宁波“小白礁I号”清代木质沉船中硫铁化合物脱除技术研究

近年来的分析与研究表明,海洋出水沉船的木材中普遍存在大量的以Fe S2和Fe S为代表的硫铁化合物难溶盐,它们在空气中和一定湿度条件下,会氧化生成硫酸,使木材纤维素发生快速降解,从而对木船造成毁灭性的破坏。目前,硫铁化合物的脱除仍然是世界性难题,很多国家发现的木质沉船都面临这方面的困扰。为此,本研究以宁波象山"小白礁I号"清代沉船遗址出水的船体木材构件为研究对象,研发了金属络合剂与氧化剂复配材料EDTAHO,开展了海洋出水木材中沉积的二硫化亚铁的去除技术初步研究,取得了良好的保护效果。本研究结果可为后续脱水定型和加固修复打下良好的基础,有利于海洋出水木质船体的长期保存。     

Wrap a Wreck! In Situ Conservation of a Ship on Land Suffering from Fungal Decay

Many sixteenth- to eighteenth-century shipwrecks have been found after land reclamation in parts of the former Zuiderzee, one of the busiest waterways in Dutch history. After the land fell dry, some shipwrecks were excavated, destroyed, reburied, or covered with sand or clay. In the late 1970s a method was developed to mitigate degradation processes of some of the wrecks remaining in good condition by wrapping them in plastic foil. The idea was that the plastic would prevent evaporation and lateral subsurface flow. Wet conditions prevent decomposing of wood by especially soft rot fungi. Oxygen will be rapidly depleted by decomposition of organic matter.

Recent monitoring of wrapped shipwrecks has shown that this method of preventing rot worked exceptionally well. We adapted wrapping using new technology nowadays applied for sealing tunnels and landfills. We will present the implementation requirements, materials and new adapted method for wrapping shipwrecks.     

“华光礁一号”南宋沉船船板中硫铁化合物分析

鉴于硫铁化合物对海洋出水木质文物的特殊危害,通过 X射线衍射(XRD)、等离子体发射光谱(ICP-AES)和 X射线光电子能谱(XPS)等分析手段,对“华光礁一号”南宋沉船船板残块中的硫铁化合物进行了分析研究。结果表明,所采集的样品中含有大量的 Fe和 S元素,并且其分布深度至少可达 4cm。两种元素的化学状态基本可分为铁的氧化物、硫铁化合物、硫酸盐和其它还原性硫四大类。其中,硫铁化合物主要以 FeS和 FeS₂形式存在,并已部分氧化成硫酸盐。因此,在后续的保护处理过程需着重对其酸化过程进行控制,以有利于文物的长期保存。     

Sulfur and iron analyses of marine archaeological wood in shipwrecks from the Baltic Sea and Scandinavian waters

Analyses of marine archaeological wood from shipwrecks in the Baltic Sea area, Kronan, Riksnyckeln, Tattran, the Puck Bay Boat and the Ghost wreck, and at the Scandinavian West coast, the Göta wreck, Stora Sofia and the Viking shipwrecks of Skuldelev, show accumulation of sulfur compounds. The penetration profiles of sulfur and iron into the wood and the speciation of characteristic sulfur groups were evaluated by combining X-ray spectroscopic analyses, in particular S K-edge XANES (X-ray absorption near edge structure) and X-ray fluorescence, with ESCA and elemental analyses. The combined analyses support the hypothesis that hydrogen sulfide produced by sulfate-reducing bacteria reacts and accumulates at low iron concentration mainly as organically bound sulfur, which as in previous studies was found by X-ray spectro-microscopy to accumulate in lignin-rich parts of the wood cell walls. The presence of iron(II) ions from corroding iron promotes formation of pyrite and other iron(II) sulfides, which easily oxidise in aerobic conditions with high humidity. No significant differences in sulfur and iron accumulation were found in wood from shipwrecks in the east coast brackish water and the west coast seawater. Sediments from three wreck sites, the Göta wreck, Stora Sofia and Kronan, were analyzed to a depth of a few decimeters and showed especially at the Stora Sofia high sulfur concentrations, exceeding 3 mass%. S K-edge XANES analyses of the sediments showed mainly reduced forms of sulfur, in particular pyrite and iron(II) sulfides together with elemental sulfur.     

