Changes in Moisture Characteristics of Waterlogged Archaeological Wood Owing to Microbial Degradation

Studying waterlogged archaeological wood moisture characteristics can provide strong support for the safe dehydration and preservation of waterlogged wooden artifacts. Herein, six waterlogged archaeological wood samples with moisture contents of 154%-968% chosen from two ancient Chinese shipwrecks, Nanhai No. 1 and Changjiangkou No. 2, and six non-degraded modern wood samples of the relevant corresponding species were selected to study the moisture characteristics by low-temperature nuclear magnetic resonance (NMR) and the dynamic sorption of water vapor (DVS). It was found that the six waterlogged archaeological wood samples exhibited three deterioration states: slightly, moderately, and seriously deteriorated. Wood deterioration caused significantly increased fiber saturation point (FSP) values for waterlogged archaeological wood. This is mainly owing to changes in the pore size distribution of cell walls. Moreover, NMR is more accurate than DVS in obtaining FSP for severely degraded samples. Additionally, moisture content was positively associated with wood deterioration. Maximum water content (MWC), free water content, and bound water content exhibited an exponential relationship with the basic density (BD). The contribution of bound water in waterlogged archaeological wood was less than that of modern wood and decreased with deterioration.

Automated summary

Studying the moisture characteristics of waterlogged archaeological wood can provide support for the dehydration and preservation of such artifacts. In this study, waterlogged wood samples from ancient Chinese shipwrecks and modern wood samples were analyzed to understand the deterioration states and the relationship between moisture content and wood deterioration. It was found that the deterioration of wood led to increased fiber saturation point values, mainly due to changes in pore size distribution. NMR was found to be more accurate than DVS in obtaining these values for severely degraded samples.