出土饱水云南松的超微构造特征

对云南剑川县出土的木质文物进行了研究,从超微结构层面更深入地解析了饱水古木的降解情况。出土的云南松(Pinus yunnansis)古木在饱水环境中淹埋了4 000多年。降解主要发生在晚材管胞,而且降解在晚材部分并不均匀:一些未降解的完好管胞分布在降解严重的管胞中。透射电镜观察显示:降解从S1/S2和S2/S3的界面开始;对于一些降解较严重的管胞,到腐朽后期细胞次生壁全部发生降解,只留下复合胞间层;细菌侵蚀是云南松饱水古木降解的主要原因。固体核磁共振结果表明:纤维素和半纤维素降解严重,木质素也出现了一定程度的降解。本研究可为其后续的加固保护提供科学的参考依据。

Ultrastructural characteristics of archaeological Yunnan pine buried in a waterlogged environment

Wooden artifacts excavated at Jianchuan County in Yunnan Province, China, were investigated to better understand the degradation aspects of waterlogged archaeological woods. Excavated Yunnan pines (Pinus yunnanensis) have been deposited in the mud soil for more than 4,000 years. Degradation occurred mainly to latewood tracheids but degradation in latewood was not uniform:intact tracheids were also present among the severely degraded ones. The results of transmission electron microscopy (TEM) show that 1) degradation started at the interface between S1/S2 and S2/S3 layers; 2) secondary cell wall layers were all degraded in the advanced stage of decay, leaving only compound middle lamella; 3) erosion bacteria were found be responsible for degradation of waterlogged archaeological Yunnan pines. However, soft rot cavities were not found in these samples. Solid state nuclear magnetic resonance (NMR) data coincided with degradation patterns, showing the preferential degradation of cellulose and hemicelluloses, whereas lignin polymer showed resistance. Degradation patterns of the waterlogged archaeological Yunnan pines were similar to those of the wooden artifacts which were excavated from wet environments.