“小白礁Ⅰ号”沉船部分木质文物微生物病害观察与损伤评估

为掌握宁波"小白礁Ⅰ号"古沉船船体结构的状况,以及为该沉船的后续保护提供科学依据,本研究利用光学显微镜和电子显微镜技术,在显微和亚显微水平上观察了该沉船部分木质文物的组织和细胞结构。观察分析发现,对该沉船木质文物有较大影响的微生物主要是侵蚀细菌(Erosion bacteria,EB)和钻管细菌(Tunneling bacteria,TB);借助文献提供的标准,评估了该沉船不同部位木质文物的结构现状及不同备检样品中的细菌的侵蚀程度。评价结果表明沉船木质文物的侵蚀情况从轻度到完全损坏程度不同。本研究也分析了导致木质文物损伤程度差异的原因,并根据分析结果就该沉船木质文物保护涉及的生物学问题提出了建议。     

Marine electrical resistivity tomography for shipwreck detection in very shallow water: a case study from Agropoli (Salerno,southern Italy)

A marine electric resistivity survey was carried out over a submerged beach along the Agropoli shore (Salerno, Italy) to detect buried objects of archaeological interest below the sandy seabed. We found a shipwreck, a military vessel that probably sunk during the Salerno landing operations of the allied forces in the Second World War. Resistivity data provide information on the vertical and horizontal extension of the shipwreck, which is characterized by very low calculated resistivity values (about 2–5 ohm m). Such values differ significantly from the sand and the bedrock values (5–40 ohm m). Although the presence of the shipwreck is clearly visible from geoelectric data, the joint application of electric, magnetic and multibeam bathymetric techniques reduces the ambiguities inherent in each method. As shown in the Electrical Resistivity Tomography (ERT) and confirmed by the Digital Elevation Model (obtained from the processing of bathymetric data), the shipwreck extends more than 30 m in NE–SW direction and it is about 13 m wide. The global extension of the relic is consistent with the magnetic data, that are characterized by a magnetic anomaly with an amplitude of about 1800 nT and similar dimension, as inferred from the estimation of source boundaries obtained from the computation of the analytic signal. The results of our survey encourage the use of marine geoelectrical methods for the detection of buried archaeological targets, particularly in locations where the use of seismic prospecting is not effective (e.g. very shallow water with sandy sea-bottoms). The integration of different geophysical methods allows to better define the extension, depth and thickness of buried objects, suggesting that such an approach is the most effective for underwater archaeological investigations.     

Pollen-wood analysis at the Neapolis harbour site (1st–3rd century AD,southern Italy) and its archaeobotanical implications

Three Roman shipwrecks (Napoli A and Napoli C – 1st cent. AD; Napoli B – 2nd century AD) were recovered in the sandy-silt sediments representing the infilling of a protected inlet of Neapolis harbour (Naples, southern Italy). Extensive wood analysis suggests that a very attentive selection of species was made in shipbuilding, the choice of timber being related to wood technological properties and to the structural uses of the construction elements. Pollen data obtained from the coeval sedimentary layers revealed that all the timber taxa (apart from Picea/Larix) were present in the surroundings of the study area. The identified forest taxa are very common in the Mediterranean basin and thus the pollen-wood comparison was not able to define the location of the shipyards. Broad comparison with western Mediterranean wrecks evidenced the peculiarity of the Neapolis ships where the systematic use of both Juglans regia and Cupressus sempervirens was highlighted. Archaeological, biogeographical and archaeobotanical considerations suggest the local provenance of the ship C and constrain the possible origin area of both the ship Napoli A and Napoli B to central-southern Tyrrhenian coasts.     

Assessing the Impact of Typhoons on Historic Iron Shipwrecks in Chuuk Lagoon Through Changes in the Corrosion Microenvironment

The corrosion microenvironment of a dozen Second World War iron shipwrecks in Chuuk Lagoon, Federated States of Micronesia, was investigated to see if there were any measurable changes caused by a recent major typhoon. Seven previously inspected wreck sites were used for calibration to assess the environmental impacts. Five new wrecks, including the Fumitzuki, a destroyer of the Imperial Japanese Navy, were assessed at up to twice the depth of previous studies. The new data showed that the logarithm of the corrosion rate falls linearly with depth to 36 m. Measurements of corrosion potentials, concretion thickness and pH showed that many of the vessels suffered partial deconcretion during the typhoon Maysak in April 2015 with concomitant increases in the rate of decay. Regrowth of the colonising marine organisms are presently ameliorating the impact of the typhoon.     

THE CHARACTERIZATION OF WATERLOGGED ARCHAEOLOGICAL WOOD: THE THREE ROMAN SHIPS FOUND IN NAPLES (ITALY)*

Three apparently well‐preserved shipwrecks dating back to Roman times were brought to light near Piazza Municipio in Naples (Italy), during the excavation for the construction of Line 1 of the subway. The shipwrecks were covered by marine sand and silt, below the water table. In order to establish the nature and the extent of wood degradation and, therefore, determine how best to preserve the shipwrecks, a diagnostic investigation was carried out. The study involved the identification of wood species, chemical characterization of the residue component and physical and micro‐morphological characterization.     

