Monachon Mathilde, Albelda-Berenguer Magdalena, Lombardo Tiziana, Cornet Emilie, Moll-Dau Friederike, Schramm Janet, Schmidt-Ott Katharina, Joseph Edith
Laboratory of Technologies for Heritage Materials, University of Neuchâtel, 2000 Neuchâtel, Switzerland.
Swiss National Museum, 8910 Affoltern am Albis, Zürich, Switzerland.
Eur Phys J Plus. 2021;136(9):937. doi: 10.1140/epjp/s13360-021-01908-9. Epub 2021 Sep 14.
An innovative bioextraction method was tested and compared to common chemical extraction for the preservation of waterlogged archeological wood (WAW) artifacts. During burial, WAW artifacts accumulate iron and sulfur species forming iron sulfides. These compounds are harmless in the burial environment, where the oxygen content is low. But upon excavation, the WAW undergoes the oxidation of these compounds, and thus, irreversible physical and chemical damages occur. Fresh and archeological oak and pine samples were selected as representative species of WAW artifacts. Fresh samples were previously artificially contaminated to ascertain the presence of iron and sulfur. and natural iron chelators, called siderophores, were investigated to extract iron and sulfur as a 2-step biological treatment (BT) and compared to sodium persulfate-EDTA as chemical treatment (CT). Consolidation and freeze-drying were performed on the samples after BT and CT as traditional conservation protocols. BT and CT efficiency was evaluated through Raman, inductively coupled plasma-optical emission (ICP-OES), and Fourier transformed infrared (FTIR) spectroscopies. Raman and ICP showed that most of the iron and sulfur was extracted after BT, while some sulfur species remained present on CT samples. None of the extraction methods resulted in a degradation of the wood, as ascertained by FTIR analyses. Yet, all samples presented visual modifications after conservation. Pine samples treated with BT illustrated the oxidation of the species. Present principal component analysis (PCA) and analysis of variance (ANOVA) which were selected as statistical approaches and validated BT as a promising alternative extraction method, with encouraging extraction rates and less alteration of the sample appearance.
一种创新的生物提取方法经过测试，并与用于保存水浸考古木材（WAW）文物的常见化学提取方法进行了比较。在埋藏过程中，WAW文物会积累铁和硫物种，形成硫化铁。这些化合物在氧气含量低的埋藏环境中是无害的。但在挖掘时，WAW会发生这些化合物的氧化，从而导致不可逆转的物理和化学损伤。选择新鲜的橡木和松木样本以及考古样本作为WAW文物的代表性物种。新鲜样本事先经过人工污染以确定铁和硫的存在。研究了天然铁螯合剂（称为铁载体）作为两步生物处理（BT）来提取铁和硫，并与过硫酸钠-乙二胺四乙酸作为化学处理（CT）进行比较。作为传统保护方案，在BT和CT处理后对样本进行了加固和冷冻干燥。通过拉曼光谱、电感耦合等离子体发射光谱（ICP-OES）和傅里叶变换红外光谱（FTIR）对BT和CT的效率进行了评估。拉曼光谱和ICP结果表明，BT处理后大部分铁和硫被提取出来，而CT处理的样本上仍有一些硫物种存在。FTIR分析确定，没有一种提取方法导致木材降解。然而，所有样本在保护后都出现了外观变化。用BT处理的松树样本显示出物种的氧化。选择主成分分析（PCA）和方差分析（ANOVA）作为统计方法，验证了BT是一种有前景的替代提取方法，其提取率令人鼓舞，且样本外观变化较小。
