Characterisation of waterlogged archaeological wood from Nanhai No. 1 shipwreck by multidisciplinary diagnostic methods

Multidisciplinary diagnostic methods were applied to evaluate the preservation state of waterlogged archaeological wood (WAW) from ancient Chinese shipwreck Nanhai No.1. The characterisation combines micromorphological, physical, and Fourier transform infrared (FTIR) analyses to overcome limitations of using a single analysis. The micromorphological analysis used the whole-slide imaging (WSI) method to identify wood species and determine the decay class. The collected samples were graded as Class 2 (moderate decay) or Class 3 (severe decay). Bacterial and fungal attacks on wood tissues were evident, and the decay pattern of erosion bacteria (EB) was verified. The maximum water content obtained from the oven-drying and freeze-drying methods confirmed that the micromorphological features can be used to grade the decay class. In tandem with hierarchical cluster analysis, FTIR measurements classified four clusters, including moderate and severe decay groups. FTIR also revealed that the chemical alteration of WAW was mainly due to the depletion of polysaccharides. Increased knowledge of WAW degradation and feasible diagnostic methods are beneficial for further conservation strategies.