Shipwreck archaeology of the Lakshadweep Islands, west coast of India

Archaeological investigations in the Lakshadweep Islands have brought to light the presence of a large number of shipwrecks and the archival records have the details of some of these wrecks. Northern islands and reefs of Minicoy were the locations of shipwrecks prior to 1865, but the trend changed with the opening of the Suez Canal. Various organisations including the National Institute of Oceanography, Goa, have focused on Minicoy, Byramgore, Suheli Par, and Bangaram Island for detailed exploration of shipwrecks, and the findings suggest that due to submerged coral reefs, atolls, and other shallow hazards a large number of ships were wrecked in Lakshadweep waters.     

Morphological,chemical and physical changes during charcoalification of wood and its relevance to archaeological contexts

Wood exposed to a heat source can be transformed into charcoal if subject to conditions of carbonisation (in the absence of air) or charring (in restricted air). Charcoal recovered from archaeological sites can yield fundamental information to our understanding of human economic and cultural development over time and (ecological) setting. This work describes the morphological (anatomy, degree of shrinkage), physical (reflectance) and chemical (elemental, molecular composition) properties of charcoal in relation to heat source and wood variables. In this study charcoal and charcoal fuel were experimentally produced whereby temperature (160–1200 °C), time of exposure (2–1440 min), heating rate (high and low) and wood type (angiosperm and conifer) were varied. The results show that charcoal, often described as an inert, black material, has different chemical and physical properties in relation to the investigated variables. By using these different properties it is possible to distinguish between the different types of fires (domestic and industrial) exploited by humans in the past. Morphological analyses and reflectance measurements are effective tools for this purpose and can be used in wood exposed to temperatures of 300 °C and above—temperatures which are relevant to archaeological research. Angiosperm and conifer wood react in different ways when exposed to heat and thus the taxonomic identity of archaeological material needs to be known. Chemical analyses can be used for wood exposed to temperatures below 400 °C whereas elemental analyses of the carbon content can be used for wood exposed to temperatures up to a maximum of 650 °C.     

Selective reburial: a potential approach for the in situ preservation of waterlogged archaeological wood in wetland excavations

Excavations at Dispilio, a prehistoric lakeside settlement in northern Greece, have revealed a significant number of vertical wooden piles that need to be protected during and after excavation. Lifting of the piles is not possible and approaches such as reburial, cannot currently be implemented as excavation is still in progress. In 2005, several posts were “selectively buried” on an experimental basis, by encasing them in PVC pipes and backfilling with the surrounding sediment. This approach appeared to be capable of protecting the piles during excavation and be a potential solution for their post-excavation preservation. This preliminary study sets out to asses if this alternative approach to reburial could be an effective in situ preservation method.     

Going underground: experimental carbonization of fruiting structures under hearths

We show that carbonized fruits and seeds recovered from Middle Stone Age deposits in rock shelters are likely to have been carbonized as part of post-depositional processes. We buried indigenous South African fruits, nuts and seeds at pre-determined depths and distances from the centers of experimental fires. The cold ashes of the hearths and the sand surrounding them were subsequently excavated, using standard archaeological techniques and dry-screening. The fruiting structures from the oxidizing part of the fire were burnt to ashes, whereas those buried in sand under anoxic conditions survived in varying forms. Those buried 5 cm below the center of the fire were carbonized; those buried 10 cm below the center of the fire were dehydrated; and those 5 cm and 10 cm below the surface at the outer edge of the fire were unaffected. Size, moisture or oil content of the original fruit or seed did not appear to influence whether or not carbonization took place. Temperatures recorded 5 cm below the experimental fires suggest that the carbonization occurred at or before a maximum temperature of 328 °C, and also at lower maximum temperatures (152 °C) that were maintained for long periods. Even when the quantities of a particular wood are controlled, open fires may produce variable underground temperatures and the temperatures below ancient hearths would have been equally variable. We suggest that Cyperaceae (sedge) nutlets, the most numerous fruiting structures in the Sibudu Middle Stone Age archaeobotanical assemblage, occur in the shelter as a result of human activity, subsequent burial, and accidental carbonization when hearths were built directly above the buried nutlets.     

