes a multidisciplinary (micromorphological, physical and chemical) evaluation of the state of preservation.     

甘肃出土糟朽木器的形态与结构分析

甘肃出土木器依据形态与结构划分,属于典型的糟朽木器类型,材质外观特征与特性明显。制作材质鉴定表明,基本类型有①松科云杉;②松科冷杉;③柏科圆柏。通过对糟朽木器形态类型、结构属性、影响因素及发生改变原因剖析,指出了糟朽木器材质在经历了第一阶段的转折性根本改变后（含水率远低于纤维饱和点）,即将面临第二阶段的转折性根本变化（含水率略高或接近于平衡含水率）,而这一阶段的改变结果对器物将是毁灭性的;为了避免出土器物在短期内形态发生剧变,运用生物切片、扫描电镜分析技术对木质纤维显微结构进行了观察和研究,研究结果与结构病害腐变结果相吻合。选取与糟朽器物同期考古出土的糟朽棺板木作为分析对象,分别对其化学成分、容积重、含水率以及力学性能进行了实验测试,测得糟朽木器降解损失超过50%,含水率约为10.5%,力学强度指标与正常材质相比,均有明显的下降,且相对差异较大,最大约为正常木材强度的60%。对比分析结果,得出了结论：①糟朽木器的形态与结构状况与实验生物切片分析、电镜显微结构观察和研究结果相吻合,同时材质成分、容积重与力学性能测定结果为上述分析结果提供了有力的数据支撑;②致使糟朽木器形态和结构发生改变的主要因素是胎木含水率,其值是非恒定的并随外部环境而改变,因此含水率可用于反映糟朽木器的材质特性;③纤维饱和点与平衡含水率是影响、衡量和评估糟朽木器形态与结构的两个重要的物理参数;④鉴于糟朽木器的材质特性,后期保存应尽量避免与水分的直接接触,需要严格控制其胎木的含水率,且维持恒定、稳定的保存环境,这点对后期糟朽木器的保存是非常重要的     

DETERIORATION ASSESSMENT OF WATERLOGGED ARCHAEOLOGICAL LIGNOCELLULOSIC MATERIAL VIA 13C CP/MAS NMR*

This study investigates the residual chemical composition of waterlogged archaeological lignocellulosic material found in Greece. Hazelnut pericarps and oak wood found in a 16th‐century wreck, along with endocarps of olives dated at 300 bc , were examined. ¹³C CP/MAS NMR was applied to compare fresh and waterlogged archaeological materials. Results show qualitative alterations in their composition. The virtual absence of peaks at ~21 ppm and ~173 ppm, corresponding to hemicelluloses in all archaeological materials, indicates that these constituents can be an important indicator in assessing the type and degree of deterioration.     

Wet-Site Excavation and Field Methodology at Butrint,Albania: The Roman Forum Excavations Project

Since the start of archaeological research at the UNESCO World Heritage Site of Butrint (Bouthrotos/ Buthrotum) in southern Albania, archaeologists have allowed the water table to serve as a limit to archaeological excavation. From 2011 to 2013, the Roman Forum Excavations (RFE) Project conducted the first wet-site excavations at Butrint, reaching depths of up to 4 m below the water table in the ancient urban center. Well-preserved wood and other organic remains were recovered from waterlogged deposits, dating as early as the 7th century b.c. Major changes in RFE Project methodology emerged in response to wet-site archaeology. Unskilled local workers were trained to become local excavators. This significantly improved excavation techniques and recording procedures and enhanced the quality of the archaeological data, showing the high degree to which seemingly disparate elements of field methodology are intertwined.     

饱水古木材难溶盐分析

为研究饱水古木材中难溶盐的成分和分布,基于电感耦合等离子体光谱、X射线衍射以及显微共聚焦激光拉曼等分析手段对出土出水饱水古木材表面和纵向横向不同取样深度的元素含量和分布、表面凝结物以及纵向横向切面颗粒物的物相进行了分析。分析结果表明饱水古木材含有大量的Fe、S和Ca元素,包含这三种元素的凝结物主要由难溶盐和不溶物组成。难溶盐主要分为两大类,一类为钙盐(包括硫酸盐、碳酸盐和磷酸盐等),一类为硫铁化合物(包括硫铁矿、黄铁矿、磁黄铁矿等);不溶物包括各类铁氧化物(如针铁矿、纤铁矿、赤铁矿和水合氧化铁)以及硫单质等。难溶盐分析结果有助于有针对性地对饱水古木材难溶盐尤其是对古木材危害比较大难溶盐进行预防控制和有效脱除。     

New trials in the consolidation of waterlogged archaeological wood with different acetone-carried products

Some acetone-carried consolidants for waterlogged archaeological wood were tested in order to evaluate treatments able to save time and energy. In details, colophony (rosin), two esterified colophonies (Rosin 100^® and Rosin 459^®), a mixture of colophony with PEG 3400 and a vinyl acetate - vinyl versate copolymer (Vinavil 8020S^®) were tested. The treatments were carried out at temperatures of 20 and 35 °C on waterlogged maritime pine, elm, oak and beech. The materials came from the archaeological site of the ancient ships of Pisa (Tuscany, Italy) and were dated back to VII cent. BC – II cent. AD. To evaluate the processes, equilibrium moisture content and dimensional stability of treated wood samples at different relative humidity, and retention of impregnating products were measured; moreover macroscopic and microscopic examination were also run to respectively assess the shape and appearance of treated wood and the way of deposition of consolidants. The results highlighted that natural and modified colophony treatments gave the most satisfactory results both in the maintenance of shape and dimensions of samples and in the stabilization with respect to RH variations. Moreover, the equilibrium moisture contents of samples treated with R100 and R459 were much reduced in comparison to the other consolidants and to untreated archaeological wood. This fact was related to the high retention values of those products that occluded most of the porosity including the microporosity of cell walls. Therefore, in terms of higroscopicity treated wood was more similar to impregnating substances rather than to decayed wood. This fact was considered helpful in contrasting the moisture-related negative effects in cases of eventual faults in the climate control during e.g. exhibition and in protecting treated wood from the risks of new fungal attacks.     

