Abstract The Viking Age wooden artefacts recovered in the early 1900s from the Oseberg mound (Norway) and treated with alum, are today highly degraded. This is due to the effects of the alum-treatment and the reactivity of alum and alum-derived salts [1]. Some of the artefacts from the Oseberg collection that were treated with alum were also coated with a drying oil: boiled linseed oil. These artefacts appear to be better preserved with respect to those not treated with linseed oil. In order to assess the effect of linseed oil on wood preservation, an alum-treated archaeological wood fragment from the Oseberg collection treated with linseed oil was investigated by three analytical techniques: gas chromatography coupled with mass spectrometry (GC/MS), pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and high-performance liquid chromatography coupled to electrospray ionisation and quadrupole time-of-flight mass spectrometry (HPLC-ESI-Q-ToF). These techniques provided important information on the molecular composition and state of preservation of both archaeological wood and aged linseed oil. Py(HMDS)-GC/MS was applied to assess the state of preservation of the main wood components, lignin and polysaccharides, in the presence of linseed oil and alum treatments. GC/MS and HPLC-ESI-Q-ToF were used to perform lipid characterisation and to investigate the lipid degradation and oxidation processes. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and elemental analysis by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS) were performed to give information on the corresponding inorganic components, particularly the composition and distribution of the alum. Samples taken at different depths from the surface of the archaeological wood fragment were analysed and compared. The results showed that, although the wood was highly depleted of carbohydrates, it was better preserved than previously analysed Oseberg artefacts not treated with linseed oil. Results from GC/MS and HPLC-ESI-Q-ToF suggested that the linseed oil played a mitigating role in terms of wood degradation. The behaviour of the lipid material, which was more oxidized on the wood surface than in the core, was the opposite to that usually encountered in archaeological wood, suggesting a selective oxidation of the linseed oil. This unusual pattern of wood degradation was not mirrored by the inorganic components: alum was found to be more abundant at the surface of the fragment than at depth, as would be expected, but no decomposition products were found. However, the alum appeared to mainly consist of ammonium salt, rather than the potassium alum documented as the treatment material for the Oseberg artefacts.

中文翻译：

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亚麻油清漆对明矾处理考古木材的保护作用

摘要 1900 年代初期从 Oseberg 土墩（挪威）回收并用明矾处理的维京时代木制工艺品如今已高度退化。这是由于明矾处理的影响以及明矾和明矾衍生盐的反应性 [1]。Oseberg 收藏的一些用明矾处理过的手工艺品也涂上了干性油：煮过的亚麻籽油。这些人工制品似乎比未用亚麻籽油处理的人工制品保存得更好。为了评估亚麻籽油对木材防腐的影响，通过三种分析技术研究了用亚麻籽油处理过的 Oseberg 收藏的经明矾处理的考古木材碎片：气相色谱与质谱联用 (GC/MS)、热解气相色谱/质谱 (Py-GC/MS) 和高效液相色谱与电喷雾电离和四极杆飞行时间质谱 (HPLC-ESI-Q-ToF) 耦合。这些技术提供了关于考古木材和陈年亚麻籽油的分子组成和保存状态的重要信息。Py(HMDS)-GC/MS 用于评估主要木材成分、木质素和多糖在亚麻籽油和明矾处理下的保存状态。GC/MS 和 HPLC-ESI-Q-ToF 用于进行脂质表征并研究脂质降解和氧化过程。X射线衍射（XRD），进行傅里叶变换红外光谱 (FTIR) 和扫描电子显微镜与能量色散 X 射线光谱 (SEM-EDS) 结合的元素分析，以提供有关相应无机成分的信息，特别是明矾的组成和分布。对从考古木材碎片表面不同深度采集的样品进行了分析和比较。结果表明，虽然木材的碳水化合物含量很高，但它比之前分析的未用亚麻籽油处理的 Oseberg 人工制品保存得更好。GC/MS 和 HPLC-ESI-Q-ToF 的结果表明，亚麻籽油在木材降解方面发挥了缓解作用。脂质材料的行为，在木材表面比在芯部氧化得更多，与通常在考古木材中遇到的相反，表明亚麻籽油的选择性氧化。这种不寻常的木材降解模式并没有被无机成分反映出来：发现明矾在碎片表面比深度更丰富，正如预期的那样，但没有发现分解产物。然而，明矾似乎主要由铵盐组成，而不是记录为 Oseberg 人工制品处理材料的钾明矾。