The Armoured Cruiser HMS Defence: a case‐study in assessing the Royal Navy shipwrecks of the Battle of Jutland (1916) as an archaeological resource

This paper presents the findings from a survey of one of the shipwrecks of the Battle of Jutland, and is extracted from a longer currently unpublished report which examines the six known Royal Navy wrecks. While all of the wrecks yielded unique insights into the battle, Defence was a particularly surprising case. The extant remains of this wreck showed for the first time how the ship was destroyed and explains what some eyewitnesses reported at the time. Intact and unsalvaged, it is a source of much valuable archaeological and historical data. © 2012 The Author     

The Yenikapı Byzantine‐Era Shipwrecks,Istanbul, Turkey: a preliminary report and inventory of the 27 wrecks studied by Istanbul University

Salvage excavations conducted in the Yenikap? quarter of the historic peninsula of Istanbul by the Istanbul Archaeological Museums 2004–2013 have brought to light the Theodosian Harbour on the Sea of Marmara. In addition to thousands of archaeological artefacts, a total of 37 shipwrecks dating from the 5th to the 11th centuries AD were uncovered, constituting the biggest collection of medieval ships uncovered at a single excavation site. The present article deals with 27 wrecks in the charge of the team from Istanbul University's Department of Conservation of Marine Archaeological Objects, consisting of 23 merchantmen and four galleys. The wrecks are presented with their general characteristics. The preliminary evidence from the Yenikap? wrecks regarding the development from shell‐based to skeleton‐based philosophy is discussed, and various building phases presented.     

Management of Historic Shipwrecks Through a Combination of Significance and Conservation Assessments

Abstract

Corrosion modelling of decay rates of the iron wrecks in Port Phillip Bay, Victoria, has enabled an estimation of the speed at which the historic resource of iron shipwrecks is disappearing. Use of the significance ranking of the iron wrecks, based on the Australian National Standards for significance assessment, provides a useful guide to decision-making, but decisions based solely on these criteria can lead to less than optimal results. From the corrosion rates and the amount of residual metal thickness in structural elements it is possible to determine a conservation ranking that is based on the need for intervention and the chances of being successful in stabilizing the wrecks. The arithmetic product of the significance and conservation rankings defines the treatment score or ranking which forms the basis for rational decision making about deployment of resources.     

Chaco Canyon reburial programme

Abstract

Chaco Culture National Historical Park in northwestern New Mexico contains a wealth of archaeological resources, including 150 large earth and masonry structures under active management and preservation. In response to loss of original fabric from exposure over the last 100 years and more, as well as from continuous cycles of maintenance and repair, an extensive and long-term reburial programme was embarked upon in the late 1980s. The overall context of the site and the decision to undertake reburial as a principal conservation strategy is described in Part I of this paper. Part II provides a summary of the results of partial reburial at Chetro Ked, one of the ‘great houses’ of the canyon, in which protection of original timber was the main objective. Most of the wood at Chetro Ked could be covered only by a shallow overburden of soil, necessitating a specialized reburial design and materials to exclude moisture. Recent evaluation of the efficacy of the wood reburial was undertaken. Problems and shortcomings that were identified have led to re-design of part of the reburial and more careful attention to quality control during the intervention, as well as to selection of more appropriate geosynthetic materials. Additional monitoring techniques have been developed to allow direct withdrawal of samples of wood for assessment of deterioration.     

The use of geosynthetics for archaeological site reburial

Abstract

Applications of geosynthetic materials in reburial practice include geotextiles for separation, filtration and protection (cushioning); geomembranes and geosynthetic clay liners for infiltration control; geonets and geocomposites for sub-surface drainage; and geocells for erosion control. Mechanically stabilized earth reinforcement using geocells, geogrids and geotextiles can also provide substantial benefits for reburial projects by reducing lateral earth pressure against backfilled structures. Other aspects of modern geotechnology that may be useful for reburial projects include micro-piles and soil nailing for foundation and excavation support and evapotranspirative capping technology to establish the depth of soil cover required to isolate a structure or artefact from moisture and temperature fluctuations. Optimal application of these geotechnologies requires an understanding of the basic engineering principles associated with their implementation, as well as knowledge of the factors influencing archaeological site preservation.     

Using foraminifera to distinguish between natural and cultural shell deposits in coastal eastern Australia

Foraminifera are single cell protozoa that are ubiquitous in marine environments. Although the hard casings, or tests, of foraminifera are routinely studied in the earth sciences, they have been little studied by archaeologists, despite their potential to contribute to understandings of coastal site formation processes and palaeoenvironments. In this study techniques and methods of foraminiferal analysis are developed and applied to the problem of distinguishing between natural and cultural marine shell deposits, using the Mort Creek Site Complex, central Queensland, Australia, as a case study. Results allow separation of natural and cultural deposits based on foraminiferal density. Natural deposits were found to have >1000 foraminifera per 100 g of sediment, while cultural deposits exhibited <50 foraminifera per 100 g of sediment. Results allow us to better understand site formation processes at the Mort Creek Site Complex and highlight the potential of foraminiferal analyses in the interpretation of terrestrial marine deposits.