古旧木材保存状况多参数检测研究进展

作为人类文化遗产的重要组成部分,古旧木材保存状态的评价及保护至关重要。为了推进对古木材保存评价的深入研究,通过对多参数检测(微形态学、物理学、化学)在微观尺度下评价古旧木材保存状况及腐蚀机理的研究成果进行了综述,在介绍了从木材细胞形态、物理孔隙结构、化学组分含量、分子结构、分子量分布等方面对古旧木材进行评价的基础上,较为全面地阐述了检测各参数的不同表征方法,包括扫描电镜法、氮气吸附法、高效液相色谱法、气相色谱/质谱联用法等,具体分析了不同表征方法间的优缺点,说明了多参数检测古旧木材保存状况的可行性及重要性,并希望以此为切入点探讨古旧木材的宏观力学性能。研究结果在木质文化遗产和历史木构建筑的保护方面具有极大价值。     

Provenancing East Mediterranean cedar wood with the <Superscript>87</Superscript>Sr/<Superscript>86</Superscript>Sr strontium isotope ratio

⁸⁷Sr/⁸⁶Sr isotope ratios of cedar wood from forests in the East Mediterranean have been compiled in order to investigate the feasibility of provenancing archaeological cedar wood finds. Cedrus sp. forests furnished a great amount of wood in antiquity, for purposes ranging from ship to temple construction, and for fashioning cult statues and sarcophagi. The ⁸⁷Sr/⁸⁶Sr signatures of archaeological cedar samples may be compared with the preliminary dataset presented here to help determine the geographic origin of wooden artifacts. Sample sites include two forest areas in the Troodos Massif of Cyprus, five in the Lebanon, and two in Turkey’s Taurus Mountains. Sr ratios for wood varieties (i.e., early heartwood, late heartwood, sapwood, and twig wood) demonstrate relative uniformity between the xylem types frequently recovered from archaeological contexts. As such, this pilot study also assesses important issues of archaeological sampling and the geographical factors that influence Sr uptake in cedar trees of this region. While the regional signatures are distinct in most cases, small sample sizes and range overlap indicate the need for additional methods to make a case for a certain source forest. Alone, this method continues to be best used to disprove assumed wood provenances.     

Investigations on pre-treatment prior to freeze-drying of archaeological pine wood with abnormal shrinkage anisotropy

The current research is aimed at determining the nature of changes in the dimensions and hygroscopicity of archaeological Scots pine (Pinus sylvestris L.) wood after treatment with polyethylene glycols and vacuum freeze-drying. The research was undertaken on mature sapwood with narrow annual rings and a small percentage of latewood. The experimental material used in a comparative assessment is characterised by a considerable degree of wood degradation, but low tangential and radial shrinkage and relatively high longitudinal shrinkage. The waterlogged samples were treated with aqueous solutions of PEG 300 with final concentrations: 8, 12, 16 and 20% (v/v), to which PEG 4000 with final concentration: 15, 20 and 25% (w/v) was added. After freeze-drying and seasoning of samples in the air at RH 30, 40, 50 and 65%, the water content of the samples and the degree of shrinkage of wood in three anatomical directions were determined. The dimensional stability of the samples was also determined on the basis of ASE values at RH 50%.     

出土饱水云南松的超微构造特征

对云南剑川县出土的木质文物进行了研究,从超微结构层面更深入地解析了饱水古木的降解情况。出土的云南松(Pinus yunnansis)古木在饱水环境中淹埋了4 000多年。降解主要发生在晚材管胞,而且降解在晚材部分并不均匀:一些未降解的完好管胞分布在降解严重的管胞中。透射电镜观察显示:降解从S1/S2和S2/S3的界面开始;对于一些降解较严重的管胞,到腐朽后期细胞次生壁全部发生降解,只留下复合胞间层;细菌侵蚀是云南松饱水古木降解的主要原因。固体核磁共振结果表明:纤维素和半纤维素降解严重,木质素也出现了一定程度的降解。本研究可为其后续的加固保护提供科学的参考依据。     

Trade or Trash: an examination of the archaeobotanical remains from the Byzantine harbour at Caesarea Maritima,Israel

A rich collection of waterlogged plant‐remains was recovered from the harbour at Caesarea Maritima, Israel. These remains were identified and represent several varieties of fruit, nut, cereal crop, crop by‐product and weed species. The two areas where remains were recovered provided assemblages that were different in composition. Trade or trash are the two interpretations discussed. In either case, however, the information derived from the assemblage is of archaeological importance, as the species present can aid in economic, dietary and trade reconstructions. © 2010 The Author